1983 300D caliper bolt won't torque HELP!! - Page 2 - PeachParts Mercedes-Benz Forum

BodhiBenz1987 · #16 03-12-2009, 04:39 PM

Quote:

Originally Posted by jmak124

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.

Good call. It's a good idea to replace the bolts when you replace the calipers anyway. Hopefully the threads in the mounting bracket are OK.

JimSmith · #17 03-12-2009, 04:40 PM

Quote:

Originally Posted by turbobenz

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.

Turbobenz is correct. Whenever you buy new brake parts that require you remove the calipers, you get new caliper bolts from the dealer. They also typically have some blue locking compound dabbed on the threads and they are not intended to be reused. Doesn't mean I haven't, but the idea is the bolt is a safety item and for the few bucks it costs it is not worth installing a damaged bolt that will shear in an emergency.

If the threaded hole the bolt fits into is damaged you should drill and tap it to the next size and use the same grade of bolt in the larger size. It is a lot safer to come up with McGyver fixes for the "go" side of the car's systems than to compromise on the "stopping" side.

Jim

whunter · #18 03-12-2009, 05:55 PM

Quote:

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.

Front caliper bolt MB# 1234210271

MBDFahrer · #19 03-12-2009, 06:06 PM

Quote:

Originally Posted by whunter

Front caliper bolt MB# 1234210271

Thanks whunter, are the bolts the same for front and rear?

Also, I figured I'll post a picture of the mount, the odd thing is the lower hole is the one that's having bolt issues, but the top one has shiny threads

whunter · #20 03-12-2009, 06:22 PM

[QUOTE=jmak124;2137548]Thanks whunter, are the bolts the same for front and rear?

Also, I figured I'll post a picture of the mount, the odd thing is the lower hole is the one that's having bolt issues, but the top one has shiny threads

Rear caliper bolts. MB# 1234230071

t walgamuth · #21 03-12-2009, 07:08 PM

I'd take that to a machinist and have the lower thread helicoiled. It obviously had a problem previously. Hence the cutting mark on the threads.

I would not drill it out to the next bigger size. It might not leave enough parent metal in the caliper to be safe.

Remember it won't break until you hit the brakes really hard in an emergency situation!

turbobenz · #22 03-12-2009, 08:40 PM

Idk even about helicoiling it. These a tremendous amount of force here. id say either drill and retap it and use a larger but 10+ grade bolt or get a new spindle

t walgamuth · #23 03-12-2009, 09:16 PM

If a helicoil works for a head bolt it should be ok for a caliper.

bgkast · #24 03-12-2009, 09:23 PM

The threads look OK to me. I would find a new bolt and try it out before doing any drilling.

Mark DiSilvestro · #25 03-13-2009, 05:47 AM

Quote:

Originally Posted by turbobenz

Idk even about helicoiling it. These a tremendous amount of force here. id say either drill and retap it and use a larger but 10+ grade bolt or get a new spindle

A larger bolt won't fit the caliper.
I really wouldn't want to drill that oversize too!

Happy Motoring, Mark

whunter · #26 03-13-2009, 05:12 PM

Never helicoil or bore and re-tap steering or brake components = they are safety systems.

A used steering knuckle or trailing arm is cheaper than your life..