4 speed driveline length

[matt540]

I have a 69 with 454 and muncie 4 (m20).  The car started life as a 6cyl 3 speed. The car has a pretty good driveline vibration, and the driveline seems to be custom done at a shop.  Does anyone know what the factory length was for this application? 

[tom]

There was no 454 drive line available. My understanding is there are different mounts for 6 cyl, small block, and big blocks. Each mount locates the engine a little bit forward or backward compared to the others. If all else is good, your best bet might be to have your shaft balanced, or measure carefully and have a shaft made to fit.

[JohnZ]

Big-blocks used unique engine mount frame stands AND a unique transmission crossmember - see:

http://www.camaros.org/trans.shtml#Crossmembers

[william]

454 engines differ from all other big-blocks of the era in that they are externally balanced. This means the balancer and flywheel MUST be for a 454 engine. If either or both are not 454 specific parts vibration will result. The balancer is easy to spot as it has a scalloped area; don't know how to spot a 454 flywheel.

Another source are the motor mounts. '69 frame brackets are narrower and shorter than '67-'68. Unforunately '67-'68 motor mounts will fit on them. The fit is sloppy and the engine is positioned too low in the chassis. The correct '69 mount is a very tight fit on the bracket-if there is any gap the mounts are wrong.

[matt540]

I did not know there was a unique transmission crossmember, I cannot see it making a mechanical difference, knowing a small block can bolt in the same place as the big block, however incorrect it may be.  I do have the correct front towers and my flywheel and balancer are externally balanced.  I don't have a real problem with having a custom driveline made up, I was just hoping someone would know what GM did on the 396 cars and took out some of the chance for error on my end, and give me some kind of spec to compare to the driveline I have in the car now.

[tom]

my interchange book gives a part number of 3970521 for all 69 muncie 4 speed camaro, and z28's. It does not give measurements. The used to be free info package from Chevy specs 2 shafts for the 69. Scanned image linked below.

[william]

That info does not agree with the 1969 Camaro AMA specs from Chevrolet. All '69s with Muncie 4-speed used the same basic driveshaft: 49.56" C-C. 50.46" is the '67-'68 piece; longer due to smaller U-joint trunions. I believe in production Muncie driveshafts did differ based on application. Z/28s probably had a shaft balanced to 7000 rpm.

Here also it is possible to mix parts. If you have a '68 axle [1 brake line clip per side, U-bolt pinion flange] a '69 driveshaft will be too short and there may not be enough yoke engagement.

[Sauron327]

Are the driveline angles within tolerance? Did you check them with a guage? Did you read this?http://www.camaros.org/bellhousings.shtml

[matt540]

Well............. the bad news is pretty much what I expected.  My driveline is at least 50 9/16 c-c, longer than any driveline in any first gen.  I downloaded a measurment chart from Denny's drivelines website and I'm going to get back under the car.  At least I have something I can compare to now, factory specs, my driveline, and my car.
I have also seen a lot of talk on the correct offset yoke.  Chances are good this is wrong too, can I tell if I've got the right one?

[william]

I would not be concerned with yoke offset. That's been discussed for years with no real conclusion. The 'normal' position for the U-joint trunions is a 90º offset. Z/28s are often seen with much less; sometimes they are nearly in line. Any driveshaft shop can make a new one for you but this may be a good time to step up to a HD piece.

[JohnZ]

I did not know there was a unique transmission crossmember, I cannot see it making a mechanical difference, knowing a small block can bolt in the same place as the big block, however incorrect it may be. 

The big-block driveline is offset 1" to the passenger side from the small-block location, and the trans mount bolts in the crossmember are also offset to that side.