joey bagadonuts

Quite by accident, I discovered that the installation of a TRG strut brace eliminated my tire rub. When I upgraded my 91 C4 to 7" wide fronts, the front tires would rub the tirewells during acute turns which I corrected by using 1/4" spacers.

In preparation for a recent track event, my mechanic noticed these spacers, removed them and said they prevented my allow lug nuts from achieving a safe number of turns around the standard-length studs--he confirmed this by trying open, steel lugs. Additonally, the spacers' flat design did not provide the wheels with additional support as would the hub alone. So I thought, no big deal, I'll just put them back on when I've completed my track events.

In the meantime, I thought I'd see how bad the rub was and, to my amazement, it was gone. I tried locking the the steering in both directions, with the radio off and windows down, and nothing. The only thing I could think of which might have delivered this improvement was the installation of the strut brace. That item was installed AFTER I had upgraded my wheels with spacers. I'd never heard of a strut brace eliminating rub, but it seemed to be a logical conculsion.

Any thoughts?

jonfkaminsky

Thats interesting, I would think It shouldn't have much effect in the low-speed to static case. If you are going slow enough to put you head out the window and be able to hear rubbing while turning acutely at full lock, I think you are below speeds where the bar is going to make that much difference. If it did, cool, bonus.

joey bagadonuts

Jon,

I think the only way your car can move with steering locked one way or the other is at relatively low speeds. Also, I don't think I want to see if the rubbing reappears by locking the wheels through a hairpin turn at high speeds. Yeah, I know should take one for the team and see how well the strut brace holds things together, but I'll just be grateful that I can return the spacers for a full refund at Pelican Parts--they're awesome.

jonfkaminsky

Joey-

I guess what I was trying to say was that the strut brace stiffens the chassis and helpd prevent the shock tower area from moving under the force in cornering. In turn, if such chassis movement results in changing the camber of the wheel...you could get rub.

How you would evaluate the above at low speed is what I was pointing out as seemingly difficult to do as the brace would seem to not be coming into play at low cornering forces (wow, is that all one sentence).

joey bagadonuts

... but apparently it DOES come into play at slow speeds. That's what I found surprising.

Prior to the strut brace, I would get rub at very slow speeds; afterwards, it was gone. These incidents seem to indicate that camber will change even at very slow speeds without a strut brace. Can anyone confirm this?

jonfkaminsky

Yeah I guess your right. When you turn the wheel there would seem to be changes in camber to maintain the correct steering arc as dictated by the steering geometry. Technically, any amount of turn moves the wheel up in relation to the chassis, as a result from body roll. This would increase negative camber. So yeah, I think you are right. Your rubbing must have been by a gnat's *** to change things under very low speeds, though.

Adrian

It is easy to confirm though. Remove the strut brace and see if the rub returns. However just to show how fickle and strange things are. With my Pirelli 7000s (dumped, horrible things) with 10mm steering stops 205/50ZR17 fitted on 7JX17 Turbo wheels I had wheel rub at full lock. Now I have installed Toyo T1S Proxes, 225/45ZR17s on the same wheels and I have no wheel rub at all. Strut brace was installed prior to the Pirellis,
Ciao,
Adrian
911C4

PS: The 225s are also installed without spacers. I did purchase them but they did not fit. They will now because we made the hole in the centre bigger. However, my mechanic in his stress left my winter rear spacers (15mm installed). I am now going to install the 5mm spacers up front and leave the 15mm spacers on the rear and see what the wider track does for my handling. I will then remove all the spacers and do it all again. Handling comparisons that is. Having the wider rear track has made a positive improvement in my subjective opinion. Combined with the 225s up front the handling is more precise, slightly heavier and the understeer is almost gone. In fact I get the feeling sometimes it now wants to oversteer a bit.

joey bagadonuts

Ah, the C4 Club President has chimed in. Good to hear from you, Adrian. I'll give the strut brace removal test a shot as time permits.

BTW, I appreciate all the information you provided through John Miles's website. I also downloaded the Excellence articles and implemented most of the changes recommended (except the shocks--I could shoot myself!). In your piece, I think you called your newly modified C4 a go kart. Well, my day at the track left me feeling like I was behind the wheel of an F1 racer. Talk about grip! I was taking the sweepers at speeds my instructor could not believe (as peeled himself off the windhshield).

The Pirelli's seem to be a good choice for me right now, but I'm dying to see how a set of slicks perform with my set up. And yes, I will get the Koni's some time in the near future.

Thanks, guys, for the feedback.

Adrian

Dear Joey,
Give me some more HP and I will change from go-kart to F1. F1 have traction control now so they are catching up to the C4s, "slowly",
Ciao,
Adrian
911C4

PS: For the "real" KONIs it might be hard. However give Jason a call at Paragon he might still have some stuff in stock. 225s on the front also make a huge difference.

Jeff Curtis

Joey, get yourself a set of 3mm (1/8") spacers...they are legal, and safe for the number of threads contacting the wheel stud - search an earlier post called "what spacers do I need", I believe.

I shudder in fear when I hear of guys using 6mm, even 5mm spacers with factory aluminum lugs! Count the number of turns, AND do what your mechanic did with steel lug nuts and you'll be amazed at the obvious hazard this arrangement could create.

I found a set used from a guy in D.C. and ever since installing them, my 215/45 17s don't rub anymore. <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />

BTW, I use 245 Hoosiers up front for track events, but that's another story that requires longer wheel studs and 6-7mm worth of spacers!!

3mm spacers are difficult to find, I have a friend who just cut out several sets, he owns a machine shop. Send me an email to let me know if you want a set and I'll refer you to him directly...thanks to him, I now own two sets!