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1993 500SL
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272 Posts
Discussion Starter #1
This is my first venture into the land of wheels studs/bolts and I already learned the hard way when I removed a spacer to see if I liked it or not and the the bolts entered the hub farther and removed some of my rear brake springs!!

Since my car did not come with the factory wheels my question is:

What is the proper length of the wheel bolt/stud that should enter the hub?
The fronts don't seem to be as particular as the rear but I would like to know what the factory inset is.

Any help would be greatly app'd.
 

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Departed 1998 SL500 (and the Pano is in Bogota)
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10,999 Posts
I read somewhere it is 6 to 7 turns. May be you can remove the wheel and count the threads in the hub.
 

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1998 Pano SL500; 1993 SL500; 2005 ML270cdi
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The length of the thread that actually enters the hub should be 20 mm.
More and you'll chew up your rear parking brakes. Less, your wheels will fall off :D
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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9,833 Posts
Rule of thumb 1.5 x thread diameter, therefor 1.5 x 12mm = 18mm.

Rule of MB, If you use the rule of thumb you will break something. You will find yourself limited to about 12 mm for this application.
 

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1993 500SL
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272 Posts
Discussion Starter #5
Im currently running with 20mm in the rear and 35mm in the front. I took off a 15mm spacer in rear and chewed it up....fronts seem to be fine with 35mm as far as i can tell..

thanks much. I'll shoot for 20
 

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Departed 1998 SL500 (and the Pano is in Bogota)
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Can you verify 20mm is about 6 to 7 threads ?
 

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84 500SEL AMG, 90 560SEC AMG, 85 500SEC AMG Widebody
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1,752 Posts
Is your spare also different than stock (usually, the spare isn't changed)? If OEM, then get a correct lug and test insert it into the spare and measure the length out the back.

al
 

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1998 Pano SL500; 1993 SL500; 2005 ML270cdi
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Can you verify 20mm is about 6 to 7 threads ?
Not without counting, however 6 to 7 threads doesn't sound that many for bolting on a wheel.

When I had problems with my rear brake springs I measured the threaded stud holes from the front face of the rear brake drum to the inner face and got 20mm.
Remember I was fitting 10mm spacers per wheel so I wanted to know the exact amount of thread depth so the rear brake springs would not be fouled.
 

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Departed 1998 SL500 (and the Pano is in Bogota)
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I thought you may have a bolt handy, that's why I asked.
I don't have a spare bolt either and I am too lazy to go out and remove one just to count the turns. If I know the screw pitch, I can calculate, but again too lazy to look for the pitch data.
 

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Departed 1998 SL500 (and the Pano is in Bogota)
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got factory 16" inch spare but no bolts so....:confused:
In that case you WILL NEED to get a set of lug bolts for that or your spare would be useless (might as well leave it off the trunk to save weight !)
 

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1992 500SL, 1988 560SL, 1977 450SL, 1999 E320 4matic
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772 Posts
The length of the thread that actually enters the hub should be 20 mm.
More and you'll chew up your rear parking brakes. Less, your wheels will fall off.
from "Redliner"


Redliner,
Now I'm thinking...A few months ago I had to repair my tire and while removing the 16 inch spare tire, the shop while placing my AMG wheel, the one with the tire that had to be fixed, accidentally placed just ONE of the larger lug, ment only to use with the stock 16" spare wheel, in the lug wheel hole. He realized what he had done and remove it and placed the correct size lug bolt. I was watching. So occasionally now that wheel, I hear a noise sometimes as it goes away when I stop, then proceed. Do you think that my rear parking brake assembly could be damaged? I did not think anything was wrong when I drove away from the tire shop, as I heard no noise but days later is when I first heard the noise while driving slow threw an alley way.
carltwo
 

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1993 500SL
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272 Posts
Discussion Starter #13 (Edited)
when I put the wrong length in....my wheel wouldn't move!
I ended up damaging 2 of the springs in there,
that was 35mm in....fronts seem to be no problem...

somewhere between 20 and 35 is the key


I ordered some new spacers and they come with a smaller set of bolts....
I should have 28mm going into the wheel...

I'll keep you posted if im fixing brake springs again!
 

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1998 Pano SL500; 1993 SL500; 2005 ML270cdi
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Carl, if you are getting a noise from a rear wheel especially after a long lugbolt was used, I would suspect a loose or broken retaining spring.

Nosaint, 28mm. of thread is too long if that is the amount of thread going into the hub. As a previous poster stated, the surest method is with the wheel removed push a lugbolt through the hole and measure how much thread is exposed. It should be 20mm. (Including the thickness of any wheelspacer)
 

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1993 500SL
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272 Posts
Discussion Starter #17
I need 2 sets of lugs..one for inspection (which says no spacers) and one for right after that!

The 28 was just for inspection purposese....Can I grind the bolt down to 20 or should I just buy another set?
 

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1998 Pano SL500; 1993 SL500; 2005 ML270cdi
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The 28 was just for inspection purposese....Can I grind the bolt down to 20 or should I just buy another set?
The lugbolts have an unthreaded portion that passes through the wheel. If you grind off any any threads the lugbolt will bind when it reaches the unthreaded portion and the wheel won't be bolted tightly to the hub, in other words it will be loose on the hub. This will cause serious damage to the wheels, affect the handling and is very, very dangerous. You could of course cut more threads with a die, but I would not advise that.
The short answer is to buy the correct size lugbolts.
 

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1993 500SL
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272 Posts
Discussion Starter #19 (Edited)
First off, thanks for all the great info,
Second, none of the ones I have now have a unthreaded portion. Im guessing the best would be a threadless portion in the amount of the wheel itself and the spacer?

 

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1998 Pano SL500; 1993 SL500; 2005 ML270cdi
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They look like H&R spacers :thumbsup:
You shouldn't have any problem with those lugbolts if you have to cut or grind them.
What I did was to push a couple of lugbolts through the wheel then slip on the spacer and then measure the available thread that was protruding.
 
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