Advice/help with auto to manual swap 67 GTO
 

Hello all,

I recently acquired this 67 GTO. It has a 400 in it. The car came from the factory with a manual transmission (I'm not sure which one) but at some point it had a TH-400 swapped in. I would like to remove the auto and put a manual back in. I know a lot of people are doing Tremec swaps right now but I have no interest in that.

All I want to do is put an original style manual back as close to the stock configuration as possible. This will keep costs down, and cost is a concern - this is not a restored car - it's even more on the beater side of being what most would call a "driver".

From what I have gathered so far, a swap back to a Muncie M20-21-22 or Dearborn 3-speed would be fairly straightforward as the linkage mounting tab (I think) is still on the frame and the crossmember and driveshaft can remain the same. What I am hoping someone can help me with is a list of parts and maybe part numbers of the stuff I will need to start gathering to get the swap done such as bellhousing, clutch linkage, shifter and shift linkage, clutch and flywheel, etc.

I'm what most would call a backyard mechanic but I've gotten my hands into some semi-advanced stuff. I swapped a 5-speed into a Ford Crown Victoria and I can handle any kind of maintenance short of rebuilding motors, rear ends and transmissions. I feel more than capable of pulling this off in my garage, I just need some guidance as I am BRAND NEW to Pontiacs and haven't really worked on stuff much older than 70's and 80's vintage.

Thanks for any help. Car is in storage for the long NY winter right now so I plan to use the next 4 months to budget and gather parts and expertise and tear into it around May.

Get the correct 67 pedal set up.
You will need a console too.
Make sure the stud for the z bar is on the frame first.
I did this swap. Went Muncie first, now a tkx.
Not to hard to do.
Just use 1967 parts. Especially the pedals.

Sent from my SM-A136U using Tapatalk

Good choice to put it back as built.
I will add, to save a few bucks, you don't have to have a console.

https://live.staticflickr.com/65535/...52e2b617_h.jpg

Make sure you get an m20 unless you have a 3.90 or steeper gear

This company has nice stuff.

https://4speedconversions-com.3dcartstores.com/

Also, FranksPontiacParts.com is a good source for original parts.

Call SK speed at 631-957-9427. *I forgot about Brian at SK right there in New York. He's a Muncie guru with tons of parts.

Excellent info, thank you guys. And I do have the manual console!

Can anybody tell me what Muncie transmissions are compatible with the 67 GTO? Are there certain casting numbers/part numbers/donor cars I should be looking for?

X2 on both of these! 4speed conversions has been very helpful (and knowledgeable!) when I have contacted them.

Dennis Maroudas in Kentucky has also helped me out.

Good luck!

James Q

You will need a 60” driveshaft. The TH-400 driveshaft is a different length. The yoke is different also

You can use almost any Muncie 4 speed except long tail shaft big car transmissions. If you're not looking for originality you can use Chevy, Buick or Olds. There are minor differences that can be worked around. Make sure your clutch disc matches the input shaft spline of the trans you use. Get trans first then buy a clutch to match. Some trans have speedometer cable on the left and some on the right. You can get a cable length to match. You will need a pivot ball that screws into the side of the engine. If this is NOT the original engine make sure that the pilot bearing fits into the rear of the crankshaft. Some Pontiac engines that came with automatic transmissions never had the crank drilled for one. Good luck.

Over the life of my '67 I swapped back and forth between the original Muncie and a T400 several times and only had to change the driveshaft yoke out. The two driveshafts only differ by something like a 1/4" or less and I don't really know why Pontiac bothered with two driveshafts so close together..

Oh man that worries me. I know the engine in the car now is NOT the original and I have no idea what it's out of or if the crank is drilled for a pilot bearing. This was my brother's car and he passed away - I have no way of knowing what's there without pulling the TH400 and looking. What a colossal waste of time if it's not drilled.

Is there a particular flywheel I need to spec out, or just look one up for a 67? Did they have different diameter clutches in 67?

Thanks for all the info, guys. I'm assuming if I keep my current driveshaft there will be enough room on the slip to make up for 1/4" difference?

As far as the yoke, what will I need to source? Just a yoke from a manual trans car? What is different about the automatic yoke?

Also, has anyone used this kit or stuff from this company before? I know "OEM is best" and all but this kit would eliminate a lot of headaches for a decent price.

https://www.thepartsplaceinc.com/pro...bushings/16891

Also thanks for the info on the Muncie. I am currently scouring my local Facebook marketplace for one. They seem pretty common, all of them seem to go for around 850-1200.

That kit seems reasonably priced and complete. You won't have to waste lots of time searching for and then shipping parts. You still need a bellhousing. I swapped a 4speed into my 67 Tempest back in 1981 and used the original 2speed auto driveshaft, no problem. The yoke on a th400 IS different . We'd like to see better pics of the car please. PS I'm in Poughkeepsie.

I ran into the same problem with an automatic coded 66 389. After having the motor rebuilt ! We were able to custom fit a brass bushing into the rear of the crankshaft. Been there for 25+ years. The yoke you need is very common. A 350 automatic and 2 speed tranny use the same yoke.

I bought all my swap parts thru Ames, except I fabricated the clutch linkage with heim joints from McMaster. Everything fit well and I would recommend. As far as the flywheel, make sure you note if the flywheel you’re looking at is neutral balance or factory balance.

Ames p/n’s:
R135B pedals $99
R101 pedal pads $12
R167RK full linkage kit (z-bar, linkage, springs, fork etc) $259

A T400 driveshaft is a different length than one for a 2 speed auto, T350 or manual trans.

Based on what I've found, the TH400 driveshaft is like 5/8" difference. I assume that won't necessitate a new or modified shaft. The yoke - does anyone have a part number or just look for one off a TH350 or 2-speed auto?

Encouraging to hear that something like that is possible.

Yes, an original '67 GTO w T400 had a 59 3/8" long driveshaft with the med length 3R T400 yoke. For a '64-67 Pontiac A-body with a small output shaft Muncie, you'll need a driveshaft 60.00" long center to center on the 3R ujoints. Thats assuming your cars rearend is:
-the original or a replacement Pontiac 8.2 10 bolt rear,
-or a late '67-70 Type "O" Olds 10 bolt (smooth 12 bolt cover),
-or '68-70 BUICK 10 bolt.


There are no visible part numbers on original GM driveshafts. Just different styles, & lengths. Originally there were color bands that quickly helped the assembly line worker ID the version of driveshaft shaft. Have quite a few excellent condition used driveshafts & have sold several dozen others. One of the expenses is today's crazy shipping prices. When I ship a driveshaft, it's an oversize shipment & I typ ship in a section of PVC pipe from Lowes to prevent damage.

Keeping in mind the car was originally a manual, I'm curious if the manual driveshaft was mated to the TH400 yoke. Again, we're talking less than an inch difference. Like I said I've never had a car like this but worked on many others - that's a very small difference that can usually be made up with the slip yoke's travel without much if any vibration or issues. Am I completely off base?

I have a TH400 and M20 that I swap back and forth with the same driveshaft. They take a different yoke because of the output shaft difference. Some yokes are "flat" or "square" and some have an offset more like a "Y". It's another detail that can affect the required length.

Is there a concern about flywheels being properly balanced? Once again I'm not sure what this 400 motor is out of or what was originally behind it. If this is an "automatic" motor (hopefully with the crank drilled anyway) will I need a specific flywheel? Am I making this too complicated? Haha.

I assumed that was the case. A fraction of an inch difference shouldn't call for a new driveshaft in my experience.

Would this yoke work? If so, what does this "type" of yoke implicate as far as length of the driveshaft?

https://www.ebay.com/itm/162598893087

Can anyone tell me if I should be looking at a flat diaphragm or a raised diaphragm clutch? I'm looking at basic Luk 10.5" clutch kits but they offer both styles.

The raised diaphragm fingers use a shorted throwout bearing and the flat diaphragm fingers use a longer throwout bearing.

Seriously WTH? Why offer both kinds, there must be a reason! I'm in for quite an education with this thing.

And while I'm at it, how do these cars like the throwout bearing to ride? Lightly pressed up against the clutch fingers or with a small air gap?

I just checked my '67 service manual and they have lengths listed. 1967 GTO manual driveshaft listed at 60" and T400 driveshaft is listed at 59.34" so the difference is .66" which is more than I thought I measured way back when. Anyway, my car came with the Muncie and I swapped to the T400 all the years I drag raced it and never had a problem just swapping yokes.

Thank you for the insight, sir. I like hearing from people with experience especially on a job this involved.

I'm starting to think maybe I should determine what year this 400 is and what it might have been out of before I order a flywheel. I will have to pull numbers off it in the spring when it comes out of storage. Or are all 60's and 70's 400's the same as far as flywheels go?

I'm sorry guys, it must be frustrating being a Pontiac expert reading through my confused drivel. I'm trying to learn.

The person that made it work for me is pretty much in your back yard . Mike Felt is his name and he builds Pontiac motors. He lives in Hudson Falls. PM me if your interested in contacting him.

The driveshaft should be long enough to just clear the differential yoke when installed. You don't want the yoke hanging too far out of the transmission. It is only supported by a bushing. Don't want that thing hanging out there whipping around! I'll try to remember to post up pics of the two yokes I use. I think, from fully seated in the transmission, to engaged in the differential yoke, you only want 3/4". The one in the link is what I called the flat or square one.

I found a screaming deal on a rebuilt Dearborn Toploader 3-speed out of a 65 Mustang in the next town over. Would this be a feasible swap and what yoke and driveshaft length would I need? Would the Mustang version be compatible at all, or are the input shafts different?

I was planning Muncie 4-speed then this deal popped up - he's practically giving this toploader away and to be honest, the thought of the 3-speed doesn't bother me at all.

This recollection is going back to the early 70s when I was in a partnership and racing dirt track 61 Pontiac bubble top cars. The front bearing retainer on the ford transmission is larger in diameter than the one intended for GM usage. This is where the throwout bearing slides, other than that item, they may be the same. Many years ago a swapped a ford bearing retainer onto a GM dearborn version transmission, because the retainer had cracked, and immediately found we would have to turn down the ford part to use with a GM style throwout bearing.

This was in the early 70s, so I can't remember if we even tried a ford throwout bearing on the Pontiac fork, or not. I do remember though using the ford retainer after turning the OD down to fit the gm bearing. You may have to use a ford clutch disc too, I can't remember if the spline on the input is the same, or not.

The Pontiac 3 speeds that came in the early cars were not all that beefy, plus they were almost impossible to find. That was the reason we were using a dearborn out of a GTO, in out 61 Catalina race car. We also had a 64 block so the GTO aluminum bellhousing, with the ford pattern was a natural to change into a stock car.

I'm fairly certain that some members on here have used the ford toploader 4 speeds in Pontiac cars, because they broke so many Muncies, maybe one of them will respond about the input spline and what clutch disc to use. Also the input shaft where the pilot bearing rides may require a custom made pilot bushing. It's been too long to remember all the details.

Hope some of my ancient recollection is a help to you.

A great help, thank you very much! If I used the Mustang transmission, I could probably just get a Ford throwout bearing (hoping it would work in the Pontiac fork - which I assume it probably would) and Ford clutch disc and pressure plate (10.5 or 11"). Like you said that leaves the pilot bushing/bearing which seems to be the biggest crap shoot. I don't own a lathe or know anyone who does custom stuff like that.

On the pilot bearing, I believe that you could take a Pontiac bushing, and just drill the hole larger, because ford had a tendency to make more robust manual transmission parts than GM did in that time period. If anything I'd bet the ford input shaft is larger in the pilot bearing area. I do remember reading somewhere that the ford 4 speed toploader input shaft was 1 1/4 inches, which makes it much larger than the GM input shaft, but I can't remember what size the ford input shaft was on the ford 3 speed we robbed the bearing retainer off of.

I know we used a 10.5 inch disc, because Pontiac flywheels still hadn't been drilled for an 11 inch clutch, but the transmission we were using came out of a GTO, so it had the GM version input shaft already.

I'm sorry I can't recall all the specifics, but it's been over 50 years since I did all this. I believe the year I graduated from high school, making it 1970.....:eek:

I appreciate the insight sir.

IF the only issue is the pilot bearing, I'm sure that a local machine shop could drill it out to the proper spec. Hopefully that's the only issue and you actually have a local machine shop. Good luck. I swapped my 67 Tempest to a 4 speed back in '80 and at the time I was able to find all the Pontiac parts. At the time I hadn't ever seen any 4 speed Pontiacs. I just collected the parts and did the swap....I drove the car home from school on Friday as a 2 speed auto and drove to school Monday in a 4 speed Tempest....got pulled over on the first ride doing "I don't even know how fast you were going"(State Trooper quote, no ticket, strong warning)...ahh the good old days.

From what I'm gathering, finding the parts to swap in the Dearborn will be more trouble than its worth. Guess I'll stay with the original Muncie plan.

In the mid 70's I used a 3 speed Dearborn for a while in my '67, and it's not that big of a deal to swap in. It was out of another '67 GTO that it was born in. The pilot bearing was not a problem for me when putting it in place of my Muncie. You will need the clutch disc for the Ford input shaft and the proper yoke for the output shaft. Of course you also need the shifter and linkage that go with the transmission. The Pontiac bell housing has provisions for the Toploader to bolt on, and the front bearing cap will fit fine within the bell housing opening.
I saved the drive shaft with yoke, along with two Toploaders out of GTO's. They haven't been on the road in 40+ years.

Can anyone recommend a good quality, oil impregnated bronze pilot bushing? And does anyone know what the correct size bushing is for a 60's-70'e era Pontiac 400?

Is this right?

https://www.jegs.com/i/McLeod/673/8-1380-1/10002/-1

I've also heard people recommend a bushing from Novak but the size isn't listed...

https://www.novak-adapt.com/catalog/...shings/gm1-gm/

Thanks again to everyone for the help. Picked up a nice bellhousing locally for $100, picked up a nice OEM Hurst shifter setup for a Muncie with shift rods for $250 (from someone who didn't know the value of what they had). I just ordered new shifter bushings for it as well. Progress!

The part number is 690023.. That is a Dorman part #. Advance Auto

Apparently, not all bronze pilot bushings are the same. Went through this a while back. I was told that they should be solid bronze (or they can mess up the input shaft). Anyway, someone recommended using a magnet to make sure there is no metal in the bushing.

I tested a couple and the ones from Ram Clutch passed but the Pioneer PB75 failed. I eventually went with an NOS 'bearing' which is what Pontiac used originally verses Chevy using bushings.

[QUOTE=nhcd538;6399858]Can anyone recommend a good quality, oil impregnated bronze pilot bushing? And does anyone know what the correct size bushing is for a 60's-70'e era Pontiac 400?

Autogear makes a good bushing, I’ve bought a couple:

https://www.autogear.net/

I ordered over the phone, quick and easy.