M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => General Topics => Topic started by: mikesjo on February 04, 2007, 03:15:54 AM
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What are the pros/cons. Will the increased negative camber increase tire wear significantly? Will camber corrective front shock mounts offset the negative camber from the m3 CABs? I have these sitting at home and wondering if I should put them on or get a pair that are centered but solid (don't know what brand though, havn't looked into this).
The car is on H&R Race and Bilstein sports already.
Opinions welcomed!
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They are for increased caster mainly due to their "offset" character. Slap em on and get an alignment and enjoy. Caster isn't harsh on tire wear. Camber isn't as harsh on tire wear, it's usually "toe" that eats your tires up. I always run zero toe as a nice compromise.
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Camber will eat up the inside edge of your tire if you run too much on the street. This can be corrected by having the tires unmounted, rotated and remounted once in a while.
By the way e9ine, zero toe is terrible on your car. When you accelerate, your tires are actually toeing out, making it more difficult to corner. You are killing your mileage, handling, and making things harder on yourself.
On a front wheel drive car, you want zero toe because as you accelerate, the wheels pull themselves together for some toe-in. FWD increases toe on acceleration, rwd reduces toe. Add a little, it will make the car come alive, and will not hurt your mileage, in fact it will help it.
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How do you fix toe since it increases tire wear?
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Sheepdog,
E30's actually gain negative toe under rear suspension squat.
Zero toe is just fine but the car will feel a little "loose". A little negative toe is good to keep the car tracking straight.
To adjust the toe, just go to an alignment shop. They will adjust the tierods.
M3 CAB's are good. They improved the feel of my car at all speeds. It is hard to have too much caster.
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Thanks for the info guys :). Guess I'll be putting them on then. I've got some new tie-rods to go with them as well.
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By the way e9ine, zero toe is terrible on your car. When you accelerate, your tires are actually toeing out, making it more difficult to corner. You are killing your mileage, handling, and making things harder on yourself.
Zero toe has always worked fine for my daily driving, auto-x and HPDE application. I got the tip on the zero toe from some "respectable" people and don't see any -ve effects as per your description with regards to those variables.
I have run -ve camber, zero toe and as much caster as possible and my car hasn't ever had any issues cornering. I have had others drive my car and never had any complaints about grip.
I got approx 12 months out of my 17" tires which were used with these settings as I drove the car daily. I say that's not too bad of a compromise :D
I'll try see if I know anyone running a set up with -ve toe to try and see if I can get a practical "feel" of any differences.
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Newbie here. What does camber, caster and toe do. Thought I'd ask since we're on the topic.
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google is your best friend for "noobie" questions, as they have all been answered before,
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I might be getting the car corner balanced or at least get the rear alignment set with the Kmac eccentric bushings and I'll check to make sure what the "recommendation" on toe is seeing as the car will see less street use. I like to hear about opinions such as these settings and will obviously jog my mind on the "why" on zero toe. As I pondered on this a bit more - it seems to have been related to "street use" so we'll see if some toe out will help the car or not. I did some searching through my notes and I think s.one who had a track m42 run between 1/16 and 1/8 total toe or so....hmm....
One of my old alignment print outs.
Camber || Caster || Toe
LF -3.5deg || 9.1deg || 0.14deg
RF -3.2deg || 9.1deg || 0.15deg
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I remember someone posting an agressive sport alignment specs on the internet somewhere. A local guy tried this out and worked very well. I do recall him saying there was some agressive toe settings, but he recommended to be very careful driving on the highway as it was very twitchy. But for an auto-x, I guess the added steering assistance can come in handy. I need to find these specs again as I lost all my bookmarks...
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I would appreciate something if you do find your "cheat sheet"
I am going to use a diff. vehicles for auto-x and track applications. Twitchiness on the highway can go from :D to :eek: real quickly with the crazy maniacs out there!
I think my alignment guy might be friendly enough to let me try both configs and decide which settings will work - if I can "mark it" and readjust it for dual purpose (if I end up having to use one car) that would be awesome.
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In trade-school I setup a 60's Stang' with 90's Vette' specs... The owner loved it… Drove incredible.
Anyhow, about 1/16 - 1/8in toe in on front should work well on the street. You can go more, but you will start to see tire wear issues begin, I would not go much over 1/4in. unless it is a track car. I am at 3/16 right now if I remember right. Drives well.
Auto literature will tell you to have at least a little toe in (in front) on a rear wheel drive and a little out (on front) on front wheel drive. Squat is not the problem, it is acceleration, the wheels are pushed back by friction, causing a toe-out effect. That is why you toe-in in the first place. More toe helps turn in on cornering. On the rear, toe-out is preferred so that under acceleration they push/pull in. However on some racecars, they even toe in the rear as it really makes a car corner. Basically a driven wheel is toed out, non-driven are toed in, making all things neutral when driving.
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OP, you might want to consider AKG's 70A polyurethane non offset bushings if you won't be tracking. I'll say I'm quite satisfied with them. You can read a review in the 'product review' forum on r3v.
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Yeah I was looking at those, but then the ride would be a bit stiffer and harsh in the front. It's already harsh enough with the race springs :D.
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i have this for camber adjustment
(http://img.photobucket.com/albums/v621/fabianyee/PICT3250.jpg)
and custom made control arm bracket with PU bushes for increase castor.. will attach some photos later.
handling is sharper with the custom made control arm bracket together with all the other suspension mods (IE swaybars, APEX springs, pillowball camber plates, pillowball rear mounts). The ride is firm but handling is pretty neutral.
Off topic, this is one of the shots of my car going sideways at the Sepang F1 Circuit in the wet due to not-so-good rear street tyres.
(http://img.photobucket.com/albums/v621/fabianyee/DSC_6386.jpg)
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That is why you toe-in in the first place. More toe helps turn in on cornering. On the rear, toe-out is preferred so that under acceleration they push/pull in. However on some racecars, they even toe in the rear as it really makes a car corner. Basically a driven wheel is toed out, non-driven are toed in, making all things neutral when driving.
I'm afraid you've got this all backwards. At least for a BMW. Having toe-out on either end of a modern car with decent suspension (I don't know about stick axles), RWD or FWD makes that end inherently unstable. As in, it responds to changes in steering more quickly, and doesn't like to go straight. Toe-out improves turn-in. Toe-in is for stability.
Toe out on the rear of a track car is downright scary as the rear end doesn't want to stay behind the car. Only in an autocross car, and most likely only FWD would you ever want toe out on the rear as it helps the rear rotate. But it's a no-no at high speeds. Slight toe-in, or zero on the rear is usually a good starting point. For a pure street car, even more toe in.
Slight toe-out on the front is more common, as it improves tun in. Sure, the car isn't going to center quite as well, but it's fine even for a daily driver. For a track car, a good starting point on the front is 0. Autocross, definatly toe-out. For a pure street car, you do a bit of toe in on the front so it centers well, and like you said, at speed, the wheels turn out ever so slightly, almost to 0.
Anyway, back to the topic. Offset bushings. Go for it. Caster is good. :)
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I'm afraid you've got this all backwards. At least for a BMW. Having toe-out on either end of a modern car with decent suspension (I don't know about stick axles), RWD or FWD makes that end inherently unstable. As in, it responds to changes in steering more quickly, and doesn't like to go straight. Toe-out improves turn-in. Toe-in is for stability.
Toe out on the rear of a track car is downright scary as the rear end doesn't want to stay behind the car. Only in an autocross car, and most likely only FWD would you ever want toe out on the rear as it helps the rear rotate. But it's a no-no at high speeds. Slight toe-in, or zero on the rear is usually a good starting point. For a pure street car, even more toe in.
Slight toe-out on the front is more common, as it improves tun in. Sure, the car isn't going to center quite as well, but it's fine even for a daily driver. For a track car, a good starting point on the front is 0. Autocross, definatly toe-out. For a pure street car, you do a bit of toe in on the front so it centers well, and like you said, at speed, the wheels turn out ever so slightly, almost to 0.
Anyway, back to the topic. Offset bushings. Go for it. Caster is good. :)
Strange, yes, it appears you are right on BMW's.
That is opposite of many other cars. Then again, from what I have seen on BMW suspensions, that is about par for the course.
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to make it simple...
FWD cars usually have slight toe out on the front wheels because under acceleration, the wheels tend to toe in. so while in motion, the wheels are close to 0.
RWD cars usually have slight toe in on the front wheels because under acceleration, the front wheels are stationary and the rear is pushing the car. this causes the front wheels to toe out. again, while in motion the front wheels will be close to 0.
rear is ALMOST always 0 or slight toe in on any setup. as ecpreston stated, toe out in the rear will cause high speed instability as well as yaw.
of course when it comes to auto-x, drifting or any sort of racing setup, the rules are much different...
also, when turning in any car, the front wheels tend to toe out slightly due to the geometry of the suspension setup. it also has a lot to do with the oversteer/understeer and differential theories.
*** oh yea and i agree on the m3 CABs... more positive caster is always a good thing - they wouldnt put them on an m3 if it wasnt! ***
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I'm just finishing my first set of tires after I installed E30 M3 CABs. I have H&R sports and Bilstein sports. I saw no significant tire wear problems with this setup. I did rotate the tires throughout their life.
The one negative about the M3 CABs is that it gives me a little problem with larger tires. I have some studded snow tires mounted on the bottlecaps. Because the front tires are more forward than before, the larger than stock snow tires can rub a bit if I jack the wheel all the way.
The car does feel a bit more squirrely on the highway though.
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The car does feel a bit more squirrely on the highway though.
squirrely being good? what brand/size non-snow tires did you get?