Transmission Extension Housing Bushing

[Gene K.]

What is the correct alignment for the fluid feed hole in the bushing that goes into the transmission extension housing? This is for an FMX transmission. There are two slots in the extension housing. One near the top and one at the bottom. The old bushing was installed with the feed hole at the bottom. It makes more sense to me to put it at the top so the fluid feeds from the top and drains out the bottom. Of course if the hole is actually a drain hole, it belongs at the bottom. I can't find any reference to alignment in the shop manuals.

A few more notes and questions:

The C6 uses the same bushing, so if anyone has experience replacing one in a C6, that may help.

The transmission was rebuilt by a local shop less than 700 miles ago and was working fine. I started getting vibrations that would come and go at highway speeds and they got worse every time I drove it. The 8 inch rear end and possibly the drive shaft were replaced by the previous owner. (He took lots of "short cuts" with everything he did so I have had to fix many things. You can see one of them with the wire supporting the E-Brake cable to make it clear the exhaust in the photo. It is on my list of things to fix…) As it was working fine, I figured the balance on the driveshaft was okay. The U-joints all seem tight. However, the extension housing bushing felt too loose to me because I could move the yolk enough to get a small gap between it and the seal. Yes, it leaked even though it was a new seal. Looking at the length of the driveshaft (51" CL to CL on the U-joints), it appeared to me to be too short. The slip yolk was extended 2" from where it bottoms on the spline shaft and my theory is the extra leverage on the bushing caused it to fail. I have a 52" drive shaft on order from CJ Pony Parts which will give me about 1" of extension which from I have read is a more typical number.

Question: When replacing the driveshaft, I can have the slip yolk and drive shaft balanced as an assembly, but what about the pinion yolk? Should it be balanced with the rest of the assembly?

Thanks,

Gene K.

 

[VegasFastback]

I just tried to look it up in the Ford manual and it doesn't say anything about orientation.

 

[Gene K.]

I just tried to look it up in the Ford manual and it doesn't say anything about orientation.

Thanks for trying. None of my manuals, including my Chilton's Auto Trans manual for a variety of transmissions, give any indication for any transmission. I guess it is something they assume you just put it back the way it was installed and don't ask questions.

I will ask one of the local transmission shops on Monday to see if I can get an answer.

 

[VegasFastback]

Post when you figure it out I'm doing the same thing right now.

 

[droptop73]

What does the extension housing look like? Is there a groove? Is there a hole? How does it compare to the bushing? It appears the notches in the bushing may want to align with the notches in the extension housing. It looks like there may be a notch or groove running the length of the bushing judging from the witness marks on the bushing.

It's not generally necessary to balance a driveshaft with the companion flange from the rear end. If you remove the companion flange you have to reset the pinoin preload which normally means a new crush sleeve that requires disassembly of the carrier. Not wrth it IMO.

BTW, I had a very significant vibration at highway speeds (65-75) that would come and go. I found the tires were out of balance, correcting this reduced the vibration dramatically. Replacing a very soft transmission mount also helped a ton. There is very little vibration left.

I normally set up a driveshaft with 1/2 to 1" of travel on the yoke. Slide the yoke all the way in and pull it back out 1/2 to 1" to measure for driveshaft length. 2" is WAY too much. My original driveshaft was a little too short, especially after adjusting the wheelbase to center the rear wheels in the opening.

 

[Gene K.]

I couldn't get in touch with the shop that did my transmission so I called a different one I know. The person there said it had been so many years since he had worked on an FMX that he couldn't remember all the details. What he did say was that there is very low stress on extension housing bushings. They normally don't wear out so they are not necessarily replaced during a rebuild. Of course he normally does not work on 42 year old transmissions either. He remembers transmissions from the fifties that just used a bronze bushing with no lubrication holes at all. He said it probably won't matter which slot I line the hole up with. Given that, I will probably just put the new one in with the hole on the lower slot like the one that came out. I will try to call the original shop again tomorrow to see if I can get another opinion.

Correct. There are two grooves or slots in the extension housing that run more than the length of the bushing. (See photo) The notches in the bushing help align the hole with the slot, but they do not line up with the slots. They are offset a bit. The notches face the rear of the transmission so you can see them as the bushing goes in. I think the factory tool may have had pins that engaged the notches and rails that engaged the slots to keep the bushing going in correctly. Perhaps that is why there is no mention of orientation in the manuals as there would be only one way to install it.

The tires are definitely a possibility too. They are old and came with the car. The reason I have not replaced them is I am waiting for new, different size wheels from JEGS. The original ship date when I ordered was 3/09/2014 and they now pushed that back to 6/17/2014 due to factory issues. If I would have known that when I ordered...

Also if you are going to do this yourself without removing the extension housing, you will definitely need the extraction and installation tools. Atec P/N T-0161-A or T-0161-B. It takes quite a bit of force to remove the bushing. Trying to install the bushing without the tool will likely result in a mushroomed edge or bulge in the bushing making installation of the slip yoke very difficult or impossible. I have heard shops sometimes have to hone the bushing after installation which requires removal of the extension housing. I will find out soon.

 

[droptop73]

Good deal Gene, I'm glad you have it figured out.

 

[Gene K.]

I talked to the shop that rebuilt my transmission today. The technician said he always puts the oil feed hole down when there is a choice. I installed the bushing that way today. Using the installation tool, a lot of patience and light taps, it went in without damaging it. Periodically heating the extension housing with a propane torch just enough to keep it warm seemed to help the bushing go in easier.