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> Need Limited slip diff, I WANT MORE TRACTION
Joe Ricard
post May 23 2007, 08:21 AM
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Ok, so now that we have stepped up the game and have found more lateral cornering G's I am in lifting the inside rear tire again.

No rear sway (of course)
High rebound rear shocks 200 lb rear coil over.

high rebound koni race shock and 21mm torsion bars in front with 22 Weltmiester bar. set as much as I can before the car pushes.

So looking for advise on LSD what's available and what's the difference of each in an autocross application.
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IronHillRestorations
post May 23 2007, 08:41 AM
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It kind of depends on your driving style. The clutch pack type LSD is smoother to lock up, where the Torsen type (Quaife or Guard) is a little snappy when it locks, which may be better for autocross. Guard is making both styles, and IIRC the cheaper is no less than $1200 or so. Plus you'll have to have the ring and pinion set which is a spendy proceedure. With the LSD you will probably want to run a rear sway bar. You'll like the LSD for several reasons. At least that's my .02. I had a clutch pack OE 901 style that I had in a 3.0 six conversion, and it was smooth. Really helped keep the power down, but it was just a street hot rod.
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Joe Ricard
post May 23 2007, 09:02 AM
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I have no problems on the street because I don't generate that kind of cornering forces. I would go straight to jail.

However AX courses with big sweepers let me put down power is a different animal.

Whay can Honda guys and F body guys get an LSD for less than 500 bucks new?

Why can't I use that stuff is a different carrier.
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ConeDodger
post May 23 2007, 09:40 AM
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Paul Guard told me that his Torque Biasing unit is best for autocross with a few track days thrown in. But that he would go with the LSD for track days with a few autocrosses thrown in. If you get the distinction...
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J P Stein
post May 23 2007, 10:12 AM
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With a front set-up similar to yours, I've found that 250 lb rear springs will allow
the inside rear to unload, 275s won't allow that.
I was able to tighten the front bar to bring the car back to neutral.....just a touch of oversteer actually.

Springs are cheeper that LSDs. Get all 4 to stay on the ground, then worry about
LSDs. I'd like to get a TB diff fron Guard but $$$ is short.

Opinions are like assholes, everyone has one.(IMG:style_emoticons/default/biggrin.gif)
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Joe Ricard
post May 23 2007, 10:25 AM
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Well so far JP, your advice has proven to be the best of anyone out there in 914 land.
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Chris Hamilton
post May 23 2007, 01:37 PM
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Could someone post some links to these for sale? I'm specifically interested in a clutch pack diff.

Thanks.
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jhadler
post May 23 2007, 02:09 PM
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Hey Joe,

I think JP's comment is really good. Take a look at most of the competitive mid engined cars in SCCA autox, and you'll find many run a whole bunch of spring with no LSD. Where you start to find diff's more is in the higher prep classes where simply the raw power starts to exceed the capabilities of the tires. Form the sounds of it, you've got lots of power, but haven't yet overwhelmed the tires in a straight line. So a suspension change to keep all four feet firmly planted may be more effective. Especially in tighter turns where a LSD can possibly induce understeer if you don't have the power to get both tires loose.

Another thing to look into is chassis bracing. If you've got flex under load (and with the big slicks, I'd expect that), then you make it that much harder for the tires to stay planted.

I think in XP you've got carte blance to go for a full cage and tie the suspension into it. Not possitive though, worth looking at the rules again. And reinforcing the trailing arm mounts too...

-Josh2
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Joe Ricard
post May 23 2007, 03:15 PM
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Thanks Josh, Seems like we have a plan. Now for me to execute it.

Ain't this fun? I love playing with cars.
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Chris Pincetich
post May 23 2007, 04:03 PM
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(IMG:style_emoticons/default/agree.gif)
Especially when the frequency of ordering and installing the wrong parts for a certain application is signficantly reduced (IMG:style_emoticons/default/beerchug.gif)
I was watching a honda do the sweeper last weekend, and his best was when the inside rear tire was lifted (and locked-must be trail braking) for about 140 of the 180 degress (IMG:style_emoticons/default/huh.gif)
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grantsfo
post May 23 2007, 04:30 PM
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The Guard TB LSD made a huge differnce in my car. I think people minimize the advantages of LSD for our cars. It goes beyond putting power down. The LSD helps with traction overall. The car in transitions handles better too.
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jhadler
post May 23 2007, 04:37 PM
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QUOTE(ChrisNPDrider @ May 23 2007, 02:03 PM) *

I was watching a honda do the sweeper last weekend, and his best was when the inside rear tire was lifted (and locked-must be trail braking) for about 140 of the 180 degress (IMG:style_emoticons/default/huh.gif)


That's actually ideal for a car like a small Honda or VW. The suspension dynamics for a FWD car are a lot different than a RWD. For the Honda, the only purpose the rear wheels serve is to keep the gas tank from dragging on the ground... Okay, an exageration, but the rear wheels really don't _do_ that much in a front driver. The front wheels are doing everything (steering, acceleration, and braking). They've exchanged the roll stiffness in the rear, for roll stiffness in the front, to keep the inside front on the ground as much as they can. Like when a 914 or 911 lifts an inside front, but with even less of an impact on the handling of the car.

As for the wheel stopping? Try spinning the wheel of a car while it's off the ground. It doesn't just spin like a bike wheel. It'll stop pretty quickly once there isn't a load on it. That rear wheel will stop rotation pretty quickly once it comes up.

That was a well driven Honda.

A1 and A2 VW's are the spookiest, with the torsion beam rear axle, you can sometimes clear a beer can under those wheels... BTDT, and went too far...

-Josh2
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J P Stein
post May 23 2007, 06:38 PM
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I hate a thread where everyone agrees....Iff'n I was smarter, I come up with something radical. Lemmesee.
I argee with Grant on the TB diff.
I agree with Josh on the FWD cars & chassis stiffening.
I agree with Chris on the parts buying.
I agree with everything Joe says cept when he says he is fast.`

Ah ha.....I don't argee with Chris H on a clutch pack LSD for AX, but if you must have one: Guard Transmission 888 89 GEARS
Thank God, some contraversy.(IMG:style_emoticons/default/biggrin.gif)
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Chris Hamilton
post May 23 2007, 07:16 PM
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QUOTE(J P Stein @ May 23 2007, 05:38 PM) *

I hate a thread where everyone agrees....Iff'n I was smarter, I come up with something radical. Lemmesee.
I argee with Grant on the TB diff.
I agree with Josh on the FWD cars & chassis stiffening.
I agree with Chris on the parts buying.
I agree with everything Joe says cept when he says he is fast.`

Ah ha.....I don't argee with Chris H on a clutch pack LSD for AX, but if you must have one: Guard Transmission 888 89 GEARS
Thank God, some contraversy.(IMG:style_emoticons/default/biggrin.gif)


It's not for my car, it's for my dad's car ( that andrew drives ). We've having a hard time keeping traction even with all 4 wheels planted firmly on the ground with R250 compound 9 inch wide goodyear eagles.

We're going to need it at parade this year.

Anyways it's not me you're disagreeing with, it's my dad. (IMG:style_emoticons/default/biggrin.gif)
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Joe Ricard
post May 23 2007, 09:05 PM
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The only thing that is good about a clutch pac LSD is they like to be rebuilt allot.
R250 slicks do not lend them selves to straight line acceleration. Road race tires are made to provide lateral grip.
Drag radials are made to provide straight line acceleration.

And am too fast but not as fast as my co-driver. Sumpin like you and Britain. (old fart).
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Joe Ricard
post May 23 2007, 09:09 PM
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Nanner nanner
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Chris Hamilton
post May 23 2007, 09:14 PM
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Well we'll be going ahead with the clutch-type limited slip on Lee's order, and if anyone disagrees they can feel free to prove their point to him at either the parade this year or any of our local events. It's not really my decision though, I'm just tasked with sourcing one, and all necessary materials. (IMG:style_emoticons/default/biggrin.gif)

I'd like to add, even though I already did that the red 914 isn't getting one any time soon, this is for the blue 914.
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Chris Hamilton
post May 23 2007, 09:18 PM
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QUOTE(Joe Ricard @ May 23 2007, 08:09 PM) *

Nanner nanner
(IMG:style_emoticons/default/biggrin.gif)


I see your 914 and I raise you like 30 TTODs out of the last 33 events ( approximate )

(IMG:http://www.thextremeresources.com/boshi/images/cars/Library_4125crop.jpg)

Those wins were with the old built 2.0L, now we have around double the horses trying to eat our tires.
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Joe Ricard
post May 23 2007, 09:54 PM
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Race cars are supposed to win at autocrosses. Yea we gots a few of them Fancy schmancy TTOD's too. including 2 very dominating lapping days @ No Problem raceway.
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SirAndy
post May 23 2007, 09:58 PM
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QUOTE(Joe Ricard @ May 23 2007, 06:21 AM) *

No rear sway (of course)


you got a cage? if so, a rear bar can be beneficial in keeping both wheels on the ground ...

not as good as a LSD, but worth a shot. oh, and 200lbs seems a bit soft.

i run 250lbs and feel like i could still go a bit stiffer ...
i also run a stock rear swaybar. much less wheel-spin than i used to have.
(IMG:style_emoticons/default/bye1.gif) Andy
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