fast951

Wes, you will need to convert all the parts from the engine to the tranny (flywheel, clutch assembly, bell housing, torque tube (not sure about the shifter and linkage)., and the starter all from 951.
The problem is the crank sensor. The 968 has a 60-2 trigger wheel the 951 has a different setup.
If you decide to do the conversion, I might be able to get you a black box to convert the 951 signals (2 of them) to generate a 60-2 signal for your 968.
Wouldn't it be simple get a 968 flywheel. Someone was making one, I just need to remember their contact info.

fast951

You can get anything made for enough $, but why? The gearing ratio is one of the nice features on the 968.

Thom

Well, with enough torque I would imagine spending most of the time with the right hand on the shifter.
No doubt it must be greatly efficient on the track but for some road use it might be a bit overkill over a S2 tranny.

A friend has got this upgrade in the work anyway, so I sure hope to find out in the near future.

Mercedesben

here is a pic of the swap

User 41221

Ben,

Hate to be the bearer of bad news, but that "different shims/80% locking" is a myth. What happened is they inserted the wrong shims (2.5mm from a 951S tranny instead of the 2.0mm shims that should be there) in the tranny, wrongly thinking that it would create greater locking, when in fact, all they did was jam something in there with insufficient clearance that will cause improper wear. Been there, done that and bought the VERY expensive t-shirt in the process!

Give Kevin Gross a shout at kgross@connact.com, he's the absolute best 951 tranny guy that I know of and he will get you set up properly. He did the final build on my gearbox and I cannot say enough good things about him.

The S2 r&p is awesome, tho, isn't it?

Regards,

Mercedesben

That gear ratio is perfect, I cant wait run it on the track!
I will call the shop that built the trans and see what they did, I will have the shims removed if it is a bad situation.
I am still kicking myself for selling my old car, as this one is getting close to where the blue car was but I still have to do a WG, MAF and I still do not have sport seats! I hate having to start over!
I know that you are taking great care of the car!

CMF

I hit rpm limiter (7200) with 5th gear in one mile and speed was 260km/h (police radar)
S2 tranny, 265/35/18 tyres.

Olli Snellman

Several Audi's use similar transmission which have a speedo pickup like 951 trans have.You can modify your 968 trans to use this Audi part and have your 951 speedo work without problems; so no need to convert your original system to get impulse from ABS. I suppose it's quite difficult to find such a parts from the USA, since most Audis probebly have auto trans, but here in europe it's a different story, because we still prefer manual transmissions.

User 41221

Don't let them tell you that they can convert a factory lsd carrier from 40% to 80% locking. It doesn't work. That low speed binding that you are experiencing is shim wear, not "locking" and will result in a complete gearbox rebuild in about 5-6k miles, if not more quickly.

I love the blue 951! I have one of John's Stage II turbo's on it now, plus my typical Bilstein/968 M030 suspension on it, 968 rear wing and mirrors, a new head, ceramic coated headers/exhaust, resealed front end and a few other goodies, plus the other stuff that you already knew I had put in it and am VERY happy!

Out of curiousity, I am convinced that the car had a new engine put in it fairly recently (I have NEVER seen cylinder walls *that* clean before and there are a few other clues as well) and am wondering what you knew about its history. None of the receipts I have from its past show any indication of a new engine.

Regards,

Oddjob

As Scott said, I dont think "shimming" works with a clutch type LSD for increasing lock. I assume that shimming implies that an additional or thicker friction plates were installed in the LSD.

Currently only the Turbo S LSD internals are available from Porsche. So if you need to rebuild a regular (pre M758 LSD) you need to replace the pair of friction discs and the pressure cups. I just went through this, and I recall that damn pressure cups are $150 each. So a couple things are possible: either the shop thought that adding the thicker friction discs w/o upgrading to the later/thinner pressure cups will increase the % lock, or they were cheap and did not want to pay for the cups.

The proper way to increase lock is changing the ramp angles on the pressure cups. This requires either maching the cups, or have custom ones made. You can check with Guard Transmission - they offer aftermarket LSDs with various % lock, and I think they may be willing to sell the different pressure cups, and they they may fit in a factory ZF LSD housing.

Now, if the shop did increase the % lock, using a proper method, you can potentially get some wheel hop when making tight turns. I have a custom worked LSD that is close to 100% lock under load, and it definitely hops when making tight turns - backing out of the driveway, moving the car around in the paddock, etc. It makes it a solid rear axle, and the inside tire has to spin slightly to keep up with the outside - so you get s slight juttering or quick/repeating "slip-stop" effect.

Mercedesben

I find out exactly how the shop did the lock on the trans, it is annoying but this thing is a rocket out of the corners.
Scott, I have no records of a new engine, but if I remember the records went back quite a ways. (I belive Steve Baum who orginizes the hershey swap meet every year was a previous owner you can easily track him down.
That is a cool find, but I believe the engine has just been maintained well. I made a huge mistake getting rid of that car, but I am having fun building another.

A 944 turbo is like herpes once you get rid of it another one replaces it.

Oddjob

Here is a somewhat long read on clutch-type LSDs. Gives some information on how to change the locking rates, and discusses both changing the ramp angles and also using different thickness friction discs or spring washers to change the preload, which also changes the release torque; so it sounds like "shimming" can possibly be done to correctly increase % lock.

http://www.guardtransmission.com/velocity.htm

My locking rear diff. is on a track/race car only. I dont think I would use it on a street car. I recall Paul Guard saying that upto 50-60% lock is fine for street, but anything higher should be for track only.

I also built up an S2 LSD trans to put in a 951. The LSD came out of an 87 951 box; I left it stock 40/40%, since that particular car is a street mostly/occasional DE car, and I did not want to deal with the juttering when making tight turns.

It would be a pain and cost some $ to drop the trans, pull the LSD, and swap in stock parts. So unless you get a bad feeling about how it was built, I would be tempted to deal with the high lock, until you need some other trans work done (which is hopefully never...).

Also, you can try different trans fluids and additives. Certain synthetics are very slick and require friction modifiers to be added, to ensure synchros and clutch type LSDs work properly. Im not really recommending this, but if you think your LSD is too "grippy", it may work to use a very slippery synthetic which may allow the friction surfaces to slip easier (??). But it would be detrimental to your synchros on down shifting.

theedge

He could also weld an Electromotive 60-2 wheel onto the front crank pulley and mount a VR sensor to trigger off it.

Thom

Will the 968 single mass flywheel from Porsche Motorsport work with a 951 bell housing ?

Mercedesben

The guy I bought my S2 trans from replaced it with a 968 unit and turned the same track times at Summit Point with both transmissions. He did say he could pass better with the 968 unit. there was no huge advantage other than the extra gear for the hwy.