C5 Diff to Big Car Saginaw with C5 Rear Suspension
Posted: Mon Mar 20, 2017 4:20 pm
Back in October 2016 several inquiries were received from Registry members interested in updating their 'stock' Crown conversions to something more dependable and durable. They were aware that a number of members had very successfully changed their Crowns over to BC Powerglides mated to Corvette C5 differentials. For them this was an unacceptable combination because they still wanted to manually shift gears. A dependable 4-speed manual transmission or even a reasonably priced 5-speed manual transmission is the direction that they were looking to go. To add additional interest to the topic, the inclusion of a narrowed Corvette C5 rear suspension was added to the discussion. At the time I had conversations with Chris Wills, Mike Levine and Archibald Evans on this topic. All three members are quite familiar with what it takes to upgrade a 'stock' Crown conversion and so their expertise on this topic was welcomed.
In my conversation with Mike Levine, he pointed out one obvious, but frequently overlooked problem with any upgraded power train in a Corvair that uses a manual transmission rather than an automatic. If you have an engine with high HP and torque grounded to fat sticky tires, you can expect to break something in between if you drag race or speed shift. The best manual transmission and differential will tolerate this type of abuse for only a limited time. Mike pointed out that the 'stock' Crown setup in good condition will handle up to 450 HP, but it's not bulletproof. He believes that a Jerico 4-speed mated to a C5 differential is a great choice, but also indicates that using a BC Saginaw is easier. Here's Mike Levine's comments from 12-24-16:
Well, the making of the mainshaft to replace a Original Crown is easy, same as one for Wills style.
The replacements that I do are superior to the originals. With me supplying everything about $300.
I can have the Jerico to C5 adaptors made just like the one in the racer for 7 to 800 bucks.
A freshly rebuilt Jerico is about $2500 and another $150 to have the mainshaft resplined to fit the C5 Diff.
A big car Saginaw to C5 is easier as the mainshaft doesn't have to be reworked.
About the same price for that adapter.
You can also put an unmodified big car Saginaw mainshaft in a Crown Transmission with a C5 adapter and still retain the Crown Shifter.
The adapters are easy.
Figuring the rear wheel bearings and axle shafts plus the Shifter is the hard part if you want to retain the stock suspension as with my racer.
I can have all the adaptors and mainshafts made easily.
I just can't afford to make one of each and have them sit on the shelve. Mike
An email from Archibald Evans on 10-21-16 offered the following:
I appreciate your thinking of me. Yes I have a lot of NOS parts left over from Aesthetic Design Engineering LLC. And I have resources. I have: full-size Sag to C5 diff and to Quick-Change, Jeroco to C5 diff and to Quick-Change, I also have Corvair Sag to C5 diff and Power-Glide. As well as a plethora of support parts...
Arch followed up with a phone call on 10-21-16 in which he indicated that he can provide adapters to mate BC Saginaw 4-speeds to C5 diffs for $450.
WHERE FROM HERE?
Before the PCG Workshop in Bowling Green, I had several emails from Keith Waters, a newer member who lives in TN about updating the drive train of his Corvair. Keith indicated that he is willing to document with a CAD program all the dimensions necessary to fabricate the parts for installing a C5 Differential and C5 rear suspension under a Corvair. He sent some pictures and asked for any drawings that show the Corvair alignment points.
His inquiry prompted the following email to a select group of Registry members:
Guys,
You were selected to receive this email based on your description of your Corvair conversion and it's features shown on the Registry website.
The Registry has had a number of inquiries from members looking to update their Crown drive trains with C5 differentials and C5 rear suspensions. As a group I am hoping that many of you can offer your expertise and fabrication skills to help other members avoid a lot of duplication and unnecessary expense. Some of you have already converted your conversions to C5 diffs and few have made the C5 rear suspension modification too. To date I am not aware of any members who have drawings and/or dimensions for their modified C5 rear suspensions.
We have a new member who has started working on the CAD drawings for the C5 rear suspension. Keith Waters lives in TN and is willing to share the dimensions with other members once he gets everything documented. Here's what Keith has to say:
Hey John,
I received the T shirt. Thanks. Since then I have started working on the CAD drawings of the C5 rear suspension. Since dimensions are rare, I have been working off of pictures and what little dimensions I can find. I take pictures of the rear suspension I have and paste them into my cad software. I mic what dimensions I can. I found a diagram of the C5 cradle mounting points on the frame, so I have that spacing. The differential in the attached pictures is almost finished. Those are mostly hard dimensions taken from my diff. The cradle is not quite finished. The A arms I just started. Still have the upper A arms, spindles, shocks,etc. to go. When I get it all in CAD, then I can then I can start on the Corvair dimensions. Once I get that then I can determine how much needs to be cut out of the corvette cradle. The Corvair info is going to be harder to get and measure.
It is a slow process. Do you know of anyone that has any drawings of the Corvair frame alignment points, or any other info that may be useful? Anything would be appreciated. Look at the attachments and see what you think. I made two of the pics with white background more suitable for printing.
Keith Waters
Keith has also sent some pictures of what he has done so far. See attachments below.
Can anyone provide Keith with any drawings that show the Corvair frame alignment points? If so, you can speed up his work. You can call Keith at 865-435-2169. If you send him an email, please copy your officers on any correspondence. We all hope to learn from this joint project as we try to improve our cars and make them more competitive. All information developed from this project will be shared with all members and will be displayed on our website.
I'm counting on you guys to assist us with this project and I look forward to seeing your comments and ideas.
John, Pres
RESPONSES RECEIVED TO MY EMAIL:
1. Bruce Weeks was the first to respond with the following note on 3-18-17:
I have some dimensions from doing my Boxster S/C4 rear suspension, but I'm out of town until 3/29. If you don't get any answers before that, I'll dig them out.
2. Then Don Millspaugh sent the following note on 3-19-17
Hi;
My Corvair is actually in Texas getting the body done, C4 Front suspension, Camaro Grill and body stripped and painted. I’ll be using the C5 rear suspension but with a Boxster trans axel mated to an Audi 2.7TT V6 or V8. I just ordered (2)
Sets of frame alignment drawings and will send one set to you for information and use for club members. I won’t be doing my Corvair (65 convertible/mid-engine) for a while (66 Shelby replica, 77 Bronco, 75 TR6/V6) too many projects.
Please send an address so I can forward the diagrams to you.
Have a great day
Don Millspaugh
3. Mike Levine followed with following email on 3-19-17
I stayed with the stock rear suspension and adapted the C5 wheel bearings and Hubs.
If you are a current Crown this is the simplest way to do it.
There are some flaws Though which I will address;
The drive train is offset to the left 2 inches. On the street this isn't an issue but on the track, with multiple laps of 140 + MPH the shorter left axle runs hotter. Add the fact that the car is lower and your drive shaft angles get severe. The cure? Raise the back of the transaxle and center the drive train.
When I install the 433 SBC I will make the changes.
I have played with expensive high temp Grease and high temp silicone boots and can get the left axle to live through a race weekend. The right axle never gives an issue.
I will gladly take servicing an Axle with out the worry of destroying a diff than going back to the stock diff which is a Bomb waiting to go off.
Which ever way you convert or build its an expensive and time consuming build but the rewards are worth it. Mike
4. Paul Beck responded with the following note on 3-19-17:
I agree with you, Mike, on the offset. Wish I had given it more thought, centering everything up would have made things easier, like being able to have a replacement halfshaft on hand.
Paul
5. Jim Hart offered the following comments on 3-19-17
Keith,
I’m not on the road yet, but I’ll give you what information I can. I am changing my direction from originally using a Porsche 930 Turbo transaxle, I have plans for it involving a 914. My goal is to have something I can romp on without cringing, so I currently have a 2004 C5 differential and an adapter plate from Archibald Evans. I’m mocking up using an empty LS block with a Lakewood scatter shield and a Saginaw case adapted to the C5. The transmission planned on is an aftermarket aluminum Ford toploader 4 speed (also with an adapter from Arch) which unlike a Saginaw was designed for big blocks and is VERY stout. It’s also available in close or wide ratios. It’s the forerunner to Jerico 4 speeds and the same bolt pattern, but unlike it will have sychro gears. Like the Saginaw, bell housings are available from Chevy BB or SB to Jerico.
I’m running 315/35-17 on 11” in the rear. Backspace on the fronts is 4.5”, and 7.5” on the rears which from the outside gives identical “dish” front and rear. That backspace is within ¼” of the maximum the wheel manufacturer would build. With that tire in the back I had to remove the stock spring perch, ‘tub’ the wheel well 3” and roll the fender lips up. With all of that done I can run a C5 subframe which has been narrowed by 8” (and 4” per axle). In addition, a relief must be cut in the passenger side rear of the aluminum subframe to clearance the positraction housing. I’ve also found that the diff can be positioned rearward an inch or so if you need it. The axles only go to about 4 degrees.
Anything more than 8” from the subframe and you run the lower control arm mounts into the diff. Any less than 8” out of the subframe becomes problematic as you push the wheels into the outer wells (I did NOT want to cut or re-shape the outer wheel wells).
If I can be of any further assistance, please contact me.
Jim Hart
6. Bruce Weeks sent the following on 3-19-17
I too, set the diff back 1" as well as down 1" from the hub C/L. Back put the balancer behind the rear seat front cross member, and down lowered the rear roll center to 5.07" off the pavement.
7. Chris Wills added the following comments on 3-21-17
John,
Because the C5 diff is not offset like the Corvair, I moved my engine over to the passenger side by 1.25" Now this keeps the suspension equal on both sides. Not sure if there is enough room to keep the Crown offset dimension and have room for the C5 A arms on the drivers side.
Chris Wills
8. Mike Levine then added a picture of his prototype C5 cradle with the following comments on 3-21-17
I built this on the fly. I'm swapping diffs this week for the Mitty, the 3.42 is coming out and the 3.15 is going in. The cradle I built is just the prototype that I plan on altering some day.
I will take picks of everything when I take it out.
But yes, I will share all my info no problem.
9. Cary Eisenlohr responded to Chris Wills (item #7) comment on 3-21-17
Chris,
We were talking about the same thing at our corvair meeting last night in So Cal. We didn't know of there was enough room in a crown sub frame to move it over that much with out causing other problems. For sure you must keep the suspension arm lengths equal length.
Cary
10. John Lanning sent the following email to Mike Levine on 3-21-17
Mike,
When you move from the prototype to the finished cradle is it possible to set it up in CAD for others to use? If you don't have or use CAD, do you know someone who does? Maybe you should consider making C5 cradles for other members?
John
11. Mike Levine responded back with the following comment on 3-21-17
When I make the final edition you can have the original and do what you want with it. Mike
12. Paul Beck responded back about offering his design (with automatic transmission)for other members to use on 3-21-17
I certainly don't mind sharing information with anyone that needs it. I don't do CAD and am not aware of anyone in the area that has the capacity to do it. I'll be glad to take as many pictures as I can if those would help. Also remember that my mounting design has many features that John Black used on his conversion and John may have additional information.
Paul
13. Chris Wills responded back to Cary Eisenlohr (item #9) with the following comment on 3-21-17
I have a Kelmark crossmember that I modified and the C5 A arms fit. I did not use the C5 lower cradle though.
14. Richard Miller posted the following comments and asked a question about C6 & C7 diffs on 3-22-17
your post ,, and research ,, on C5 conversions being a good example
though differential is not directly applicable to my car ,, adapting
the corvette hubs and brakes may well prove useful in my future as I
would like to get rear discs on my car ..
all info on our conversions is helpful to those of us who drive them
consider the Corvair ,,
has any car been more tinkered with ? more swapped around ?
front , rear , and mid engine all in corvairs ,,, ever see a mid or
rear 69 Camaro ?
rear wheel drive , front wheel drive ,, 4 wheel drive in corvairs
4,6,8 cylinders , air and water cooled
front , mid and rear radiators
Chevy small , big ,, and LS ,,( I haven't seen a 348/409 ... yet )
ford , Chrysler hemi , Buick , Oldsmobile and Cadillac
also imports ,, Nissan , Honda , Subaru and Audi
have all powered conversions I have seen ,, mostly within our members cars
automatics of two , three and four speeds
3,4,5 speed manual trans
straight axle , front and rear , suspensions ,,and IRS and IFS from
corvettes to custom built
gasser look , pro street , pro touring , road racer , drag racer
and corvair engines have in turn been in cars , trucks , RVs , boats
and airplanes
what an inspirational car it is to be the subject of so many tinkering minds
any way ,, thanks for all you do for the Registry
one question if I may , I posted on a thread but never got a response
are later C6 and C7 differentials same as C5 ?
15. Keith Waters appreciates the response and interest from members. He sent the following email with some updated pictures on 3-22-17
WHEN VIEWING PICTURES, CLICK ON THEM FOR FULL SIZE VIEWING
Hey John,
I have managed to add a few more parts. I did not model the engine block. It was obtained off of the internet. Spindles need more work.
The only critical dimensions at this time are the cradle mounting holes and pins, wheel base ( hub to hub ), upper and lower "A" arm mounting points, and a few others. If you look closely you will see that the C5 frame mounting points that I have do not coincide with the cradle hole elevations. The frame locating points are located at the bottom of the purple cylinders. Tops are irrelevant. If I were to raise the front of the cradle it would throw off the alignment of the "A" arms, diff center line along with trans and engine center line.I may have the wrong dimensions of the C5 frame points but they sure seem close in all other aspects. I am pretty sure that the "A" arms are parallel to the ground. Maybe some members can see what is going on and relate back. They may have a C5 or friends that have C5's. Good pics would be great.
In the mean time, I will continue to add parts until I am satisfied that I have all that is necessary then start on the Corvair model.
Keith Waters
16. Four additional pictures submitted by Keith Waters with the following comments on 3-28-17
Attached are some new pics after adding shocks, engine heads and a few other engine parts. The Corvair was bought ($55) on the internet. I turned some parts transparent and removed a lot of other parts that were irrelevant. Stock Corvair wheels and tires at this time. Corvair body may or may not be exact. I understand that these models are made from pictures. Still looks pretty good. I have to do the transmission, bellhousing, and a few others. Nothing has been narrowed at this point. Still many details to go over. I was incorrect on the C5 saddle position. The A arms are parallel to the ground viewing from the rear. It is not from the side. The cradle tilts up in the front. The frame elevations ( bottom of pink cylinders ) I showed in the previous pics were correct. I have tilted the cradle and all parts attached to it.
Starting to run out of hard dimensions. I am amazed at the lack of information on the C5 Corvette on the internet. Especially the suspension drawings, geometry and the like.
Still working on it a little at a time as I get info.
Keith Waters
17. On 4-19-17 Keith Waters and Chris Wills talked by phone and Keith sent the following email regarding that conversation:
I spoke with Chris Wills this evening. Great conversation. Nice guy.
We went over a lot of stuff and he has some good advise. He is to send pictures of what he has and maybe I can get something I need from them.
I have had a little time to look at narrowing the C5 cradle. The difference between the Corvette and Corvair track width is 7 inches. I think I am going with 8 inches narrower. This is a bit short but will allow a little wider wheel and tire combo. There is an interference issue on the right side. A 7 inch narrower cradle will also have the interference issues. As you can see in the pictures,( DIFF STOCK 1 and DIFF STOCK 2) the diff will hit the narrowed cradle. In picture (STOCK UP 1&5 1) the diff is raised up 1 1/2 inches. This clears the cradle. I also thought about moving the diff rearward 2 inches and up 1 1/2 as in pictures DIFF 1 and DIFF 2. I am not sure about the interference of the shocks as of yet. This would help in the comfort zone in the drivers seat. This would have to have a 3/4 inch plate added to the cradle but that's not a big deal. The quest for info goes on.
Also on the thought pattern is to use C5 Corvette rear frame rails so the upper A Arms would be located correctly along with the upper shock mounts.
Keith Waters
18. On 4-20-17, Archibald Evans posted the following comment:
I have adapters and welding fixtures for this adaptation... ADE
19. On 4-21-17 Keith Waters received the drawings from Don Millspaugh regarding Corvair Frame Alignment Points and commented:
I purchased this same drawing off of E-bay about 3 weeks ago. (about $8.00) It is kinda crude and measurements are done with a tape measure on some dimensions. It did have some useful measurements but not sure if any are factory dimensions.
20. An additional 11 pictures were submitted by Keith Waters on 5-10-17. This latest work includes 3D images of a narrowed C5 suspension.
Attached are some photos of the work I have done lately. The photos of the C5 cradle is the work of a $50,000 3D scanner. Along with $10,000 software and a $3,000 laptop. I just wish they were mine. They were a fellow that spoke at our Tennessee Inventors Association meeting last month. Works for Prototyping Solutions out of Birmingham, AL. If you look close, you can even see the casting marks. It will scan at a resolution within .002 of an inch. That's a little less that a hair. It took about 30 minutes to scan. It took me many hours to do the same part shown in previous pics in the forum and is not as precise. The pink cradle is the same scan with 8" removed from the center.
The other pics are of the drawings I have and were put into my 3D printer. They are 1/3 scale. I thought this may be cheaper than cutting up the real thing for now. The cradle alone took 16 hours to print. I bolted on the Differential side covers and rear cover as they were made separately. Also the diff mount. I still have to design the spindles and print them.
I am going to get a C5 bare frame tomorrow to see what I can use from it. Hoping to use the rear frame rails as they locate the cradle, upper "A" arms and shock mounts. Maybe one day I can start on the real thing.
Just wanted to let you know I am still working on stuff.
Keith Waters
In my conversation with Mike Levine, he pointed out one obvious, but frequently overlooked problem with any upgraded power train in a Corvair that uses a manual transmission rather than an automatic. If you have an engine with high HP and torque grounded to fat sticky tires, you can expect to break something in between if you drag race or speed shift. The best manual transmission and differential will tolerate this type of abuse for only a limited time. Mike pointed out that the 'stock' Crown setup in good condition will handle up to 450 HP, but it's not bulletproof. He believes that a Jerico 4-speed mated to a C5 differential is a great choice, but also indicates that using a BC Saginaw is easier. Here's Mike Levine's comments from 12-24-16:
Well, the making of the mainshaft to replace a Original Crown is easy, same as one for Wills style.
The replacements that I do are superior to the originals. With me supplying everything about $300.
I can have the Jerico to C5 adaptors made just like the one in the racer for 7 to 800 bucks.
A freshly rebuilt Jerico is about $2500 and another $150 to have the mainshaft resplined to fit the C5 Diff.
A big car Saginaw to C5 is easier as the mainshaft doesn't have to be reworked.
About the same price for that adapter.
You can also put an unmodified big car Saginaw mainshaft in a Crown Transmission with a C5 adapter and still retain the Crown Shifter.
The adapters are easy.
Figuring the rear wheel bearings and axle shafts plus the Shifter is the hard part if you want to retain the stock suspension as with my racer.
I can have all the adaptors and mainshafts made easily.
I just can't afford to make one of each and have them sit on the shelve. Mike
An email from Archibald Evans on 10-21-16 offered the following:
I appreciate your thinking of me. Yes I have a lot of NOS parts left over from Aesthetic Design Engineering LLC. And I have resources. I have: full-size Sag to C5 diff and to Quick-Change, Jeroco to C5 diff and to Quick-Change, I also have Corvair Sag to C5 diff and Power-Glide. As well as a plethora of support parts...
Arch followed up with a phone call on 10-21-16 in which he indicated that he can provide adapters to mate BC Saginaw 4-speeds to C5 diffs for $450.
WHERE FROM HERE?
Before the PCG Workshop in Bowling Green, I had several emails from Keith Waters, a newer member who lives in TN about updating the drive train of his Corvair. Keith indicated that he is willing to document with a CAD program all the dimensions necessary to fabricate the parts for installing a C5 Differential and C5 rear suspension under a Corvair. He sent some pictures and asked for any drawings that show the Corvair alignment points.
His inquiry prompted the following email to a select group of Registry members:
Guys,
You were selected to receive this email based on your description of your Corvair conversion and it's features shown on the Registry website.
The Registry has had a number of inquiries from members looking to update their Crown drive trains with C5 differentials and C5 rear suspensions. As a group I am hoping that many of you can offer your expertise and fabrication skills to help other members avoid a lot of duplication and unnecessary expense. Some of you have already converted your conversions to C5 diffs and few have made the C5 rear suspension modification too. To date I am not aware of any members who have drawings and/or dimensions for their modified C5 rear suspensions.
We have a new member who has started working on the CAD drawings for the C5 rear suspension. Keith Waters lives in TN and is willing to share the dimensions with other members once he gets everything documented. Here's what Keith has to say:
Hey John,
I received the T shirt. Thanks. Since then I have started working on the CAD drawings of the C5 rear suspension. Since dimensions are rare, I have been working off of pictures and what little dimensions I can find. I take pictures of the rear suspension I have and paste them into my cad software. I mic what dimensions I can. I found a diagram of the C5 cradle mounting points on the frame, so I have that spacing. The differential in the attached pictures is almost finished. Those are mostly hard dimensions taken from my diff. The cradle is not quite finished. The A arms I just started. Still have the upper A arms, spindles, shocks,etc. to go. When I get it all in CAD, then I can then I can start on the Corvair dimensions. Once I get that then I can determine how much needs to be cut out of the corvette cradle. The Corvair info is going to be harder to get and measure.
It is a slow process. Do you know of anyone that has any drawings of the Corvair frame alignment points, or any other info that may be useful? Anything would be appreciated. Look at the attachments and see what you think. I made two of the pics with white background more suitable for printing.
Keith Waters
Keith has also sent some pictures of what he has done so far. See attachments below.
Can anyone provide Keith with any drawings that show the Corvair frame alignment points? If so, you can speed up his work. You can call Keith at 865-435-2169. If you send him an email, please copy your officers on any correspondence. We all hope to learn from this joint project as we try to improve our cars and make them more competitive. All information developed from this project will be shared with all members and will be displayed on our website.
I'm counting on you guys to assist us with this project and I look forward to seeing your comments and ideas.
John, Pres
RESPONSES RECEIVED TO MY EMAIL:
1. Bruce Weeks was the first to respond with the following note on 3-18-17:
I have some dimensions from doing my Boxster S/C4 rear suspension, but I'm out of town until 3/29. If you don't get any answers before that, I'll dig them out.
2. Then Don Millspaugh sent the following note on 3-19-17
Hi;
My Corvair is actually in Texas getting the body done, C4 Front suspension, Camaro Grill and body stripped and painted. I’ll be using the C5 rear suspension but with a Boxster trans axel mated to an Audi 2.7TT V6 or V8. I just ordered (2)
Sets of frame alignment drawings and will send one set to you for information and use for club members. I won’t be doing my Corvair (65 convertible/mid-engine) for a while (66 Shelby replica, 77 Bronco, 75 TR6/V6) too many projects.
Please send an address so I can forward the diagrams to you.
Have a great day
Don Millspaugh
3. Mike Levine followed with following email on 3-19-17
I stayed with the stock rear suspension and adapted the C5 wheel bearings and Hubs.
If you are a current Crown this is the simplest way to do it.
There are some flaws Though which I will address;
The drive train is offset to the left 2 inches. On the street this isn't an issue but on the track, with multiple laps of 140 + MPH the shorter left axle runs hotter. Add the fact that the car is lower and your drive shaft angles get severe. The cure? Raise the back of the transaxle and center the drive train.
When I install the 433 SBC I will make the changes.
I have played with expensive high temp Grease and high temp silicone boots and can get the left axle to live through a race weekend. The right axle never gives an issue.
I will gladly take servicing an Axle with out the worry of destroying a diff than going back to the stock diff which is a Bomb waiting to go off.
Which ever way you convert or build its an expensive and time consuming build but the rewards are worth it. Mike
4. Paul Beck responded with the following note on 3-19-17:
I agree with you, Mike, on the offset. Wish I had given it more thought, centering everything up would have made things easier, like being able to have a replacement halfshaft on hand.
Paul
5. Jim Hart offered the following comments on 3-19-17
Keith,
I’m not on the road yet, but I’ll give you what information I can. I am changing my direction from originally using a Porsche 930 Turbo transaxle, I have plans for it involving a 914. My goal is to have something I can romp on without cringing, so I currently have a 2004 C5 differential and an adapter plate from Archibald Evans. I’m mocking up using an empty LS block with a Lakewood scatter shield and a Saginaw case adapted to the C5. The transmission planned on is an aftermarket aluminum Ford toploader 4 speed (also with an adapter from Arch) which unlike a Saginaw was designed for big blocks and is VERY stout. It’s also available in close or wide ratios. It’s the forerunner to Jerico 4 speeds and the same bolt pattern, but unlike it will have sychro gears. Like the Saginaw, bell housings are available from Chevy BB or SB to Jerico.
I’m running 315/35-17 on 11” in the rear. Backspace on the fronts is 4.5”, and 7.5” on the rears which from the outside gives identical “dish” front and rear. That backspace is within ¼” of the maximum the wheel manufacturer would build. With that tire in the back I had to remove the stock spring perch, ‘tub’ the wheel well 3” and roll the fender lips up. With all of that done I can run a C5 subframe which has been narrowed by 8” (and 4” per axle). In addition, a relief must be cut in the passenger side rear of the aluminum subframe to clearance the positraction housing. I’ve also found that the diff can be positioned rearward an inch or so if you need it. The axles only go to about 4 degrees.
Anything more than 8” from the subframe and you run the lower control arm mounts into the diff. Any less than 8” out of the subframe becomes problematic as you push the wheels into the outer wells (I did NOT want to cut or re-shape the outer wheel wells).
If I can be of any further assistance, please contact me.
Jim Hart
6. Bruce Weeks sent the following on 3-19-17
I too, set the diff back 1" as well as down 1" from the hub C/L. Back put the balancer behind the rear seat front cross member, and down lowered the rear roll center to 5.07" off the pavement.
7. Chris Wills added the following comments on 3-21-17
John,
Because the C5 diff is not offset like the Corvair, I moved my engine over to the passenger side by 1.25" Now this keeps the suspension equal on both sides. Not sure if there is enough room to keep the Crown offset dimension and have room for the C5 A arms on the drivers side.
Chris Wills
8. Mike Levine then added a picture of his prototype C5 cradle with the following comments on 3-21-17
I built this on the fly. I'm swapping diffs this week for the Mitty, the 3.42 is coming out and the 3.15 is going in. The cradle I built is just the prototype that I plan on altering some day.
I will take picks of everything when I take it out.
But yes, I will share all my info no problem.
9. Cary Eisenlohr responded to Chris Wills (item #7) comment on 3-21-17
Chris,
We were talking about the same thing at our corvair meeting last night in So Cal. We didn't know of there was enough room in a crown sub frame to move it over that much with out causing other problems. For sure you must keep the suspension arm lengths equal length.
Cary
10. John Lanning sent the following email to Mike Levine on 3-21-17
Mike,
When you move from the prototype to the finished cradle is it possible to set it up in CAD for others to use? If you don't have or use CAD, do you know someone who does? Maybe you should consider making C5 cradles for other members?
John
11. Mike Levine responded back with the following comment on 3-21-17
When I make the final edition you can have the original and do what you want with it. Mike
12. Paul Beck responded back about offering his design (with automatic transmission)for other members to use on 3-21-17
I certainly don't mind sharing information with anyone that needs it. I don't do CAD and am not aware of anyone in the area that has the capacity to do it. I'll be glad to take as many pictures as I can if those would help. Also remember that my mounting design has many features that John Black used on his conversion and John may have additional information.
Paul
13. Chris Wills responded back to Cary Eisenlohr (item #9) with the following comment on 3-21-17
I have a Kelmark crossmember that I modified and the C5 A arms fit. I did not use the C5 lower cradle though.
14. Richard Miller posted the following comments and asked a question about C6 & C7 diffs on 3-22-17
your post ,, and research ,, on C5 conversions being a good example
though differential is not directly applicable to my car ,, adapting
the corvette hubs and brakes may well prove useful in my future as I
would like to get rear discs on my car ..
all info on our conversions is helpful to those of us who drive them
consider the Corvair ,,
has any car been more tinkered with ? more swapped around ?
front , rear , and mid engine all in corvairs ,,, ever see a mid or
rear 69 Camaro ?
rear wheel drive , front wheel drive ,, 4 wheel drive in corvairs
4,6,8 cylinders , air and water cooled
front , mid and rear radiators
Chevy small , big ,, and LS ,,( I haven't seen a 348/409 ... yet )
ford , Chrysler hemi , Buick , Oldsmobile and Cadillac
also imports ,, Nissan , Honda , Subaru and Audi
have all powered conversions I have seen ,, mostly within our members cars
automatics of two , three and four speeds
3,4,5 speed manual trans
straight axle , front and rear , suspensions ,,and IRS and IFS from
corvettes to custom built
gasser look , pro street , pro touring , road racer , drag racer
and corvair engines have in turn been in cars , trucks , RVs , boats
and airplanes
what an inspirational car it is to be the subject of so many tinkering minds
any way ,, thanks for all you do for the Registry
one question if I may , I posted on a thread but never got a response
are later C6 and C7 differentials same as C5 ?
15. Keith Waters appreciates the response and interest from members. He sent the following email with some updated pictures on 3-22-17
WHEN VIEWING PICTURES, CLICK ON THEM FOR FULL SIZE VIEWING
Hey John,
I have managed to add a few more parts. I did not model the engine block. It was obtained off of the internet. Spindles need more work.
The only critical dimensions at this time are the cradle mounting holes and pins, wheel base ( hub to hub ), upper and lower "A" arm mounting points, and a few others. If you look closely you will see that the C5 frame mounting points that I have do not coincide with the cradle hole elevations. The frame locating points are located at the bottom of the purple cylinders. Tops are irrelevant. If I were to raise the front of the cradle it would throw off the alignment of the "A" arms, diff center line along with trans and engine center line.I may have the wrong dimensions of the C5 frame points but they sure seem close in all other aspects. I am pretty sure that the "A" arms are parallel to the ground. Maybe some members can see what is going on and relate back. They may have a C5 or friends that have C5's. Good pics would be great.
In the mean time, I will continue to add parts until I am satisfied that I have all that is necessary then start on the Corvair model.
Keith Waters
16. Four additional pictures submitted by Keith Waters with the following comments on 3-28-17
Attached are some new pics after adding shocks, engine heads and a few other engine parts. The Corvair was bought ($55) on the internet. I turned some parts transparent and removed a lot of other parts that were irrelevant. Stock Corvair wheels and tires at this time. Corvair body may or may not be exact. I understand that these models are made from pictures. Still looks pretty good. I have to do the transmission, bellhousing, and a few others. Nothing has been narrowed at this point. Still many details to go over. I was incorrect on the C5 saddle position. The A arms are parallel to the ground viewing from the rear. It is not from the side. The cradle tilts up in the front. The frame elevations ( bottom of pink cylinders ) I showed in the previous pics were correct. I have tilted the cradle and all parts attached to it.
Starting to run out of hard dimensions. I am amazed at the lack of information on the C5 Corvette on the internet. Especially the suspension drawings, geometry and the like.
Still working on it a little at a time as I get info.
Keith Waters
17. On 4-19-17 Keith Waters and Chris Wills talked by phone and Keith sent the following email regarding that conversation:
I spoke with Chris Wills this evening. Great conversation. Nice guy.
We went over a lot of stuff and he has some good advise. He is to send pictures of what he has and maybe I can get something I need from them.
I have had a little time to look at narrowing the C5 cradle. The difference between the Corvette and Corvair track width is 7 inches. I think I am going with 8 inches narrower. This is a bit short but will allow a little wider wheel and tire combo. There is an interference issue on the right side. A 7 inch narrower cradle will also have the interference issues. As you can see in the pictures,( DIFF STOCK 1 and DIFF STOCK 2) the diff will hit the narrowed cradle. In picture (STOCK UP 1&5 1) the diff is raised up 1 1/2 inches. This clears the cradle. I also thought about moving the diff rearward 2 inches and up 1 1/2 as in pictures DIFF 1 and DIFF 2. I am not sure about the interference of the shocks as of yet. This would help in the comfort zone in the drivers seat. This would have to have a 3/4 inch plate added to the cradle but that's not a big deal. The quest for info goes on.
Also on the thought pattern is to use C5 Corvette rear frame rails so the upper A Arms would be located correctly along with the upper shock mounts.
Keith Waters
18. On 4-20-17, Archibald Evans posted the following comment:
I have adapters and welding fixtures for this adaptation... ADE
19. On 4-21-17 Keith Waters received the drawings from Don Millspaugh regarding Corvair Frame Alignment Points and commented:
I purchased this same drawing off of E-bay about 3 weeks ago. (about $8.00) It is kinda crude and measurements are done with a tape measure on some dimensions. It did have some useful measurements but not sure if any are factory dimensions.
20. An additional 11 pictures were submitted by Keith Waters on 5-10-17. This latest work includes 3D images of a narrowed C5 suspension.
Attached are some photos of the work I have done lately. The photos of the C5 cradle is the work of a $50,000 3D scanner. Along with $10,000 software and a $3,000 laptop. I just wish they were mine. They were a fellow that spoke at our Tennessee Inventors Association meeting last month. Works for Prototyping Solutions out of Birmingham, AL. If you look close, you can even see the casting marks. It will scan at a resolution within .002 of an inch. That's a little less that a hair. It took about 30 minutes to scan. It took me many hours to do the same part shown in previous pics in the forum and is not as precise. The pink cradle is the same scan with 8" removed from the center.
The other pics are of the drawings I have and were put into my 3D printer. They are 1/3 scale. I thought this may be cheaper than cutting up the real thing for now. The cradle alone took 16 hours to print. I bolted on the Differential side covers and rear cover as they were made separately. Also the diff mount. I still have to design the spindles and print them.
I am going to get a C5 bare frame tomorrow to see what I can use from it. Hoping to use the rear frame rails as they locate the cradle, upper "A" arms and shock mounts. Maybe one day I can start on the real thing.
Just wanted to let you know I am still working on stuff.
Keith Waters