Lately my B110 understeer badly on wet road.
Slight decrease in dry road.

Front Wheel spec:
Hayashi 13x5.5jj et10 185/60R13 + 10mm spacer
Rear Wheel spec :
12x4.5jj et22 155/80R12

Front Suspension spec:
Std absorber(change to higher visco oil)
Custom Lowered n Stiffer spring

Rear Suspension spec :
WELD DIFFERENTIAL
STD Leaf Spring
Merc 123 Absorber (Rough Ride)

Alignment specs:
Front Left Front Right
Toe = 0.3deg 0.4deg
Camber = -2.5deg -2.5deg
Setback= 27.5mm 32.5mm
Caster = 3.8deg 2.8deg
KPI = 9deg 9deg
Max Right= 43deg 35deg
Max Left = 33.5deg 42deg

I already tried to increase/decrease frt/rr tyre pressure but still getting hard understeer..
Wat seems to b the problem???

could be the welded diff thats causing it?

I was going to say the same thing.

Welded diffs are for race cars or powerful street cars in countries where you dont get jailed for screeching tyres.

My money is on the welded diff for sure. Typical charateristics is understeer into corners and oversteer coming out. Do yourself a favour and swap the welded centre out for an open spinner or even better a LSD unit.

Ronald while I too suspect the welded diff is the root cause you have several things going on with the set up. First what condition does it understeer? Corner Entry? Mid Corner Exit? Under Acceleration?? Steady throttle?

First there is the welded Diff, then you're using 60 series fronts (stiff sidewall) in combination with 80 series rears (tall soft side wall). Also you put stiffer springs in the front while leaving the stockers in the rear which will also changing the balance toward understeer. Finally while you put heavier oil in the front dampers if it can't control the stiffer spring the front tires will be oscillating up and down (read not on the ground)

Put the open diff back in, get a matched set of tires, if the rear isn't lowered to match the front correct it and then see what it does.

Tom

Thanks for all the reply...
I welded the diff quite sometime d...
It was ok tat time...
Is when im when i steer into corner medium speed(wet road)my car started to understeer even i didnt throttle.
I get worse when i suddenly steer while cornering...
Stiffer rear suspension will oversteer more rite??

Yes stiffer rear will mean more oversteer or less understeer but you have to fix the root cause. Go step by step: first find a standard diff install it see what that does. Next get 4 of the same tires on the car. It just seems like you've get a really off the wall set up on the car trying to get a round a problem........which caused this problem.

Tom

one of the biggest issues witll be the difference in tyres front to rear as well as the wider front track compared to the rear(12 mm spacers and such a large contact patch of tyre).

get some 18560 on rears and lower it- leave the lock diff for now and you should see far less understeer. fine tune from there with stockdiff center if you want or add swaybars into the equation. should balance out a fair bit

I used a welded diff with the 1200 GT5 car (picture avi). Car handled very well on the race track. Never drove on road. The welded diff required a "throw it in there" type of steering, throttle, brake style. If I tried to drive smoothly into a corner it would understeer quite a lot. If I drove like I was a bit "mad" at it things went much better. Biggest thing that I did chassis-wise was to free up the leaf springs as much as I could and install an adjustable panhard bar to allow for adjustment of the rear roll center as track conditions varied.

I agree that the wwelded diff is probably causing the majority of the problem.

Thanks again for those replies...

Unfamiliar : I dont really get why wider rear tyre with lock differential will understeer less when i use 15580 tyre...
Can u describe how?
BTW my rear is lower the front d,if i lowered it summore i think it wont look nice... :D
TQ...

As for the lock diff,i need it for track use... :)
Im trying to make my car understeer less but remain lock diff...