Martin S.

Rebuild your Porsche 993 Limited Slip? I was...faced with a stock LSD that had simply failed, and failed quite some time ago. Since I track the car, I want to have every advantage allowed in my class. There are no points for a failed LSD.

It had been rebuilt eons ago with stock clutch packs @ ANDIAL. They offered me RS packs with a $800 surcharge; I passed. I had Guy Ober at Guy's Independent in SLO, CA extract the LSD with the ring gear. Next time, I will ask Guy to remove the ring gear before we ship it to Paul. He doesn't like to spend valuable time removing ring gears, my bad. In addition, the ring gear adds to the freight cost.

Getting back to why Guard Transmission? I had heard that Paul Guard at Guard Transmission did a great job and it wasn't super expensive...that caught my attention as I am on a racers budget just like lots of you. Had I an unlimited budget, I would have simply purchased the Guard GT LSD...down side, about $2,200 just for the unit, + the labor to install it.

Here is what I got for about $500, don't have the final bill yet:
Replaced the 12 ring gear bolts,
4 friction discs (High Performance),
2 plain plates,
2 Belleville washers.

In addition, they are sending me the old friction discs to you so that I can see how slick the Carbon ones get. He noted that have been discoloring the oil. I noticed that too. I will take some pics and post them up.

Once the LSD is in, Paul recommends Swepco 201, and not to use synthetics. I will listen to him. He is a LARGE LSD, tranny and gear specialist. You have to trust your experts, just as pilots trust their instruments.

He also recommends driving the car for 100 to 150 miles on the street just to break it in, and to get the feel of having a working limited slip.

In conclusion, dealing with Paul Guard and his assistant Mike was a very pleasant experience. If you send in your LSD sans ring gear, they can re-build it in a day. I can hardly wait to get it back and do my required test drive of 150 miles. I will be all over that!

gordo993

My car didn't come from the factory with limited slip. Can it be added? Will it cost the above mentioned $2,200 in parts?

If so, I can wait...

TheOtherEric

Martin, I did the same exact thing as you, and have been very happy with the results. I think you'll find improved braking stability, and some understeer coming out of corners (which is not a problem, just a little different).

Terry Adams

I rationalized buying a new Guard LSD by selling the worn OEM LSD for $400 and getting in on the group buy for $2100. I got the added benefit of viewing the Guard LSD on my coffee table for a few weeks before I had it installed.

Martin S.

Gordo,

You can add a limited slip, the question is, do you need it, or do you want it?

I tracked my car for years with a worn out LSD. These darn 993 cars are so well engineered (Or I am numb?) that I didn't even know it was gone. I had no excessive wheel spin coming out of corners.

My 2007 competition have working LSDs in their cars. I want to be on an even playing field with them...ergo, the rebuild.

As you can see from the string, I am not the only one rebuilding their LSD...but in your case, you don't have one.

If you track your car, the LSD will be helpful on acceleration and deceleration, cornering too. On the downside, as mentioned in the string by TheOtherEric, there will be a little understeer powering out of the corners. I can handle that,that is why we have sway bars and driving skills (I have the asway bars but have questionable driving skills).

If you want a LSD, if you need an LSD, then there are basically 3 choices that I know of (Well actually 4)
1. Buy a 993 factory LSD and rebuild it...you'll be out $1,400 and 5+ hours of labor to integrate the LSD into your transaxle,
2. Buy a Porsche Motorsports LSD, $2,500 +, and pay to have it installed,
3. Buy a Guard GT LSD for about $2,200 and pay to have it installed.
4. Install a Torsen Torque Biasing LSD, not a good idea with a 993 and our LSA suspension. With Torsen, the lock up in acceleration is provided by gears.

With the conventional LSD, there are clutch packs. They do wear out eventually.

In summary, if you track the car, the Guard GT LSD would be a very attractive option. Were I you, this is the way I would go.

Or, if you don't track the car...save your money...all of the above simply my opinion based on my experience.

long_beach_968

While mine is out cali motorsports said they would tacke the LSD rebuild for $500. But as much understeer as I have coming out of the corners, I dont think its gone yet. (68K)

clubsport1

Standard Porsche lsd plates tend not to last more than 25-30k miles on a car used for occasional trackdays and DE...obviously how often it is tracked will make a difference.
My diff was ineffective at 24k miles, I heard yesterday that my new diff plates have arrived from Porsche motorsport Germany to be fitted next week

Apparently the uprated plates are the same as those fitted to the current 997GT3RS, shame to have "kettle" parts on a proper car, but with a mere 300bhp they should last a while

Flying Finn

Thanks for the tip Martin, my LSD I'm sure has been busted for a loong time so this sounds interesting.

Paul902

Martin,

I did the exact same thing this winter since mine was worn out, too. I have nothing but praise for the experience, knowledge, service, and attention of those guys at Guard!

ColoradoMark

$500 is a LOT less than I wold have expected. I looked on p-car but didn't see LSD removal instructions. I assume this is easist if you drop the engine and tranny together then pull out the LSD, or can it be done without dropping the tranny? Of course if you drop the engine that now opens up the whole, while I'm in there..., can of worms and it will no longer be a $500 bill!

gordo993

Thanks for clarifying, Martin. My car handles beautifully on the track (at least at my skill level!!) and seeing how I only do 2 DE's per season, the expense faaaar outweighs the need. That's money that can be well spent on other areas of the car.

chris walrod

No worries -- the diff will drop out with the lump and box in the car -- remove the driveshafts, remove both output flanges (center bolt) unbolt the diff cover casting, and the slimy chunk of metal will come right out.

Martin S.

"No worries -- the diff will drop out with the lump and box in the car -- remove the driveshafts, remove both output flanges (center bolt) unbolt the diff cover casting, and the slimy chunk of metal will come right out."

It took my mechanic 1 hour to extract the LSD. If you send it out for a Guard rebuild, let Paul Guard know you heard about it on Rennlist. He already has my money; I get nothing out of the plug.

chris walrod

This is a little surprising. I drained the Swepco 201 the PO had in the car and replaced it with Mobil1 syn. I was having a little trouble shifting, especially when cold, just about all gears. Now, it is very much improved with virtually no syncro lag at all!

This same thing happened to another fellow that I service his 964 for -- took out the Swepco, replaced with M1 -- problems went away --

The Swepco is great for the Porsche syncro gbx's -- not so much (me thinks) for the Borg Warner syncro transmissions found in 911's from 1987- on.

FWIW.

avidtest

I had my LSD rebuilt last week by Guard. About $500 (plus labor from the local shop for removal and re-installation) and now I have four plates instead of just two. I was itchin' to try it out last weekend and went to Spring Mountain track in NV w/ the local PCA for a two day TT. 3rd lap into my 1st session and I can no longer shift gears. Pull into the pit to see what's going on with a sinking feeling. I can get it to shift, but it's very hard. Sometimes it'll go into a gear and other times I need to wiggle the shifter a lot before it'll go into a gear. Something was loose in the gear box. Had a fellow take a look and he figured the plate in the box was loose because it was hard to shift in every gear. Needless to say, I was a little mopey as my weekend was coming to a close just as it was beginning. Loaded up the trailer and headed back to San Diego.

Previous to this, I had been having issues shifting from 2nd to 3rd on the track. I'd regularly crunch 3rd. Also, when I picked up the car w/ the new LSD (prior to the TT event), I was shown some sizeable metal slivers that had come out of the tranny, along w/ the old fluid (yikes). Figured I'd be able to get through the weekend though because those slivers could have been in there for up to a month from when I last changed the fluid.

Took the car back to the shop and am now I'm thinking that I'd not only have to get the issue at hand repaired, but that I'd be paying for steel synchros and other tranny parts. I was pretty sure that the tranny had not been dropped when the LSD was removed and subsequently re-installed and that it was just a conincidence that my tranny failed right after the LSD rebuild.

Got a call from the shop today and am very happy to find out that the P.O. had already gotten into the gear box. The car already has steel synchros. Sweet! However, I'm still thinking I'm going to be faced w/ an ugly bill.

Apparently, there are a couple of cotter pins in there and one of them had gone bad a while back (which was causing me my 2nd to 3rd gear crunching issue) and the 2nd one went bad on the track. Looks like the only parts I'll be needing are those two pins, plus labor. That sure as hell beats an invoice for a bunch of new tranny parts though. For what it's worth, I was out at La Jolla fishing for yellow tail on my kayak this morning when I got the call, so it's very possible that I missed something in the translation, but that was the gist anyway. (BTW, got a 20lb. yellowtail out there today).

Even better; it looks like it'll be done in time for this weekend's autox and I'll finally get a chance to try out that new diff.