I had a wonderful idea of welding a rear diff and putting it into my car so I can do doughnuts and have a little experiment with. So to speak this is one of the mini projects that I have. I went to "U Pull R Parts," the north yard and pulled out a rear diff/carrier from a MY90 Legacy AWD auto tranny. These MY90-MY91 run a 4.111 whether it be an auto or manual tranny. MY92-MY94 run a 3.9 for autos and the Turbo Legacy where as the manual non-turbo Legacies run a 4.111. SO I have a 4.111 rear diff/carrier and its 4.111 ring gear on it. I ask my brother to weld its spider gears and spider gear to the carrier/housing. We get it welded and during welding, Lee and I dropped out the rear diff. After welding, we swapped ring gears between the differentials/carriers and torqued the 8 bolts. Then we put the welded diff into the case, torqued the bolts, swung it under the car, plugged axleshafts in, jacked up the diff case, tightened screws/bolts, put gear grease in (SMELLY!!!), and drop out with the inside tire scrubbing in every corner. I went to a DIRT parking lot to test it out. I didn't go to a dry pavement lot just yet because I know that I don't have THAT much power to break the tires loose. So i turn the steering wheel, go around in a circle and gas it. The car gets sideways and then the rearend SWINGS around! Next thing you know I'm sitting there spinning like a top! I try this at another gravel lot and the same thing. Then I take her to this S turn.... and turn in with slight understeer, so I give it some gas so the rear wheels aren’t fighting each other during deceleration. The turn starts to open and I gas it. The rear end just stepped out and kept it like that. It almost felt like a RWD car, then again I've never driven a RWD car near the limits at all. Next stop, clover ramp. I go into the ramp at my usual safe speed 45mph and then start approaching the limits of my tires. I was surprised the car still stuck at the same speed. In contrast, the car would TURN-IN when I gassed it. Let off and it'll push/understeer due to it being a locked/weld diff. So to speak, POWER oversteer, LIFT-OFF THROTTLE understeer, light gas neutral/slight understeer?. Next was doughnuts on dry pavement. I didn't think that I WOULD be able to do them due to the power that I have. Just an axle-back and free-er flowing air filter doesn't do much really, some but not a whole lot. So I come to an intersection, not a stop light one but just a stop sign one. I make a u turn i 1st gear and gas it a bit. It just starts to get a little sideways and then I clutch in, pull the e-brake, get a little sideways, gas and let go of the clutch. It now starts to get sideways and the circle gets smaller, then it just spins like a top. I start to see tire smoke and the smell. EWW I pull off another one of these at my cousin's house and the driver side front "bumper to bumper" axle shaft BREAKS at the joint near the hub. So now the center diff is working hard to keep the front driver side front from spinning. I HAD to drive home from Cliff road (Matt, near you?) on 35E back to St. Paul.... I was light on the gas during starts and light on acceleration so to NOT over spin/heat up the center diff. The next morning I grab another axle shaft from the STEALERSHIP and install it in. After doing so I go out and pull another SH*TTY ( LOL ). SMOKEY! So Yia's car is now broken and he needs tools. So I go over with some air tools and air tank, jacks and jack stands and start wrenching. I get home the next night and noticed that the rear tires aren’t chirping anymore. I then try to pull another SH*TTY and can't get the rears to come around with a e-brake pull. That's when I knew that it wasn't working anymore, thus thinking the welds broke? Hmong New Years day and I was going to drive my car. Just a light dump of the clutch at 4k and it jumps then CLUNK, and the car grinds mad. I slip it again and grinding noises. Then I think to myself, "Well, there goes the passenger front axle shaft." I climb a wheel up on the curb and because of the stiff rear bar, I climb up one front wheel. I ask my people to observe wheel spin from the rear, NONE. Then reverse one rear tire up on the curb and ask them again for the front, NONE. I do the same for the other side and no wheel slippage from the rear at all. ------This is when I concluded that either a rear half shaft spline is stripped or the rear diff/ spider gears are broken. The nest day we drop the rear diff out and find out the bad and good news. BAD: Broken spider gears. They literally broke in HALF! GOOD: My ring gear and the pinion gear are still good. Lucky THAT didn’t chip or else I would have had to find me a 3.9 rear diff pinion and ring gear OR the whole rear diff with the case and everything. We swapped ring gears again, stuck the OPEN diff back in. The car would hop or jump along when I would be in 1st gear making regular corners on the street with the WELDED diff. Now it’s just back to the smooth stuff and power understeer. The rear bar helps but not like what a rear LSD or welded diff would. I’m going to try to weld it again, now this time the whole thing is going to be almost filled up. Yea, I’m cheap but this WAS a risky thing that I pulled off. If you’re not as CRAZY and don’t want to try things out like this then I’d suggest you purchase a LSD like what Matt said to me. But yea, I’m cheap, so haha! Pictures of DOUGHNUT marks. Can’t really see them because it rained before I went back to take the pic. Pic of the case and diffs. The one on the right is the broken one, the left is my stock one.
Clap! Clap! Clap! Bravo... you sure have the time and extra cash to throw around. Just don't get yourself in deeper trouble in the process.
