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Old 10-03-2003, 01:31 PM   #1
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Default Unespected handling due to shock oil change - please explain

I'm running on carpet with rubber tires. Stock class. One way diff. Pro2.

My car tend to be a bit loose in the rear - I know how to fix it and have it almost as I like. I just needed some fine tuning.

So I went from 60 to 50 wt oil in the rear shocks. The rear became more loose, however, it was more predictable.

So I switched shocks front / rear, (50 front, 60 rear) and the car now handled the way I want.

Only problem is, I dont understand it. It was unespected, I supposed that softer oil would gain more grip. In addition, the front springs are quite more stiff than the rear, and I suppose there should be a certain relation between springs and shock oil - some kind of guideline would be appreciated

Can someone please explain?
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Old 10-03-2003, 02:24 PM   #2
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By going to a lighter oil in the rear, the weight transfer to the front happens quicker entering a corner, thus probably why it felt loose. When you switched them around, the opposite happened. Hope this helps
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Old 10-03-2003, 05:04 PM   #3
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i had the same thing happen, and i wondered why?

so, do you mean that stiffening the rear end settled it down, so it feels more predictable? if so, i think i'll try switching it.
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Old 10-03-2003, 05:28 PM   #4
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Cole Trickle;

Thicker Oil will make the Car react Quicker to direction changes, but SLOW down the weight transfer from Front to Back. And vice versa with lighter weight oils.

What you will probably find is the Car now is lazyier to direction changes with the Thinner Oil in the Front. If so, just go up in the Front Oil wt until the Car is the way you like it.

Also too little Droop can make the Rear loose off throttle.
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Old 10-03-2003, 05:42 PM   #5
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Shock oil controls the speed of weight transfer, not how much. So the reaction to a shock oil change varies depending on traction level, speed of the car as it corners and the corner itself.
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Old 10-03-2003, 05:47 PM   #6
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Default Re: Unespected handling due to shock oil change - please explain

Quote:
Originally posted by Cole Trickle
I'm running on carpet with rubber tires. Stock class. One way diff. Pro2.

My car tend to be a bit loose in the rear - I know how to fix it and have it almost as I like. I just needed some fine tuning.

So I went from 60 to 50 wt oil in the rear shocks. The rear became more loose, however, it was more predictable.

So I switched shocks front / rear, (50 front, 60 rear) and the car now handled the way I want.

Only problem is, I dont understand it. It was unespected, I supposed that softer oil would gain more grip. In addition, the front springs are quite more stiff than the rear, and I suppose there should be a certain relation between springs and shock oil - some kind of guideline would be appreciated

Can someone please explain?
Okay, as Pops said (and, strangely enough I never seem to disagree with him. . .wierd) and as Jack said, the oil controls the rate of change.

so, when you went to a lighter oil in the rear, it allowed the rear to transfer weight faster, especially on acceleration when weight is transfered rearward. If it gets too fast (too light) it can get loose because the tires get a lot of transfer quicker than they can handle - you now have to deal with it in your fingers. . .

It's all about weight transfer.
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Old 10-04-2003, 06:02 AM   #7
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In the same line as the other guys here.

The rear end has more weight, so with lighter oil it reacts more.

I used to run the Pro2 quite often withstiffer springs at the rear.
It became more stable.

Which is something different then more grip.
But at least as important!
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Old 10-05-2003, 01:31 PM   #8
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Quote:
Originally posted by popsracer
Cole Trickle;

Thicker Oil will make the Car react Quicker to direction changes, but SLOW down the weight transfer from Front to Back. And vice versa with lighter weight oils.

What you will probably find is the Car now is lazyier to direction changes with the Thinner Oil in the Front. If so, just go up in the Front Oil wt until the Car is the way you like it.

Also too little Droop can make the Rear loose off throttle.
Thanks all.

Pops, you're right on. And you're right, it became more "lazy".

Thanks again, I got something here to work on. And maybe, I sould even try the harder springs in the rear. Until now, I've always found it was better with softer springs in the rear, but why not give it a try.
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Old 10-05-2003, 05:23 PM   #9
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Cole Trickle - I always run harder springs on the rear, I find that if I run lighter springs at the rear it wants to move around more and I can never get the car too work with my driving style. I also found that I can run less rear toe with harder rear springs. Shock oil and pistons are usually a little lighter in the front. This is with high traction foam/bitumen.
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Old 10-06-2003, 01:46 AM   #10
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Hmmm. Did some re-thinking; I've tried harder springs rear, than front before, but never succeded. Actually, I had to soften the rear pretty much, when I mounted the one-way, simply to gain more traction in the rear. Any comments?
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Old 10-06-2003, 01:49 AM   #11
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Quote:
Originally posted by popsracer
What you will probably find is the Car now is lazyier to direction changes with the Thinner Oil in the Front. If so, just go up in the Front Oil wt until the Car is the way you like it.

Also too little Droop can make the Rear loose off throttle.
Yep, go up front wt will take out the lazynes, but I believe I should go up in the rear too, to maintain the relative harder rear?
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Old 10-06-2003, 06:17 AM   #12
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Quote:
Originally posted by PizzaDude
...It became more stable.

Which is something different then more grip....

I am at the opinion that grip equals stability. I could be wrong, so please explain further....
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Old 10-06-2003, 06:27 AM   #13
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I'm wondering about the relation between the springs and the damping on your car. If you're running 50 or 60wt oil with relatively soft springs, the car will be overdamped, and could feel slow to respond to direction changes and bumps. I always use the springs to control the amount of body roll, bump handling, and the feel of "grip" (i.e soft to ride the bumps well and create more "grip", hard to stop the car becoming vague to direction changes from too much roll, and create less "grip"). I then adjust damping for the right "feel" as the car goes round the track, basically to make it's responses smooth, not twitchy, or lazy.
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Old 10-06-2003, 11:05 AM   #14
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Default Unexpected handling

Guys;

Are you mixing Tire compounds Front to Rear?

I personally do NOT like to mix compounds (except with Foams) as it is easier to keep a balanced set-up with the same Tires/inserts at both ends of the Car.
Otherwise you might need "unconventional" set-ups that require stiffer Springs at the Rear than the Front and IMHO, the Car will be faster with the balanced set-up (though slightly harder to drive).

Last edited by popsracer; 10-06-2003 at 05:03 PM.
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Old 10-06-2003, 11:13 AM   #15
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Quote:
Originally posted by Cole Trickle
Hmmm. Did some re-thinking; I've tried harder springs rear, than front before, but never succeeded. Actually, I had to soften the rear pretty much, when I mounted the one-way, simply to gain more traction in the rear. Any comments?
Agreed.

This is because the Car will rotate much quicker off Power when using a One-way. Some set-up changes are usually required and definitely a different type of driving style.
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