Limited Slip Differential

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MBillings
Posts: 76
Joined: July 7th, 2006, 11:00 am

Limited Slip Differential

Post by MBillings »

I'm thinking about adding a Torsen type limited slip to the Vee. Anyone with experience using that type of limitied slip? Does anyone have a suggestion from whom to buy one? Thoughts? Comments?

thanks,

Mike Billings
SR Racing
Posts: 1205
Joined: June 24th, 2006, 1:58 pm

Re: Limited Slip Differential

Post by SR Racing »

We use them in our Spec Miata's. They typicaly need a rebuild after a couple seasons, but they seem to work ok.

Of course, they aren't legal in FV and with a zero roll suspension and 60HP they would be of no use. Only if you have lots of HP and/or are lifting a wheel in the corner do they help.
DanRemmers
Posts: 293
Joined: June 24th, 2006, 7:21 pm

Re: Limited Slip Differential

Post by DanRemmers »

Has anyone run a 1915 in solo competition yet? I can see how the extra torque may cause slippage, but I'd like to hear from those who have driven them exactly what the difference is. Anyone? Beuller?
vreihen
Posts: 577
Joined: August 5th, 2006, 9:39 pm

Re: Limited Slip Differential

Post by vreihen »

Is Peloquin still making anything for the aircooled market?

http://www.peloquins.com/

I see a note that he's working on a new Type-1 IRS diff, but don't know if he is still producing any of the other aircooled stuff.....
Lynn
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Joined: June 24th, 2006, 11:15 pm

Re: Limited Slip Differential

Post by Lynn »

Vern Maxey and Robert Moore are using 1914's. I drove Robert's car at the Kansas City Midiv and my co-driver, Andy Hohl, has driver Vern's car,also on the KC lot. I don't think any of the four of us see a need for a limited slip.

My understanding of a Torsen was that if the inside wheel came off the ground, it was no better than an open diff.
69 Beach Solo Vee, #65 FM

85 Lynx B Solo Vee

71 Zink C4 Solo Vee
FM4SOLO
Posts: 129
Joined: June 26th, 2006, 4:17 pm

Re: Limited Slip Differential

Post by FM4SOLO »

As an owner of a Miata with a torsen, Lynn is correct. If one wheel loses all traction (lifts), it acts like an open rear.
Charles
MBillings
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Joined: July 7th, 2006, 11:00 am

Re: Limited Slip Differential

Post by MBillings »

I just returned from the Packwood Tour and Pro. In both events there were large sweepers. And, in both events I spun an inside rear tire. The 1915 cc engine makes enough more torque that I felt a need to have limited slip.

When I spoke to the Babbs (D/Mod Lotus) and an A/Mod driver (car based on a Super Vee), both said the Torsen was the "way to go". The Babbs had used one when they were in A/Prep, but don't use one now because their car make too much horsepower. :?: The A/Mod driver still uses his (and makes well over 300 hp on a turbocharges VW engine).

I'm a little confused about the horsepower comments. I'm also confused about the comments that lifting a rear wheel make the Torsen ineffective. Is the comment regarding totally off the ground or slipping? My case is a slipping inside rear wheel, not one that is totally off the ground.

Jim, the new solo vee rules allow for a limited slip. In talking to Chuck Voboril, it was offered as a tuning aid. I believe instead, it may be necessary as a torque management solution.

Comments?

Mike
MBillings
Posts: 76
Joined: July 7th, 2006, 11:00 am

Re: Limited Slip Differential

Post by MBillings »

I just returned from the Packwood Tour and Pro. In both events there were large sweepers. And, in both events I spun an inside rear tire. The 1915 cc engine makes enough more torque that I felt a need to have limited slip.

When I spoke to the Babbs (D/Mod Lotus) and an A/Mod driver (car based on a Super Vee), both said the Torsen was the "way to go". The Babbs had used one when they were in A/Prep, but don't use one now because their car make too much horsepower. :?: The A/Mod driver still uses his (and makes well over 300 hp on a turbocharges VW engine).

I'm a little confused about the horsepower comments. I'm also confused about the comments that lifting a rear wheel make the Torsen ineffective. Is the comment regarding totally off the ground or slipping? My case is a slipping inside rear wheel, not one that is totally off the ground.

Jim, the new solo vee rules allow for a limited slip. In talking to Chuck Voboril, it was offered as a tuning aid. I believe instead, it may be necessary as a torque management solution.

Comments?

Mike
MBillings
Posts: 76
Joined: July 7th, 2006, 11:00 am

Re: Limited Slip Differential

Post by MBillings »

I just returned from the Packwood Tour and Pro. In both events there were large sweepers. And, in both events I spun an inside rear tire. The 1915 cc engine makes enough more torque that I felt a need to have limited slip.

When I spoke to the Babbs (D/Mod Lotus) and an A/Mod driver (car based on a Super Vee), both said the Torsen was the "way to go". The Babbs had used one when they were in A/Prep, but don't use one now because their car make too much horsepower. :?: The A/Mod driver still uses his (and makes well over 300 hp on a turbocharges VW engine).

I'm a little confused about the horsepower comments. I'm also confused about the comments that lifting a rear wheel make the Torsen ineffective. Is the comment regarding totally off the ground or slipping? My case is a slipping inside rear wheel, not one that is totally off the ground.

Jim, the new solo vee rules allow for a limited slip. In talking to Chuck Voboril, it was offered as a tuning aid. I believe instead, it may be necessary as a torque management solution.

Comments?

Mike
MBillings
Posts: 76
Joined: July 7th, 2006, 11:00 am

Re: Limited Slip Differential

Post by MBillings »

sorry for the multiple posts. My PC just went nuts. :roll:

Mike
Lynn
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Joined: June 24th, 2006, 11:15 pm

Re: Limited Slip Differential

Post by Lynn »

Mike, you might Google Torsen diffs and look them up in howthingswork.com. As I understand them Torsen (Torque Sensing) diffs need some grip at both wheels in order to function. If one wheel is off the ground there is no torque at that wheel for the diff to sense.
69 Beach Solo Vee, #65 FM

85 Lynx B Solo Vee

71 Zink C4 Solo Vee
FM4SOLO
Posts: 129
Joined: June 26th, 2006, 4:17 pm

Re: Limited Slip Differential

Post by FM4SOLO »

My experience with the Torsen is that it works very well until one tire loses contact with the surface. When I went to a larger tire (Kumho V710's) on a stock Miata with a Torsen, I began to experience inside wheel spin on tight corner exit. Observers said I was lifting the inside tire off the pavement. It should work just fine in a Solo Vee in sweepers.
Charles
vreihen
Posts: 577
Joined: August 5th, 2006, 9:39 pm

Re: Limited Slip Differential

Post by vreihen »

My own $0.02 is that an LSD of some type would be useful to counter the huge amount of rear camber change in swing axle cars, or at least in my car, anyway. I've got pictures of my Vee with literally half the contact patch on both tires cambered clean off the pavement under acceleration, and was thinking that I should just be running narrow spec FV tires instead of wide Solo Vee tires if I'm getting the same contact patch either way. :shock: Granted, my suspension package is really messed up right now, but that doesn't stop me from recommending that you check out pictures of your own cars at launch and see how much rubber is left touching the ground once the suspension squats.

Also, did the rule change include welded diffs? Since the snowmobiles are handicapped by live axles in the rear, it might be worth a shot to try out a welded diff (way cheaper than torsen) to see how evil/helpful it is in real life.....
qreshadow

Re: Limited Slip Differential

Post by qreshadow »

Arthur,

When the MAC first started researching the changes we were going to suggest for the Solo Vees, our first draft, if you remember, contained an allowance for a locked(welded) diff. We wanted to keep the potenial costs down as low as possible and with the researched high cost of an LSD, this seemed like a good idea. However, after talking to a few shops who had done that to their cars and experienced violent failures, we decided that for safety reasons we would withdraw that allowance and only allow LSDs. That's why a welded or locked rear is not on the allowance list.
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Larry Bradley
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Joined: June 25th, 2006, 12:26 pm

Re: Limited Slip Differential

Post by Larry Bradley »

It will eat some horsepower.

Larry
Now a promise made is a debt unpaid, and the trail has its own stern code.
ultimate42
Posts: 30
Joined: June 25th, 2006, 7:33 pm

Re: Limited Slip Differential

Post by ultimate42 »

The problem here is mis identifying the issue. Your problem is not with the diff, it is with the "lifting" of the inside tire. What you are actually doing is allowing too much droop in the rear suspension. Where the only problem you have now is wheel spin, with more aggressive driving you will get body roll--leading to roll over! You did not say whether you have a z-bar or zero-roll suspension, but the solution should be the same: eliminate the droop and keep both wheels flat on the ground.

Once you have conqured this, I will wager that you will find that you no longer need a limited-slip, and that having one will only increase understeer.
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