Wheel bolts too long? Alloys on a W209

James99

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I recently bought a CLK W209, my first Mercedes and a really lovely car. But I've noticed some juddering at motorway speeds. It turns out the rear wheels have 6mm thick spacers. The spacers are not hubcentric and so the alloy wheels (replicas) aren't quite centred. The front wheels have no spacers and are fine.

I want to get rid of the 6mm spacers on the rears but I wonder why they were there in the first place? The tyre fitter thought it may be to stop the wheel bolts hitting the parts inside the hub.

So I'm wondering what length wheel bolt is best to use? Could I please trouble someone to tell me on a W209 how far standard Mercedes wheel bolts protrude out the back of a standard wheel? Then I will compare it with these wheels and bolts and change them if necessary. Thank you very much!

In case it is of interest, the wheels are 18x8.5" ET35 front and rear. The bolts are conical with a thread length of 27mm and (with the 6mm spacers in place) take 6 turns to tighten fully.

Thank you again.
 

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The wheels on a 209 with the size 18 x 8.5j should have an off set of 30 so the spacers have been added to bring the wheels a little further out to compensate.

MB wheels are hub centric, that is they center on the hub and the wheel bolt just keep the wheel in place, the answer would be to have hub centric spacers in order to keep the wheels in line, but you do need hub centric wheels to be correct.

What ever you do there should be 12mm of the wheel bolt sticking out of the rear when the bolt is pushed through the hole, that is the max that you can have on the rear wheels or they will foul the parking brake shoes.

You can get the correct parts/ spacers from the link

http://www.alloywheelsdirect.net/information/fitting_chart/mercedes-benz
 
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James99

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Thank you for all your info, Malcolm. I did wonder about the difference in offset, but I've never found a hub-centric spacer with such a small thickness as 5mm. Even on that site, the 5mm spacers don't appear to have a flange for the wheel to mount on http://www.alloywheelsdirect.net/option/fitting_kits so the wheel would still be supported by the bolts, but I will ask them.

I was hoping to move away from spacers altogether if possible, and hoping the difference in offset of 5mm from spec was close enough.
 

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I think that if you bolt the wheel on without the spacer, I do not think that it would touch anything, so that is worth a try, 7mm or just under ½ an inch is neither here nor there.

Now with regards to the wheel bolts, the shortest standard bolt from MB is 28mm, you could try one bolt, and as you do it up spin the wheel to be sure that they are not going to touch the brake components. they are easy to cut down or to grind off the ends, as before 12mm is the standard.

Are they MB wheels by the way
 
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James99

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Thanks for that Malcolm, yes I'd prefer to go without the spacers if possible.

I'll check out the bolts as you suggest (Hmmm I can't spin the rear wheels safely just using the car's own jack can I? Think I need help from a garage maybe). With only 6 turns to fully tight, I'm thinking the current bolts can't be protruding very far into the hub at the moment but I haven't measured it yet.

They aren't MB wheels unfortunately, just replica AMG alloys (there is no make stamped on them.)

Thanks again Malcolm.
 

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Thanks for that Malcolm, yes I'd prefer to go without the spacers if possible.

I'll check out the bolts as you suggest (Hmmm I can't spin the rear wheels safely just using the car's own jack can I? Think I need help from a garage maybe). With only 6 turns to fully tight, I'm thinking the current bolts can't be protruding very far into the hub at the moment but I haven't measured it yet.

They aren't MB wheels unfortunately, just replica AMG alloys (there is no make stamped on them.)

Thanks again Malcolm.

The wheels do need to be hub centric or the problem of balance will not go away.

I have just measured a 14mm wheel bolt and 12mm is correct to be in the hub, or sticking out of the rear of the wheel. the pitch of the thread is 1.5mm and 6 turns puts it in the hub by 9mm, so with the standard 12mm bolts you have 3mm clear, so it will be a bit tight, 25mm bolts would be more like it.

Yes to spin the wheel the car would have to be out of P and the hand brake off so not an ideal situation.

If the wheel bolts are touching the brakes a ticking can be heard as you spin the wheel.

The garage may have just one 14mm x 25 bolt that could be used for testing, please note the the fixing bolts are radius and not tapered
 
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James99

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That is really kind of you to have done all that Malcolm, thank you very much! :)

I think these alloys are quite a lot thinner than MB ones where the bolts go through the wheel, hence the shorter bolts probably needed. The bolts I have are tapered as it happens rather than radius, and they seem to mate with these wheels correctly (non MB alloys are tapered sometimes as I understand it?)

I will get along to a garage and do as you suggest. Thank you for all your help!
 

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They aren't MB wheels unfortunately, just replica AMG alloys

The 18" option from MB for a w209 would have had a staggered set up with 7.5J x 18 front & 8.5J x 18 rear.

Russ
 
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James99

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Ah right. These are AMG look-a-like wheels fitted by a previous owner.
 
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James99

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Just to add some info here in case it is of interest... I took out the space-saving spare wheel and its bolts that are clipped to it - wheel and bolts all unused. The bolts on the spare stick out 14mm from the back of the wheel (possibly up to 15mm - it's a little hard to measure even with digital calipers, but at least 14mm.) So from this evidence 14mm is ok for the bolts to stick out and still not interfere with the rear hub assembly, for a W209 CLK (M12x1.5 bolts).

I've been trying various shorter wheel bolts on my OEM alloy which has 60 degree conical seats. Bolts with a 22mm long thread (made by Graystone) stick out 17mm the back of the wheel. They need 7.5 turns to tighten fully. There is no clicking when I spin the wheels on a jack stand, but I sometimes hear a clicking (once per rev) with these when driving, although there has been no known damage to the parking brake fortunately. Bolts with a 20mm long thread (unknown make but they do measure 20mm thread) stick out 14.5mm and need 5.5 turns to tighten fully. There is no clicking with these ones.

I would go with the 20mm long threads all round, but 5.5 turns doesn't seem enough does it? I might try 21mm thread length next to see if I can get the turns above 6 but still avoiding the clicking sound.

If anyone has any comments or my thinking is wrong anywhere, please say, thank you!
 
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The spare wheel bolt are for a different thickness of wheel,,that is why they are supplied.

Any more than 12mm then there is the risk of damage to the parking brake.

The thickness of the hub flange is no more than 5mm and spare thread goes all the way through and out the other side,,so 5½ turns is fine,,as long as 2mm is all the way through the axle flange then nothing more to be gained in going further
 
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James99

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Many thanks for your reply, Malcolm.

Sorry if it I didn't make it clear but in fact I was measuring how far the special spare wheel nuts stick out the back of the spare wheel that goes with them. On my 2003 W209 it measures 14mm. They are unused originals in a plastic box attached to the wheel so I can only assume 14mm sticking out into the hub for this type of car is ok. I would measure a stock CLK wheel with stock nuts but I don't have access to one unfortunately.

Thank you for the reassurance about 5.5 turns. That's interesting about the thickness of the flange, I thought it must be thicker. And so that makes absolute sense. Thanks again for all your input!
 

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Many thanks for your reply, Malcolm.

Sorry if it I didn't make it clear but in fact I was measuring how far the special spare wheel nuts stick out the back of the spare wheel that goes with them. On my 2003 W209 it measures 14mm. They are unused originals in a plastic box attached to the wheel so I can only assume 14mm sticking out into the hub for this type of car is ok. I would measure a stock CLK wheel with stock nuts but I don't have access to one unfortunately.

Thank you for the reassurance about 5.5 turns. That's interesting about the thickness of the flange, I thought it must be thicker. And so that makes absolute sense. Thanks again for all your input!

Thanks James,, about the bolts and the spare wheel:D:D
 

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Just to add some info here in case it is of interest... I took out the space-saving spare wheel and its bolts that are clipped to it - wheel and bolts all unused. The bolts on the spare stick out 14mm from the back of the wheel (possibly up to 15mm - it's a little hard to measure even with digital calipers, but at least 14mm.) So from this evidence 14mm is ok for the bolts to stick out and still not interfere with the rear hub assembly, for a W209 CLK (M12x1.5 bolts).

I've been trying various shorter wheel bolts on my OEM alloy which has 60 degree conical seats. Bolts with a 22mm long thread (made by Graystone) stick out 17mm the back of the wheel. They need 7.5 turns to tighten fully. There is no clicking when I spin the wheels on a jack stand, but I sometimes hear a clicking (once per rev) with these when driving, although there has been no known damage to the parking brake fortunately. Bolts with a 20mm long thread (unknown make but they do measure 20mm thread) stick out 14.5mm and need 5.5 turns to tighten fully. There is no clicking with these ones.

I would go with the 20mm long threads all round, but 5.5 turns doesn't seem enough does it? I might try 21mm thread length next to see if I can get the turns above 6 but still avoiding the clicking sound.

If anyone has any comments or my thinking is wrong anywhere, please say, thank you!

My neighbour bought a set of new wheel studs for his 320 SL , as a couple of them had been broken tyring to get them off. On fitting the new ones the seemed to go very tight before clamping the wheel, after lots of checking that the studs were correct we bought am intermeriate tap to clear the threads . To our supprise this took some doing considering that all the threaded holes are 'open' in the hubs. But after a bit of a struggle all of the new studs screwed into the hubs all the way down there threads by hand without issue. On refitting the wheels they nipped up just as they should, I would suggest you do this to your hubs just to make sure
 
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James99

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My neighbour bought a set of new wheel studs for his 320 SL , as a couple of them had been broken tyring to get them off. On fitting the new ones the seemed to go very tight before clamping the wheel, after lots of checking that the studs were correct we bought am intermeriate tap to clear the threads . To our supprise this took some doing considering that all the threaded holes are 'open' in the hubs. But after a bit of a struggle all of the new studs screwed into the hubs all the way down there threads by hand without issue. On refitting the wheels they nipped up just as they should, I would suggest you do this to your hubs just to make sure

Many thanks for that. Very, very interesting! In my case the wheel bolts are clamping hard up against the wheel before going to the wheel though so I think the threads in the hub are clear.
 
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James99

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Thanks JetTech, yes that's what I've read about here and elsewhere. Now I have shorter wheel bolts on the rear that take only 5.5 turns to fully tight, I'm sure they don't go near the parking brake mechanism inside the rear hubs. They don't make a noise either.

For what it's worth, the remaining issue now is that those bolts on the rears are too short for the front wheels - they will only screw 3.5 turns till tight on the fronts, and that's with identical wheels front and back and no spacers anywhere anymore. (The front hub must have a few millimetres extra thickness before the beginning of its thread.) 3.5 turns would be unsafe so for now I'm using longer bolts on the front wheels. But I'd really like the same bolts all round in case a garage gets hold of the car one day and mixes the bolts up.

I'd love to find out with a W209 CLK how many turns it takes original Mercedes bolts on original Mercedes wheels to tighten on the rear hub! ;)
 

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Thanks JetTech, yes that's what I've read about here and elsewhere. Now I have shorter wheel bolts on the rear that take only 5.5 turns to fully tight, I'm sure they don't go near the parking brake mechanism inside the rear hubs. They don't make a noise either.

For what it's worth, the remaining issue now is that those bolts on the rears are too short for the front wheels - they will only screw 3.5 turns till tight on the fronts, and that's with identical wheels front and back and no spacers anywhere anymore. (The front hub must have a few millimetres extra thickness before the beginning of its thread.) 3.5 turns would be unsafe so for now I'm using longer bolts on the front wheels. But I'd really like the same bolts all round in case a garage gets hold of the car one day and mixes the bolts up.

I'd love to find out with a W209 CLK how many turns it takes original Mercedes bolts on original Mercedes wheels to tighten on the rear hub! ;)


This is something I'm also trying to get to grips with, albeit on a W201 190E in my case. I bought a set with 28mm threaded section and the wheels spin fine on the front, but still catch on the rears. I managed to turn the steering to full lock, jack up the front and with a torch I managed to see behind the hub as the wheel was spun by hand - sure enough, I could see the bright silver tips of the new bolts protruding a little behind the hub.

It's a pity it's not so easy to see this same view on the rear, as I now need to make a couple of measurements with the bolt through the wheel (off the car) and mark a length at which to cut them down. I shall then compare this to Malcolms sage advice, which is to make them the thickness of the wheel +12mm.
 

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Any more than 12mm then there is the risk of damage to the parking brake.

The thickness of the hub flange is no more than 5mm and spare thread goes all the way through and out the other side,,so 5½ turns is fine,,as long as 2mm is all the way through the axle flange then nothing more to be gained in going further

OK, here are my new bolts suitably cut down to wheel thickness +12mm

DSC06717.jpg


This appears to give me approximately 7 turns of thread into the hub and 2-3 turns going back towards the wheel. Am I safe to proceed to use these on the rears now? They are short enough not to snag the parking brake, and hopefully long enough to do the job of holding the wheel on.
 

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7 turns on a 1.5 mm thread equals 10.5 mm, you could allow one more thread though it looks fine.

I notice that they are taper bolts
 

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7 turns on a 1.5 mm thread equals 10.5 mm, you could allow one more thread though it looks fine.

I notice that they are taper bolts

Thanks Malcolm, some of the bolts will have the extra thread due to the orientation of the bolt in the vice as I completed my hand made cuts. I'm guessing it's the clamping force between head of the bolt/wheel/hub that makes for a tight fit rather than anything else, and any more threads that stick out the back of the hub/drive flange are superfluous?

Yes, the bolts I eventually needed were taper, as the wheels I have are MB 15 hole copies, this has given me all sorts of problems obtaining the correct bolts to complete the job.
 


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