[davidgto]

Is the drive shaft in a 65 GTO the same for a 4speed and automatic??

[Bill Hanlon]

'66 Chassis Parts Catalog says they are not the same.

[Kenth]

Due to the difference in the splines of the transmission output shaft, the propeller shafts for the automatic and manual transmissions are not interchangeable as a unit
However they are all 60" long and shifting for the correct yoke they will interchange.

[chrisp]

Originally Posted by davidgto

Is the drive shaft in a 65 GTO the same for a 4speed and automatic??

If 27 spline then the answer is yes .

[John V.]

In '64, all T/6 & T/8 used the p/n 5679580 driveshaft, automatic, 3 spd & 4 spd according to the '66 MPC.

Only exception was when the Chevy Powerglide automatic was installed in lieu of the Buick Super Turbine automatic. In '64, the air-cooled Powerglide was used as an alternate to the air-cooled Super Turbine in some of the 6 cyl builds. The driveshaft for it used rubber torsional dampeners. Every now and again a Powerglide equipped 6 cyl Tempest turns up but I believe they were not very common. In any event, PMD stopped using the Powerglide for '65.

Not sure how the '65 5695098 driveshaft differed from the 5679580 but it would seem they should both fit. I'm guessing the '65 man trans driveshaft was beefed up in some respect.

The HD 3 spd was the Dearborn trans, obviously required a unique driveshaft.

[Sirrotica]

FWIW, about 50 years ago I spit out the driveshaft of my 65 GTO 4 speed, (I believe it was bent, because it vibrated above 50 MPH since the day I bought it) and went to a junkyard, and got one from from a 65 Tempest 326 2 speed auto and changed it on the side of the road. That driveshaft stayed in the car until I sold it. I never changed the yoke, I just slammed it in.

Now it's been nearly 50 years, and going entirely from memory, I'm fairly certain it fit right in without changing anything. I was surprised that an auto trans had the same spline yoke as the 4 speed, and it was the same length too, but it did.

BTW not a hint of a driveline vibration after changing the driveshaft, so nice not to have the shifter vibrating constantly. The guy I sold it to bought it without the engine and transmission, and he transplanted a 326 2 speed from a 65 Tempest into it, as far as I knew, he also kept that same driveshaft with the automatic transplant.

[davidgto]

Thanks fellows

[Lemans64]

Just curious as to wha the driveshaft length is, weld to weld. have a 65 Tempest shaft here, believe to be from a 8 cylinder car, and wondering if all were same length. Getting old so not sure if it was 65 1/2 or 56 1/2, LOL. Will have to remeasure. Yoke was same as it is in my muncie right now.

[johnta1]

I believe these are measured ujoint centerline to ujoint centerline.


1965 Driveshaft Specs:





The front yokes may have to be changed to fit your car transmission.

EDIT: This is for Big Pontiacs, have to find Tempest

[johnta1]

Couldn't find measurements for A-body in Service Manuals.
(1966 was 60" though)

Here is some pics of the A-body differences between years.(according to Service Manual)

These are for Automatics:











And the 1966 shaft dropped the taper:








I'd still say with a change to the correct yoke for tranny, these would all fit, may not be numbers correct though.

[John V.]

John, those illustrations are "somewhat" consistent with the p/ns I posted.

The one you posted for '64 is ONLY for use with the Chevy Powerglide according to the MPC, it is the only one with the Rubber Torsional Dampeners as shown in the illustration. The Powerglide was only used in SOME but not all of the 6 cyl builds.

The other 6 cyl builds and all '64 V8 builds (man trans and automatic) used the same driveshaft as all '65 Auto Trans builds, p/n 5679580.

Can you post the '65 manual trans driveshaft illustration?

I assume it will show the dimensional differences.

There was no difference between a '64 and '65 Muncie, 3 or 4 spd, in terms of output shaft. And also no change between the '64 & '65 Super Turbine. In '64, all of them used the p/n 5679580 driveshaft so they will interchange with no difference in yoke. 27 spline output shaft on all of the trannies.

Even the '64 Powerglide had a 27 spline output shaft so I'm not sure what was unique about it other than the smaller diameters and the rubber dampeners.

It may also interchange as far as fit but probably not a good choice beyond its original application, the smaller dia. makes it functionally weaker. Was Chevy concerned that the Powerglide was so fragile that it required some cushioning to absorb driveline shock? Only reason I can think of for the rubber dampeners.

The '65 man trans driveshaft will also interchange for fit in all '64 & '65 auto trans and man trans applications with the functional exception of the rare '64 Powerglide application. I expect it is a heavier duty design so should be a "preferred" choice.

[johnta1]

They only showed those pics. Text said they were for automatic only.


The 1966 was the 1st one that showed a 'straight' shaft and (I think) siad all were the same for auto or manual.

[Sirrotica]

In past experience Pontiac and chevy use different U joints so the yokes on the chevy shaft would have smaller bores in them, plus external vs internal snap ring retainers.

FWIW, friend of mine had a 64 chevelle 283 4 speed and as has been noted it had the rubber harmonic sleeve, after he wrecked it I got the driveshaft from it to use in my 63 Tempest transaxle conversion because I was using a chevy saginaw 3 speed. I had also installed a 62 corvette rear axle in. The hope was it would be the right length, and right size U joints, however it wasn't.

I had to use 2 driveshafts to make one. It was one of the only GM driveshafts I had ever seen with the harmonic rubber sleeve between 2 different size tubes. I believe it was only 1964 A body chevelles that it came in, and possibly the 215 Powerglide equipped Tempests, it surely could have been used in a few 65s, but I never ran across one that I recall.

Hope that information may help............

[Kenth]

1964 GTO STD transmission is the 3 speed Muncie M12 with 27 splines output shaft, same as the optional M20, M21 and A/T M31.

1965 GTO STD transmission is either the 3 speed Muncie M12 with 27 splines output shaft OR the 3 speed Ford, Dearborn M13 with 28 splines output shaft.
The optional M20, M21 and A/T has 27 splined output shafts.

Also, for 1966 GTO the 3 speed Dearborn M13 with 28 spline output shaft was optional floor-shift only.
STD transmission with column shift was the 3 speed Saginaw M11 with 27 spline output shaft.

So, for 1965 (and 1966) GTO not all driveshafts are the same, even though the length are.

[footjoy]

How do you know if you have a drive shaft with the rubber in it. I have a 65 Tempest 6 cylinder 215 with a 2 speed air cooled trans.

[Sirrotica]

There are 2 different sized tubes roughly 1/4 inch difference in OD, there is a rubber sleeve between the 2 tubes where they are stepped in size, easy to see when under the car.

If my memory is correct, the step was in the rear half of the shaft about 3/4 of the way towards the rear, but that was 50 years ago too.

[footjoy]

Originally Posted by Sirrotica

There are 2 different sized tubes roughly 1/4 inch difference in OD, there is a rubber sleeve between the 2 tubes where they are stepped in size, easy to see when under the car.

If my memory is correct, the step was in the rear half of the shaft about 3/4 of the way towards the rear, but that was 50 years ago too.

My drive shaft is out of a 1965 tempest 6 cylinder car. Is it ok for about 325 horse power? Can it be balanced?

Thanks Greg

[Sirrotica]

Originally Posted by footjoy

My drive shaft is out of a 1965 tempest 6 cylinder car. Is it ok for about 325 horse power? Can it be balanced?

Thanks Greg

They were balanced at the factory. As long as the rubber is still in good shape (if it's one of the harmonic shafts) and the shaft is straight, it should be able to be balanced.

The factory shaft is probably good at that HP level, but it depends on how much corrosion it suffered through the years whether the tubing is still thick enough. Probably a good idea to take it to a shop that builds driveshafts for an evaluation. Tubing that has endured road salt over the years weakens.

[John V.]

Review post #11.

If you have the original driveshaft in the ‘65 auto trans Tempest it should NOT have the rubber isolated driveshaft. That driveshaft was ONLY needed when the Chevy Powerglide was installed behind the 6 cyl in ‘64.

The Powerglide was only used occasionally in ‘64 but was NOT used in ‘65 so you should NOT expect your driveshaft to be rubber isolated.

The ‘65 auto trans Tempest regardless of engine should have the same driveshaft that was used in ALL ‘64 Tempests including GTO regardless of transmission or engine except for the occasional 6 cyl with Powerglide.

The ‘65 manual trans Tempest did get a new driveshaft that was likely beefier but otherwise interchanged with the auto trans driveshaft.

The driveshaft was factory balanced. The one you SHOULD have was sufficient for a ‘64 GTO. 325 HP net would be more than the 348 HP gross that a ‘64 Tripower GTO was rated but I suspect should be okay at that power level. Never heard of a factory ‘64 GTO driveshaft breaking but I’m no racer.

[footjoy]

Originally Posted by John V.

Review post #11.

If you have the original driveshaft in the ‘65 auto trans Tempest it should NOT have the rubber isolated driveshaft. That driveshaft was ONLY needed when the Chevy Powerglide was installed behind the 6 cyl in ‘64.

The Powerglide was only used occasionally in ‘64 but was NOT used in ‘65 so you should NOT expect your driveshaft to be rubber isolated.

The ‘65 auto trans Tempest regardless of engine should have the same driveshaft that was used in ALL ‘64 Tempests including GTO regardless of transmission or engine except for the occasional 6 cyl with Powerglide.

The ‘65 manual trans Tempest did get a new driveshaft that was likely beefier but otherwise interchanged with the auto trans driveshaft.

The driveshaft was factory balanced. The one you SHOULD have was sufficient for a ‘64 GTO. 325 HP net would be more than the 348 HP gross that a ‘64 Tripower GTO was rated but I suspect should be okay at that power level. Never heard of a factory ‘64 GTO driveshaft breaking but I’m no racer.

I checked and it is the regular drive shaft no rubber.

Thanks Greg