rebuilding and upgrading my AOR, with pics

last summer i bought an aor transaxle for my ecotec swap. i was tossed up between an aot and aor (the 3.87 fdr would actually be better for my engine) but i actually found an aor first, and being stronger in other ways, it was a no brainer. the transmission i got was put together for a v8 swap, so it had the n/a fifth gear swap done, however for my car that wasnt going to work. i figured that while i had the back apart for the 5th gear swap id install the stiffening plate, and things kinda snowballed from there. i decided to pull the entire unit apart to have a look-see, i dont want to have to go into this thing again. im taking pics along the way, for those that want to see whats these units look like. im not going to do a step by step walkthrough, imo if you are familiar with manual transmissions these arent that hard to work on.



to get the 5th gear bearing bolt off i used a spare input shaft coupler in the vice


rear housing removed, this is 5th gear


diff cover removed, thats the gear that drives the cooler pump


front case removed


removing the rear bearing race. a puller that big isnt needed, a 3 jaw will work fine, but having a proper gear puller makes it really easy


here is the rear housing, this is where the stiffening plate goes


here is the stiffening plate on the center housing


at this point im a little sceptical on the whole idea of the stiffening plate. i get the idea, but looking at it on the case and it doesnt seem that it would do much. im also a little worried about the plate restricting the return cooler flow. the cooler inlet is directly being the one shift rail, but it has a clear path to move into the main case. with the plate in place it would hit the plate and have to run down by the bearing. my biggest concern is the rear section will end up filling way up with oil and it could end up with oil frothing, and possible starve the front of the case. these are just some initial observations, i need to look into that some more.

i pulled the diff apart but forgot to take pics, ill grab some tomorrow.

Thx for this. Following. Been some years since I've had one apart, nice to refresh.

/Following.

I have an AOR that I will be needing to rebuild as well. Unfortunately I do not have any experience in transmission rebuilds, so I was sending it Kevin Gross, but haven't gotten around to it. Interesting to see its "guts" per say.

Do you or anyone else find the stock diff substantial to use with the LS swap, or does most everyone upgrade?

the factory lsd only has 2 friction discs in it, its kinda lame imo. it is a 4 spider gear diff though, it will take the power. reading on the kit car forums lots of people say the factory lsd is plenty strong.

many people who race will go with an aftermarket diff. im going to run the factory diff, im just going to put the thicker external spline discs in to stiffen it up a little.

took some pics of the diff



the guts taken out the the case


the spider gears


the clutch clutch plates


for those that may have looked into the plates in the lsd that are available, the steel plate with the 4 tangs is the selectable one, available in 1.9mm, 2.0mm and 2.1mm. this diff has the 2.0mm ones in it. my breakaway torque before disassembly was 23 ft/lb, or 31 n m. im trying to remember the spec (i looked it up the other day and cant find it again) but thats on the high side. im planning to install the 2.1mm plates to stiffen the diff up a bit.

is there a way to just swap in a lsd diff in say a 5p trans ? and is it doable at home i never mesured trans parts or change a diff

you can swap a factory or aftermarket lsd into a non lsd transmission. if you have ever built a rear differential its really the same principals, you need to have the proper gear pattern and backlash. when you change the diff carrier you pinion depth doesnt change, all you need to set is your backlash, its as simple as measuring the backlash of the old setup, and run a gear pattern, and once the new carrier is installed change the carrier shims till the backlash is the same, and the gear pattern should match.

if you dont understand my last paragraph, dont attempt it. ive seen many rear diffs people have worked on that didnt know how to do it, and it always ends up noisy and costing more money to fix. to remove the differential the front case half needs to be split from the rest of the transmission, so there is a fair bit of work involved. a shop should charge around 6hrs to install one for you. however it may be better to keep your eyes open for a good used lsd transaxle. the cost of an lsd diff ($500 for a used stock one up to $2500 for a real good one) and 6 hours labour to install (figure $600, plus some gaskets), a good used turbo lsd transaxle isnt terribly priced ($750-$1500 depending what one it is), plus in the end you have a spare non lsd, or you can sell that to get some money back.

i got the rear housing machined for the stiffening plate. i used my friends benchtop cnc milling machine, unfortunately the housing was too tall to machine with a fly cutter, i ended up having to machine it with a 1/4" end mill, and had to cut half of it, move the housing on the table and cut the other half. took a while, but i always have fun using this small machine.







one thing i didnt think about till i already started machining was the dowel pin holes, as you can see, they are now gone. after some looking every picture ive found of the machined covers shows people arent machining them deeper. to me thats an issue, the rear cover needs to be properly indexed to the case to prevent loading the rear bearing to one side. so thats something i have to tackle yet, and i need to make some longer dowel pins.

im still pondering the cooler return oil thing, but after a little more looking im not going to leave it alone. on the cast iron case, at the bottom left of my above pics there is one drain hole, that gets partially blocked off by the stiffening plate and you end up with a very small channel. on the right side of the bearings, right under the shift rail holes is another drain hole, the plate blocks that, and for oil to flow into that the level would be as high as the bottom shift rail, and thats even a restricted path.

i keep running across this picture on google



its pretty obvious here they are trying to direct the oil onto the gears themselves, i dont think this is needed, in fact, i dont think there is any benefit at all in these transaxles, i cant say ive seen a picture of an over heated or oil starved gear. im thinking about maybe running a small -3 line into the rear housing and a larger -6 hose the main case somewhere. im still thinking about this, id like to find more info on the setup in that picture, would be some good food for thought

so ive been picking away a little while waiting for parts. got the case cleaned up and started checking bearing preloads and such. i came to a startling discovery with the pinion shaft, it didnt seem to have much preload on the bearings, and upon measuring with the dial indicator it actually had .004" of backlash. the pinion bearings look in very good shape. the preload specs for the pinion bearins are 200-400n cm new (or 18-36 lb/in) and 30-60n cm for used bearings (2.5-5 lb/in). my only thought on whats going on is someone replaced the pinion bearings and set the preload to the used bearing specs. either way, this would seem to support the theory that the pinions become loose and hammer back and forth and cause the case to break. now out of all this, the gear pattern is perfect, so i just need to find some shims for the rear bearing so i can get this tightened up.

ive also come to a decision on what im doing about the oil cooler return. im going to put a fitting on the top of the cast iron case and run a -6an hose to it, as well as run another -6an to the rear cover in the factory location. this should keep the rear section from filling up with oil. really doing this may be overkill and i may be able to just return all the oil to the rear cover, but i feel a lot better doing it this way.

i got the pinion preload sorted out. i had to add a .006" shim to the existing stack to get it where i was happy. its now sitting at 7 lb/in rotating preload, im quite happy with that for used bearings.

got few other things checked off on the list. i drilled and tapped the cooler return hole in the main case section.



i also made the fittings to go into the factory oil return and the pump. quite simple, i just used a couple off the shelf -8 and -6an fittings and machined them down. this is one of those times i really like having my benchtop lathe. best $350 i ever spent.





im going to run a fan temp switch to turn the oil cooler fans on and off. initially i thought our drain plug was just 3/4" npt but later found out it was metric. i decided to just drill and tap the factory drain plug for my fan switch, it actually worked out pretty well




last thing i machined up some longer dowel pins for the rear cover. from what i can see, most people seem to skip this when adding the stiffening plate and just run the cover unindexed. i dont like this idea, so i did it properly



so now that i have everything sorted out ill be sending the case out to sand blast and ill be powder coating it before i assemble it.

Great job!
I hadn’t considered the dowel length issue.

To clarify, did you put the cooler return in the housing in front of the stiffener plate and avoid restricting return oil through the plate?

The cooler return is now going into 2 places. One hose will go into the rear cover in the factory location, the other goes into the main case section above 2nd gear. This will split the oil return and stop the rear cover from filling with oil.

Got it. I thought mentioning the return twice was a typo. Again, nice transaxle.

everything is cleaned up and masked for media blasting now. with that all taken care of i decided to tackle the diff.



all i did with the lsd was inspec it and change the external splines plates from the 2.0mm to the 2.1mm thick plates to add some more preload. i reused the internal splines friction plates, they were still just as thick as new so i decided to save the $100. i also put in a new set of diff bearings just for good measure. the end result with the thicker external splines plates was the break free torque going from 32 lb/in stock to 125 lb/in.

now there was some discussion in another thread about how to id an aor lsd vs a regular lsd, so i grabbed some specs off of my aor diff for comparison.

thrust washer thickness- 1.77mm
cup spring thickness- 2.07mm
internal splines friction- 2.53mm
external splined plate- 1.97mm (original) 2.06 (new "2.1mm")

finally got a change to sandblast and powder coat the trans case. turned out pretty good.






now i can start putting the transmission back together

i didnt take many pics while putting it back together, aside from one small detail. i meant to, but i got a little frustrated once i got everything in the center case and discovering i forgot to install the reverse detent in the back of the case, one of the first things you have to do.







now for the small detail. i discovered while assembling it that the gasket set didnt come with the o-rings or oil pump gasket. figured no big deal, ive got o-rings and the ill just silicone the pump cover. turns out the pump binds up without the gasket. i only found one place listing online (cogscogs.com) but after ordering it i got an email back saying its no longer available. there were 2 different options for it, a 0.20mm and 0.15mm, im hoping just the one i ordered is nla and the other isnt, but im not holding my breath. im going to have to track down some very thin gasket paper and try and cut my own.

still havent gotten to putting the trans in the car yet, but i have now mounted my trans cooler. i ordered this cooler from summit, going off the listed dimensions i would have been able to put it where the factory cooler sat, mounting it off the bellhousing. turns out the dimensions were wrong, and ive had this thing for months, so no returning it, so i just made something work.





its in a less than ideal location with no direct air flow. looking at the factory cooler and a few options other people have done, it doesnt seem to be a big issue. the 2 fans pull a lot of air across the cooler so i think it will work alright. plumbing it will be a little interesting, however ive found some low enough profile fittings to get it done.

Excellent thread, very nice cooler/fan setup

For some reason I can't see photos from the start of the thread? They're just blank and if I try to open the picture directly it says 'url expired'

yea ive been using facebook to host pics and apparently the links expire after a couple months. im working on uploading all my pics to another photo host, ill have to go through and repost them.

ive rehosted all my photos of my swap. click the link in my signature

[/quote]




[/quote]

Just curious how you're getting power for the fans through the stub axle.

im running a real small invisible generator in the stub shaft, , its gonna vary voltage so the fans spin faster with more speed. and also dont worry about how im gonna bolt the axles up, i plan to use bluetooth to transmit movement from the transmission to the wheel hubs

got a couple pics of the final assembly with all the oil lines made up. its now ready to go in