[benspeeder]

So it was a tough season mechanically with four dnf finishes. Two bearing failures one being the new left rear bearing failing right after replacement. Then a cv torn and cooked up followed by a nasty grind going on in the transaxle. I just dropped off the car to be overhauled for next season and have the trans looked over.



So, what is the best trans diff combo for road racing a 968? I believe the car had a 911 G50 diff in there from the previous owner.



I've heard that a 944 short gear trans with clutch limited slip might be the hot setup. Curious what folks think and costs.



Another question, I've got about 20 race weekends on the rod bearings. When should I have those replaced? Any other key stuff I should replace?



Don't want dnfs next year!



But I did get four wins and second in PRO IT so overall the season was OK and made a few grand in winnings

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[craigawoodman]

The 968 uses the same diff centre as the G50 (but reversed given the gearbox orientation). That said, <acronym title='Limited Slip Differential'>LSD</acronym>'s for a 968 are not that common. I was told any <acronym title='Limited Slip Differential'>LSD</acronym> is better than none, but a clutch <acronym title='Limited Slip Differential'>LSD</acronym> will also work under braking where a quaife type will not. The amount of lock-up will also be an issue.



I managed to get a clutch type <acronym title='Limited Slip Differential'>LSD</acronym> which immediately took around 1 plus seconds a lap off my times. The gear ratios would depend on the track and ultimate speed you are looking for. Until I put the supercharger in the car, I never used 6th gear (on the road or the track). I now use 6th on the road a lot (it dramatically drops noise within the car) and had to use 6th going down Conrod straight.



I did 4 years of motorsport on an engine with 115,000km on it and never had a problem and rebuilt the engine last year only to make sure it was right for the SC install and I was using oil (but valve guides were right and no internal / ring issues - so go figure). There was no real issues found during the rebuild. What is the maximum rpm you are running the car to?



THe clutch would be more of an issue - I have been through two so far. Water pumps - get the right one first.

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[94SilverCab]

I bought the OS Giken from RS Barn...it ROCKS!!! I met the reps from Giken at SEMA last year and they were a bit surprised that I had it on a street car, so I'm certain its perfect for racing.



Jay

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[flash]

i can understand why he was a bit surprised. first, it's a bit pricey for what most people would put in a street car (clearly he doesn't understand our obsession). also, it's a tad noisy and might bug some people, especially in a hardtop where the noises are amplified and not masked by cabriolet wind noise. obviously this would not be a concern in a track car.



that being said, having driven jay's car, i can say with a certainty that that unit definitely hooks up. i was quite impressed with how tight it was. i like the one i have, but that one does hook up a bit more, and it was easily noticeable.

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[94SilverCab]

I should have cross posted this in the 968 Vanity thread...spare no expense for the 968.



Per Flash's comment, the unit is not "noisy" at any level and the build quality can be described as "surgical". (added October 26).



Jay





Jay

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[benspeeder]

Thanks folks

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[Dubai944]

Not sure if you can you get a Guard Transmission <acronym title='Limited Slip Differential'>LSD</acronym> for the 968 box? My main box is an S2 5 speed with 951 5th gear with Guard Transmission 80/80 <acronym title='Limited Slip Differential'>LSD</acronym> which works very well for racing. The GT <acronym title='Limited Slip Differential'>LSD</acronym> makes a massive difference in stability braking into corners.



I have used a 968 box a couple of time while my box was being rebuilt. I understand it is a stronger box overall but I preferred the 5 speed ratios.

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[flash]

last i checked, you can get both the torque biasing and clutch type from guard.



regarding the "noise" of the giken, it isn't huge at all (hence my choice of the word "tad"), but i noticed it in both cars i was in that had one. in the cab, it would be hard to hear, and unless you're like me, constantly listening for noises, you may not even notice it. in a hardtop, it was easier to hear, though even in that car it was fairly easy to ignore. in a race car this would obviously not be an issue at all. in a street cruiser, it might be. it's pretty subjective, based on how annoyed somebody gets about noises. some dynamat in the rear would probably take care of it in either case. regardless of all of that, it was definitely a good unit, and i liked how it performed. were i to do it over again, and were going to buy one for a car that would see any track time, i would not hesitate to choose that unit.

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[Cloud9...68]

I'm no expert on this topic, so maybe someone could educate me, but given that N/A 968's aren't exactly torque monsters, is the "ultimate" <acronym title='Limited Slip Differential'>LSD</acronym> really the best use of funds? I have a Guard torque biasing unit, and I've never wanted for traction under any circumstances, street or track. Now, slap a supercharger in, or slice off about 700 lbs, and it might be a different story...

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[DaveN]

I will be looking for an <acronym title='Limited Slip Differential'>LSD</acronym> setup next year and I have decided as well not to buy the ultimate just for street driving. I'm a little leery of used <acronym title='Limited Slip Differential'>LSD</acronym>'s (mainly because I don't know what to look for) so the Guards is probably what I will do.

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[flash]

i don't think you'll be unhappy with it. i like mine just fine for how i drive it.

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[pure&amp;simple]

I have the OS Giken, which is a good value for the money. Guards is more expensive, but is built to handle a bit more power (up to 500+ hp if I remember correctly). For me, the Guards was overkill.

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[benspeeder]

[quote name='craigawoodman' timestamp='1319461481' post='116952']The 968 uses the same diff centre as the G50 (but reversed given the gearbox orientation). That said, <acronym title='Limited Slip Differential'><acronym title='Limited Slip Differential'>LSD</acronym></acronym>'s for a 968 are not that common. I was told any <acronym title='Limited Slip Differential'><acronym title='Limited Slip Differential'>LSD</acronym></acronym> is better than none, but a clutch <acronym title='Limited Slip Differential'><acronym title='Limited Slip Differential'>LSD</acronym></acronym> will also work under braking where a quaife type will not. The amount of lock-up will also be an issue.

I managed to get a clutch type <acronym title='Limited Slip Differential'><acronym title='Limited Slip Differential'>LSD</acronym></acronym> which immediately took around 1 plus seconds a lap off my times. The gear ratios would depend on the track and ultimate speed you are looking for. Until I put the supercharger in the car, I never used 6th gear (on the road or the track). I now use 6th on the road a lot (it dramatically drops noise within the car) and had to use 6th going down Conrod straight.

I did 4 years of motorsport on an engine with 115,000km on it and never had a problem and rebuilt the engine last year only to make sure it was right for the SC install and I was using oil (but valve guides were right and no internal / ring issues - so go figure). There was no real issues found during the rebuild. What is the maximum rpm you are running the car to?





I'm running it up to 7,200 and at Watkins Glen I was running it off the rev limiter in third coming onto the front straight and really putting some work to the motor. It was the way to get a pass done in a tough spot but fourth would be better for longevity



irst.[/quote]

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[DaveN]

Good info, tks. I thought the Guards was cheaper but I guess not. I emailed them for the MSRP but no reply yet. Maybe it was the Torsen that was around 1500.00 a set. If that's true then the OSG at 2K is not so bad.

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[flash]

it was the last time i checked. i think it was around $1300 for the torsen type, and the giken was more like $1700 or something like that. maybe it went up?

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[94SilverCab]

For a couple of hundred dollars there is a remarkable difference...the OS Giken is well worth the $$$.



JMHO,



Jay

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[MC968CS]

I use the OS Giken. It is a good unit.

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[ds968]

I could not really feel that much of a difference driving a 968 with <acronym title='Limited Slip Differential'>LSD</acronym> vs. mine without, even when pushing them hard in turns, but never tried it in a braking situation so no idea if that has a more pronounced effect. I suspect in an autocross or track race where I would take the cars to their absolute limits, driving one with and one without the difference would be huge and I could easily tell the change in handling, but in what I would call fairly aggressive steet driving...nothing for me. Then again, I have a really lousy butt-o-meter so I'm not the best judge to appreciate the value of things which might make just a subtle difference in street driving conditions.

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[Dubai944]

A good <acronym title='Limited Slip Differential'>LSD</acronym> can be worth seconds a lap on a track. 'Aggressive' street driving really doesn't begin to approach the level of effort a race car is subjected to and the noticeable differences are going to be more subtle, particularly on cars with relatively low stock power levels.

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[dave968]

J3 Racing in Atlanta put a used Cup car <acronym title='Limited Slip Differential'>LSD</acronym> in my 968, works great, god value, ~1500 installed a few years ago, Charles Greer also had J3 install one in his car.



Dave

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