Replacing gears in an H9 Differential Case

[joekayakguy]

My plan is to replace the failed Pinion gear 4215 in an H9, 3.55 Limited Slip Differential Case 4204 in the rear on my 89 F150. I was going to replace all 4 gears (2 pinion 4215 and 2 Side gears 4236), Thrust washers, Differential Pinion Shaft 4211 and Differential Pinion Shaft Lock bolt from another salvaged H9.

This would all be replaced in the same position on the same shaft, in the Differential Case on my truck. I think the wear patterns would be a non-issue because these pieces have always been together in the same configuration from the Donor H9. Is there any reason I can’t or shouldn't do this?

Thanks, Joe

 

[conanski]

Given the tolerances of the parts you're talking about here you won't have a problem with this swap, the gear mesh of the pinion gears will vary quite a bit as the clutch packs wear so these aren't "setup" like the ring and pinion.

 

[joekayakguy]

Thanks Paul,

I think the same as you. However, I have had two local Mechanics tell me I won't get 1000 miles before they fail because they weren't "married" to the set. They have scared me enough to make me want to swap out the entire Axle and brake drum assembly. I have bled brakes, but never tried to get those gears back in. (they come out fine when they break)

I think I'm a coward here? Joe

 

[conanski]

I have bled brakes, but never tried to get those gears back in. (they come out fine when they break)
I think I'm a coward here? Joe

I think the mechanics are being overly dramatic, if you want to look at it as they describe you are keeping that "matched" set together just installing it inside a different housing and I don't see how that would shorten their life. If this were a R&P set I'd agree with them but not for these tag-along components which have machine tolerances no tighter than your average brake drum.

Inserting them is no big deal either once you know the trick, the side gears have to go in first obviously with the clutch packs behind them, and then the two pinion gears are rolled(or spun) into place.. which they will want to do naturally so mind your fingers. And since you're in there now is the time to restack the clutch packs with alternating friction/pressure plates instead of the factory setup, this adds 1 extra friction plate to each side and removes 1 or 2 pressure plates(can't remember) and this increases friction through the clutches which decreases axle slip, and it should also increase spring preload which will also increase the positive traction of the differential.

 

[Fellro]

I did that exact thing to an F150 last summer. The rear was clunking due to the gear teeth breaking off on one of the gears. No issues and they have certainly logged over 1000 miles on it by now.

 

[joekayakguy]

Thanks Guys,

I'm loaded up for the Pick and pull yard tomorrow. I'll let the availability determine what I do.

Hey Roger, Didn't you pull your Transfer case and trans last summer right after I did mine? I assume all went well?

Thanks guys, Joe
I'm so glad my Truck doesn't ask... "Does this differential cover make my rear end look too big?"

 

[Fellro]

Had to do the 88 after the clutch went, don't remember what time of year it was, might have been summer. Works great now. I can even get the fill plug out now... fixed that while it was down.

 

[joekayakguy]

Pulled and carefully marked locations of donor gears in ziplocks from a 1995 H9. I was paying for them and was told if I pulled the gears I had to buy/pay for the entire rear. After thinking about it I want back and pulled the entire rear. Had I known that I wouldn't have walked/spun the Pinions out. Getting them back in and lined up should be interesting.

Joe

 

[Fellro]

It really isn't that bad, The main trick is the spring clip, the rest is cakewalk.

 

[joekayakguy]

Case closed. Rear in, Brakes and lines all done. Sway bar links and Shocks replaced. I expected more trouble from the spring in the differential. It took a few times "walking" the gears back and forth. Thanks for all the support. Now I gotta track down a new noise????

All the best, Joe