E34 Rear Tire Wear

[bimmerman]

Ok guys, I know this topic has been discussed to death so please excuse me for bringing it up again. My E34 wears out it's rear tire only on one side. The left side. The right side seems fine. Any ideas why? Enquired with Stampford if anything can be done and the reply was "It's an E34. Live with it!" :cry: Please take a look.....

 

[chaiks]

Better seek 2nd opinion. Try Consistent Distinction @ Old Klang Road. You on stock suspension & rim? Don't think mine has such problem.

 

[bimmerman]

Originally posted by chaiks@Feb 19 2005, 08:53 PM
Better seek 2nd opinion. Try Consistent Distinction @ Old Klang Road. You on stock suspension & rim? Don't think mine has such problem.

Where in Old Klang Road is this Distinction place bro?

My suspension is stock standard but my rims are not. Maybe the rear springs are worn out but if my suspension or rims are wrong then both tires should wear out right?

See the picture, can you tell if my rear springs are worn by the ride height?

 

[ehoe]

Well having pronounced -ve camber on the rear tires on an E34 is a common problem. Its a known fact that almost all UDM have negative camber for better handling as part of their design. For the E34 the rear suspension is fixed type configuration and thus cannot be adjusted for allignment purposes.

So having good condition suspension components such as bushings, springs, absorbers, etc are vital in keeping the camber settings correct in stock configuration. Seeing your car is having stock suspension, it sure looks like one of the suspension components may be worn out so causing the pronounced -ve camber which causes inner tire wear. Have yr mechanic check all the bushing (trailing arm bush, pitman arm bush. carrier arm bush) and also your spring and shocks to make sure nothing is excessively worn down.

I also have been having this inner wear problem just like you for quite sometime and I have just renewed all my bushing and the -ve camber is now not so pronounced. I'm running on sport suspension so my car is running at a much lower height so I will not be able to totally have the original camber settings of the E34 unless I put in corrective bushings.

Oh and remember to rotate your tires from left to right and right to left to even out the wear every 10k km. I see you are running on directional tires so you will need to dismount the tires to rotate them. Good luck and hope you find the problem before your tires go totally bald on on side.

 

[bimmerman]

Thanks Ehoe, I did have an alignment guy take a look at my undercarriage and all bushings did not show any signs of cracks or damage he says. Can worn bushings be confirmed visually anyway? If it's not the bushings then it must be worn springs or bad shocks like you said. My shocks arent at their best but I don't think it's the shocks because it only affects the left tire.

How bad is your tire wear Ehoe? Is it comparable to my left tire wear or not as bad? Are they equal on both tires or does yours wear out severly on one tire and less on the other?

I suspect it's possible that the tire wear on my car is caused by the car being lowered. Not by sports suspension but sadly by sagging rear springs. I understand that all cars have different camber settings on right and left sides so if a car is lowered, one side could still be within specs and won't cause pronounced wear while the other side is already over the specs causing severe wear. What do you think? :dunno:

 

[ehoe]

Originally posted by bimmerman@Feb 19 2005, 11:20 AM
Thanks Ehoe, I did have an alignment guy take a look at my undercarriage and all bushings did not show any signs of cracks or damage he says. Can worn bushings be confirmed visually anyway? If it's not the bushings then it must be worn springs or bad shocks like you said. My shocks arent at their best but I don't think it's the shocks because it only affects the left tire.

How bad is your tire wear Ehoe? Is it comparable to my left tire wear or not as bad? Are they equal on both tires or does yours wear out severly on one tire and less on the other?

I suspect it's possible that the tire wear on my car is caused by the car being lowered. Not by sports suspension but sadly by sagging rear springs. I understand that all cars have different camber settings on right and left sides so if a car is lowered, one side could still be within specs and won't cause pronounced wear while the other side is already over the specs causing severe wear. What do you think? :dunno:

Bimmerman,

Before I renewed all my rear bushings, my inner wear on both tires was pretty bad, much worst than yours. My tires only lasted me 1+ year and only approx 20 - 25k km and that was with constant rotation of the tires. Visually you should be able to see if certain bushings are worn out like the pitman arm bush & trailing arm bush but certain bushes like carrier arm bush & axel mount bush is tough to see visually. You have to remove them to really check them properly. Not sure if there is any other way to check them so I guess check with yr mechanic, he should know best.

The springs and shocks plays a big role too. Recently I had uneven wear on my front tires as well and I noticed that my ride height was a lot lower than it normally is so I suspected worn out shocks. Visually they look fine with no signs of leaking oil but when I had them removed they were indeed leaking oil already. The damping rate was weak as a result and the car got lower and lower over time and eventually my tire even started to rub the fenders when going over big humps. So this also cause uneven wear on the tires. So weak shocks and springs do contribute to uneven wear too so thats why I mention u have to check them too. For my case the right absorber was more worn than the left so there was more uneven wear on the right tire as a result. So in your case seeing only one rear tire has inner wear on one tire, it could be because that side of the spring + shocks are weak or worn out.

I suggest you bring it to a qualified mechanic to have them checked out, I am only suggesting possible causes based on the limited info u gave me. Good luck.

 

[bimmerman]

Thanks Ehoe, really appreciate your feedback and advise. I think I'll start by changing the rear springs and shocks first and then monitor the situation from there on. Big possibility that the tire wear is caused by the left side being lower due to weak springs or dead shocks causing more -ve camber. Are you on lowered springs?

 

[ALBundy]

Bimmerman, its hard to judge the condition pf the trailing arms bush by visual inspection. It may not be necessarily cracked to be causing excessive wear on your tires.

Anyway, my current setup has -ve camber of 2.5 to 2.8 on the rear and there are no problems with tire wear.

Al

 

[ehoe]

Yup I'm running on lowered springs, Bilstein Springs & Koni Sport Shocks. So my ride height is at least 1 - 1.5" lower than stock standard. I'm also on 17'' running 235/45/17.

 

[bimmerman]

Thanks for the feedback again guys!

Went to rotate the rear tires just now (dismounting and swapping left and right tires) and also to check the camber. Here are the findings:

1. Left rear camber is -2.3 degrees
2. Right rear camber is -2.0 degrees
3. Shocks are new! Previous owner was not lying when he said he changed them!!
4. Rear left tire will not last more than 2 months!!

So now based on Albundy's camber specs which is more than mine I'm beginning to think that my tire wear condition is not ride height induced. Looks like I need to change all my bushings and maybe even the pitman arm bush!

Another thing I was also considering is changing rims since mine is currently the wrong offset at ET11. Was thinking of upsizing to 17" too.

Factor in the cost of all the repairs, new rims (used rims actually) and new tires and whoppee do! More credit card debt!!! Woe is me :cry:

 

[flash]

Originally posted by bimmerman@Feb 21 2005, 02:14 PM
So now based on Albundy's camber specs which is more than mine I'm beginning to think that my tire wear condition is not ride height induced. Looks like I need to change all my bushings and maybe even the pitman arm bush!

Another thing I was also considering is changing rims since mine is currently the wrong offset at ET11. Was thinking of upsizing to 17" too.

Factor in the cost of all the repairs, new rims (used rims actually) and new tires and whoppee do! More credit card debt!!! Woe is me :cry:

Take it a step at a time... :wink:

 

[bimmerman]

Originally posted by flash+Feb 21 2005, 02:31 PM-->QUOTE (flash @ Feb 21 2005, 02:31 PM)

 

[ehoe]

Here are a pic of my rear tires just for the sake of comparison. You'll notice there is still -ve camber even after I have renewed all bushings. This is normal coz that is part of the design of the suspension. But the -ve camber is a lot better now compared to before. Sorry didn't have pictures of the before bushings were replaced.

 

[bimmerman]

Originally posted by ehoe@Feb 22 2005, 04:59 PM
Here are a pic of my rear tires just for the sake of comparison. You'll notice there is still -ve camber even after I have renewed all bushings. This is normal coz that is part of the design of the suspension. But the -ve camber is a lot better now compared to before. Sorry didn't have pictures of the before bushings were replaced.

Thank you for the pics bro. Both your tires look like the condition of my right side tire. Which is very very good indeed for a E34.

I've done some deep thinking these few days as to what the biggest contributor of tire wear could be and please read and let me know if there is a flaw in my logic.

1. Tire wear on the inner side of the tire is definately caused by negative camber.

2. Toe-in will cause tire wear on the outer side of the tire.

3. By combining negative camber and toe-in, uneven tire wear can be reduced because both your inner and outer side of your tire will wear out evenly by compensating for one another.

4. When your bushes are not in good shape, your toe condition cannot be maintained thus you could have your toe-in reduced or even have toe-out thus you lose the compensating factor for negative camber.

Thus my problem is not a lowered ride caused by weakened springs because you guys are riding lower than I am. My problem is that my bushes are dead thus my car will toe-out during acceleration and toe-in during braking and return to it's normal state when stationary so alignment machines cannot tell me anything.

My tire wear condition is caused by bushings!!!

Correct ah? :dunno:

 

[ehoe]

Holy cow, that is one heck of a complicated but very interesting deduction to your tire wear problem. Errr... I'm no expert and from what I can make sense of from what you are trying to explain, I suppose you are right to an extend.

However even if the toe in will help to even out the wear, why would you want that?. We are trying to avoid unnecesarry tire wear if possible and having misalligned tires not only makes your tire botak faster but it affects also your fuel consumption and performance (coz there is more rolling resistance/drag mah). Well like I said I'm not a tire or allignment expert so I'd better not comment too much. Perhaps someone with more knowledge on the said topic could enlighten us?

On another note tho, have you ever noticed that your ride height is not equal on the left and right side of the car. This is more noticeble on lowered cars than stock cars. That could also explain why you would have more -ve camber on one side compared to the other. Apparently this unequal ride height is an 'inherit design' just like the -ve camber for most UDM's. So theoritically speaking if the ride height is not equal, the lower side should have more -ve camber due to the fixed configuration suspension of the E34 and thus cause more inner tire wear. In another words the inner wear should be worst on one side than the other. Makes sense ah???. :dunno:

As you can see from my rear tire height (pic), the right side is lower than the left side by a couple of mm. Was told that this is normal. Perhaps I'm too overweight and all that years sitting on the right side driving has made the springs sag. hahaha. Anyway I suggest you try to resolve your tire wear problem first before upgrading to 17'' coz the bigger rim & tire combo will definately botak a lot faster than your current 16''. And 17'' tires are a whole lot more expensive than 16" dude!. :yahoo:

 

[bimmerman]

Ah yes, Toe and Camber. Both are compulsory in road going cars and especially in BMW cars. I do know a little about this topic from my younger days of tuning Tamiya RC cars. So the theory would still apply on big boys toys like the E34 too. Here's a snippet of what little I know.

1. Toe: More toe-in can make your car track straighther but as a result you lose steering sensativity. Too much toe in will cause drag and tire wear on the outer side of your tire. Toe-out on the other hand will give you very quick steering response but will cause your car to wander about and wear out your tires on the inside. All road going cars have a small degree of toe-in dialed in for straight line stability while circuit going track or race cars have less toe-in or even toe-out to quicken steering response.

2. Camber: I can't explain it too well but negative camber will cause your tires to scrub less during cornering thus increasing your car's cornering ability. Negative camber will give you inner tire thread wear while positive camber will give you the opposite.

So on a road going car like the E34, you'll have a small amount of toe-in and negative camber which gives a combination of straight line stability and imporved cornering grip while they cancel out one anothers inner and outer tire thread wear pattern. Like killing 2 birds with one stone and killing a perfectly good Dunlop SP9000 as well when your toe angle can no longer compensate for your negative camber. Like on my car.

Like that I think :dunno:

 

[ngkm]

I think someone has mentioned this.
Since E34's tend to lean/sag towards the drivers side (blame it on a car designed for lhd weight distribution), the driver's side will have less neg. camber compared to the passenger side.

Actually I also swap the left and right rear shocks (springs and absorber) after sometime to even their compression state.

cheers.

 

[ALBundy]

Whoa BImmerman, you also used to be RC kaki??

 

[bimmerman]

Originally posted by ALBundy@Feb 24 2005, 09:35 AM
Whoa BImmerman, you also used to be RC kaki??

Ya man! I was into RC but not hard core fueled cars, just the slightly inferior battery powered but highly detailed Tamiyas.

Had a Frog, Super Champ, Wild Willy, Sand Scorcher, Nissan King Cab, Ferrari F40..... But that was like 20 years ago man! But thought me a little about camber, castor and toe settings.

The sand scorcher was a VW beetle based chassis and was accurately scaled with it's engine (electric motor) way back at the rear end thus inheriting the nasty Porsche 911 type handling (sudden killer 180 degree oversteer!) and was non-adjustable.

I filed down it's suspension parts and added washers elsewhere to change camber angles and even managed to increase front castor by moving it's lower suspension arms forward. When I was done with the car it totally lost it's 911 traits and handled more like a 996!

Only a handful remain in my collection today.