Diff.?

[cbaker65]

Does anyone here know anything about different diff oil weights in the front & rear diffs do
an what each weight does for performance of a 4x4 on road car?

I think that I need a different weight set up in my diffs on my Ld3 on road car for
more better stability & control!
What I'm thinking is a heavier weight in the rear an a lighter weight in the front to help
control for spin outs.

 

[GAJ]

I have no experience with this, but I understand that the thicker the fluid the less the slip. A thicker fluid makes the diff more of a limited slip diff, giving traction at both wheels.

 

[cbaker65]

I have no experience with this, but I understand that the thicker the fluid the less the slip. A thicker fluid makes the diff more of a limited slip diff, giving traction at both wheels.

In all of my years being in the hobby ,I have not ventured in the different diff oil weights!...

But what your saying makes sense.
My theory is that if I put a thicker oil in the rear it will lug the rear down some ,forcing more
transfer torque to the front ,maybe helping control spin out!..

 

[Certified Mike]

Then again, if you want more front traction, if you go heavy in the front, you'll have a front posi...

 

[cbaker65]

Then again, if you want more front traction, if you go heavy in the front, you'll have a front posi...

I will have to experiment!..

 

[HPIguy]

Back when I raced touring cars, I was always tearing into the diffs to tune the car for different tracks. A lot of it comes down to driver style, track layout, and how you want the car to feel also. Thicker oil in the front diff will help "pull" the car through the corner and make it less tail happy, but at the expense of wanting to push the front more. The inverse will give you more aggressive turn in, and the ability to "push" the car into and through the corner with throttle, but you need a good feel for your braking and throttle inputs, as the car will want to rotate the rear more. Bear in mind, spring rates, shock pistons and oil weight, camber, caster, and roll center all play a part in this as well. I generally ran thicker rear diff fluid on large fast tracks where I could use the throttle to help plant the rear, and the inverse on tight twisty layouts where coming off the corner was more important, as you couldn't carry momentum like a big track. Tire wear patterns will help tell you what the car is doing also. If the fronts are wearing faster than the rear, you're over driving the front end. If the rears are wearing much faster than the fronts, the car is either lighting up the rears from too much diff (you'll realize that one pretty quickly ), or your suspension setup is off and not letting weight transfer quick enough under throttle. Which will still spin the tires, but you if your suspension setup is on you won't have near as much violent snap oversteer.

When I first went from 2wd stadium trucks to touring cars, I felt like you needed an engineering degree to get the darn things to handle properly.

 

[cbaker65]

Back when I raced touring cars, I was always tearing into the diffs to tune the car for different tracks. A lot of it comes down to driver style, track layout, and how you want the car to feel also. Thicker oil in the front diff will help "pull" the car through the corner and make it less tail happy, but at the expense of wanting to push the front more. The inverse will give you more aggressive turn in, and the ability to "push" the car into and through the corner with throttle, but you need a good feel for your braking and throttle inputs, as the car will want to rotate the rear more. Bear in mind, spring rates, shock pistons and oil weight, camber, caster, and roll center all play a part in this as well. I generally ran thicker rear diff fluid on large fast tracks where I could use the throttle to help plant the rear, and the inverse on tight twisty layouts where coming off the corner was more important, as you couldn't carry momentum like a big track. Tire wear patterns will help tell you what the car is doing also. If the fronts are wearing faster than the rear, you're over driving the front end. If the rears are wearing much faster than the fronts, the car is either lighting up the rears from too much diff (you'll realize that one pretty quickly ), or your suspension setup is off and not letting weight transfer quick enough under throttle. Which will still spin the tires, but you if your suspension setup is on you won't have near as much violent snap oversteer.

When I first went from 2wd stadium trucks to touring cars, I felt like you needed an engineering degree to get the darn things to handle properly.

Thnx.
The car is always tail happy even at 1/2 throttle ,an it is way over powered!
I think it is a little bit of everything like you suggested ,My rear shocks are real stiff an
my camber & toe ends probably need to be set up as well in which they are set straight up
right now with out angle.
The diffs ,I don't have a clue on whats in them ,I didn't build this car ,a friend of mine did about
6 or 7 years ago.
I will deal with the suspension first an give it a run an see if theres any improvement.
But I definitely need to get into the diffs an get some proper oil in there,,,UGH....LOL I hate
messing with diffs ,its a lot of screws an the a lot has to come off to open the diff.
I had the diff case open before ,but only to install the 2 spd .

 

[cbaker65]

I have my work cut out!
The clutch finally went out on the Ld3 ,so off with the engine......
I got to take the diffs apart an put some mud in them!.....BLEH.....Oh well ,got the w-end!
The whole top part ,brakes an 2spd has to come out to do the work!.....BLEH

 

[Certified Mike]

Fun fun fun! Been dealing with 1:1 issues lately... Fitting that work in with a schedule is even more fun! At least you can leave yours apart!

 

[cbaker65]

I don't like to take things apart an leave it ,things tend to get lost.
I had to do a brake job on my pickup last month ,did one side ,then
discovered that I had to replace the brake slave ,an it had to be ordered ,I was furious ,
because it was the old drums an they have a lot of springs an clips an you have to
remember how they go,Thank God I had taken a picture of it!

 

[Certified Mike]

Lol! I have done my share of drums and shoes, springs, clips, wheel cylinders etc... Yeah, I don't like to leave things apart either... But sometimes that's how it goes... I try to order more than I think I need... That way when I break things, rusted parts etc... They are already beside me and ready... Can always return what you don't use.