h55 breakin and other questions

[bram]

Hello,

I just finished a h55 install and tcase rebuild in my 87 fj60. Does anyone know what the recommended breakin procedure is for the h55? I just drove it for ~5 miles and a noticed just a bit of high pitch whine, mostly when accelerating and decelerating. Not very loud, pretty sure its just normal for new gears, but my beat down 4 speed didnt make that noise.

Another question is what is the normal operating temp for the tranny and tcase? I put my hand on them after the drive and they were both just a bit too hot to hold your hand on. Maybe the tcase was a bit hotter than the h55 but they were similar. Normal? I dont remember ever paying attention to the temp of trany and tcase before but I thought, particularly for the tcase since I rebuilt it myself, that a high temp might be indicative of incorrect preload (i measured about 16-18 in*lbs after shimming).

 

[klinetime574]

I had the same thoughts when I put my 5 speed in. I just drove it slow and changed the oil after 500 miles. Trans and transfer. (New bearings in transfer-case)

Been about 7 thousand miles, have the third batch of oil in it. Second was discarded after a trip.

Everything seemed to get more warm, but I never paid attention to what it was before. I think the 5 speed still has some breaking in to do. Does not seem as "smooth" (or is it worn? lol) as my 4 speed did back when I started driving my 60.

Will watch for others feedback.

 

[Output Shaft]

I remember clearly, believe it or not, when I swapped out my 4 speed for a new H55F way back in 1989. Yeah it's been a while, but those kind of memories never leave you.
It now has 210,000 miles on the tranny.

Yes, definitely it runs hotter when new than the 4 speed did (at 40,000 miles) and not just because it's driving in 5th gear. I noticed that right away (and remembered it!). That has to be because of more friction until the gears fully break in. Nothing to worry about. (Hindsight).

Yes, 5th gear has a whine. But overall my tranny was noticeably quieter than the 4 speed.

I didn't do anything special about changing gear oil intervals. Maybe replaced the first fill after 1000 miles, then followed the FSM recommendation.

I've always run 75W-90 synthetic gear oil in it and it's still running fine & quiet, though the 3rd gear synchro isn't quite as grippy as it used to be.

If you use synthetic gear oil and make sure that the oil level is always correct and change it at the specified intervals, it will outlive your truck.

Count on it.

Here's a picture of its innards after 210,000 miles and 27 years.
Synthetic oil keeps everything sparkly clean.

 

[Oldtoy74]

Can't really add to your whine or rebuild, although I have been using 75-90 synthetic in my box also, pretty sure this box is now in its 3rd 60s, after I did conversion, did update bearings and idler in transfer before before installing, towing in 5th for 6000klms etc, beach driving, still going great, treat them with respect, they should just keep giving

 

[bram]

those pics are amazing. I have some autozone 80w90 in there now, which i guess I will run for about 1k. After that I am switching to red line MT90 (already ordered).

I'll take some measurements with an IR thermometer so others have some reference.

 

[klinetime574]

@Output Shaft x2 Those pictures are amazing. Your 5 speed has lasted longer than my 4 speed did, and you definitely have more miles on your rig than I do!

Maybe I'll switch to MT90 or similar later on. Do you guys also run that in the transfer-case?

 

[Output Shaft]

25 years ago, the only synthetic gear oil available was Mobil 1 75W-90. I filled both TMS & TFR with it. It's best to have the same oil in both so when that input shaft seal starts to leak, it's the same oil migrating.

Mobil doesn't recommend that oil any longer for transmissions. It's a bit too slippery. Redline MT-90 would be a good choice or Mobil Delvac Synthetic Transmission Fluid 50 (that's what I'm using now).

 

[4Cruisers]

25 years ago, the only synthetic gear oil available was Mobil 1 75W-90. I filled both TMS & TFR with it. It's best to have the same oil in both so when that input shaft seal starts to leak, it's the same oil migrating.

Mobil doesn't recommend that oil any longer for transmissions. It's a bit too slippery. Redline MT-90 would be a good choice or Mobil Delvac Synthetic Transmission Fluid 50 (that's what I'm using now).

I'll be using the Delvac when I install my new H55f and split transfer case into my '86 FJ60 project later this summer.