Wheel alignment

[colifecape]

Hello, this is my first post and first Merc, I`m also finding that mine wants to go left. This is not that big an issue when driving but the steering wheel sits off to the right slightly which is irritating and want to lock when parking right. Self centreing is poor.
Ive read in other posts that the tyres can be a cause, I`m running on 245`s at the back and 225`s at the front (17"). The cars to go back to the dealer to have a check donebut I brought this up in the test drive. Geniuses lost the security key for the wheels as well.
What to check for first as well as gettin fed Bull from dealership....

 

[television]

Welcome to the forum It does look as though some tracking has been attempted with locking the steering wheel in the straight ahead position,

The pulling to the left is common,,but can be corrected when set up right

 

[SQ_W211]

OK then further to the oringal issue. I have had new tyres fitted at the back yesterday and then had the gymetrical alignment done. On the alignment it shows as -1.5degree camber out on front both sides and on one side at the rear which wasnt adjusted as there are no bolts fitted. The is ride is alot better than before but there is still negative camber which will need to be sorted once the camber bolts are fitted which i will have to check with someone to see if they are worth doing as Wheels in Motion mentioned that Camber bolts will still only allow .5 degree adjustment so i will still be out by 1 degree.

Anyway.... for now I have spent over £500 in 2 days and have to put the camber bolts on hold for next few months.

Will keep everyone posted with update.... Meanwhile is there anyone on this forum who has experienced a similiar issue? how much negative camber did they have after lowering? How much was then adjusted by fitting Camber bolts?

Thank you for all your views

 

[colifecape]

Car returned and all is well. Their workshop had replaced a track rod end and never rechecked the alignment....

Cheers

 

[television]

Car returned and all is well. Their workshop had replaced a track rod end and never rechecked the alignment....

Cheers

Thanks for posting back with a good result

 

[Stucoupe]

Am so tempted to whip a wheel off and understand these bolts. Can anyone explain why the bolts get replaced? I've never heard of it before.

As for cost of bolts, if its possible, I'd go down my local trade centre to buy some. I have a local outlet, that sells bolts. I asked for a bolt to match the one in my hand (a bike engine mount bolt); they asked how many; I said one; he said, "what, one box of 1,000".... erm no, just one number bolt thanks, ha! Price... £1.00. Plus cost of a single drop of Locktite.

As for alignment, the costs seems normal. I was paying circa £70 for front alignment on my VW at a specialist, for laser jig and labour to adjust.

 

[television]

Any bolts on the suspension and brakes should be replaced as a safety requirement it is in all of the MB work papers

 

[SQ_W211]

I think the bolts that we require for Camber adjustment arent fitted to our cars so they need to be fitted first before anyone can attempt to adjust the camber.


I have lowered my car thats why Camber is out on my car by 2Degree all around which means Wheels dont site flat on the road and thats the reason they have lower life on the inner edges.

From MY understanding (And I might be wrong in thinking this) These are special bolts which can only be purchased from MB directly and they cost £12 each on normal but I was quoted £20 when I booked mine with MB.

Fitting these bolts isnt easy work so thirdparty alignment company charge £30 a corner but MB quoted me £125+VAT for Alignment plus any required bolts(this is good deal if I need 2 or more bolts as £70 is normal going rate for alignment anyway)

Hope this helps further

 

[Stucoupe]

Any bolts on the suspension and brakes should be replaced as a safety requirement it is in all of the MB work papers

I've heard of it with some types of car and bike. But if you went replacing bolts on every race prep bike, you'd get through tonnes per post-race strip downs. They key to bolts is to never over tighten - which most mechanics never torque up. Stretching a bolt will loose its strength capabilities as soon as its put in, and therefore you'd be driving on a potential stripping bolt.

VW have sets of bolts for the rear brake caliper for instance; circa £10 per side. Reason being they have Locktite on the ends - I always used same bolts and used my own Locktite. Never any issues of coming out.

I'd be more concerned with wheel nuts, as tyre fitters often go overboard. When you undo them and they go crack, after you jump on the spanner, you know they've over done it. Those bolts I'd think about replacing. Often see McGuard on fleabay for about £20 a set.

But still interesting to hear though - thanks.

Amo - thats interesting too. Is it a bit like how they don't give you an oil dipstick too? ha.

 

[Number_Cruncher]

Stu - the bolts referred to are special bolts which are eccentric - so, by turning the bolt and nipping the nut up again, you move the centreline of that suspension bush, and so, adjust the geometry. You won't be able to buy these eccentric bolts from anywhere but MB.

On a note of bolt usage. Generally, (although there are exceptions), bolts on cars with a torque plus angle specification are bolts which are taken up to their yield point during installation, which means you cannot re-use them. These also tend to be the most critical fasteners and joints.

Sometimes, bolts in this category are given a maximum length measurement, MB cylinder head bolts, for example - if the bolts are shorter than a given value when removed, they can be re-used. However, if I were replacing a cylinder head for someone else, I would fit the new bolts regardless - then, you know it's been done right, and the customer can see the new bolts on his invoice, and also can see the job hasn't been bodged.

Bolts with just a torque specification are much less critical, they aren't damaged during installation, and, apart from those with new loctite on them, generally can be re-used.

Nuts, however, are a different matter. Every time you install a nut, you damage it by taking the last thread(s) beyond yield, and, for serious race use, you should consider never re-using any nuts.

 

[Stucoupe]

On a note of bolt usage. Generally, (although there are exceptions), bolts on cars with a torque plus angle specification are bolts which are taken up to their yield point during installation, which means you cannot re-use them. These also tend to be the most critical fasteners and joints.
.

Joints - will this include the suspension? I can understand the new screws to an engine, as they tend to have low torques and thus so easy to over tighten etc and have imperfections. On something like a suspension strut, will the torque not be high, and therefore unlikely to be stretching the bolt; I had the impression that these things were typically designed with a yeild of 80 percent, giving a 20 percent error margin; thus if sticking to torques you'd never stretch.

Regardless, I guess if you're talking safety, £30/bolt is a small price to pay.

Eccentric bolts on suspension - fascinating stuff, pretty cool.

 

[Number_Cruncher]

>>I had the impression that these things were typically designed with a yeild of 80 percent,

Yes, if you were designing a conventional bolt to be tightened by a torque wrench, 80% of yield would be a good point to aim for - using most of the capacity of the bolt, but allowing for some of the inevitable scatter in bolt pre-load which you get from torque controlled tightening.

The problem, as I've written about before, is this scatter. When you install a bolt, you're trying to elongate it, so that it then clamps together the parts you're trying to hold. Applying the torque is a very indirect means to that end - it would be much better if the stretch of the bolt could be measured directly.

One way round this is to devise a torque plus angle setting which *just* drives the bolt to it's yield point. Typically, after the joint has settled a bit, the bolt then relaxes down a parallel line on a stress/strain curve to it's initial linear characteristic, and you end up being able to use the bolt more efficiently - say at 95% of yield. Remember aiming at 80% for a conventional bolt probably means you're actually getting anywhere betweeen 65% and 95% of yield, so, you need to over design the bolt to suit.

The only drawback of taking the bolt deliberately into its yield zone is that you know you are damaging the bolt, and hence, these bolts should either simply be replaced, or, where checking criteria exist, checked before re-use.

If you can get hold of a copy, one of the better places to look for high performance bolted joint design guidance (where the method of bolt tightening is included in the analysis process) is the German standard, VDI-2230.

>>will this include the suspension?

Yes, on most modern cars, this is the case.