Isuzu SUV Forum banner

MUA5 Transmission to Transfer Case Seal and Synchro questions

361 Views 8 Replies 3 Participants Last post by  Enemigo
Hello Gentleman.

First time post here. I've been lurking quite a long time as I purchased a very clean 2002 Trooper limited with a dead 4L30E for next to nothing about a year ago. I did a good bit of reading on 4L30e problems and repairs hoping it was repairable but full well knowing I might be pulling it out. And if I was pulling it out, well... a 5 speed was going to be going in in its place. After lots of reading here and finding a promising 5 speed from a 98 3.2L amigo I found at a yard nearby... Suffice it to say I've embarked on the 2nd option.

I genetically inherited the "while you're in there" disease from my father and decided to take a crack at installing the Revolution Gear 3:1 low gears in addition to doing the engine's rear main seal, and the front output shaft seal cough "while I'm in there." Upon reading as many forums as I could about the process I've stumbled across a few forums mentioning the seal between the transmission and T case failing and letting all the trans fluid leak into the T case. At the moment have the T case completely stripped down and ready to clean and reassemble with the new Low gears. My "while I'm in there" disease is screaming at me and telling me to replace this seal between the Trans and T case since I am literally able to lay eyes and hands on it as we speak. However I can't find any info on a part number. Just the mention of a mystical forum member named "Jerry" mentioned here.

Does anyone have any Intel or P/N on this seal or know who said "Jerry" is? With 140k miles on the clock of the 98 amigo donor I'd love to freshen up anything that is cheap and easy, like this seal.

Additionally another puzzle; while looking as photos from forums documenting the 3:1 gear swap I noticed something. The dog-toothed gear (I don't know the correct term, please educate) that sets on the top of the shaft (engages low range gears) that comes in from the transmission has 3 blank slots where some small keys COULD sit. (mine pictured below)
Gear Crankset Bicycle part Automotive tire Wood

Hand Tool Wood Auto part Metal

I say could because I did have them on the same dog-toothed gear that sits on the 3'rd shaft that engages the front output for 4wd along with some kind of synchro mechanism. (mine pictured Below with keys removed)

Camera lens Camera accessory Cameras & optics Lens Teleconverter

Table Wood Flooring Floor Wood stain

On Revolution Gear's own ebay listing there's a shot of a transfer case that Doesn't have them on the primary input shaft (like mine). And another shot of one that does with the addition of some kind of brass toothed plate. (photos of both below).

Automotive tire Machine Differential Motor vehicle Auto part
Automotive tire Motor vehicle Gear Bicycle part Automotive design

I guess what I'm asking is, is it ok that mine lacks all that? Did some T cases have synced 4wd engage and others didn't? Additionally do I have the option of putting in a synchro'ed 4wd lock if I source such parts. I'm not that interested in upgrading unless someone on here convinces me, I'm just looking to put my mind at ease that someone hasn't been in here before and left some parts out before I reassemble.

Thank you for your time, wisdom and intel. I've really appreciated this community at a distance and am excited to finally engage with y'all.



See less See more
1 - 1 of 9 Posts
Yes, mine is a 2002 but it was an auto. I'm swapping in a 5 speed out of a 98 amigo 3.2L. My understanding is the AR5 and the MUA5 are quite different units. You are correct in that the MUA T case is integrated into the transmission. However the 2 halves remain separated internally and each have their own oil supply. Here's a pic below of the seal that separates them (t case side).

View attachment 129778

There's one part of me that's ready to just drill a hole through it, run a screw in it and pull it out. If I could just turn it over I'll see the Part Number. My only fears are 1: what if I drill through the part number (would be just my luck). And 2: what if I can no longer source a new seal (would "also" be just my luck). I'd PM JLEMOND but I'm still too new of a member. I have to make a certain number of posts before I'm allowed to PM people. If you'd be willing to shoot him a PM and send him towards this thread I'd be hugely grateful. Otherwise I'll just keep puttering around and making friends and comments on here until I can PM people 😂
your best bet is to email jerry. [email protected]

1 - 1 of 9 Posts