Corvair Transmission Information (for Mirages)

[Hezath]

Hey guys, I was wondering if we could collect some information in this forum on the Corvair transmissions that were put into the Can-Am / Mirage.

I'm obviously very new to these cars. They run a four speed transaxle from a mid 60's Corvair, which has been flipped around to face the wrong way, and bolted onto the back of a Kelmark cast alluminium adapter/bellhousing (was this developed specifically for the Mirage?)

These have a pretty simple old-style clutch fork with a hydraulic slave bolted to the side of it, and the master cylinders likely vary a lot as the cars came with all kinds of pedal boxes.

But what do we know about the transmissions? What modifications were usually done to the transmissions?
I understand that Kelmark offered various aftermarket parts to improve the strength of the gearboxes?

Do we know what final drive ratios were available? Were these gearsets common with any other G.M. vehicles?

Are there are parts which are universal between different models of G.M. vehicles?

I think it makes sense to have this resource on our forum.

[Lee71]

Kelmark Engineering

was an automotive specialty shop established in 1969 and based in

Okemos

, Michigan. It focused on high-performance custom V8 drivetrain swaps, the modification and production of rear and mid-engined cars, and custom-built

turn-key

automobiles (the Kelmark GT). Until 1986, Kelmark Engineering manufactured kits and complete, finished, turn-key vehicles which were either Volkswagen-based or built on tubular race car-type frames. The outfit gained its name from Russ

Kel

ler and Randy Markham, the two co-creators who started the operation. Up until at least 1989, the Kelmark GT was still available as a kit albeit the manufacturer was

Kelmark Motors

in

Holt, Michigan

. The cars are all "rare" models, but the

Volkswagen

-powered Kelmark GT was the most popular.

[Lee71]

Kelmark V8-Vair a mid-engine V8 conversion for the Chevrolet Corvair.^[1] This mid-engine conversion turned the rear engined Chevrolet Corvair transaxle around 180 degrees and used a special bell housing and input shaft to bolt the V8 where the stock air-cooled engine would normally be connected. This makes the rotation of the differential backwards.The main advantage of the Kelmark Conversion is increased power and good engine placement in terms of weight distribution. The setup has a 40/60 front to rear weight distribution ratio. The main disadvantage of the Kelmark Conversion is that it requires the turning of the trans-axle 180 degrees, flat, and connecting it to the engine with a bell housing adapter. A stronger shaft is needed to withstand the torque of the V8 engine. Also, since the ring gear turns backwards it requires a free flow oil system or a reverse cut ring and pinion gear set. They also required a heavy duty differential or differential modifications. The Corvair differential was not designed to handle more than 250 hp (190 kW). When you put the power and torque of even a mild V8 to the stock differential, it tries to split the case from the pinion gear being forced against the ring gear.In the early days, Crown created a modified Volkswagen differential carrier by adding two extra pinion gears to the existing two gears which in effect lessened the load and made the differentials last longer. It was called a Beef-a-diff. When Corvair transaxles started to be used in high performance applications the differential again being a weak spot was modified by adding two more pinion gears. This created a cross legged look whence the "spider" nickname was derived

[Gollum]

Strengthened 'CIDCO' diff:

http://www.corvair.com/user-cgi/cata...?show_page=126

http://www.corvair.com/user-cgi/cata...?show_page=128