MUA5 Bearings/Synchro Replacement

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MUA5 Bearings/Synchro Replacement

Postby chevelle3504speed » Wed Jan 20, 2021 4:25 pm

Hey guys,

I've decided to replace bearings and synchros on my '90 model MUA5 trans after 350k. This trans has been run out of oil (both trans and transfer case) and driven on for at least a couple of hundred miles. I only noticed when I started hearing a horrendous whining coming from it. I filled it up with oil and it quieted down much to my surprise. I have pulled the front half of the case off and am surprised at how good it looks inside. Cluster gear and shift forks look great, and it is very clean. Gears are not sharp. This appears to be a pretty durable trans., based on what I've put it through. Anyway, I purchased a kit with bearings, synchro, and seals; pn ZMBK220WS manufactured by USA Standard Gear https://www.carid.com/usa-standard-gear ... ation_mail

I hope parts are of good quality in this kit. I am wondering if anyone on here has done this job and would be willing to provide helpful insight about how the trans comes apart. Is there a manual somewhere I could consult for such a task?

Thank you,

Andy
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Re: MUA5 Bearings/Synchro Replacement

Postby Ed Mc. » Thu Jan 21, 2021 4:11 am

Hi, Andy that's quite a tough transmission you have there!

Here's an old thread with a few pics and some good info, maybe that will help:

https://forum.planetisuzoo.com/viewtopi ... 5&p=231517

Here's a link to a downloadable scanned-in version of the 1988 Trooper shop manual:

https://www.mediafire.com/folder/tnmpva ... suzu_Share

You'll find Chapter 5, "Transmission With Transfer Case" quite useful, I reckon! :mrgreen:

Your 1990 MUA5 is virtually identical to the 1988 version; even if you had a V6 model, the internals are laid-out the same. Slightly different gear ratios between the Four and Six transmissions, different bell housing configuration, and the 4-cyl has a larger input shaft diameter. But either one will come apart and go back together in similar manner.

HTH & G'luck with the rebuild.....ed
'90 3.4 Troop LS;
'89 Troop RS (Exhaust Valve Challenged), now gone to a Good Home!
Yes, I am a Trooper-Holic!!!
Keep On Troopin' !
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Re: MUA5 Bearings/Synchro Replacement

Postby chevelle3504speed » Fri Jan 22, 2021 3:24 am

Ed,

Thank you very much! I saw the post you referenced, but not the manual. I am downloading it right now and will take a look.

Andy
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Re: MUA5 Bearings/Synchro Replacement

Postby chevelle3504speed » Fri Jan 22, 2021 3:34 am

Chapter 5 looks to be a great reference, indeed. Thank you again.

Andy
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