Hmming noise from rear as I cruise in gear from 3000rpm down to 1500rpm.

92DSMGSX · May 26, 2003

i looked into my repair manual from Haynes and I found how to fix the problem. but i dont understand this whole preload thing. You have to take an inch torque wrench and see how much torque u have to put to turn the wheel/axle correct? then what? whats the preload deal and the excessive gear play? help!

92DSMGSX · May 26, 2003

and barney, whats the backlash? how do you check to see how many inches it is?

92gsx-act2100,slightly ported 14b, 2.5" cat back, balance shafts eliminated, walbro 255 fuel pump, symborski shift kit, clear corners, polyurethane motor mounts, jdm 4g63t engine, magnacore wires, iridium plugs, hacked mas, kyb agxs, eibach sportlines, polyurethane suspension bushings, blitz fatt turbo timer..
1/4 mile-14.950 @91.76mph(first time drag racing)
60' - 2.212(shitty!!!!)

Rodman · May 26, 2003

Yea, so what is this 'shims' thing the Haynes manual talks about if the preload is out of spec, more importantly IS this what is causing the sound?

92DSMGSX · May 26, 2003

yeah! I read that too man! hm... someone that knows this stuff should help us out. a lil help? :-( i dont wanna go and try to fix it and fuck shit up that i cant fix!

barney · May 27, 2003

Preload - when you set up a bearing you don't want it so loose the gear can slop around and you don't want it so tight the bearing wears out. Hence, adjusting preload.

Lash - where the ring and pinion gears run together the teeth mesh. Metal expands when it gets hot so you don't want the teeth to mesh too tighly or the gears will bind. On the other hand, too much lash puts slop in the rear end that you can feel when driving. The amount the gear teeth mesh is adjusted with shims- a fancy name or washers of various thinknesses.

Setting up a gear box is an art. If you don't feel up to doing it, there's probably a shop nearby that can do it for you. Most of the expense is pulling the differential out of the car which you can do yourself.

Rodman · May 28, 2003

Ok, so where are the 'shims' placed in relation to the ring, bearing and pinion gears?

turbo90awd · May 28, 2003

I once disassembled a 3-bolt rear that I broke some teeth off of during a hard launch. The shims that you guys are discussing are wedged between the main bearings and the inside wall of the diff. housing. There were 2 shims on one side and 3 on the other. I've read the procedure for adding and removing shims before in the shop manual and it really is a pain in the ass. You need a dial gauge to measure the gear tension once you adjust the shims because if it is too tight, the shims wear out and you're back at square one. As mentioned before gear lash is pretty important too so, you need to mark the pinion gear teeth with some paint and see where the teeth are touching in the ring gear's landings. Then you need to adjust the gear lash to put that resting place right in the middle of each tooth. Too much on the outside or inside will cause gear noise and eventually damage the gears.

I thought about all of this and became disgusted with the whole procedure. Maybe a replacement diff. would be easier, certainly not cheaper though.

92DSMGSX · May 29, 2003

alright now i understand. thank you, but how do i go about fixing it? just like what it says on Haynes manual?

turbo90awd · May 29, 2003

The Haynes manuals are cheesy and don't cover all the details to the point where I would be happy tearing a diff. apart. You really want an OEM shop manual or the DSM manual CD that you can get from www.manualcd.com

You will need several special tools to do a rebuild of the rear diff. properly:

dial gauge with a flexible arm and clamp type base.
large vise
set of feeler gauges for checking clearences of shims
bearing press (not totally sure but, I remember them being hard to pry off)
special oil proof paint to mark tooth mesh for checkin gear lash
good torque wrench (drivetrain parts have to be torqued down right unless you want them falling apart)

Get some blue loctite too.

I recommend that you check out the OEM shop manual before you take it apart. You'll see what I mean. Also, don't forget that you have to buy all the replacement parts too. They aren't cheap and they'll most likely need to be ordered because they are not usually stocked.

Good luck.

92DSMGSX · May 29, 2003

sounds like a lot of work. I haven't really done too much with drivetrain internals. Should I take it to the dealer/shop if i dont know what im doing? also, is there another solution to getting this noise fixed? just torque the pinion flange nut correctly? hm.. i think i shouldget a shop to do it right cuz ill probably be lost... but any other ideas?

92DSMGSX · May 29, 2003

one more thing...
how many hours/time will it take a mechanic to work on it to get a 'rebuild' done? because i dont want to pay incredible amount in labor, if so, i might have to do it myself

, parts are gonna be expensive also correct? what all parts need to be replaced? I might need to only adjust the lash because i hear a clunk when i shift.. that might be the problem. ahhhhhh i hate cars..but i love em'.

o well i

FastRthenU · May 30, 2003

funny you guys should be talkin about this. I just got my car back on the road after I installed tons of new parts. The rear end started to make noise on decel. mostley at around 3000-2500. I thought the lash was out, and i would fix it on the weekend. But it got worse everyday. Till yesturday the diff broke on me. IT thumps lika a bastard in the rear, but still drives. I think i broke a few teeth. Or maybe the whole carrier

turbo90awd · May 30, 2003

I broke 2 3-bolt diffs. on my 1990 TSi and 3 driver's side rear axles before I learned my lesson. I finally broke down and got a 4-bolt setup and it lasted for the entire time I owned my car. The coastdown noise showed up at some point but, I really didn't have the tools for the job.

My opinion is this:

If you have a 1990-1991 AWD car with a noisy/broken rear diff., just ditch it and the rear axles and get a 4-bolt. Game over. You'll be glad you did it. The 4-bolt can take some serious beatings and never break down on you.

If you already have a 4-bolt that is noisy then you can, find another diff. (probably cost you $200-300) or you can buy the parts ($100-200, depending whether you need a new pinion or ring gear) and pay some shop $50-100 (not counting removal of rear diff from car) to put them in for you.

In the end, the repair will get you going again but, you should make sure the diff. is built by someone with experience otherwise you'll end up in the shop again. I'd bet that the folks over at TRE (Team Rip Engineering) might have some experience with this and could make some suggestions as to the best way to handle the rebuild. Perhaps TRE could suggest some stronger parts to get a longer life from the diff?

92DSMGSX · May 31, 2003

good post turbo90awd, how long does it take to get the rear diff off the car? theyre fuckin heavy right? seems liek long because u didnt really add the amount of time in the labor.. I have a 4 bolt diff. and i think its getting worse everyday. Im tryin to look for a place that has experience with rebuilding rear differentials. and also how long does it take to rebuild the diff in case some shop tries to rip me off.. lol thanks dudes!

turbo90awd · Jun 2, 2003

The diff. weighs about 25-30lbs. You can drop it alone.

You need to:

Drain the diff.
Use 2 - 12mm wrenches to loosen the nuts/bolts on the axle flanges.
Use 12mm wrenches to loosen the drive shaft from the diff. drive flange.
Use a brass hammer or rubber mallet to tap on axle flange to crack loose.
Use a prybar to pry the axles out of the diff.
There are 2 - 16mm bolts going from the subframe down into the top of the diff. (If I remember properly) You need a stubby 16mm wrench to crack them free (very little clearence up there).
There are 2 or 3 16mm bolts going into the back of the diff. (cover) through a support bracket that is butted up against the diff. cover.
Once these bolts are free, the diff will tilt down fron the front and then you can pull the back down while moving it towards the front of the car.

Enjoy.

92DSMGSX · Jun 10, 2003

what all NEW items do I need from the mitsubishi factory(oem parts)? Or where can i get them online? I am going to take it to a shop that works on transmissions/drivetrain so i need to know what all new parts I SHOULD get rebuilt. Thanks!

Hmming noise from rear as I cruise in gear from 3000rpm down to 1500rpm.

92DSMGSX

92DSMGSX

Rodman

92DSMGSX

barney

Rodman

turbo90awd

92DSMGSX

turbo90awd

92DSMGSX

92DSMGSX

FastRthenU

turbo90awd

92DSMGSX

turbo90awd

92DSMGSX

Top Contributors this Month

Recommended Communities