kos11-12

There is a conical spacer inside the arm , ERP have designed a great kit, also the spacer/adapters are machined to fit inside the ball bearing so it is a very tight fit with no slack at all ....
Concerning dirt, I have rubber boots to fit but I left it like that for now to see what's going on, the weather here in Cannes is very mild , similar to CA, we have 30/ 35 deg C at the moment ....shorts, T shirts & swiminwear,

kos11-12

Hi Guys,
I drove the car for a few miles yesterday, the steering feel very sensitive like a Gokart, like I just need to turn it a bit for the car turn a lot from before, the wheels seam to follow a lot more road imperfections (size is 225), it does pull straight and also when braking...

Steve I would appreciate your comments...

Did I mess the tie rod geo, even if the tie rods are parallel to the ground?
Is the ball bearing outer tie road to aggressive for road use , making the car, to much focus as a race car now.
Should I use a different wheel alignment set up: front is;
Camber 2°09
Caster 4°45
Toe 0°13
Or fit the 93 RS uprights ...
What is the difference in terms of feel, between running an ERP with ball bearing or OE 993 RS outer tie rod

Steve Weiner-Rennsport Systems

Hi Konstantin,

Rod angles cannot tell you much without ride height information to provide some context. The bottom line though is that you must bump-steer the car with the gauges to measure YOUR bump steer at your ride height to see what you have. Its a laborious process, but that's the only way to do this properly.

Rod ends on tie-rods are generally used on race cars to enhance steering precision and facilitate repairs/replacement when necessary. I don't use them on road cars simply due to longevity issues. Adding a rubber boot over the ends extends their durability, but they do not last as long as the OEM Porsche part.

Your alignment looks OK for track use.

The RS uprights & matching tie-rods make a far bigger difference for correcting bump steer and overall feel, compared to the ERP parts by themselves, do. The ERP items can also be used with the RS inners.

sml

i still want to hear about these bump steer symptoms.

i am at RS-5mm and the car feels great. cannot feel any bump steer issues.

kos11-12

thanks a lot Steve

I will check bump steer, I may have now to much camber ....for a road/track car
the rose joints are not so expensive but need an alignment every time its replaced...

SML
when lowering the car the pivot point of the tie rod is not centre so when the car compresses the tie rod shorten the distance and pull the wheel in also when compressing by hitting a bump road at hight speed or braking very hard, so the wheel would move in when the steering is still straight, but it could get worst if you hit a bump when turning...

sml

but could you feel any impacts/symptoms when driving?

i dont notice any probs at RS-5mm .. but i am not a highly tuned racing driver.

kos11-12

You don't feel it all the time , correcting the tie rods geometry and fit better engineered part is suppose to make the feel of the steering more precise and smoother,
My car may have become to much of a track focus witch would not be enjoyable on public road but on track....
I will have to see if I can improve as it is, otherwise, decision will be to revert or fit the 993 RS uprights, I think the rose joint may have made it too precise...maybe less camber...so the wheels would be flatter on the ground ,
First think first I will measure bump steer...
Will keep you updated...

Gus

I ordered a set of rod ends and made my own - works great -

kos11-12

Very good !! Did you measure the bump steer ? Do you have the 993 inner tie rods ?

I will measure mine soon ....to much work at the moment, I did more driving on twisty mountain roads ; it's really good on corners really holding the line where it's been set with no hesitation no movements into the corner, can even increase speed into it, basicly much faster into corners , my passager she tap me on the shoulder so I though that was a good sign...
What concerns me is fast motorway driving, don't really want to drive it fully concentrated for 600 km , anyways I need to do more driving and measure the bump steer properly, I have a good plan for that, will let you know soon...hopefully

panzerfaust

im pretty surprised to here you say that. ERP kit does just that lowering the attachment point of the steering knuckle. yes you can alter the bumpsteer with this kit like this.

now to cure the lowered roll center that inadvertently increase the roll leverage of a drastically lower car yes you will have to monkey with uprights or pickup points.

respectfully

pf

Rub

Just wanted to revive this thread, and see what the final consensus was after more driving.

Also, curious as to exactly why everyone has reservations against doing this on a 964 to correct for bump steer on a lowered car. In researching ways to correct the bump steer, all expert opinion seems to say that this can't be done, and that the only solution is to spend $5000 on 993RS uprights and all of the supporting parts (tie rods, rotors, calipers, pads, etc). Seems like it is a common mod to reverse the mounting point of the tie rod on some other cars, so why not the 964?

porsche mania

the garage I use have suggested making me a kit like this for my car except that it would have an adjustable offset to the carrier so it could be adjusted to suit various ride height. Can't understand why anyone wouldn't think this would work as its common practice on almost every other car converted for the track. I can see that they won't last like oem parts but who's 964 does average yearly mileage anyway, so I'm not bothered replacing every year or two! The cost is next to nothing as well. As for bump steer I've noticed it on corners where the outside tyres on the car are really loaded up and then falls into a dip in the road and as the car g's out in the dip the wheels toe out and as they return they toe in. This is ok if both wheels do the same but if all your weight is on one one side of the car then it's like adding an eight of a turn of lock without meaning to! Probably ok if you have Mike tysons grip but a 911 isn't meant to be wrestled around a track

Steve Weiner-Rennsport Systems

Precisely!!

The ONLY way to alter bump steer is by raising the steering arms on the hub carriers, something the 993 RS ones do.

kos11-12

Hey guys ,
what a coincidence ....
I just have some news; I have been driving with the kit for a while now with absolutely no issues, like about 5000 km, we recently dismantle the ball bearing to see how everything is, with the guys at the new garage I use in Paris France, (the guys have a lot of experience on prototype race cars for decades) Basicly we decided it was a tad on the edged and the guys just finish to modifie the arm of the uprights, they drive the car and report it was perfect.
Et voila basicly, best it to mod the arm of the upright to avoid being to much on the edge and yes it is possible and cheaper to mod the upright, but to be done by an expert who is going to calculate the angle of the arm,
I suppose for those who will build a car from scratch it worth buying the RS uprights and so on , and save another 1,5 kg on each corners ,
Cheers
Konstantin

kos11-12

I will post pictures in a few days, here is a couple of interesting pictures, one from Bill a Rennlister we all know, showing the difference between the 2 arms, the RS is up and at an angle this is why the bump street kit has a large spacer underneath and on the other picture from someone in the Pelican forum, we notice the bolt is almost shaving the inside rim, we can quite clearly see on this last one the angle of the RS arm