To get -2.5° front camber my shop used 7mm of shims per side. Front ride height was lowered 10mm to bring it into spec. Car weights 3150lbs - absolutely stock, no option, no A/C build with full fluids, full gas and OEM tool box.

 

mds,

Appreciate if you could explain the part about lowering the car to bring it into spec - what spec are you referring to? I've ordered a set of shims to target -3 to -3.5 deg up front. I've already lowered the front ride height by 5mm to compensate for the additional push brought on by having rear spoiler shims. Will I have to lower it more with the additional camber?

 

Hi Weng,

The spec I'm referring to is from the French workshop manual which states ride heights of 115+5mm front and 128+5mm rear (115 to 120mm front and 128 to 133mm rear). The USA manual does not have this information yet.

If you look under the front of the car, just inside of the brake ducts you will see the heads of three bolts. The front measurement point is from the ground surface to the bottom of the middle bolt head. The rear measurement point is a little harder to find. Looking from the rear, just inside of the end of the sway bar, you will see a suspension eccentric. A little bit forward, inside and below you should see a locating bore. It is a little bit hidden, you may have to hunt to find it. Measure to the lower surface of this bore.

My car arrived with a ride height of 125/128 - about 10mm to high in the front. So in addition to installing the shims, my shop lowered the front and did a corner balance. Installing shims and adding camber probably does not affect ride height, but I could be wrong.

 

With my car and several that have been described here, the vehicle was delivered with the front height about 10mm high. (I'm wondering if this isn't done intentionally by the factory.) My street mechanic encouraged leaving it at that height because the suspension will settle significantly. My race mechanic recommends lowering to spec. (or lower) to get the performance now and raise it as needed to counter settling.

My race mechanic has made his own shims, using an OEM part for the pattern. He services a number of race teams' cars from club racers to The Racer's Group (he was pit crew for their LeMans victory and since). Seems like a good idea to me.

He says that it works the same on the GT2 & 3 as on the Cup and RS: they get as much camber adjustment as possible at the top of the shock tower and then shim out to get the rest of what they want. He said there was no issue with caster and that they don't use the off-center holes in the A-arm. As I say, these cars are raced by a number of different drivers/teams, so I would guess he knows what he's talking about (I don't). You can call him (Bob Sanderson) at 770-457-5550 (Atlanta).

 

Gentlemen:

This is a very timely discussion. As has already been posted in another thread in this forum, I just bought Watt's GT2 and I'm trying to deal with this very issue of shims. I've been to dealers and they really have no idea what's going on. Both looked up the shims on the PET CD and found that the left shim is about $160 and the right shim is about $10. They also said that both needed to be ordered from Germany and there is no telling how long it could take for them to arrive - 6 weeks or 6 months.

Here's the really confusing part. On the PET CD for the GT3, there's only one shim listed - in different thicknesses, of course. My understanding is that the front suspension of the GT2 and GT3 is the same, so why would there be a left and a right part for the GT2 and only one part for the GT3?

In any event, I know Bob Sanderson because he's been out to both of my TracQuest DE events at Road Atlanta. Great guy. I take it he's selling the shims for both the GT3 and GT2? I believe the cars come with 1 mm shims. I want to run 2 degrees negative, with the ability to go down to at least 1.5 degrees and up to at least 2.5 degrees. Does anyone know which shim (thickness) I need for that camber adjustment range?

Btw, regarding ride height of the GT3, I seem to remember hearing somewhere that Porsche had to sell them higher than they should be in order to comply with DOT standards. Does anyone know if the GT2 is the same? I don't know if my car has been lowered from the time it was delivered, but I can tell you I wouldn't want to run it any lower on the street. It's already as low as my 996 Cab, which is extremely low for an every day driver.

 

"Btw, regarding ride height of the GT3, I seem to remember hearing somewhere that Porsche had to sell them higher than they should be in order to comply with DOT standards. Does anyone know if the GT2 is the same? I don't know if my car has been lowered from the time it was delivered"

Toddler,

your car is stock high

us gt2 same as euro high

 

Todd, GT3 shims are available in 1, 2, 3, and 7mm pairs from the factory. They arrived from Gert in less than two weeks. Here are the part numbers:

996 341 543 90 Shim 1 mm
996 341 543 91 Shim 2 mm
996 341 543 92 Shim 3 mm
996 341 543 93 Shim 7 mm

The 7mm was back-ordered so had my shop stack several narrower ones. They ended up using 7mm to get -2.5 degrees. However, the top mounts differ slightly car to car so you may need something a bit thicker or thinner. They should work on the GT2 as long as its suspension uses the same two-part track control arm from the Cup car.

At 115mm height, the front spoiler is a little less than 5 inches above the ground. The brake ducts are about 2.5 inches.

 

Todd, I spoke with Bob just a few minutes ago. I've taken a look at the shims he had made. Normally, I much prefer to use Porsche parts, but there are times when I compromise. One was the adjustable drop-links (for putting the GT3 front sway bar on my 986): the Motorsport parts are >$800 ea.; TRG makes a replica for $400. These shims may well be another exception, in this case because they are so damn simple. The pattern isn't complex and the engineering is as simple as it gets: aluminum bar stock in the specified thicknesses. Bob's copies looked well-finished (deburred, unstained, etc.); I would guess that other shops have done or could do the same easily enough.

Anyway, to clarify some of my earlier information, Bob tells me the Motorsport recommends doing the grosser camber adjustment at the shock tower and fine tuning it with shims. However, he goes on, the tower permits only a degree or so of adjustment, and he has clients who race with -4 degrees and more, so the shims provide most of the adjustment. (I believe he made his in 1mm, 3mm, and 5mm thicknesses.) He has indicated that these parts are completely interchangeable betweeen GT2, GT3, and Cup.

BTW, the disks in the A-arms he calls "caster pucks" and confirms that they use the center holes all the time. I forgot to ask what the others are good for.)

 

Mark, Viken posted a picture of the multiple bores in the arms. See this thread. Being offset rearward, the second non-centered bore must affect caster somehow.

By the way, how did you get the radio out of the dash?

 

Yes, I feel sure it must affect caster. Some shop manual pages Viken posted indicate that the off-center holes are used for race set-ups only. Since Bob does race set-ups up to -5 camber and doesn't use those off-center holes, it makes me wonder what they're really good for.

To get the radio out of the dash, I paid a mechanic. (Oh, the shame!)

BTW, car on Longacre scales today: 3040 pounds w/ 1/2 tank (GT3 seats and rollbar, no A/C, no radio ).

 

Mark (and others):

Thanks for the input. Fyi, I had emailed Gert myself and he sent me the same info, along with prices. I also spoke with Peter at Performance Imports. He said Bob would have to call me back with the answers to some of my questions. I've been waiting, but I presume he didn't because he was on the phone with you. :-)

From what Peter told me, Gert's prices are actually a bit better than Performance Imports' prices, and Gert is selling factory parts. Frankly, it doesn't matter much to me either way because anything Bob had fabricated and is selling is top drawer, I have no doubt. Now I'm just trying to figure out which shims to get. I may wind up getting 3 mm and 5 mm shims and that way I'll be covered, unless someone tells me definitively that one or the other size is definitely the size I need.

 

Todd, I purchased the 1, 2, and 3 and would gotten the 7mm if it were not back-ordered. The car is shipped with 1mm installed. My shop ended up stacking all that I had ordered together with what was already on the car to make a total of 7mm per side. This enabled them to get -2.5°.

 

Thanks, Mike. Sounds like getting pairs of 2 mm and 3 mm shims is what I need to do. Combined with my 1 mm stock shims, that will give me the ability to have any thickness up to 6 mm, which should be enough to get me the 2 degrees negative maximum I want. The 2 mm and 3 mm shim pairs are 31 Euros and 52 Euros per pair respectively from Gert, so for about $100, I'll be all set.

Now, about those PCCB's . . . :-) Seriously - is there anywhere to get the Pagid Yellow and Green pads for less than the dealers charge? This is likely a question for GT2 owners since I'm guessing few GT3 owners ordered the PCCB option.

 

You can get them directly from Porsche Motorsports...they are about $550 a set if I remember correctly.

Based upon what I've learned and been told here by some capable people, the yellows are good on the track and the greens will cause more wear. See Bob Rouleau's posts they are very insightful, backed up with considerable experience and devoid of emotion.

 

Hi Colm:

I know Bob from the 911 list over the past several years, and we've already had an extensive telephone discussion about PCCB's. However, I don't recall if we discussed which pads to use on the track. But I believe you know Arnaud, from bulletin boards and from my TracQuest events. I believe he said that the Yellow Pagids don't hold up at all on the track, and that he went through the better part of a set in one event at Laguna.

Either way, even if $550 is for fronts and rears, that's damn expensive. The Pagid Oranges I've been using on my 996 Cab cost about $175 for the fronts and about $150 for the rears.