Looking at a 98 Explorer XLT - advice please

[J_C]

^ After some more reading I have a better understanding what the transfer case clutch is doing. It's variable current and increases or decreases the amount of multi-disc friction/slippage instead of gearing to achieve the 10% torque steps.

It seems to measure front and rear drive shaft speed 50 times a second, and according to the wiki article linked below it seems to need 1/3rd a revolution of wheel spin mismatch to kick in which would not happen merely using same size tires but some with more tread remaining on them, BUT if driving conditions were to cause it to lock up the clutch then different tire diameters could still pose a problem, even going dead straight on pavement.

HOWEVER, I am still not convinced that this transfer case / system implies that there is always torque to the front wheels. On the contrary the design implies that clutch off, 0% front torque would make the most sense for fuel economy and wear, even if only a slight bit, when there is no rear wheel slippage measured.

https://en.wikipedia.org/wiki/ControlTrac

 

[koda2000]

That's correct. The only time drive to the front wheels kicks in is when there's slippage and different tyre size doesn't matter then.
I have different pairs front to back on mine and it makes absolutely no difference.
I do have some history in the tyre industry too.

I agree. The AWD V8's are a different story because all four wheels are being driven 100% of the time. There, keeping the tire diameter/wear and even brand are critical to prevent damage to the viscous coupling in the t-case.

 

[Flash]

I agree. The AWD V8's are a different story because all four wheels are being driven 100% of the time. There, keeping the tire diameter/wear and even brand are critical to prevent damage to the viscous coupling in the t-case.

It's a huge problem with the early Landrover Freelanders, the viscous coupler overheats and the silicon fluid become too thick then it's AWD all of the time and no slippage.

 

[Flash]

^ After some more reading I have a better understanding what the transfer case clutch is doing. It's variable current and increases or decreases the amount of multi-disc friction/slippage instead of gearing to achieve the 10% torque steps.

It seems to measure front and rear drive shaft speed 50 times a second, and according to the wiki article linked below it seems to need 1/3rd a revolution of wheel spin mismatch to kick in which would not happen merely using same size tires but some with more tread remaining on them, BUT if driving conditions were to cause it to lock up the clutch then different tire diameters could still pose a problem, even going dead straight on pavement.

When Auto is selected the front diff can only get 35% power, it won't lock up.

HOWEVER, I am still not convinced that this transfer case / system implies that there is always torque to the front wheels. On the contrary the design implies that clutch off, 0% front torque would make the most sense for fuel economy and wear, even if only a slight bit, when there is no rear wheel slippage measured.

https://en.wikipedia.org/wiki/ControlTrac

That's correct. In all but fairly extreme conditions there is no drive going to the front wheels when Auto is selected.

The automatic system works quite well IMO.
I've tried it out by over doing it on a wet road and that front drive just pulls you right out of a slide.

Another thing I did was to take off on soft sand in Auto with 38psi in the tyres.
It groped about a bit then took off and kept going. That was with Highway tyres on the back and Grand treks on the front.

 

[1992explorerMi]

Wait brighton mi ?? I just looked at a explorer that was rhd and look identical to that and the trans was messed up shifted really hard into 3rd after it got warmed up

 

[1992explorerMi]

Disregard my last message the one i looked at was a 96 i almost bought it because rhd are rare in the states. But im assuming there is a brighton in aus.