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Advantage of lock diff


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7 replies to this topic

#1 EA82Turbo

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Posted 28 June 2004 - 05:25 PM

Hi ya all :)

New Zealand rally car guy again.

I am thinking of locking up the diff, an LSD would be better but I have no money.

Would there be any advantage in having a lock diff over a normal diff in a gravel rally situation?

Cheers
Hayden :drunk:

#2 sandman

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Posted 28 June 2004 - 05:33 PM

My experiences have been that a limited slip in a sand or gravel racing situation is better than open or fully locked. Fully locked will give you a loose end coming out of a corner. The posi helps to defeat that but still applies power to the other wheel to help pull you out. Also you can play around with the posi to loosen it up or tighten it up.

Any other situation I would say lock it up.

IMHO.

#3 bushbasher

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Posted 28 June 2004 - 05:45 PM

A welded diff will cause the car to oversteer while turning in or out of a turn, where the car is still turning but has more or less equal pressure on each tire. The welded diff will cause both rear tires to lose traction and slide a bit more. This can be used to get the tail out more if thats something that would help you. It will also increase traction in a straight line and in a hard turn where the inside wheels might otherwise start spinning.

I would go to a parts yard, find another diff of the same ratio, weld it up and put it in. If you don't like it put your original diff in. Its only 4 driveshaft bolts, 3 diff bolts, and 2 roll pins to pull or install a diff.

#4 EA82Turbo

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Posted 28 June 2004 - 05:49 PM

I have a 3.7:1 diff sitting around but need 3.9:1 I think. Is changing the ratio difficult?

#5 Do It Sidewayz

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Posted 28 June 2004 - 06:54 PM

I think the majority of the guys on here are Offroad guys...and i don't think they know how a rally car is and needs to be tossed around.

I'm building a rally car right now, and i'll be using a LSD, because it came with the car.

Other wise...i also ice race, and we've used Open, Welded, and LSD rear diffs.

The Open diff is useless, and you'll loose alot of time out of tight corners.

Welded diff is good on grippy surfaces. You need to be really committed while driving with a locked rear diff. If you are just "putting" around you are going to experience oversteer, But if you toss the car around like you should, it is great and gives you lots of grip. If you get to really slippy stuff like Mud or Snow/Ice you are going to get understeer, and you'll loose time on turn entry. The locked diff likes to be driven sideways with the power on. For 90% of gravel roads around here a locked diff is great (and cheap)

A LSD is the best i think. it doesn't give you the best of both worlds, but it is a great compremise. You don't have the all out turnability of an Open diff, or the All out traction of an LSD, but you can drive the car much "cleaner" which leads to faster stage times.

My advice...Weld up the diff, just make sure you know what your doing...I have seen someone with a welded diff have the spider gears come apart and spit gears through the rear diff casing.

Also...save up for a LSD

#6 EA82Turbo

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Posted 28 June 2004 - 07:20 PM

Thanks for the great info 'Do it sideways'! I think lock diff sounds like the one for poor people like me that can't afford a LSD :burnout:

At the moment I dont seem to have too much more traction than the 2wd boys. The roads around here that we race on pretty fast, mostly 90-140kph corners on lose dry gravel.

Will a lock diff help me carry more speed thro these types of corners or create too much oversteer and slow me down?

#7 Do It Sidewayz

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Posted 28 June 2004 - 07:22 PM

Thanks for the great info 'Do it sideways'! I think lock diff sounds like the one for poor people like me that can't afford a LSD :burnout:

At the moment I dont seem to have too much more traction than the 2wd boys. The roads around here that we race on pretty fast, mostly 90-140kph corners on lose dry gravel.

Will a lock diff help me carry more speed thro these types of corners or create too much oversteer and slow me down?


you will be able to carry more speed. it will take a different driving style

#8 rallyruss

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Posted 29 June 2004 - 02:09 AM

I think the majority of the guys on here are Offroad guys...and i don't think they know how a rally car is and needs to be tossed around


I guess I am in the minority group then.:rolleyes:

I would avoid a welded or spool type rear end. a good lsd is your best bet for cornering. espically if you are just geting started in the sport. its better to finish farther back in the pack than to DNF.

as stated you will be sidways (or backwards) a lot with a solid rear end. also lost of strain on your drive train components.

a locker would work good as well but I dont know of any available for our cars.




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