Wheel size info

[celticfdguy]

I have a 2001 Ford expy eddie bauer. I replaced the rear tires with bigger tires then the front ones I have. I meant to replace the front with the same size ones I put on the rear but haven't gotten to it yet. That being said, Long Island is due for some snow today/tonight.

I was told by Mavis that until I replace the front tires with matching the rear size I cannot use 4x4. Is this true? I was told I would blow out a transfer box if I tried to use it?

 

[FordandPolaris]

This is true, you will see some odd stuff even with A4WD I am pretty sure. I did the same thing with my truck when I did my 33's, but in 97-98 we have the option for 2H. I drove in A4WD by accident and the system did not work well at all (bucking, felt like the front was binding). If you haven't done the brown wire mod, pull fuse 104 under the hood until you can get the fronts put on.

 

[celticfdguy]

OK, i may be ignorant, so bare with me... but, afwd is enabled all the time? I thought when 4H or 4L was off my truck was a rear wheel drive truck?

Ive had the wheels setup like this for 6 months and everything drives just fine... so, am I in the clear? or i def shouldnt use 4H or 4L?

 

[FordandPolaris]

Yes your truck is constantly in A4WD. They had what was called a center axle disconnect in the 97-98 models, which allowed for the transfer case to completely disengage the front diff and only have rear wheel drive. For whatever reason they got rid of it for model years 99-02 before bringing it back again for 03 through the current trucks. I think it does depend on just how big the rears are from the fronts. I went from a 31" tire to a 33" and that did seem to upset the A4WD. As long as I was in 2H it drove just fine. Month later I put the big ones on the front, and the A4WD worked fine as well. I would say keep it out of 4H unless you really need it.

 

[celticfdguy]

OK, that is great to hear. So 4L would be okay to use?

I dont have the the tire size different, but to the naked eye they dont look significantly different at all.

If I put into 4H could I damage anything or would it just make the truck act strange?

 

[kmh1596]

I would think as long as it's snowy (and slippery) out, you'd be okay to use 4H.... But not on any bare roads... under any circumstances.. and don't put it in A4WD

 

[celticfdguy]

I thought my truck is in 4AWD all the time? I have three settings on the knob:

4AWD
4H
4L

Its on 4AWD all the time. I havent ever used 4H or 4L since going with a slightly larger tire in the rear.

 

[SWAGGA]

Yes your truck is constantly in A4WD. They had what was called a center axle disconnect in the 97-98 models, which allowed for the transfer case to completely disengage the front diff and only have rear wheel drive. For whatever reason they got rid of it for model years 99-02 before bringing it back again for 03 through the current trucks. I think it does depend on just how big the rears are from the fronts. I went from a 31" tire to a 33" and that did seem to upset the A4WD. As long as I was in 2H it drove just fine. Month later I put the big ones on the front, and the A4WD worked fine as well. I would say keep it out of 4H unless you really need it.

A question I've yet to have answered... on the 97-98 modles with the 2wd option on the transfer case, is there any chance of awd kicking in, thus requiring the "brown wire mod"?

 

[FordandPolaris]

I thought my truck is in 4AWD all the time? I have three settings on the knob:

4AWD
4H
4L

Its on 4AWD all the time. I havent ever used 4H or 4L since going with a slightly larger tire in the rear.

It is! If the surfaces you drive on are slippery, then the system should take care of excess bind by simply causing the two tires to slip. If it is on dry surfaces, the system bind will not do this, until it builds up enough energy to defeat the friction of the tire against the pavement. Do not use 4L ever with different sized tires. I cannot attest as to what may happen, but the truck goes into maximum torque and grip mode (essentially, obviously this isn't an actual description from Ford haha), which is not going to be good for the system having two different tires. Also you would only be able to do about 5-10 mph... Your A4WD will work fine in snow, I promise. I only use 4H when I am offroad. As long as there is pavement beneath the wheels, the truck will pick up the wheel slip and work just as well as it would in 4H. In fact it might even work better. The A4WD is designed to deliver varying amounts of torque to the front based on its calculations of wheel slip (which are lightning quick). The 4H option simply splits torque, 50% in front, 50% in rear.

 

[FordandPolaris]

A question I've yet to have answered... on the 97-98 modles with the 2wd option on the transfer case, is there any chance of awd kicking in, thus requiring the "brown wire mod"?

No, if the truck is in 2H mode, it is strictly a rear wheel drive vehicle. If I want to do some playing in the snow in a parking lot, I use 2H to get the rear end to rotate hard... The truck does not put any torque to the front wheels no matter how much rear wheel slip it detects. The brown wire mod simply is a makeshift way for someone with a 99-02 truck to have the same options as the 97-98's had from the factory (as well as 03's and up).

 

[SWAGGA]

No, if the truck is in 2H mode, it is strictly a rear wheel drive vehicle. If I want to do some playing in the snow in a parking lot, I use 2H to get the rear end to rotate hard... The truck does not put any torque to the front wheels no matter how much rear wheel slip it detects. The brown wire mod simply is a makeshift way for someone with a 99-02 truck to have the same options as the 97-98's had from the factory (as well as 03's and up).

Thanks for the clarification!

 

[FordandPolaris]

No problem haha, learn a lot about how the truck works when you are spinning through a parking lot!