Skids changing down

[Matt777]

Hi, I have a problem that when I change down that the front n/s wheel can lock up briefly, toyota said i'm to harsh with the clutch because it's a big engine but I find that hard to believe especially as it's in rear wheel drive mode so that shouldn't affect it. Any ideas??

My Surf is a KZN-130 3 litre Turbo Diesel

[exmee46]

Hi, I have a problem that when I change down that the front n/s wheel can lock up briefly, toyota said i'm to harsh with the clutch because it's a big engine but I find that hard to believe especially as it's in rear wheel drive mode so that shouldn't affect it. Any ideas??

My Surf is a KZN-130 3 litre Turbo Diesel

The 2wd/4wd actuation is made by simply sliding a collar across the front n/s axle to lock the wheel end of the shaft to the drive from the front differential. So in fact, there is drive to the front diff all the time from the gearbox, although none reaches the wheels since the diff allows the n/s axle to rotate freely in 2wd and the o/s axle is locked to the front o/s wheel permanently. When the collar in engaged by the vacuum actautor, the wheels are then locked to the drive train. Since there is no centre diff (between front/back) , this must only be done on soft ground since any difference in rotational speed between front and back (e.g. by turning a corner or having different rolling diameters due to tyre pressure differences) will cause the drive train to 'wind up' and become increasingly heavy to drive until either a wheel lets go and skids or some component breaks.

Hard to see how you can be getting your symptoms but first thing I would check is that the 2wd/4wd actuation is working properly and that when in 2wd you can rotate the n/s wheel freely when it is off the ground.

Kev

[TonyN]

Shows how much a so called expert knows! If your on the brake at the same time, the calipers are probably sticking, if your not on the brakes then something mysterious is happening with the 4wd, which sholdn't be on on the road.

[Matt777]

just jacked it up and the wheel does spin freely, slight noise from bearing's so i'll be replacing them. The problem happens when changing down and isn't affected by braking. It is worse the faster you are going, it pulls you to that side. If you drive it gently it's ok but surely that is not correct. Any other suggestions?

[da SLUG man]

The 2wd/4wd actuation is made by simply sliding a collar across the front n/s axle to lock the wheel end of the shaft to the drive from the front differential. So in fact, there is drive to the front diff all the time from the gearbox, although none reaches the wheels since the diff allows the n/s axle to rotate freely in 2wd and the o/s axle is locked to the front o/s wheel permanently. When the collar in engaged by the vacuum actautor, the wheels are then locked to the drive train. Since there is no centre diff (between front/back) , this must only be done on soft ground since any difference in rotational speed between front and back (e.g. by turning a corner or having different rolling diameters due to tyre pressure differences) will cause the drive train to 'wind up' and become increasingly heavy to drive until either a wheel lets go and skids or some component breaks.

Hard to see how you can be getting your symptoms but first thing I would check is that the 2wd/4wd actuation is working properly and that when in 2wd you can rotate the n/s wheel freely when it is off the ground.

Kev

that's just the ADD... 4wd is selected throught the tranfer box... is it not?...

[dave.j.robbo]

just jacked it up and the wheel does spin freely, slight noise from bearing's so i'll be replacing them. The problem happens when changing down and isn't affected by braking. It is worse the faster you are going, it pulls you to that side. If you drive it gently it's ok but surely that is not correct. Any other suggestions?

Just a thought, but when you jacked it up to see if the wheel moved freely, was the truck in gear? If you were in neutral, all the wheels are effectively isolated from each other anyway...

Needs to be in gear to do this test. I assume yours is manual??

[exmee46]

just jacked it up and the wheel does spin freely, slight noise from bearing's so i'll be replacing them. The problem happens when changing down and isn't affected by braking. It is worse the faster you are going, it pulls you to that side. If you drive it gently it's ok but surely that is not correct. Any other suggestions?

Just another idea - are you sure the wheel is actually skidding - or are you just assuming it is because the car lurches to one side? Does it pull the steering wheel? If not, maybe there is something wrong at the rear with the axle location and when you let the clutch out the axle is moving out of true and making the car squirm.

Kev

[Matt777]

Just another idea - are you sure the wheel is actually skidding - or are you just assuming it is because the car lurches to one side? Does it pull the steering wheel? If not, maybe there is something wrong at the rear with the axle location and when you let the clutch out the axle is moving out of true and making the car squirm.

Kev

I put it in first gear when i checked it and yes it's manual, it definately skids you can hear it and it leaves some rubber. I've checked out on mud if 4wd spins all wheels and 2wd just does rear and it's correct.

[dave.j.robbo]

OK, a wild stab in the dark, but do 3.0 Surfs have ABS?

If they do, maybe the brake's being applied????

[Rob]

not 2nd gens, only 3rd gens as far as i know.

[Uplander]

not 2nd gens, only 3rd gens as far as i know.

Hi,
I would have a very good examination of the driveshaft to that particular wheel, by getting a prybar and testing for in and out wear. Also check wheel bearings by raising wheel from ground and getting a good two handed grip top and bottom / fore and aft to try to detect any undue movement. Otherwise can only be brake problem IMHO.

[TonyN]

I had a really manky CV in one truck, that would almost lock up when you had some thing heavy in the boot, and it was running at a sharper angle than usual. The wheel would spin nearly one turn and jam up when spun by hand, when driving would bang ever revolution. Was OK at normal angles.

I'd pull the hub drive plates and drive around and see if it still done it, this would eliminate and drive train issues, leaving you just with the bearing.

[Matt777]

Just to add. I've been out in the fields in 4wd and the wheel does not appear to lock up in either Hi or Lo ratio, which is nice, it does however continue in 2wd! it's by no means undriveable, just a bit baffling as to why. If you drive gently using hi gears and low revs it's fine but changing down to a gear that would bring the revs up say 3000+ is when it happens. Thanks for all your help so far.

[Chillitt]

is the down change moving the engine over and making something rub/ short/ground? sounds like you need a witch doctor on it..!