I recently purchased an 89 with four speed manual and 4 x 4. When placed in 4H, the front wheels seem to turn at a different rate from the back. The front wheels actually seem to jerk.

Could this be from a previous owner changing the rear end to a different ratio? Or, is there another reason?

I'm assuming that as long as I only use the 4wd offroad, there will be no harm to the transmission. True?

Thanks for your input.

 

I'm not that familiar with pre-97 Fords, but it may depend on where you were trying out the 4x4. I mean I have encountered a "jerk" (usually I then modify my driving by taking it out of 4x4) when I am offroad but have come across terrain that will not provide the tires the slippage they need to let the front and real wheels turn at different speeds. For instance, just the other week I had come from "offroad" to a dirt road and was in a hurry to turn around and was cutting a semi-sharp turn and I could "feel" the resistance - the jerking - of the vehicle actually wanting to stop on forward progression, which is the drive shafts fighting themselves....

Don't know if that info helped you are not....Oh and yes, only use offroad, and transmission isn't the only thing you could break on-road, you could break something in the transfer case or either drive shaft....

 

Your post didn't mention whether you encountered this in a straight line or while you were turning. If it happened in a straight line on even terrain you most likely have a problem. If it occurred while turning this is probably normal as the radius the front wheels follow is different from the one the rear wheels follow.

I know it's an '89 but check to see if the tags are left on the diff's. You might get lucky and still find them there. They will have a reference to the gear ratio on them. Unfortunately there's still no guarantee the gears themselves weren't changed thou.

One other thing you can do is to jack it up - both wheels on one axle. (Don't forget the jack stands! and make sure it won't roll) Put the tranny in neutral. Turn the one drive shaft by hand and count how many revolutions of the drive shaft are required to turn the wheels one revolution. Then repeat the process on the other diff. They should be the same. If not you know the problem.

Good Luck

 

My 99 does something similar when on blacktop. The front wheels do act very differently when in 4wd. Off road it won't do it, only on surfaces with extra grip like blacktop, but only in tight turns, not straight.

 

aggggghhh....tight turns...agggghhh....

You do realize that's the front drivetrain and rear drivetrain fighting themselves? That's a good way to break something really expensive...The last thing you want to do with part-time 4x4 is drive on blacktop, take tight turns, and then force the vehicle through the turn even though you feel the tough resistance....

 

LOL...yep, I know. I have only done it a couple of times luckily, mostly on snow and ice.

 

is it just me or are f-150's really fun in snow?