Quick - I need some alignment help please

[jluetjen]

Randy;
I often have used "Left Foot Braking" as you described when I was racing. An example might be to settle the front end slightly on the last left (medium speed ~90 degree left) before entering the main straight at NHIS. That would work in a Spec Racer and my IT car, but I've never had the chance to try it in a 911 yet. Anyhow, depending on the corner, sometimes when I'm really clicking, I'll even downshift while left foot braking by using the throttle to match the rev's.

My neighborhood is fairly densly populated with lots of people and dogs walking around. So in general I try to drive very defensively. I'm biased since I've got two young daughters who like to play in the yard.

[Randy W]

I understand - best of luck setting up your 911.

[bento]

so after having the ride height jacked up and having the alignment double checked, the car is still scraping on hard right hand turns. arrrggggghhhh. i was going to auto-x this weekend at candlestick with the scca but now it seems like there is no way my car is going to be ready. after throwing x thousand dollars at my suspension it is ridiculous that i will have to crap away two auto-xs post the swap. i still don't know what is going on here and i am now starting to think that it is actually the belly pan or the crash bar that is hitting the ground as i am turning. i might hve to get a friend to hang out and watch me go around a remote right hand turn to see if the car is actually touching the ground or if the fender is sitting down on the top of the tire itself. i plan on calling my mechanic and making him get in the car with me so that he can feel/hear it himself. i'll report back to base with results.

okay, you can go back to your castor debate now
db

[jluetjen]

Wow! This thread is about fender rub -- isn't it?!!! Boy we've "understeered" off track a bit!

I'm going to shut up now, because there are other folks around here who know more about fitting 7.5 inch wheels on a Carrera then I do.

BTW - Aside from the rub, how does your car handle when you are autocrossing???

[Tyson Schmidt]

Bento, if you don't think the fender is rubbing on the top of the tire there is another problem spot.
It is the fender/bumper joint directly in front of the tire. Turn the wheel (tire and wheel, not steering wheel) about 20 degrees until it is closest to this corner of the fender/bumper joint. This may be where it is making contact.

[Randy W]

Bento, Tyson may be on to something - you can grind this interface between fender and bumper down if it is the rub spot - I've had to work on this area too.

Sorry to get so off-topic on this thread, but every so often it happens. What we really need to know to help you any further is where the rubbing is occuring. Can you isolate which side the "clunking/scaping" sound is coming from? I assume the left side since this occurs on hard right turns only. I would jack the left side up, put a jack stand under the front torsion bar mount, remove the left tire, check for any suspension fatigue and look all around for rub marks on the fender, body and undercarriage. Next put white shoe polish on both edges and sides of the tire and grease on any rubbed areas of the fender/body/undercarriage that you see. Then test on right hand turns again until you get the sound and check for removal of polish or grease. Hopefully this will help isolate the area. If it's the tire, refer to my first post and see if making any of the changes make sense to you. If you need more advice about this (or castor ) please let us know.

[dickster]

ooopppsss, sorry guys missed this thread for a while.

jluetjen,

It sounds to me like your car is not "square". Since winter's coming, if it were me, I'd put it in the garage and do a complete set-up on it. This should include a complete corner weight, ride height and alignment. For the sake of academic curiosity, It would be interesting to look at your initial settings to see if something jumps out that could be causing the problem. The problem that you describe could be caused by bad corner weights, alignment, shocks, springs or tire pressures to name a few.

now that i not not want to hear! i had thought about it, but i followed the car to see if it crabs and it looks fine. i would be very interested in a corner balance, but its not easy where i live. i've been thinking of buying some equipment.

alignment has been checked, shocks are new, tyre prssures checked. front springs are fairly new by last owner, but the rears i suspect may be tired (?) originals. the rear bushes are shot - but thats both sides.

i have sort of resigned myself to overhauling everything. new t bars and bushes then go from there. but i'd love to know whats causing it...............

bento

so i took my car in to the shop and had them bring the ride height up by about 3/4 of an inch in the front via the adjustment screws. then i went off to the alignment shop and had them set the toe properly (steering wheel was off center previously) and check the front alignment. the car is allegedly at 1 degree of negative camber at the front. the car does feel better but i still hear the "clunking" sound on a hard right hard turn. i'm running 7.5 inch wide rims in the front of my narrow body car, do i need camber plates to clear them properly? i still don't quite understand why this would happen post installation of new shocks when i had no such problems on my blown out boges.

no clunking. just drives on rails in one direction, and like an oil tanker in the other!!

David Ceruti

I had another look at your post today. Another factor is that your weight in the car will keep it more level in left hand turns (assuming it is a LHD car). See if it handles the same with a passenger in the car and it will give you more info.

What to do about it? That will take a bit more thought or suggestions from some of the gurus lurking on the board. Maybe have the alignment checked with you in the car. But I think that the unequal L/F weights is one of the unsolveables in saloon car racing. I know that some guys imported LHD cars to race over here at Kyalami because most corners on a counter-clockwise track favour LHD cars

i tried with a passenger and it was excatly the same. on the road passengers don't notice, but on the track is a diferent story.

i have messed around with the front and it made no difference, i am beginning to beleive the problem lies at the rear end.

a soggy rear end can cause understeer. tired springs and bushes maybe???

its a very pronounced problem, fast sweepers and tight hairpins.

[Tyson Schmidt]

Dickster, that is classic "corner imbalance".

You may have a weak torsion bar, too much sway bar preload or just need a good corner balance.

Not to mention possibly 1 bad shock with less or more rebound than the others. Koni's sometimes get super stiff when they get old. I had just one rear shock do this. What happens is one of the plastic internal bushings breaks into tiny pieces, and clogs the passages in the shock. When I removed it from the car, it almost could not be extended by hand. Made the car handle differently left to right.

I guess now you have some figuring out do do. Good luck!

[dickster]

tyson

have you experience of this??

i got new shocks all round.

it actually feels like excessive roll.

i tried raising the left front in an attempt to "corner balance" but i think should have been lowering that corner or raising the left rear - from what i've since read. it made no difference at all.

not as easy to raise the rear. perhaps i could try raising the right front. if that makes a noticable difference i 'm on the right track (!)???

expert opinion appreciated....

[nhromyak]

http://www.grmotorsports.com/cornerweight.html

They talk about a bad corner balance making the car turn great one way, and handle bad turning the other way.

Sounds like a Nascar car!

Have fun! - I know I had fun doing a corner balance...

[dickster]

mmmm, interesting.

i'm gonna try lowering that left front and see what happens.

thanks for that.

[jluetjen]

Dickster;
If I were you I wouldn't "dick" around (oops! ) with swagging an adjustment of one of the front ride heights. The unfortunately reality is that you're taking shots in the dark and you'll be as likely to make it worse as better. Don't be intimidated by the concept of doing a corner balance and ride height. I did mine last year and I would rank it highly on the risk/reward spectrum for winter projects. Technically it's a lot easier then an engine rebuild and in a situation like yours, you will definitely appreciate the improvement. I learned a lot about my car, some specific alignement issues and ended up knowing that the corner weights are just where I want them.

Do a search on this BBS for "cornerweight" and "ride height". There are at least 3 different procedures out there that detail the process. I wrote one of them, but any of them will do. The big dollar (or Pound Sterling in your case) item is the corner weight checker. Check "Demon Tweeks" or "RipSpeed" in the UK. I'm pretty sure that they used to carry the lever type. Figure the UK equivelant of about $160 - a lot less then you'd pay to have a shop do the set-up.

Then work through the process. Unfortunately it is somewhat time intensive. But if there is a problem with the car, you will soon know what it is and be on your way to solving it. I always hate having shops do stuff like this for me because they always take the car "behind the curtain", do a bunch of stuff, give it back to you and proclaim it fixed. They never tell you what they found, what they fixed, nor teach you anything about the car. Once you have done it yourself, you'll know the answer to all of those things, and be a wiser person for it.

Besides, you're not going to use the car during the winter anyhow, are you?

Here's a couple of threads which will fill you in if you haven't read them already.

Go ahead - give it a shot!!!

[dickster]

john,

i was thinking of the lever type (cheap!), i didn't think about getting one here so thanks for the tip on where to buy one. i'll see what they've got.

don't use it in winter? its year round for me my friend, mind you these days summers aren't much different to winter

[bento]

i was just about to post to let you guys know that i had taken my mechanic for a ride and we had identified the sounds as potentially coming from the fender lip, but then i realized that you had already collectively sleuthed it out. The PO had put 16 x 7/9 fuchs on the car and had rolled the front fender lip about 2/3 of the way back. On the old shocks the compression must have been stiffer (rebound was probably screwed up as well) and the inner lip of the fender didn't have any clearance problems. I can't say from certain if this is the spot that it is rubbing on (2/3 rearward on the front wheelwell), but i'll know soon enough. I plan on rolling the inner fender lip another 2/3 inches back and see if the problem persists. hopefully i will be able to eliminate the problem asap as i would hate to miss another auto-x due to this problem.

i'm going to do a search now on rolling that lip so that you don't get cracks in the paint but anything that you think i need to know (plan to use a rubber mallet).

as always, thanks,

db

[dtfastbear]

Dave,

Have you tried putting clay or colored chalk or something up in the fender well at different places so you can isolate where the rubbing is occuring? It seems like isolating the rub spot should be priority #1. I know it is a long shot, but if you are still having problems and want to SEE what is going on, we can mount my "bullet camera" (like the one Bauman described in the Nugget last month) around there and see if we can't actually see what's going on.

As for the "positive camber" guy - well I live a couple miles from Mt. Tam (in Sausalito) and I'd be happy to take you for a ride anytime to show you what nearly 2 degrees of negative camber up front can do you in a 911 on the roads up Mt. Tam. I certainly don't have any push problems, either...

I got a new alignment two weeks ago from S-Car-Go racing, dialing in a bunch of negative camber (after installing new Bilstein sport shocks) and the result was that my fiance and I took top time of the day (me overall, her ladies) at the next autocross we did. I can't BELIEVE what a dramatic improvement dialing in more negative camber made. We'll find out what it does for our track times at Laguna and Thunderhill next month... Keep in mind this is a stock '86 carrera.

Dave - call me if you need another body for help with the tire rubbing problem.

Dean

[bento]

and my problems have almost completely gone away.
i read all of the various threads on rolling the inner fender lip and decided to go to it. i grabbed said louisville slugger and got it up in the front left fender well. the PO had rolled the fender, but only at the apex of the wheel well. with about 15 minutes of work i had rolled it an additional 10 inches on either side and i managed not to break any of the paint. yes the inner lip is a bit wavy, but who really cares. haven't auto-xd the car yet, but as far as i can tell, scraping on hard right handers is gone.

thanks to everyone for their advice and all of the various tangential information.

praying that it really is gone,
david