rear trans seal? leaks after lowered

[992dr]

Since I had lowered my truck, the rear seal has been leaking.
I noticed today that it is leaking even more, while I'm watching it.
I bought a new seal as well as a bushing.

Does anyone now how to replace the bushing?
Also, do you just pry the old seal out with a flathead screwdriver?

Any info would be greatly appreciated.
Thanks

 

[shortntall]

could be they just got hot and cold and shrunk sp?

 

[95TwinTT]

The yoke on the driveshaft should have a nice shiny polished end and then a line where it stopped going into the seal.

When you lower the truck, the yoke goes further into the transfer case. The part that is not polished, could be rusty or rough enough to quickly wear out the seal.

Be sure the yoke is cleaned and polished far enough back, for the new suspension position. Otherwise, you will go through seals often.

 

[AtomicHoe094]

good to know twin, what are axle shims used for and where do they go when you lower you car/truck???and would it help the seal problem?

 

[992dr]

Thanks TT, I appreciate it.
I'll be sure to clean/polish the yoke before reinstalling it.

Do you have any idea about the bushing?
Is it needed/necessary?

Thanks again

 

[95TwinTT]

good to know twin, what are axle shims used for and where do they go when you lower you car/truck???and would it help the seal problem?

By shims are you talking about the “wedges”? I had to use 6 degrees on my Tahoe, when the 4L80 was installed. The geometry was altered by the transmission being 4”closer to the axle. The wedges are offered in “degree’s” or fractions, to adjust the Pinion angle.

Imagine a center line drawn through the crankshaft and transmission. That line should be parallel with a center line drawn through the pinion shaft.

A U-Joint will oscillate back and forth because of the arc difference’s of their pivot points. If the angles are not symmetrical, vibrations will be present. They are often only noticed at higher speeds, like 60 mph.

In other words, the pinion angle to drive shaft is ideally equal to the angle offset of the trans to drive shaft. That way the back and forth movement is equal from both U-joints. One essentially cancels the other.

---------- Post added at 07:57 PM ---------- Previous post was at 07:52 PM ----------

Thanks TT, I appreciate it.
I'll be sure to clean/polish the yoke before reinstalling it.

Do you have any idea about the bushing?
Is it needed/necessary?

Thanks again

If you had a rough or rusty area on the yoke that started invading the seal, it is probably just the seal that needs replacement.

If there is a lot of play on the yoke, it might not hurt to do the bushing as well.

 

[AtomicHoe094]

Good information! and yes shims=wedges
Aren't the shims used for lowering a truck too? i didn't know they were used for tranny swaps?

 

[95TwinTT]

Good information! and yes shims=wedges
Aren't the shims used for lowering a truck too? i didn't know they were used for tranny swaps?

You are correct. Lowering a vehicle is a reason to use them. Any alteration of the drive train geometry should be a reason to check and correct the pinion angle.

I think a lot of people ignore the pinion angle issue. They don’t notice the vibrations or attribute those vibrations to another cause.

When the truck are raised and large tires are installed, the drive shaft speed goes down relative to road speed to the degree that the U-Joint vibration might not show up until 80 mph. Since that’s a little fast for cross country off roading, the problem may never be realized.

I don’t know about you, but I’m sensitive to vibrations and often discover them before the image in the rear view mirror gets fuzzy. lol

 

[AtomicHoe094]

so how can you really tell which angle or degree you should use say on a 4/5 drop??

 

[95TwinTT]

Lots of variables here, but it should be a repeatable number for the same wheel base and drive train.

It might be different between coil springs and leaf springs, because of the pivot points of the suspension being different.

It’s kind of a hassle to check. The truck has to be sitting with the normal weight on the rear axle. My transmission guy made up a tool in his machine shop that is a pointer 1/2" stainless rod welded to a yoke. It slips over the tail shaft and serves as a “center line”, straight edge to measure from with the drive shaft out of the truck.

I have not found any documentation on just how far off it can be before it is considered a problem or dangerous. I have just responded to vibrations, and chased it down.

Search under pinion angle and you will find lots of info. I would think that one of the dangers is if you are lowered to the point where your drive shaft is going through “center” to plus and minus angles. I’m sure that someone has come up with answers for all possible combinations.

I’m no expert on this subject. I just know to check it to be safe……..