1983 300D caliper bolt won't torque HELP!!

[MBDFahrer]

After spending a few hours of trying to replace brake lines on the 300D, I hit a snag. As I was installing the left rear caliper, all was well until it came time to torque it down. The top bolt torqued fine, the bottom one just slipped and I noticed the threads on the bolt were rounded upon closer inspection. The caliper mount looks okay but using the bolt from the top mount, it just slides in and out.



Is this just a bolt issue, or is it the caliper mount? How much would it cost to source a new part and is it worth it?

This was my brother's car and its not in use so I'm prepping it to be sold or donated and at this point, I don't know if its worth the effort depending on the issue.

[79Mercy]

the bolt shouldn't have a washer on it.

[MBDFahrer]

You can thank Tire Pros for that, they were the monkeys that SNAFUed the car enough to make my brother abandon it.

[toomany MBZ]

Originally Posted by 79Mercy

the bolt shouldn't have a washer on it.

Mine don't.
That bolt threads into the caliper.
Measure it, and get a new one, should be a softer metal than the caliper.
Good luck.

[79Mercy]

Originally Posted by toomany MBZ

Mine don't.
That bolt threads into the caliper.

no it doesn't. It threads into the caliper mounting bracket.

BTW, that is the wrong bolt for the calipers anyway.

[MBDFahrer]

Should I be looking for a new caliper bolt or just get the next size up? Also it doesn't seem like the caliper bolt is listed on FastLane.

[clarencethecool]

indeed, It sucks when you need to know the thread sizes and pitch of mystery bolts. but! take it to an ace hardware and get them to match it, dont mess with home depoo because they will not deal with metric bolts. Also, dont mention that its for a mercedes if you can, I recall going to a home depot for o rings, went looking for them and mentioned to an employee that helped me find the wrong isle that i was indeed looking for these for my mercedes.. he told me that what ever i was looking for they didnt have it! can you believe it!?? the o rings were on the next isle..

someone earlier posted that it should be softer metal than the caliper... i am weary of that.. call brake team or les shcwabb and get their opinion.. because this fastens your brakes, get it right the first time!


hope that helps

[MBDFahrer]

Thanks clarence, I'll have to go to Ace Hardware and see if I can get it. And upon further digging, I did find the original ones at fastlane, its the new AllPartsExpress (false advertising? ) that didn't carry them.

[toomany MBZ]

Originally Posted by 79Mercy

no it doesn't. It threads into the caliper mounting bracket.

You're right, sorry for the bad info.

[turbobenz]

Originally Posted by jmak124

Thanks clarence, I'll have to go to Ace Hardware and see if I can get it. And upon further digging, I did find the original ones at fastlane, its the new AllPartsExpress (false advertising? ) that didn't carry them.

No you cannot use a ace bolt. You need a SPECIAL brake caliper bolt. Brake caliper bolts take the entire stopping force of your car and need to be made of special hardened steel.


I got one by going to my neighborhood European shop and asking the shop owner if he could order me one off worldpac

cost 2 dollars and 1 day. dealer can also get them.

[johnathan1]

Junkyard!

[jfikentscher]

One of my front caliper bolts (1987TD) fell out a couple of months ago. Really made some loud scraping noises. Luckily nothing got bent.

Replaced the bolt. It was an 8MM.

[Mark DiSilvestro]

Originally Posted by jmak124

After spending a few hours of trying to replace brake lines on the 300D, I hit a snag. As I was installing the left rear caliper, all was well until it came time to torque it down. The top bolt torqued fine, the bottom one just slipped and I noticed the threads on the bolt were rounded upon closer inspection. The caliper mount looks okay but using the bolt from the top mount, it just slides in and out.



Is this just a bolt issue, or is it the caliper mount? How much would it cost to source a new part and is it worth it?

This was my brother's car and its not in use so I'm prepping it to be sold or donated and at this point, I don't know if its worth the effort depending on the issue.

Are ALL the caliper bolts like that one? They should be regular hardened metric bolts - probably grade 10.9.
Not flange-head thread-cutting bolts like the one in your photo. Hope the threads in your caliper-mount haven't been ruined by an incorrect bolt. If you have any original bolts left holding one of those calipers, that's the one you need to find a match.
In my area, there's only one supplier that carries hardened metric bolts. If you don't have such a place near you, your best bets are Phil here at PartShop, a Mercedes dealer, or off the same model car in a salvege-yard.
In fact, when I'm visiting my local Pick-N-Pull for some item, I often find lots of assorted metric bolts lying loose around vehicles where others have removed parts.
I usually grab a handfull or two to keep handy in case I run into a snag like yours.

Happy Motoring, Mark

[BodhiBenz1987]

Originally Posted by jmak124

Should I be looking for a new caliper bolt or just get the next size up? Also it doesn't seem like the caliper bolt is listed on FastLane.

http://catalog.peachparts.com/ShopByVehicle.epc?q=1983-Mercedes--benz-300d-Brake&yearid=1983%40%401983&makeid=63%40%40MERCEDES-BENZ%40%4063%40%40MERCEDES-BENZ%40%40X&modelid=6191%3AMBC|1504%3AED|10000135%40%40300D&catid=241658%40%40Brake&subcatid=241675@@Brake+Caliper+Bolt&mode=PA

I bought mine at the dealer and they worked out fine. For a couple bucks it'd probably be worth the peace of mind to know you're using the right bolt.

[MBDFahrer]

Assuming the threads in the mount aren't damaged, I'm going to order a set of bolts. As far as I know, both bolts on the left side are the wrong ones (one is a 18mm and the other is 19mm) and I didn't get a chance to check out the right side but since the shop replaced both rear calipers, I'm just going to replace them just to be safe.