ISO: Front and/or Rear Differential

[Sabrarain97]

Okay thank you very much Petros! I will see if we can do any of that, or ask the shop to do it for me when that time comes. Thanks for the advice.

[Sabrarain97]

Okay thank you very much Petros! I will see if we can do any of that, or ask the shop to do it for me when that time comes. Thanks for the advice.

[Sabrarain97]

Hi again Petros,

I was just about to do the chalk/tire test. I am wondering if when you are doing this test on a manual, the front and rear are locked, and that’s what makes this work? I feel that in my automatic the front and rear are not connected, so this might only work if I have it popped in 4WD? Are these accurate assumptions? Thanks.

[NWMO]

Sabra,

The diffs do not lock. You need to only jack up one side, leaving the other on the pavement and then count the revolutions.

Chris

[Sabrarain97]

So, even with my automatic in neutral this should work? Sorry for being repetitive, I just want to make sure my question is articulated clearly.

Thank you for your help.

[SirFoxx]

So, even with my automatic in neutral this should work? Sorry for being repetitive, I just want to make sure my question is articulated clearly.

Thank you for your help.

i'm not sure that trick will work with an auto due to the clutch packs n such. You can always try it and see what it does.

My current wagon came with miss-matched diffs. I knew this as when I put it in 4wd while rolling in neutral, the car slowed to a halt as the drivetrain bound up. I ended up pulling the trans and learned the whole trans got replaced with a junkyard special at some point..

[NWMO]

So, even with my automatic in neutral this should work? Sorry for being repetitive, I just want to make sure my question is articulated clearly.

Thank you for your help.

I’ve not worked with an automatic, but the principle still applies. When checking the front diff ratio, I would put the trans in 4WD, leave one tire on the ground and place the trans in nuetral. You should then be able to mark your tire and then count driveshaft revolutions required for the tire to make a revolution. With the similar gear ratios, maybe make two tire revolutions and then divide by two. Similar for the rear, but the trans would not need
to be in 4WD.

Chris

[Petros]

I am not that familiar with how the auto trans is geared (though I have owned two of them). but it seems to me that when the auto trans is in 4wd, it should lock out the drive train so front and rear are mechanically connected together. these cars do not have a center diff like the modern AWD cars, on the 4wd Tercel, front and rear drive train is locked together when in 4wd. that should not change with the auto trans as far as I know.

it has to be IN 4wd, and the trans in neutral, two wheels on the ground on one side, and two wheels in the air on the other side.