So today was interesting. I went to pick up my car after this long swap etc, they had just finished the ring and pinion for the rear diff.

Heres a background of the mods in the swap.

Full JDM STI motor and 6spd tranny with DCCD
I have the control unit for it
I purchased the conversion kit through rallispec which includes:
ring and pinion
propshaft etc

So we take it for a quick spin, and immediately we notice that the car feels as if the handbrake is engaged slightly . Then when you depress the clutch and turn the wheel, the car comes to a stop as if it is doing its own braking slightly.

This is odd, so the guy tells me its prolly just the lsd in the tranny breaking in etc. Blah blah blah, I head for home. I go to get on the highway and the car starts making these horrible metal rubbing/grinding sounds .

It shifts into every gear fine, and it stops making the noises when I depress the clutch. So I call up a friend and head over to his shop so that they can put it on the lift. We took it around the block so he could hear the sound etc also.

Coming back into the garage, the car locks itself up to where it can hardly be driven more then a few feet. We toss it up on the lift and check things over. The driveshafts and propshaft all look fine, so we decide to pull the plug on the rear diff.

We get it off, and its got an ok amount of oil in it, but could use more. We send the magnet in, and whats this, we pull out a chunk of the ring and pinion . Im thinking *** is wrong with the turd that put this together.

So basically the ring and pinion is fried, and it looks like my tranny is ok, hopefully . This means I have to reorder a ring and pinion and have it installed again, that and give the bill to the guys who did it wrong. From what I have heard its a hard thing to do, it has to be perfect or you have problems.

So hopefully I will have this resolved by weeks end, and be up and running finally.

Any thoughts on this?

you sure that it was a 3.90?

Originally posted by Jaxx
you sure that it was a 3.90?

Unless Rallispec sent me the wrong setup, the invoice was for 3.9

But, even if it was the wrong gears, they wouldn't have killed themselves after 10 miles like that. They would have instead caused a headache for the center diff. It's like using a STI 6spd with the stock WRX rear diff. If you do this, the rear diff wont be the one to suffer, instead the center diff will take the heat.

In my situation the rear diff took the heat, which leads me to believe that the rear diff was done improperly, but with the right gears. Hopefully this did not cause any damage to the center diff, at least for there sake.....

I've got a thread over in the transmission forum that's getting no replies: http://forums.nasioc.com/forums/showthread.php?s=&threadid=545545

I was considering doing the ring and pinion myself, but the procedure looked complicated, so I thought the "professionals" would do a better job. My dealership wouldn't do the work; said they had never done a replacement; they just order a new diff assembly. I think the shop botched the backlash adjustment. The spec is for 0.1 to 0.05 mm backlash, but I can wiggle the input shaft at least 10 times that amount. I sure hope my ring gear isn't as bad off as yours.

The tolerances were probably way to tight in the rear diff, or else there were no tolerances. With the thing assembled you should be to able to spin the pinion gear via the propshaft flange freely. The manual calls for a certain amount of torque and that's it. You should also be able to move it back and forth and feel the backlash in the diff, it's made that way so when the gears expand they don't bind, which is what sounds like happened in your case. I wouldn't have an "import tuner" type shop put that together, take it to a subaru dealer or to a transmission place. Do you know if the chunk was the ring or the pinion, they are two seperate things.

The backlash you feel when turning that shaft is supposed to be between .1 and .2mm, it's not a tiny amount, if you take a stock diff out of a car it's pretty noticable. .05mm is the maximum runout of the ring gear.

FRAGMENT: If the play is more, like you say, you'll hear major whining on accel and decel. Also you'll feel a noticable thunk when changing directions. The lash needs to be reset.

LICQUIDSK8S: Yours sounds like the tolerance was set way too tight. If you can, get the diff back to the people who did it. If not, at least pull the cover and inspect the gear for heat damage, or scoring.

Jay Storm
There's a fine line between "hobby" and "mental illness".
www.sourcemotorsports.com

Well, the shop looked at my diff today, and they told me the gears are ruined. Their mistake, so they will have to buy and install a replacement. It took about a month to get the gearset the first time.

I called Lachute to see if they have stock on the ring and pinion, and they do :banana:

Lachute also told me they have complete R160 diffs with LSD and 3.90 gearsets for $750 Canadian. Doh. That would have been a lower cost option for sure. With factory tolerances and assembly to boot.

Originally posted by fragment
Well, the shop looked at my diff today, and they told me the gears are ruined. Their mistake, so they will have to buy and install a replacement. It took about a month to get the gearset the first time.

I called Lachute to see if they have stock on the ring and pinion, and they do :banana:

Lachute also told me they have complete R160 diffs with LSD and 3.90 gearsets for $750 Canadian. Doh. That would have been a lower cost option for sure. With factory tolerances and assembly to boot.

Dah, I wish I had known of that. Thats much cheaper then doing a ring and pinion swap.

To do the swap you have to buyt the gears which are around $360, then labor to put them in $400-500. So thats around $700 - $800. Instead we can just pay $480-$500 for a brand new diff, and still have our old one to sell. Dah

Here is a pic of my NEW ring gear. This is after less that 50 miles driven at low speed. The pic isn't clear enough to show it, but the wear marks are right on the tips of the teeth, toward the outside edge. Obviously, many teeth are broken. The shop that did the work covered the gearset, but NOT the $200 worth of new bearings. I ended up buying a complete 3.90 rear diff from Lachute. This whole fiasco has cost me Can $1,400 and three weeks of down time. I shoulda just bought a complete STi rear...


http://www.deltaspeed.com/wrxparts.nsf/IMG_1964.JPG?OpenImageResource