drive bias

[lazylandy]

can any one tell me why my disco 1 would suddenly be really tail happy as soon as the road gets wet? tires are good, suspension is fine, 4wd is working fine ,just seems to want to let go doing normal speeds starts with under steer then goes into full drift, does it on gravel roads too if center diff lock is not in any ideas would be helpfull starting to get a bit dangerous.

[RangingRover]

My guess is your rear diff has blown up in some way thats caused the two wheels to lock together, making it act like a welded diff. Don't have a rear locker (ARB/Maxi/McNamara) fitted that has perhaps failed to disengage, do you? The fact that you get understeer first and then oversteer is what makes me say that. You might also hear an inside tyre skipping/slipping a bit if you do a tight turn in the dry in this case?

Having the two back wheels locked together will tend to make the front push wide, then when the front tyres actually bite, and start turning the car, the inside back wheel needs to turn slower than the outer, as it is travelling a smaller arc (this is after all the reason we have differentials, to allow for the difference in wheel speeds). If the inside wheel is locked to the outer, and HAS to turn at the same speed, it will spin faster than the road is passing underneath it, and it becomes a full drift as the outer wheel is now taking all the torque (since the inside wheel isn't providing any resistance), and will also break traction.

Other possibilities include the rear A-frame balljoint being completely flogged out, and letting the back of the body float side to side, unsettling the car mid corner, but you say you've checked suspension, and I wouldn't think that would cause initial understeer. When mine was flogged out, I just had a uneasy feeling of the back of the body floating out a little then thumping as it reached the end of the play in the balljoint - at which point you got on the power!

[lokka]

Yep i aggree with above sounds like the rear diff has some how locked up jack it up and spinn a tyre

[lazylandy]

cheers ill get the diff checked out dont have a rear locker not a single sound coming from anywhere wheels seem to spin one at a time off road just a weird new drama to figure out

[discothrasher]

do you have directional tyres on your disco cause if they are fitted wrong way you lose the tail end all the time

[lazylandy]

no i have just bought a new set of gt radial all terrains im starting to think thay are the problem, we did a trip off rd in the wet nothing even remotely hard and the slightest bit of mud would almost stop me dead with wheel spin even on flat ground i would loose all sterring control and braking..

[RangingRover]

no i have just bought a new set of gt radial all terrains im starting to think thay are the problem, we did a trip off rd in the wet nothing even remotely hard and the slightest bit of mud would almost stop me dead with wheel spin even on flat ground i would loose all sterring control and braking..

So its only done this since fitting the new tyres? If thats the case, could be well worth at least playing with the pressures, or if you can, borrow someone else's wheels and tyres for a little while.

How much pressure is in them? If it's above 35psi, drop them down to 34ish, and see if things improve. I'm guessing you would have checked them (especially having been offroad with them), but if you haven't, I have seen tyres come out of tyre places with 45-50 psi in them . Too much pressure could indeed give the understeer/oversteer you describe.

Being an all terrain pattern, I wouldn't think the tyres themselves should be low on grip - my 32' STTs don't give this issue, unless I'm pushing pretty hard on wet, tight and twisty bitumen under trees (which is to be expected). Even then, its only a little bit of nervous understeer, and not oversteer.

[matt_w]

have you checked the rear trailing arm bushes onto chassis? sometimes they let go, im running taller springs under my rangie