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HELP! Tarett Engineering 935 Front Suspension Kit and wheel rub

Hi guys!

My car came with the Tarett Engineering 935 Front Suspension Kit installed, I my mechanic is having issues getting rid of the wheel rub on tighter corners.

There is a tire rub prevention kit installed, but the wheels touch the toe rods before the rub prevention kit acts.

Tires are 215/50 so not huge.

I enclose a couple of photos, I'll try to take better one's tomorrow.

How do I fix this?

Cheers,

Dan




Last edited by dan512; 10-11-2018 at 10:50 PM..
Old 10-11-2018, 10:50 AM
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Tarett (a great company) sell the Eisenlohr Racing Products (ERP-- another great company) set up. Those are probably ERP parts.

I installed mine a few years ago.

There are quite a few variables involved.

I run 11 inch wide by 16" wheels with 12 inch wide slicks, and I do see some evidence of tire rub-- probably from around the paddock since I do not use that much steering lock on track. My evidence is rubber deposit on the arms.

When I looked at this on my car (and also desired to address potential interference with my drop links and my calipers-- there is another thread about this), I decided to try some steering rack limiters.

These can be just split collar shaft clamps with an ID and OD that fits the rack. In my case, to limit the steering lock enough to prevent excessive lock I needed something thicker than the typically ~1/2 inch thick clamps, so I made some measurements and some spacing rings out of Delrin.

After I had spent about 2-3 hours fooling around and about $30 for the clamps and had everything installed I decided that I wanted the ability to turn more to move my car around in the paddock.

And essentially that I would never have interference/rub at any steering angle I'd encounter on track.

So I de-installed everything and put it in a box in my garage.

If you are having rubbing on track, I can dig my parts out and send you the ID/OD of the clamping collars I bought from McMaster Carr.
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Old 10-11-2018, 12:31 PM
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Quote:
Originally Posted by Mahler9th View Post
Tarett (a great company) sell the Eisenlohr Racing Products (ERP-- another great company) set up. Those are probably ERP parts.

I installed mine a few years ago.

There are quite a few variables involved.

I run 11 inch wide by 16" wheels with 12 inch wide slicks, and I do see some evidence of tire rub-- probably from around the paddock since I do not use that much steering lock on track. My evidence is rubber deposit on the arms.

When I looked at this on my car (and also desired to address potential interference with my drop links and my calipers-- there is another thread about this), I decided to try some steering rack limiters.

These can be just split collar shaft clamps with an ID and OD that fits the rack. In my case, to limit the steering lock enough to prevent excessive lock I needed something thicker than the typically ~1/2 inch thick clamps, so I made some measurements and some spacing rings out of Delrin.

After I had spent about 2-3 hours fooling around and about $30 for the clamps and had everything installed I decided that I wanted the ability to turn more to move my car around in the paddock.

And essentially that I would never have interference/rub at any steering angle I'd encounter on track.

So I de-installed everything and put it in a box in my garage.

If you are having rubbing on track, I can dig my parts out and send you the ID/OD of the clamping collars I bought from McMaster Carr.
Hi Mike!

1st of all I am wondering whether the wheel rub is normal with this setup, since the seller (who also built the car) just got back to me and tells me he runs the same setup on his daily driver without any wheel rub.

But if you could send the ID/OD and a few pics over, that would be great.

I only experience rubbing on tight corners but here in Luxembourg (Europe) each road car has to pass a technical conformity test. And wheel rub is a no go. So I am likely to fail registration.

Dan
Old 10-11-2018, 01:44 PM
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Hi Dan,
I had the same issue. Expect when they were designing the 935 suspension back in the day they were not worried about loosing some steering lock and clearance on a race car. Then others copied and reproduced that design and geomenty. Asssume many people have run into this isssue and just lived with it.

I want to use my car for some occasional hillclimbs and motorkhana/autocross, so needed the lock.
Talking with Tyson (who did the engineering work on my car) we ended up modifying the lower control arm and made new attach points inboard to increase clearance on the tie rods. Works great, and while I havenít done a autocross style event yet, we tested at Willow Springs a two weeks ago running 275/17ís and no issues with clearance.

Tyson left the original mounting points there so i have the option of moving outboard later for circuit events or narrower tyres.

Tyson is PRO motorsports in Burbank, not sure where you are located but if you happen to be in LA maybe go see him if you want to modify your set up.



Check out my build below thread which has some more photos and details.

Project 77 - new build
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Build Thread:
http://forums.pelicanparts.com/porsche-911-technical-forum/985164-project-77-new-build.html
Old 10-11-2018, 02:33 PM
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Quote:
Originally Posted by DHE11 View Post
Hi Dan,
I had the same issue. Expect when they were designing the 935 suspension back in the day they were not worried about loosing some steering lock and clearance on a race car. Then others copied and reproduced that design and geomenty. Asssume many people have run into this isssue and just lived with it.

I want to use my car for some occasional hillclimbs and motorkhana/autocross, so needed the lock.
Talking with Tyson (who did the engineering work on my car) we ended up modifying the lower control arm and made new attach points inboard to increase clearance on the tie rods. Works great, and while I havenít done a autocross style event yet, we tested at Willow Springs a two weeks ago running 275/17ís and no issues with clearance.

Tyson left the original mounting points there so i have the option of moving outboard later for circuit events or narrower tyres.

Tyson is PRO motorsports in Burbank, not sure where you are located but if you happen to be in LA maybe go see him if you want to modify your set up.



Check out my build below thread which has some more photos and details.

Project 77 - new build
Iím in Luxembourg (Europe) so seeing Tyson about this is going to be hard. But I will show the pics to my mechanic. Maybe he can draw some inspiration from them
Old 10-12-2018, 12:32 PM
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I installed rack spacers to prevent rub on my old race car. made them out of nylon cutting board. they will cut down turning radius some, but stopped the rub.
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Old 10-12-2018, 12:50 PM
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Originally Posted by juanbenae View Post
I installed rack spacers to prevent rub on my old race car. made them out of nylon cutting board. they will cut down turning radius some, but stopped the rub.
There are steering rack spacers installed, but the tire hits the toe rod before the rack spacers can do their job.
Old 10-12-2018, 12:54 PM
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What wheels are you using?
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Old 10-12-2018, 12:57 PM
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Quote:
Originally Posted by dan512 View Post
There are steering rack spacers installed, but the tire hits the toe rod before the rack spacers can do their job.

add another one.
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Old 10-12-2018, 01:29 PM
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How are your offsets? Will a spacer widen the front track so you clear the rubbing when you are locked out on the steering rack? I had a problem on my where my aftermarket wheels, bigger tires started to rub on the wheel well when the rack was locked out. I put some 7mm spacers which fixed the problem...

Sent from my Pixel XL using Tapatalk

Last edited by samurai_k; 10-12-2018 at 06:03 PM..
Old 10-12-2018, 05:43 PM
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fast eddie
Why don't you just call Tarett and talk to Ira?
Old 10-12-2018, 10:54 PM
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I would try to avoid making a mountain out of a mole hill.

On my car, when I measured everything at static ride height, it was clear that I would need more than an inch of spacer on each side in order to limit steering lock enough to completely prevent interference (see the thread to which I referred earlier).

I bought a set of clamps from Mcmaster carr, and then realized I needed more spacing. I priced a set of spacers with the necessary thickness (from Mcmaster-Carr) and they were really expensive. So I made some spacers out of Delrin.

Then I checked my in-car video to make sure that I had plenty of lock for all of the corners and "correction situations" I would likely encounter.

The benefit of the clamps is that you do not need to remove the tie rods to install them. It can be a real pain to remove the tie rods (special thin wrench, overcome red Loctite, et cetera).

In any case, as I said earlier, after I was done I decided, "screw it," and removed it all.

I also spoke with my good friend/engine builder to get his advice. He built my car and was a pro racer in IMSA back in the day.

He suggested that I consider some thick rubber hose, with decent compliance and ID/OD to act as a spacer. I had some scrap on hand and made some spacers up from that and took the car for a spin on the street. Worked fine.

But later I removed the hose spacers as well.

It can really pay to make sure you know how much lock you need for driving as opposed to guessing.

In this case, the OP apparently just needs enough spacer to pass some sort of inspection.

Is it a static test or a driving test? I might just make some spacers up from thick rubber hose,, and split them lengthwise and install them. Then you can decide if/when to remove them after the test.

I will try to find the parts I made and post the dimensions, but you can easily measure the OD of the rack with the car on a lift or jackstands. Easy peasy.
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Old 10-13-2018, 08:37 AM
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Quote:
Originally Posted by Mahler9th View Post
I would try to avoid making a mountain out of a mole hill.

On my car, when I measured everything at static ride height, it was clear that I would need more than an inch of spacer on each side in order to limit steering lock enough to completely prevent interference (see the thread to which I referred earlier).

I bought a set of clamps from Mcmaster carr, and then realized I needed more spacing. I priced a set of spacers with the necessary thickness (from Mcmaster-Carr) and they were really expensive. So I made some spacers out of Delrin.

Then I checked my in-car video to make sure that I had plenty of lock for all of the corners and "correction situations" I would likely encounter.

The benefit of the clamps is that you do not need to remove the tie rods to install them. It can be a real pain to remove the tie rods (special thin wrench, overcome red Loctite, et cetera).

In any case, as I said earlier, after I was done I decided, "screw it," and removed it all.

I also spoke with my good friend/engine builder to get his advice. He built my car and was a pro racer in IMSA back in the day.

He suggested that I consider some thick rubber hose, with decent compliance and ID/OD to act as a spacer. I had some scrap on hand and made some spacers up from that and took the car for a spin on the street. Worked fine.

But later I removed the hose spacers as well.

It can really pay to make sure you know how much lock you need for driving as opposed to guessing.

In this case, the OP apparently just needs enough spacer to pass some sort of inspection.

Is it a static test or a driving test? I might just make some spacers up from thick rubber hose,, and split them lengthwise and install them. Then you can decide if/when to remove them after the test.

I will try to find the parts I made and post the dimensions, but you can easily measure the OD of the rack with the car on a lift or jackstands. Easy peasy.
Hi Mike!

Thanks for your input, that is actually what we did today, I had some thick plastic tubing lying around. We split it lengthwise and installed it on the rack. That should do the job to pass the technical check-up.

Then I will see if if bugs me in daily driving. If so, it's a 2 min. fix to remove the tubes again.

Dan
Old 10-13-2018, 10:55 AM
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Quote:
Originally Posted by samurai_k View Post
How are your offsets? Will a spacer widen the front track so you clear the rubbing when you are locked out on the steering rack? I had a problem on my where my aftermarket wheels, bigger tires started to rub on the wheel well when the rack was locked out. I put some 7mm spacers which fixed the problem...

Sent from my Pixel XL using Tapatalk
No, we already put 25mm spacers in. It helps but not enough. Any more spacers and the tires rub on the fenders.
Old 10-13-2018, 10:56 AM
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Cool.

Those are some tiny tires compared to what I run...

And some really big calipers!

How much bhp and how much dos the car weigh?

Mine is 3.6L with about 300-340 bhp and 2150 without driver. That weight includes about 250 pounds of ballast. The bhp and weight are to meet racing class rules.

Run 16 inch diameter slicks, 12 wide in front and 14 wide in back.

930 rear calipers up front and Boxster rear calipers out back. Lightweight Wilwood rotors.

Good luck with your inspection and I hope that you enjoy your driving sessions.
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Old 10-13-2018, 11:26 AM
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Originally Posted by Mahler9th View Post
Cool.

Those are some tiny tires compared to what I run...

And some really big calipers!

How much bhp and how much dos the car weigh?

Mine is 3.6L with about 300-340 bhp and 2150 without driver. That weight includes about 250 pounds of ballast. The bhp and weight are to meet racing class rules.

Run 16 inch diameter slicks, 12 wide in front and 14 wide in back.

930 rear calipers up front and Boxster rear calipers out back. Lightweight Wilwood rotors.

Good luck with your inspection and I hope that you enjoy your driving sessions.
Hi Mike,

I bought the car from Jimtweet, here is a link to the built my take on 911r / R Gruppe lightweight hot rod

The weight with a 3/4 full fuel,tank is 2088 pounds. Engine is still original, and develops 181 rwp. So you will smoke me everytime.

But yes the brakes are huge and absolute overkill 😉
Old 10-13-2018, 10:50 PM
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