BigT-65

My 65 Vette is originally a 4 speed car. At some time in the past, at least 32 years ago, someone put in a Powerglide. I have owned the car for 31 years. The Powerglide is acting up and I am thinking about putting a 4 speed back in rather than fixing the Powerglide. My question is, what kind of a job is this? And estimated cost. Maybe the Powerglide is worth something.

Velox

It's not a horrible job but there is a lot of work involved and lots of parts. You can google "4 speed conversions" and read up on some of the kits. If you are thinking of keeping your car stock, as original, then the parts are readily available, used ones all over the place, ebay etc. New parts are mostly all available at the usual vendors. You'll need M21 or M20 4-speed, whichever you want, speedo connector and proper gear, 4-speed linkage and linkage mount and support, bell housing, flywheel, clutch-pressure plate-TOB, pilot bearing, all the usual bolts for same. You'll need clutch linkage, z-bar, complete from block up to pedal assembly. You'll need to change your pedal assembly back to standard clutch and brake pedals. You'll need the clutch return spring, clutch rod springs and adjustors. The rubber boot for the fork at the bell housing. I think 4-speed is a different speedo cable but not sure. Console has to be changed from automatic one to 4-speed one. Console parts, emblems, rubber boot. You get the idea. Make a list and start sourcing parts, it will add up quickly. PG, not sure of worth really depends on numbers & dates. Good luck with your project!

Tampa Jerry

You can reach out to Chicago Pete. I know he did the conversion a few years ago. Also, if you don't care about keeping the car original, I would look at putting in a 5 speed. I have a Tremec and like driving at 70 mph at 2200 rpms. Jerry

vettsplit 63

All the work aside, you will think you have a different car. A manual trans car is much more fun to drive, IMO.

BigT-65

This looks like a lot of stuff. Assuming the transmission costs $1,200 or so would anyone want to guess at total cost including paying someone else to do it?

Frankie the Fink

A few companies offer auto-to-4 speed conversions and the parts in their kits gives you some idea of what is required; see the far right column on this web site: http://www.hurst-drivelines.com/?page_id=119
That parts listing doesn't show the clutch bellcrank or other linkage; perhaps because they offer both a manual and hydraulic clutch option and you have to choose.

There is also the company that replaced Keisler (Silver - something or other) and a few others. Sounds like money is a big concern and these kits aren't cheap -- but if you go with somebody that supplies everything it might be an advantage if problems crop up later on. My '67 Chevelle SS-396 was converted from auto to Muncie 4-speed with all original correct parts and it still never felt or acted quite right. Shifted fine but the clutch action was always strange feeling...

ejboyd5

If your car was born as a 4-speed the chances are large that not everything was changed over to a factory original automatic configuration when the conversion was done. Velox's list is comprehensive, but I'm betting that a fair number of manual transmission fittings and trim pieces are still on your car. Go for it.

409/409

I just changed my factory 1966 Powerglide to a M20 4 speed last fall. I did it myself. I scrounged Corvette swap meets (Carlisle/Bloomington) and ebay and bought most all original parts. Cost was about 1600.00 total. I don't count the cost of trips to swap meets because I would go anyway. It is all factory correct. A lot of work, but worth it!

ack fia

Just a word of advise, don't try to use 67 pedal stuff, it is different than the earlier cars.

BigT-65

This looks like the way to go. I took a look at the Silver Sport 5 speed conversion and it was going to be almost $6,000 just for the stuff. If I was going to hunt down used original parts should I buy the transmission first ( so I will know what I have), then the clutch assembly, then all the other parts?

409/409

You don't have to buy the transmission first. You'll need an M20 or M21 depending on rear end ratio. Mine is an M20 with a 3.36 rear end (great combination, I got 19.4 MPG on the Power Tour with a stock 300HP). There is nothing different about any other parts where the transmission is concerned. 63 to 66 swing pedal assembly is the same, 67 is different. Drive shafts are the same.

409/409

I'm changing mine over to a big block this winter. I'm a firm believer in if you can't find want you want, build it. If I have to change clutch linkage from the pedal push rod to the clutch fork you can buy mine. I have not investigated that yet.
Does anyone know if that needs to be changed???

Auto Gear

When I help a customer select a gearbox; we start at the back of the car and work forward.
So, firstly: (Rear gear) x (1st gear) should equal ~9:1. Commonly you would have a 4.11 rear with a 2.20 1st close ratio; or maybe a 3.55 rear with a 2.56 1st M20. 3.36 rear with 2.56 works fine, since C2 corvettes are light weight. If you want ultimate cruising, a 3.08 rear with either a 2.88 1st gear T10 or 2.98 1st gear Italian-made Muncie gearset will get the job done

Secondly: you want to keep the driveshaft and slip yoke, so you're only interested in 27 spline output shaft Muncies, T10s and Saginaws.

Thirdly: If you don't know for SURE that the transmission has been rebuilt properly; or this is NOT a strict numbers matching resto for ultimate resale, Id avoid the 7/8th countershaft dia (the hole below the input shaft on the front of the case). Yes its more factory correct, but the clusters and inputs for these things are getting tough to find, and most are made by 3rd tier suppliers. A.G. does have 7/8" Supercases though.

Fourth on our list is the input: it'll be 10 splines for your car. Id recommend keeping this, unless you're going to be heavy handed with it

Special note:
Make sure the front bearing retainer (the cast iron snout on the front) is the proper passenger-car sized one. If its UNDER 5" in dia, its a car one; if its OVER 5 inches in dia, its for the 11" truck bellhousing. You DO NOT need an 11" clutch. A.G does make new retainers for either size.
Dont go by stampings and ID grooves cut in the input. mark one spline on the input and chuck the thing in 1st gear. Now, turn the OUTput shaft 10 times (yes I said output). Have someone count the number of turns the input goes 'round. 22 times is a close ratio (22/10 = 2.20), 25 times is the M20 (25/10 = 2.5).

Your cars muncie probably had levers in the sidecover and tailhousing with studs on them to hang onto the shifter linkage. I have spacers to use a later, larger "bolt on" linkage on the earlier, smaller stud-type levers.
Muncies had the speedo cable port on either side of the tailhousing over the years. Having the drive on the 'incorrect' side isn't mission critical, aside from numbers-matching. If your speedo cable is too short, they make 6" speedo cable extensions.
I prefer the port on the passenger side (away from the shifter linkage).
If you see a wad of silicone on the front of the case, stuffed in the countershaft hole...skip it.
If you see a series of small pin-****** around the countershaft hole...skip it Both of these are backyard fixes because the case is in poor condition.

I can recommend some builders if you'd rather deal with a reputable source, over going dumpster-diving on craigslist. We don't sell refurbished factory units. We do offer a street M20 transmission, using all A.G. components for about half a grand over your estimate.

BigT-65

It looks like the first thing I need to find out is what rear end my car has in it. I wouldn't bet that it is original so how can I find out what it is by looking at it?

Velox

Well look at the bottom on the flat surface of the case next to the spring mount area and there will be numbers stamped there, letters for the ratio code and numbers for the date code. Even if non-original diff the code stamping may still be accurate for the internals. However JUST to be sure I usually jack up the rear, put stands under the frame, trans in neutral, put a chalk mark on the driveshaft straight down and another one on the inside wheel areas where you remember exactly where it is in relationship to the body. Then just rotate the rear wheel by hand and count the revolutions of the driveshaft. When you get 360 degrees on the wheel, the number of driveshaft rotations will be close enough to identify 3.70 vs 4.11 etc

BigT-65

Thanks Velox. I'll give this a try.

BigT-65

I got under the Vette today. The rear axle has AL 4 22 65. Which I believe is Non Posi 3.08. I also did the thing with marking the drive shaft and wheel and counting revolutions. The axle rotated just a tad over 3 full revolutions so it appears to be a 3.08
I am not happy about it not being posi-traction. I never looked at the numbers before and I assumed it was posi since it had the red posi tag on it. The date 4 22 65 would probably be correct since the car was built 4 29 65. Now what about the 4 speed?

66DCJR

Took out original powerglide last winter and installed a M-20 while I had the body off.
most parts from Paragon. Clutch & brake assy. from a member.
Unable to stay out of car. So much more fun to drive. Wish I did it 25 years ago.

409/409

I put an M-20 in mine. It goes great with a 3.08 and that's what probably was in it from the factory if the 3.08 is the original ratio.

Auto Gear

M20 would be serviceable, if I were doing this from scratch, I'd look into an aftermarket "Muncie" gearset with the 2.98 1st gear (this will have a 1" countershaft dia);
or, add a Posi and 3.36 to the rear of your vette with your M20 and enjoy it.

For best street performance; (rear gear) x (1st gear) should equal 9+. Early Vettes can get by with less, due to their lighter weight, but I'd like to see 8.5 at a minimum. If you have a tall tire (28-30"), this will effectively reduce your rear gear (making a theoretical 4.11 perform like a 3.89 for example)