This is a stock 89 Firebird @ 115K miles. The 700R4 real seal has failed and is leaking slowly. Tranny operates normally, shifting is mushy, typical of its age I guess, but no slipping.

I'm getting a high-pitch squeal from the tail-housing of the tranny. I had the driveshaft fitted with heavy duty u-joints and rebalanced. This made the car a little smoother, but did nothing for the squeal. I've changed the differential fluid, all was clean in there.

When re-installing the driveshaft, I put it in neutral and turned the 700R4 output shaft by hand with the driveshaft not connected to the differential. I notice the noise is only in the forward differection, not when the output shaft is spun backwards.

Basically it sounds like high-pitched disc brake squeal, but it's definately from the back of the tranny. Someone told me it's a throughout bearing? I assume this requires a tranny removal.

Could it be the bushing in the tailhousing? But I would think that make noise in both directions. That's barely within my ability to fix (I don't have the tools). I've rebuilt motors but only swapped trannys. The speedo gears are plastic right??

I'm tempted to buy a built 700R4 online (no reputable shops in South Fla) and do a swap since mine is probably due for failure from its high mileage. Anyone can recommend a reliable 700r4 online?

Any ideas? Thanks in Advance.

 

I think you are hearing two different noises. If it makes a high pitched squeal while driving, I would be looking at possibly the rear case bushing. Sonnax makes an oversized bushing for cases that have spun that bushing.

The noise you hear when turning it by hand is the Lo-Roller clutch and is NORMAL. Its a one way clutch that locks in one direction and spins freely in the other direction. Thats why it only makes noise in one direction. You should not hear this noise while driving.

 

Thanks for the info.

On my previous 3rd gen cars with 700r4's, I turned the driveshaft by hand, both ways, and didn't hear any odd noises at all. I think I know the sound of a "proper" Lo-Roller clutch, it's like a slight mechanical rotating sound. But this noise is definately a "metallic scraping" squeal. It is exactly the same noise as when the car is driven at speed. Higher speeds produce louder/faster squeals.

If the noise comes from the tail bushing, this is the only thing I can fix with the tranny in the car right? I have to get a tailhousing gasket, the bushing, and a cutter/removal tool and bushing installer right? If the bushing is spun, isn't there a possibility of trouble even getting the tailhousing off?

You mentioned an oversized bushing; is this compensating for a damaged (spun bushing) output shaft or tailhousing?

 

I have same problem in my 84 c4 it gets louder the faster you drive and only does it in the forward direction

 

If you can beg, borrow or steal a tool like the one in the attachment, you can replace the bushing without removing the extension housing. You just need to remove the drive shaft and seal.

If you remove the extension housing, you need a bushing driver to remove and install it. Any transmission shop will do this for you (be prepared to buy them lunch or something) if you don't have the driver.