Patrol GQ Auto - RE4R03A - Missing Gears Diagnosis and Repair

[waflyer]

Great write up mate, This write up was a lot better than mine ( which I never finished writing! ) this deserves to be made a sticky

Cheers mate! Planning on finishing off this thread over the next couple of evenings.

Your own was really the catalyst for me giving this a go. With a little luck this and yours together might inspire others to give this a crack, if they, like me, have a vehicle they use for fun, don't need as a daily and can spare some time to save some $$.

[waflyer]

Next job as I said was the cleaning....definitely the worst part of the whole job. All the external surfaces were covered in 22 years of muck. The internals were covered in burnt on black friction material. Took ages to get all the bits clean and dried off:



Was also pretty amazing how fast the parts rusted (in minutes) following degreasing and drying if not oiled up with ATF fluid. Here is the pile after cleaning:



Next up the rebuild began in earnest starting with the oil pump. I basically just followed the order of the workshop manual but it is useful to do the oil pump first as you can test the two clutches towards the front of the box using it. After rebuilding each component I lubed them up with ATF pretty liberally and put the in plastic bags for storage since I was rebuilding the components over a number of evenings:



From a pile of clean/new parts assembly of the internal components is very quick. I also checked the amount of play in each clutch pack using a calliper versus the specs in the workshop manual. I guess this is important as if there is too much or too little play you might be in danger of undoing all your good work prematurely through accelerated wear. Lucky for me all tolerances were ok, however, if they are not you can get different width packing plates to account for any discrepancy. Here is one of the rebuilt clutch packs:



Once I had rebuilt all of the clutch packs, two in the front half of the gearbox, two in the back half and one on the casing, I started putting the box itself back together. This is a pretty simple process of reversing what you did on disassembly but with new seals and thrust washers. Each of the needle bearings were thoroughly cleaned with solvent and lubed up with petroleum jelly. The only slightly complicated part is checking the play in the gear assembly within the box. Using a calliper you measure the distance between the oil pump housing and the front gear set. This has to be within certain tolerances and it is adjusted using washers of different thicknesses. Luckily, again, the one that was originally in mine was to spec after the rebuild so no further change was necessary.

After a couple of hours of reassembly you end up with something like this:



...pretty much all ready to go back in!!

[waflyer]

Now to find out if it actually works after all that hard graft...

I have to say at this point I was nervous!!! This hopefully gives me an excuse for the fact that at this point in the rebuild the photographs pretty much dried up! However there was not a lot to see that others and this thread hasn't already covered but I will give a run-through anyway.

First job was to pickup and fit the reconditioned torque converter. This is a bit awkward as there is a key way in the oil pump that needs to engage correctly. Apparently if it isn't done correctly you can damage the oil pump beyond repair (as well as potentially your newly reconditioned torque converter). Fortunately there are more measurement specs in the workshop manual that allow you to check for certain if this keyway is correctly engaged. Now the gearbox was all ready for installation.

Me and a mate refitted the box in half a day or so using the same table jack as we used for removal three weeks or so before. This time though we only put the gearbox in leaving the refit of the transfer box for later. This made the whole package much lighter and easier to manoeuvre so I would definitely suggest this to others. We then used a series of chocks to get the gearbox bell-housing and the block parallel so the two would just slide together.....and they did!

After that we bolted up the flex plate to the torque converter using a bit of threadlock and then simply bolted all the bits back on including the transfer, driveshafts, oil cooler lines and coupled up all the wiring. Last job was refilling the gearbox with the 8-8.5l of fluid it required.

At this point I kept looking for things I had forgotten to avoid turning the key! But with nothing else left to do/check I put the key in it, gave it a crank and started it up. No nasty crunches was a good first sign so I was pleased with that! I was even more pleased after a minute or so of the rig running that when I dropped it in reverse it crept back and when I dropped it in drive it crept forward!!!!

So I had at least 2 gears: forward and reverse! Next up was a quick road test, which confirmed I had all forward gears and reverse working perfectly and the torque converted locked up at ~85kmh. Result!

[waflyer]

So the gearbox has been in now for a couple of weeks and 500k's or so. It's a completely different vehicle now with smooth changes. Took it for a run up to Lancelin from Perth and back and it didn't miss a beat!

Would I do it again? Yes, for sure. Although I now have a lot of respect for the gearbox mechanics around (especially the auto fellas), I reckon when you have an old truck you should know it inside out and, if you have the time, fix it yourself if you can. I wouldn't say it was hard to do but it does take a lot of time. My girlfriend felt like a widow at times so be warned a project like this (especially a month after you bought the vehicle!) could cost you more than you bargain for!

I rebuilt mine to completely standard spec. I will be adding a temperature gauge in the very near future and probably a nomad valve body shortly after that but for now I am happy with having all the gears again! Hopefully will get many more k's out of the old truck yet!

[kiwijase]

way to go man,id be shitting myself if my trans shat itsself.
Nothing like that feeling of doing it yourself eh.
Very usefull post aswell,cheers for the effort of your write-up.

[ripper]

Awesome write up, and well done on the entire job.
I had the missing gears problem very soon after I'd paid for a complete rebuild to be done. Mine was an electrical problem, but certainly not easy to fix, as it would only play up intermittently. All good in the end though.

[tricksgonefishing]

Thanks for that it is very infomative. Ive just bought a nomad valve body and a will set up a lock up switch and after reading that I think Ill add a cooler and gauge as well because I just bought a boat and will tow it with a GU 4.5 Auto

[ripper]

after reading that I think Ill add a cooler and gauge as well because I just bought a boat and will tow it with a GU 4.5 Auto

I'd do the gauge first. Looking at Davies Craig coolers, they say anything over 93C is really bad for the ATF. If you don't get that hot, the factory cooler is big enough (though I don't like the way they go through the radiator).

[spoonie]

Awesome work. Good to see its all working well. Great post.

[lg 91]

Awesome work mate my auto recently let go so it getting pulled out now I've got a second hand auto lined up out of a efi model so it's got the big tc and ribbed bell housing but now since reading this iam thinking I will keep the old box and rebuild as a spare