Changeing a power glide to a four speed

[bghandyman]

Alright looking at a '68 Monza vert 110. It's a solid car and all there even though it's all apart. current owner was in the process of restoring,and unfortunately now is under the care of Hospice with not much time left. So that being said the wife is selling everthing. My only problem with the car is that it's an automatic. How bad is it to change it over to a 4 speed. would it be worth my effort in the end? Thanks for you thoughts

[bbodie52]

There is another Corvair Forum member who recently asked the same question, and received a series of answers. His Corvair is an Early Model (EM, 1960-64), and of course your Corvair is a Late Model (LM, 1965-69) with a different body style. However, the procedures to convert would be almost identical. Only the specific parts source would vary, to match your late model vehicle.

I recommend you start by reviewing his thread in this same section 64 Monza With a PG at viewtopic.php?f=55&t=4357 and see if those responses answer your questions. Let us know if you have any further questions after reading that thread.

[bghandyman]

thanks will do

[cc_devilbiss]

I've done it on my current project car, which is a 1966. It's not difficult, but it is involved.

As Brad pointed out in the other thread, your best bet is to find a late model donor car. My donor happened to be a 1965 Corsa, which isn't ideal. The transmissions were better starting in 1966.

Chevrolet built the Corvair with all of the necessary attachment points for either an Automatic or a manual transmission. There is no cutting or welding necessary to perform the conversion. It's all bolt in stuff, but there is a lot of it. Starting at the front....

The brackets for the pedals are common between the two, but you will need the actual brake pedal and clutch from the donor car. You are better off getting them as one unit, as the automatic brake pedal is too wide to clear the clutch pedal. The clutch pedal actually actuates a cable which pulls on the clutch fork in the transmission (as opposed to pushing on it like other GM cars). The cable is routed through a pulley beside the gas pedal. I believe the pulley is attached to the same bolt as the emergency brake cable, but you will need the actual pulley. The stock pulley is plastic and is usually worn out. Clark's sells aluminum reproductions, but I made my own.

The hole for the shifter should be present under the carpet. There is a cover bolted in place, but if you remove it, the shifter should fit with no problems. (This assumes that the previous owner didn't replace the front floor.) The shifter uses a single rotating and sliding tube to select a gear in the transmission. Cosmetically, you would need to change the dash plate to get rid of the powerglide shifter.

The rear of the under-floor tunnel is different to account for the clutch rod and shifter tube. You would need the bolt-in cover and respective boots to do a thorough job, but they probably aren't completely necessary to make the conversion work.

The rear lower transmission cross member is different between the automatic and manual transmissions. You would need the proper one. The one for the automatic won't work.

As I said previously, the 1966 and up transmissions are preferred to the 1965 style. You could do a search online to see the difference, but I believe the 1966 style had an aluminum side cover instead of a cast iron one. If you are keeping the car a 110, it probably doesn't matter either way.

The bell housing for the manual transmission is different than the automatic. Unlike the bell housing on most other engines, on the Corvair engine the bell housing forms the back case of the motor. You would need to swap it out, and you will need new gaskets. Also don't forget a pilot bushing in the rear of the crankshaft. The crank should be drilled to accept one, but I'm not 100% sure.

I also think that technically speaking, the distributor centrifugal advance is different between the auto and manual cars. I doubt you would notice if you didn't change it, though.

After all of that, would it still be worth it? In my opinion, yes. I think that 4 manually shifted gears is more than double the fun of 2 automatically shifted gears.

[bbodie52]

WOW! There is NOTHING like the voice of experience! These comments would be extremely valuable to anyone who is contemplating such a conversion.

I knew that the 1966 4-speed transmission was a different design, and is considerd to be stronger than the 1960-1965 4-speed. In fact, the 1966 and later transmission was specified as the transmission needed for the Crown Mfg. CORV-8 mid-engine V8 conversion kit for the Corvair, partially because of its internal design and partially because of its greater strength. (I believe they also recommended the addition of two more spider gears in the differential to deal with the added torque and power from the small-block Chevy V8 engine). They even did a CORV-8 conversion using a big-block Chevy V8, but the added weight of the engine was problematic for the transaxle (I may not be completely correct on this -- I'm basing these comments on my teenage memory from around 1970 when I visited Crown Mfg. in Southern California and was considering trying that conversion on my own Corsa (never happened).

There should be no problem with driving a clutch pilot bushing into the into of the Corvair crankshaft. I had to do this in in 1969 when I transferred a 1963 automatic transmission engine into a 1962 4-speed Monza. All I had to do was swap the clutch housing (as you mentioned), install a pilot bushing, and then bolt in the clutch assembly.

Any 1965 or later transaxle will work (with 1966-1969 preferred, as you mentioned). The 1961 - 1964 transaxle will not work in the Late Model (LM) Corvair because of the rear suspension redesign that occurred in 1965, and the different associated suspension mounting points on the differential and the different half-shaft mounting instead of the Early Model swing axle.

Thanks for your detailed outline of the conversion procedure.