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Old 10-29-2008, 06:20 PM   #1
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Default Locked front diff ?????

I come from the on road scene but im doing my first off road race this weekend. My front diff in my caster buggy at the moment has 100k in it and i was wondering if i left it would it go any good on the dirt? In on road a locked front diff is awseome on the right track so would it be the same in off road? My centre diff was just changed to 5k and my rear now has 2k but if i don't have to do the front that would be great, no time. But if you guys suggest i do change it i would change it to 5k i think

Thanks, any help would be great.
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Old 10-29-2008, 06:24 PM   #2
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you definetly need to change the fluid in the front... i would try 5 and see where you are at...
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Old 10-29-2008, 06:37 PM   #3
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Well, my first thought is that the way you asked it sounds like you have not run this buggy at the track ever. So what could it hurt to try it. Your first time at the track will be for the experience running there anyway.
I've seen two pro setup sheets that listed an LSD up front. I am going to assume that these tracks are blue groove tracks and almost be like running on pavement, so like you said from onroad that on some tracks it would be an advantage.
If the front fluid is too thick you are going to suffer from poor off power steering right? So if it is too thick for this track try to adopt a different driving style for the day like go into corners fast and flick the brake to help the rear end rotate and power through the turn. I personally wouldn't worry about changing something I did not know about. You might like it or whatever the case may be. Although if you are experienced off road at all I don't know how you could go wrong switching to around 5k like you said and just be done with it. Tough call not knowing what the track is like and how you like to drive. Hopefully someone with more experience will add something more cofident for you. I'd just give it a try. You need to start with a baseline for the track somewhere. Good luck.
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Old 10-29-2008, 06:37 PM   #4
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That car would have zero off-power steering in dirt. You would need a blue groove high grip track for that. With that much traction, kiss your tires goodbye. If you like on-power steering, try 7K front oil.
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Old 10-29-2008, 07:16 PM   #5
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Yes, I agree. I would try either 7k or 10k. 7 would be easier to drive.
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Old 10-30-2008, 02:08 AM   #6
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Thanks guys i'm in the middle of changing the oil to 5k in my diff (no 7k) cause i know it will work so i wont have to change diff oils on the day.

Just another question, my mate who invited me to the race says to have bigger holes in your shock pistons up front with 50wt oil compared to medium holes in the rear with 35wt oil. I didn't want to say anything to him as he is a top bloke but i thought you would have the medium hole shock piston up front with the larger hole piston in the rear shocks.

Correct me if i'm wrong but the only reason i can see is that it might help the rear of the buggy to not dip when accelerating. Any help would be great.
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Old 10-30-2008, 03:33 AM   #7
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Quote:
Originally Posted by freestyles View Post
Thanks guys i'm in the middle of changing the oil to 5k in my diff (no 7k) cause i know it will work so i wont have to change diff oils on the day.

Just another question, my mate who invited me to the race says to have bigger holes in your shock pistons up front with 50wt oil compared to medium holes in the rear with 35wt oil. I didn't want to say anything to him as he is a top bloke but i thought you would have the medium hole shock piston up front with the larger hole piston in the rear shocks.

Correct me if i'm wrong but the only reason i can see is that it might help the rear of the buggy to not dip when accelerating. Any help would be great.
http://users.telenet.be/elvo/ Skip to the end "setup guide" to get the quick basics.
Not sure about the piston sizes. Most run thicker fluid up front. The different size pistons would effect a few things. It could be done to make the car more stable. Also, will jump different than if all 4 pistons were the same. Dunno for sure. I'm going to switch to different fluids next year but plan on keeping small piston holes at all 4 corners. Our track is relatively smooth.

The 50wt large/35wt medium might be to help balance it out. Like the 50wt could have been to help it jump more nose up but the larger hole could be helping the front end have more traction in the corners. Then he could have chosen 35wt/med in the rear to make the rear end balanced for something else entirely. Could have been done for cornering, jumping, or like you said to keep it from squatting too much. Ask him what he was tuing for when he did that. Everything you do effects something else...
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Old 10-30-2008, 03:38 AM   #8
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Quote:
Originally Posted by freestyles View Post
Thanks guys i'm in the middle of changing the oil to 5k in my diff (no 7k) cause i know it will work so i wont have to change diff oils on the day.

Just another question, my mate who invited me to the race says to have bigger holes in your shock pistons up front with 50wt oil compared to medium holes in the rear with 35wt oil. I didn't want to say anything to him as he is a top bloke but i thought you would have the medium hole shock piston up front with the larger hole piston in the rear shocks.

Correct me if i'm wrong but the only reason i can see is that it might help the rear of the buggy to not dip when accelerating. Any help would be great.
Don't worry. 5k should be a real good start. I started with 3k/5k/1k and noticed that my front tires were slightly wearing in the middle so I'm going to switch to about 5k/7k/1k to help front tire balooning from the center diff and get more on power steering. Once I see how that effects things I'll bet I'm going to increase the rear to 2k or 3k to get the rear end to rotate more so I don't have to tap the brakes in a couple of corners. But I'm also getting an engine with more power next year so that changes the feel too!
This will depend a lot on your track and driving style. I can see that not being sure about the extreme of 100k has been confirmed by everyone. You should do real good with 5k to start out with
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Old 10-30-2008, 03:46 AM   #9
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As a general rule:
Smaller shock holes=thicker oil
Larger shock holes=thinner oil

As for the 100.000 front i have tried up to 30.000 once with good steering off power.

If you don't have time to change it leave it as it is and go have fun.

If at the first few runs you feel that the car understeers in the corners try changing a few other things to compensate.

See below in this order:
1) use more toe out in the front
2) put bottom shock mount in the inner holes on the arm
3) use less caster
4) remove front sway bar
5) use less toe in in the rear
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