Differential - Pandora’s box or dive in?

[tcslc]

I’ve replaced every bearing on my ‘69 2000 so far. That’s been giving my HF 20T press and my arm a workout. The last of the bearings sit in the differential. I have the two pinion bearings and two side bearings in hand along with the pinion seal. After reading every diff thread and the service manual on replacing the diff bearings, I’m conflicted about whether to simply replace the pinion seal and move on or do all the bearings in the differential since it’s all out. I’ve always believed there is some voodoo in the differential setup and am hesitant to jump in. When I bought my car it wasn’t running and so I have no idea if everything is good in the diff or how to check it out of the car. Anyone been at this crossroad and have some advice to share? That pinion has been staring me down for three days now

[Habitat.pat]

I did a frame off on my 67.5 SPL over the last 3 years & decided to leave the bearings in the diff alone but to replace the input seal. The seal came out easily & the new one went in easily. Life is good! then about 2000 miles later I noticed some problems with what appeared to be the differential, so I pulled it out & everything looked fine. My problem was that the pinion wouldn't turn easily but once it broke loose it appeared to be fine until it sat for a few seconds, then it was tight again. I took it to a differential shop with a full set of bearings & told them to do what was needed. Turns out I caused the problem by over tightening the pinion nut that holds the driveshaft flange on. I tightened it to what the factory manual called for, but I found out that that value is for newly built differentials & not for old ones! Old diffs nuts should be tightened based on a torque wrench reading on the nut.

There is some voodoo in differentials, so I'd say that you should find a shop that does rebuilds on differentials & not one that just does them from time to time, you'll get a better job. I contacted Les @ CDM in Vista CA. & he had his differential guy go through it. Worth the time & money.

Peace, Pat

[david premo]

Leave your differential to those who have experience with H-190 carriers. You could easily turn it into a pile of junk and never realize where you went wrong.
Dave

[redroadster]

Usually you need a heavy steel 1/4" bench , ( because your wrestling it )with a mounted holding bracket for the housing or in this case the 3rd member and a diff spreader ,to get the diff / carrier assy out and in the housing easy ,
You have only .005 play the norm, in the assy.to housing and getting the 20+ LB carrier lined up with thin shims not torn up ,can be frustrating
Subaru s has bearings that fine thread screw in and out instead of shims

[david premo]

I have never used a spreader on any pumpkin type differentials, I have on Dana rear ends and twelve bolt style rear ends. The H-190 has more problems with people putting too much preload on the carrier bearings that ends up spreading the caps and then it won’t fit into the housing. Also yes Pat it might over torqued which causes the bearings to freeze in the race. It’s strange that that happened with just a seal change, especially when it is used bearings which bed in and are usually slightly loose. That said care should be used when working on hypoid gears as alignment and bearing tension is critical to longevity.
Dave

[JT68]

To answer the original question: It's a Pandora's box.

Feel free to change the front lip seal, but if you don't know EXACTLY what you are doing with regard to setting up a diff, you will likely do more harm than good if you take it apart.

Besides, why bother? Replace the seal and run it with new high quality lube.

If it is quiet you are golden.

If it whines, it is basically scrap metal (or maybe worth 50$ for parts) because they really are not reasonably rebuildable....$$$$.

If it is junk, just buy another "known good" diff from someone reputable. (like someone who guarantees it to be good)

[tcslc]

I ended up taking the diff to a local expert whose shop only focuses on rear ends and transmissions. Very knowledgeable guy with over 30 years owning his shop. I picked up the completed diff yesterday, and yes the price was steep but just short of eye watering. We chatted and I asked him how long it took him, and he said about 4 hours of work. He also said that he added a .008 pinion shim to get to the needed specs. Said that otherwise the pinion would have been too tight and worn the bearings. Also said that new bearings (mine are all SKF) don’t spec with the same tolerances as old bearings. The expert advice in this thread is good, either do only the pinion seal or have an expert do a full setup. I’m glad I did and now have peace of mind it’s right.

[david premo]

He probably took out .008 as adding that would have made it tighter. It’s been my experience that most of the aftermarket large pinyon bearings are a little thicker than the factory ones. I have removed shims on almost every one of them I have done with aftermarket bearings. Glad you took it to someone to get it done.
Dave