Bill Verburg

Buy RS parts through any dealer, I like Henessee in Atlanta, but it depends on where you live

Here's the rear RS parts list from a few years ago, I wouldn't bother replacing the sidepanels, but for a low, track car solid mounts should be used on the oe's

The only RS specific arms are the top rear (Kinematic) and the lower A arms as Cupcar pointed out the other arms have thinner bushes and so are already pretty stiff and the same arms are used on all cars. The effect of the RS parts is to reduce the KT rear steer effect, to eliminate it use all mono-*****. I'm very happy w/ all RS rear parts except mono-ball toe arms and solid sidemounts




The RS specific parts are marked w/ blue dots on the aluminum and green dots on the rubber and all have part #s at or above .80

These are the only RS specific rear arms



You can buy RSR arms through PMS, here is Cupcar's RSR A arms


All the A arms have a mono-ball leading joint which I have found to be sloppy and loose on every high milage 993 that I've seen, the normal trailing arm is soft rubber, the RS trailing arm is stiffer rubber and the RSR uses a mono-ball on the trailing joint

Thanks to Cupcar for these pics of the difference between the standard and RS camber adjusters, I used the RS versions and they are maxed out, to get more rear camber I'll need to buy the ERP arms



In front, looking back

all oe's use soft leading bushes, the RS changes only the trailing bushes to stiffer versions, RSR uses all mono-*****

I'm happy w/ all Elephant sport bushes GT2 mono-ball tie rods, RS wheel carriers and 8.5" wheels

creaturecat

i ordered the mixture from ER. front softer, rear sport bushing, for front control arms.
Chuck questioned my request for a mixture, said they doesn't usually do this.
There shouldn't be a down-side to this mixture, correct?
Thank you Bill V

Cupcar

In my opinion, the Walrod bearing fits between a pure monoball and an RS bushing with the direction more toward the monoball.

Walrod's probably have approaching Zero deflection during cornering - they are made of material that is much harder than an 85 Shore RS bush - and harder at both pivot points.

The Walrod's may even have a better life span than a monoball, my bet is they do but I don't know.

They are cheaper and may offer a bit of noise isolation compared to a monoball.

So, I went Walrod bushes in front.

Bill Verburg

That's what the factory RS used

Tony_KB

Bill, is the mono-ball leading joint on the rear a arms ,-which you say gets sloppy on high mileage cars- replaceable? Or is the only route to get new arms?

Bill Verburg

You have to buy a new A arm, choice is normal w/ soft trailing joint and normal KT, RS w/ spot rubber trailing joint and minimized KT or RSR w/ mono-ball trailing joint and no KT

il pirata

I just recently bought a full RS suspension kit. I checked a couple of items I paid versus Bill's list which was a few years ago (and prices have gone up) and they are the same or less. Suggest you call Sunset Porsche in Portland...you can talk to anyone in parts but Andrea handled my order and if you mention Bob from Colorado invoice #256203 she can pull up the part numbers quickly. I did a lot of other stuff as well as new bolts everywhere so you you do not want my entire list. They had the lowest prices at the time that I found/offer great service/no taxes and shipping is very reasonable.

As Bill and others have mentioned the leading arm side also wears down and cannot be replaced. I found the cost difference being getting new rubber and the cost to have it installed versus new arms to be small enough that it made sense for me just to get new arms. Now if you were to install the new rubber your self then the cost difference would be much greater.

berni29

Hi Creaturecat

I think (as has been mentioned in this thread already) that the rearmost bush in the front control arms does not have nearly as much impact as the front. The standard, RS and ERacing front bushes all have cutouts in them that allow for steering geometry changes under braking. I think as long as you have opted for a rubber front bush that replicates the construction of the standard bush then you have made the best possible choice for road use. I do not have a clue about racing.

I remember being told that if you are running your car at RS height or below you need to index the front rubber bushes. Obviously the poly's do not need to be as they are just a plain bearing.

Berni

Tony_KB

Hi Bill, What is the point for the RS having softer bushes in the front vs the back?

Bill Verburg

That was introduced in the 964s to civilize the ride, the soft leading bush is sofest in the transverse plane, this provides fore/aft compliance when the wheel hits something, the wheel pivots around its rear bush reducing the impact, but transverse stability isn't affected due to the stiffer rear bush, the RS just exaggerated that effect, it also allows the wheels to toe out under braking which allows for better stability, W/ sport/sport I don't notice any issues eevn w/ 0 static toe.

Perelet posted this nice image of what is happening over on Pelican

Tony_KB

Very good explanation, would you suggest I do that setup for my street 85% / 15% track ? Also, any suggestions on camber and toe-in angles ?

Appreciate your help!

Bonster

My cars are about the same ... my most recent was -1.25 front and -1.75 rear with zero toe. Very predictable "tail wag" but tun-in could be a little sharper imo.

Bill Verburg

You can eliminate tail wag w/ RS arms, except the toe which needs to be a full mono-ball set w/ locks

turn in gets better w/ wider wheels and sport bushes and mono-ball tierods, wider tire also helps

Bill Verburg

Absolutely, my car w/ Bilstein Cup suspension(custom valved) Elephant sport front and RS rear(tarrett toe), solid sides and RS wheel carriers is very streetable, It's much more enjoyable than the original RoW M030 that it came w/

You do have to be careful of road irregularities and transitions though

Bonster

Spend my money, Bill! Lol, just teasing. Seriously, thanks for the awesome advice. I am going to bookmark this thread for when I have time to take my car in. I might be able to do this myself, but I would rather let an expert do it. I do not have the right garage set-up anyway. I think I will do the bushes and other suspension stuff first, then re-visit the wider wheels/tires issue once I get a feel for the new set-up. I have 225-45-17 front, 255-40-17 rear ... not sure without looking it up what the offset is ... what sizes are you thinking about? I do not want to roll my fenders, btw. I am trying to keep the "stock appearance".

One other thing I have heard, while we are on the topic of set ups ... I have heard about the kinematic toe several times, but nobody around here sets it. The nearest place is four hours away in New Orleans! How important is it that I drive over there and have this done? This is NOT a full race vehicle, if that helps. I just keep hearing about it, but can't easily address it. Thanks for your awesome contributions! I have learned a ton.