997,1 GT3 LSD refurb/upgrade options

[galahad]

Hi all,
My recently acquired 997.1 GT3 is in need of an LSD refurb as it is now basically open. It has been refurbed once in the past about 30k miles back, but is now in need of doing again annoyingly!

I have done some reading online and it seems that the cup diff was a recommended upgrade, but apparently these are now no longer available. Quite a few US guys seem to go for the Guard diff, but these are very expensive by the time you've brought it over here.

Any advice as to what the best option would be? I do plan to track the car and do a few road trips so will maybe do 3-5k miles per annum, so if I do go back to the oem option, it'll probably last 4-5 years at least, but that does seem like a pretty rubbish option.

Cheers

Chris

 

[Cunno]

Did they use cup plates on diff when replaced?

The 2 option you talk about are the go to options, looking at intended use I suggest replace plates with cup plates and set up preloads correctly. I'd speak to a good quality Indy who have motorsport accounts, as I expect they will be able to source? If not your into guard internals https://www.guardtransmissionllc.com/products/limited-slip-differentials/

 

[Roro]

I agree with Cunno

Anyone have any experience with this clutch pack? Just found this online, looks like lift and drop replacement for OEM plates
https://racingdiffs.com/products/po...lsd-differential-clutch-plate-replacement-kit

One would hope this clutch pack isnt made of chocolate like the OEM plates!

If cup plates were fitting and wore out after 30k miles, then I suspect a lot of track work (which isn't a negative, I'm just sayin'). I can't believe they would wear out after 30k road-only miles. Reason I say that is I had Porsche MS cup plates fitted maybe 7/8 years ago now, and last year was told that they're about 50% worn, and I've done about 25 trackdays since fitting. Not sure of the mileage, maybe about 20k. I don't know why, but I though they'd last a lot longer

 

[galahad]

The last refurb was done by a dealer who did it to sell the car, and so went with the cheapest (standard) option annoyingly! Have been told now b a few people that Porsche Motorsport no longer make the cup diff plates and there's none left in stock.

Like the look of those racingdiffs.com plates - will do some research to see if I can find any reviews.

 

[mm450exc]

I used cup plates as well.

Check with Matt at Fearnsport.

 

[Cunno]

The last refurb was done by a dealer who did it to sell the car, and so went with the cheapest (standard) option annoyingly! Have been told now b a few people that Porsche Motorsport no longer make the cup diff plates and there's none left in stock.

Like the look of those racingdiffs.com plates - will do some research to see if I can find any reviews.

Standard diff plates are about as much use as a chocolate teapot, real weak point on 997. I heard that you can do them in, in a couple of TDs.

 

[Roro]

Do the 991/992 cars use a similar design diff or is it all electronic trickery now? I'm wondering if the 997 part has been superseded by a newer part that's more durable. I don't think I ever heard of 991 GT3 owners complain about crap OEM diffs

 

[Senoj]

What makes you think they are worn?

Lots of grip on the rear of a GT3 and it's kind of hard to feel what a diffs doing or not at road type speeds and braking forces.

I've heard cup plates are NLA

 

[VPD255M]

I have a set of cup plates that I'm looking to sell on.

I've switched to a Guard 40/60 ramp set up so these are available, been meaning to put up a post for a while but not got around to it...

They are used, my indy advises they have plenty of life.

PM me if interested.

 

[D4.driven]

Watching this with interest.. are the guards plates freely available in the uk or do you have to impetigo from the US.

Any recommendations for who would be best to carry out the work.. Fearnsport?

 

[Y2K]

Sports and Classic at Macclesfield SK10

They did some gearbox work/upgrade for my car last year. Great service. Recommended.

 

[Diggermeister]

Sports and Classic at Macclesfield SK10

They did some gearbox work/upgrade for my car last year. Great service. Recommended.

^Good advice.

They put a set of Guards diff ramps into mine (which I'd bought from JZM). It is the design of the ramps which is the weak point on the 997 platform. They differ form the 996. The short reason is that the ABS was supposed to do some of the work of controlling the rear axle, but in practice, on track, you would run through rear brakes and also get fade.

FWIW, video for those who want to know more about how the ramps and plates work in an LSD: https://www.youtube.com/watch?v=WeLm7wHvdxQ

 

[galahad]

Thanks all. I have emailed Sport and Classic so will see what they say.

I'll report back.

 

[MisterCorn]

If you do want to go down the Guard route, Matt at Guard won't deal directly with individuals, but you can get them through Matt at Fearnsport. I'm going with a Guard LSD on my turbo gearbox.

MC

 

[johntyboy]

Hi

There seems to be a lot of noise about the standard LSD plates in 996/997 diffs being made out of chocolate and not lasting very long. This isn't strictly true. Pre load of the clutch pack is very low from factory (5 to 15 NM) and only a very small amount of wear on the clutch pack results in zero pre load on the diff. This results in effectively an open diff.

There are 3 options as recommended by Matt at Fearnsport.

1. Cup Clutch pack. (Matt did not recommend for road use this is too aggressive, this pack was designed for use with slick tyres on Cup cars and road tyres simply don't have enough grip to brake away the diff resulting in a car that pushes)

2. Gaurd Transmittions Clutch pack (A great good quality replacement clutch pack which results is far more pre load than the factory set up, around 50 NM from memory)

3. Fearsport uprated Belville Washers. (The new washers are thicker and more pronounced than the factory washers, this puts more pre load on the original clutch pack. Obviously the clutch pack still needs to be serviceable but mine at 40,000 miles were).

I chose the upgraded Belville washers from Matt and fitted them myself. Quite easy and can be completed with the gearbox in the car.

My standard "Chocolate"clutch plates. Since the upgraded Belville washers were installed the Diff has worked absolutely fine and I've completed a number of track days without issue. Car now has 47,000 miles on it.

Hope that helps.

Kind Regards