awg

My AW4 lost reverse a while back, so I replaced it with one I had bought off a guy that was wrecking some '96 XJ, same year as mine

Have put ~20,000km on it and it seems ok, but I thought to strip down the old one and find out the problem, with a view to rebuilding it

(I also have another spare, but it has been ratted of solenoids, TC, and harness)

Parts are very expensive in Australia, quoted $A1500 for a rebuild kit, and $4-6k for a rebuild !

I see that rebuild kits from the USA can be imported for about $400 plus $200 postage

Rock Auto do not seem to list any AW4 parts ?

There is a number of excellent AW4 / A340 rebuild Youtubes, and I have some AT experience, I see nothing that would prevent me tackling this job...apart from the expense
(the Youtubes show how to air test clutch packs, and measure the clearances...I have learned to do this during the process of dismantling, I may strip down the failed unit first to see if I can identify the failed parts

apparently losing reverse is a common fault on these trans, mine got very hot immediately before failing

Any advice on best sources of parts would be appreciated

I even welcome unsolicited opinions

cruiser54

If one of my AW4s starts to slip, I add 3 tablespoons of Vegemite. Fixes it immediately.

Seriously, they're probably all pretty good kits.

awg

haha, Vegemite just came up on another forum I frequent, as a USA poster is preparing to host an Aussie visitor

I opined it tastes much like I would imagine heavy axle grease would, in other words its vile stuff, even some cats & dogs turn their nose up at it
(for the unknowing its a very yeasty, salty spread, that one adds to toast, one of my school holiday jobs was working in a vegemite factory

Randy Bobani

Ebay is best source for Transmission parts. Heck, even the best transmission shops use Ebay for seal/paper kits, frictions and even hard parts.

https://www.ebay.com/itm/18262097908...Bk9SR5yyhfToYA

WIT is also an option. Their website isn't the most intuitive. I suggest calling them and see how much it would cost to ship the parts out to you.

https://www.wittrans.com/parts?type=...&notPictured=1

Before ordering anything, you'll want to determine whether or not you need frictions/steels. Some kits come with them. Usually the steels in these units look ok but you mentioned that it got pretty hot. Could be a clutch failure. If there isn't much friction material in the fluid, you could focus on this being an O-ring failure. You could pull the valve body and air check the low/reverse ports (the stack of ports in the rear of the case). Each apply piston is sealed via O-ring, could've gotten hot enough to blow one out.

Do you have a hydraulic press/ arbor press/ various pressing tools? The A340 pistons are spring loaded and locked with snap-rings.......... a little tricky service.

awg

Thanks for the good info, the first source sells the OH kit for less and the freight is much less, than the options that show up via Oz Ebay

The WIT site is confusing

I do believe I will take it apart before ordering any parts, which in one way is not ideal, but if I am careful, shouldnt be an issue, no hurry on time

I can easily fab the clutch pack compression tool from a piece of ~4" diameter steel pipe and some other bits of metal I have laying around, I have a press and various snap ring pliers

I do certainly want to try and diagnose the fault while stripping it down, with air checks, and I will measure and record the installed height of all relevant parts from the end of the case, as I take it apart, even though it takes extra time. I will also video myself

If I get stuck, I can use the other partly cannibalised unit to both check correct fitment, and possibly salvage steels if needed

I will check, strip and clean the valve body, as this can apparently cause the issue too

I have taken apart and re-assembled ATs before

these series of videos are made by an AT teacher for his students, and there is another series from IPT, plus others, between them and the manual, it seems everything is covered

(Part 1)

Randy Bobani

You didn't question why he is only rebuilding the A340 down to the center support? That's like a quarter of a rebuild. For instruction purposes, he should have pulled the center support because it is the trickiest part of rebuilding the Aisin 4 Speed.

Many A340 rebuilds end with a wrecked center support. It is an interference fit inside of the case and both the case and center support are super soft cast aluminum. That means cracking and scratching and galling is not uncommon. I heat up the case with a MAP torch before pulling it. It slides right out when the case is hot and once it's out, give it a good deburr and once over with scotch brite.

awg

He does the rest of it in the other 4 parts of the Youtube series

Great tip on heating the case, I will do that

At any rate, I will put up a thread on this forum to detail what I am doing

Realistically, this job is probably still a way off, as I have a fairly long list of "to do's" and something new usually pops up

Just checking the ATSG rebuild manual, loss of reverse but everything else works is not obvious what the failure would be using this chart