REAR DIFF QUESTIONS

[vr4play]

I found some pix of the car with the new springs on it here. click. Pix are on the bottom row. New brakes are in and I figured out the high RPM power steering steering cutout. Hopefully I will be faster this weekend. I have to check the alignment again because I got the thing airborne and when I landed I had the wheels turned, it seems to have changed something because the wheel is off and it pulls a little. Nothing I can't fix. The is a pic of the landing is on page 4 2nd row in the middle.

 

[gtluke]

did you stick washers in the PS pump? i need to do mine too

 

Your diff is working fine, you suspension setup is not. What springrates are you running Front and Back, And what swaybars are you on?

I may get flamed for this, but you NEED a bigger front swaybar. You are rolling/diving too much up front, and thus you are picking up the rear inside tire. You will likely have to go up in springrate in the rear to maintain the balance, but not necesarily. The car wont roll up front as much, therefore you are staying more inside the "meat" of the camber curve, increasing front grip. so you may not even need to do much, just tune your damper settings. Getting a super stiff rear diff is a bandaid fix, and a poor one at that.

I never ran a front bar on my old galant, and I did run a whiteline rear. But I never had a problem picking up the rear tires, as the springrates were stiff enough up front. But, a combination of both is best

 

Jeremy,
With the spring rates you described, the front bar should be a lot heavier. But really I would actually go with the stiffer springs in front than in the rear since there is more mass up front to support. As is the car will want to wallow in front while being oversprung in back. That will also help keep the rear planted. There will be a bit more push but you can get closer balance with tire pressures. Then you can also put your power to the ground better.
Mike R.
PS Sorry I missed going to the autocross in Columbus a couple weeks back. How'd you do?

 

[fivestardsm]

Here is a direct bolt in with a little bit of cup swap. Read inside.. TRE Rear

 

[vr4play]

I already have an evo diff. I just want to get it upgraded so it works like a Kaaz or similar. I installed stiffer front springs before the last event and the car was better. I wend out over the weekend again and the car feels great. I am not going to change anything else for a while. I have been auto-xing these cars for a long time. This is my second one. The original one had 400 front and 350 rear and it handled well. At an auto-x it made a loud pop and quite handling well. I searched for the problem with no results. To band-aid fix it I installed 550lbs rear springs. It worked rather well. I finally decided to retire the car because the chassis had 256k on it and it had been raced since before 100k. I just swapped over the suspension thinking it should still work well. When I was disassembling everything I found a blown rear shock and a crack in the uni-body. On the car that I race now I installed new rear Koni 2g shocks and used the same springs because it was what I has around. I also installed a big front bar so I figured the heavier rear springs would help keep the balance. My buddy bought a totaled Evo 9 to strip for parts and I got the rear diff. Clutch type should work good with only 9k on it. I called and talked to John at TRE and he advised me on what fluid to use to make it work best. The stock evo diffs don't really lock up very much and need to be upgraded. I am making over 350awhp so a better diff can't really hurt. I plan to get a front one as well but don't have the money right now. I have invested a lot in this car and I takes a while to start from scratch with a new set up. The first event of the year had rain and the car did well. Fastest time of the day. The second event was dry and the car sucked. It wouldn't go, stop or turn. I have since changed the tune, tweaked the cam timing, turned up the boost, made some suspension changes and bought new brakes. Now the car seems to do it all well. I think I just need to work on the nut behind the wheel. The car has good balance with a little corner entry oversteer that can be controlled well with the wheel and the loud pedal. I do suspension for a living although I am not an engineer. I did set up the car that got 4th over all in the one lap. He could have got 3rd but had a couple of problems that dropped him back. He did his first time attack a couple weeks back and dominated the street tire class by almost 4 seconds. Its only a wrx with 2.5 block and a 30R. Nothing else special. The diffs play an important roll in the handling of the car and I think I need one that locks up a little more. If I remember right when I put the Kaaz in Mike R's rear diff he noticed a huge improvement. I don't know if I need a huge improvement but a little one would help but like I said the nut behind the well needs work first.