The Stovebolt Site Forums The Shop Area Driveline Drive Shaft vibration - Trany Bracket

55 1/2 ton - 265 - 350 trany

Have vibration in truck after about 25mph. Took to shop, they said that there needs to be another engine/bell housing bracket. Said I'm getting a twist/bind between the engine,tranny,driveshaft and universal joint. There is only the front engine brackets and a handmade bracket across the back of the tranny. The 350 is shorter than the original tranny, so the driveshaft is too short. I pulled the driveshaft today to have retubed longer. Now I need a bracket in the bellhousing area to help support.

Anybody know of a bracket being sold? Or any other advice on this issue? see picts Engine Trany mount

no pics linked so can't see the bell housing mounts are only used with a standard trans, which doesn't use any mount under the trans, the automatic bell doesn't have those mounts so the trans needs to have it's own mount, but with the original front "bird leg" mounts that places the supports awfully far apart, so what you really need is the aftermarket crossmember that catches the engine side mounts, but I don't think the 265 has provision for side mounting you DO NOT want the engine/trans attached at 3 places ... should work with front and trans mounts tho if yer not bent on spinning the tires, maybe the short shaft is more of the problem, and maybe old U-joints, or maybe the DIY trans mount isn't positioned properly

Bill

Have you checked your pinion angle?

Here's why pinion angle is important.

Have not checked, What should it be? How to adjust to that angle if off?

Thanks for the video, It was GREAT

Mark

Don't know how much frame mods were done to your truck, but on the tri5 cars a mount is available that bolts to the engine/transmission and to the original bell housing frame mounts. The engine/trans. needs to be supported in the center or on the side, I don't think the 265 had the side mounts. Check your block if it has the side mount bosses then you could put a aftermarket tubular engine mount and eliminate the front mount you have. The engine would then be mounted correctly, as it is now all of the weight is in the center and not supported.

You need an angle locator , available at Home Depot and such. Assuming your rear end is stock, it should be in the right angle. Measure it, then place the angle finder on your starter housing. The angle should be the same within a couple of degrees. Build the tranny mount to put it at that angle if it is not.

The brackets that Tommy is referring to are available from Danchuk and likely Classic Chevy Int. They were designed for passenger cars but I'm sure they can be adapted to a truck as well. It is also possible to fabricate some frame to bellhousing mounts. As mentioned previously there is too much distance between the front mounts and the rear trans mount to properly stabilize the engine/trans combo. I have seen them where all the mounts were broken because of so much stress that the only thing holding the engine in the vehicle was the exhaust system.
Fred

Hanging the engine/transmission weight on the aluminum bellhousing with support at the ends is a recipe for disaster. One hard bump could break the bellhousing and dump the whole assembly on the street.

Did someone remove or modify the crossmember between the rear spring hangers to allow clearance for the bell housing? You really need to fabricate some sort of square tubing crossmember setup with rubber mount blocks attached to the lower corners of the rear of the block to de-stress the engine/trans junction.
Jerry

The only change to this truck is the transmission and trany mount on its yoke section. The motor does not have side mount holes. Needs to have support at the bell housing.

Going to Street Rod Nats in Louisville this Sat, might find something from a vendor there??????

Took drive shaft to Republic Diesel this morning to see about a longer drive shaft. He said all new about $300. Is it possible to find GOOD used that fit for a lot less? It does need universal joints as well. He said that for only as short a length change that I would need it would not effect the angle.

Hotrod,

Do you have a pict of the cross member you speak of?

the only thing you might find is a plate that sandwiches between the block and trans bell that has brackets to catch the factory crossmember mounts, I've never seen that sort of thing available from vendors, likely have to be a DIY project .... but it really is not good to have fixed support in 3 places

if you need an automatic, you should look for an original Hydra-Matic setup

Bill

It would need to be a home-brewed setup. Most people do not use the front "bird leg" mounts when swapping to a modern automatic, but they usually have the option of using the side mounts on the later-model block with an aftermarket crossmember which pretty much balances the engine in the middle. The metal butcher who cobbled up that rear mount should be slid down a 50-foot razor blade into a barrel of alcohol- - - -that's a nasty looking mess!
Jerry

This is the way I bought the truck, don't really want to change trany's

What about this bracket I found online? Motor Bracket

all I see is pics of spring mount areas .... having bought someones mistakes it'd be best to rethink what works rather than trying to rig some kind of patch

Bill

Go look at danchuk chevy.com , tri5 chevy car place. look for motor mounts and you will see what I was talking abouit. The bracket bolts to the trans ans engine and to the original frame braqcket for the bell housing.

you'll need to link it, Danchuk has hundreds of pages of stuff .... for cars

Bill

Bill this is what TOMMY is talking about
http://www.ebay.com/itm/55-56-57-Ch...ries&hash=item4867c904ba&vxp=mtr

TOMMY this isn't going to work, because the bell housing mounts for a tri five Chevy car bolt to the frame horns on the inside of the frame. On a Chevy truck they bolt to the cross member under the bell housing.

55 Shaker,
I don't know how much frame cutting someone did to install that automatic trans in that truck. The crossmember was cut out to put the automatic trans in there. All I was trying to do was give an example of a mount that would support the engine/trans. correctly. The frame has already been modified and He needs to use something, it's a start at building something that will function to properly support the engine.

If your dealing with a vibration I still think that you need to determine the pinion angle.

Unless the long stretch between mounts is dealt with soon, the vibration is going to become a moot point. It won't vibrate at all when the engine/trans assembly is sitting on the ground in two pieces.
Jerry

Mark, that "easy as 1-2-3" mount you show in your P-bucket now is for the front mount, you already have those, and yours are factory [riveted onto frame] so that was originally a V8 truck .... what makes it a "Corvette motor"?

Bill

I was told by the previous owner that the 265 came out of a 55 Corvette. I tried running the number, could not find out for sure anywhere.

Mark,

What are the codes on your 265?

What would be the ideal setup, tranny/motor mounts for my 55 1/2 ton truck?

1955 - 265 motor & turbo 350 tranny

This can't be the first time for this configuration

There is no ideal setup for your engine trans combo. Most conversions would use a later engine which has the mount bosses cast into the block. That is what the aftermarket is geared towards. This would be a tubular front cross member with the center engine mounts and another tubular cross member for the rear transmission mount. These are available from numerous aftermarket suppliers. However, since your engine does not have the mount bosses cast into the block you would be unable to change the front mounts. The only option I can see is to fabricate some center mounts located on the bell housing to the frame as previously mentioned.
Fred

Speedwaymotors.com has a nice mount for the front to replace the 2 "bird legs", but that doesn't get the middle.

Found an article in 2003 Classic Truck Mag, 2 mounts (motor & tranny)from Classic Performance Products. Called them and they said these worked with my motor (265) and 350 tranny (55 PU). Anybody used this setup?

It should be fine like it is....but that driveshaft is definitely too short. That could be your problem. That front yoke doesn't even look like it's in far enough to reach the bushing inside the tail housing. Also check the pinion angle. There are big block Vegas with front and rear mounts that have never broken an aluminum bell housing on a bump so that's not a concern. Get the new driveshaft......you could search for a month trying to find a used one the right length.

I took it to a shop that took the driveshaft out and ran the motor to find the vibration. They said the drive shaft was too long and that with flex it the whole system it could slam the rear end.

Was told by Republic Diesel(makes drive shafts) how to measure the length needed. Take the U joints loose in the rear and push all the way I can into the tranny. Measure from center to center of joints. Then they figure less 3/4". Did that, current shaft was correct, then took to them to put in new U joints.

Still have issue. Thinking that between the front motor mounts and the current tranny mount, I'm getting a slight twist causing the vibration.