Problems with differencial/suspension?

[dysfunktion]

Hello, thanks for taking a look.
So I'm having some trouble with my 89 niss 240, some basic details that might be relevant to know listed below:
stock ka24e
j30 diff
hks coilovers
lowering springs
my suspension is very stiff, so my car will bounce on the smallest crack
The problem I'm having is using this car as a dd as well as drift car. It seems like it slides too well, everytime I take a trip over like 2hrs, or about 120mi, i get out and see that my rear tires are completely f'd up. They are down to metal within a weeks of buying NEW tires, and these are my dd tires, not drifting tires. This is what I know, I originally had a welded diff that I swapped for a j30 because the weld was about to break and it was no good as a dd, When i drive in the rain, just the smallest bit of extra power will send my car into a drift, which is fun...but impossible to drive in the rain. When i try to drive straight on a wet road, i can feel my car sliding back and forth. At first i thought it was just the tires, but when i replaced them with brand new tires, the same thing would always happen. As nice as it is to have an easy to drift car, it has become very expensive and time consuming. I'm looking for any ideas on what might be causing this? My best bet is the j30 diff, i think it is transferring power back and forth too much and that is what causing my car to slide back in forth in the rain. I also noticed that when my tires are startin to go bald, somethin as simple as driving over the painted lines on the road or any slick surface will cause a tire to slip.

Any help or ideas would be greatly appreciated.
Thanks

[rioredstang]

Trying to dd and drift is a hard nut to crack. You need a very stiff springs in the rear to drift, not good for normal driving. I don't know what spring rate you have, I have a road race car and I only run 275lbs springs in the rear. To drift you would run much higher rates 400 to 450 in the rear. With that said, I think your biggest problem is in your alignment. You need to find a good alignment shop that deals with race car suspension's. There are some good posts on here with alignment settings.
The rear suspension has alot of bump steer if the rear trailing strut rod has been adjusted. If you change your ride height with the coilovers this will change the alignment. Set your ride, then get it aligned.

[Crazyirish]

Have an alignment shop check your toe in the rear. Improper toes settings can destroy tires in no time.

[dysfunktion]

Thanks for the response, both of you. I knew my alignment was off but thought it might be something else causing the problem, didnt want to get an alignment and then end of having to change something else just to get an alignment again after. But ya, thanks for the info. Now i just gotta find a shop that will do an alignment on a lowered car here

[moso]

have you replaced the stock bushings in the rear sub frame, or gotten collars. if not you may be experiencing sub frame shift. bad bushings in the uprights and rucas or toe arms can cause unwanted alignment shifts as well.

[liquid_cool]

have you replaced the stock bushings in the rear sub frame, or gotten collars. if not you may be experiencing sub frame shift. bad bushings in the uprights and rucas or toe arms can cause unwanted alignment shifts as well.

nail on the head!...i wuld allso suggest setting the suspention..ie..caster camber ect..back to original nissan spec's...our whole team runs oem alignment spec's with coils and fully modifyed suspentions as most of us DD our rides to and from work aswell...it's still easy to break the rear out but we dont have the ride issue and fish tail effect from excessive toe, caster ect...try it..you might like the ride..good luck man.

[OutToWinPAHC]

Sounds like sloppy bushings and a misalignment issue.

[sabretooth91]

I'll piggy-back on this thread. I saw you discussing toe, camber, and caster. I'm planning on doing a suspension overhaul on my 240. How do you adjust these settings? Yes, I know it is a very noob-ish question. Sorry. I'm sure it depends on what suspension you buy. But if anyone can get me started with this, it'd be great. I'm just trying to picture it in my head before I get in over my head. Thanks.