smoking front brake

[jakl]

Hi folks, six miles into ride, my '70 280SL was pulling to the right.  Pulled over to check tire - smoke was billowing from right front wheel.  I think brake caliper froze and toasted pads.  Did I ruin the rotor?  How do I diagnose?  Can I salvage caliper or replace it?  I assume whatever I do to the right I'll have to do the left side. What about wheel bearings?  Any advice would be greatly appreciated.
Cheers,
jakl

[A Dalton]

First suspect is brake hose.
 Simple test:

 Jack wheel and apply brake pedal hard, release .
 Hand turn wheel ... if stuck, open bleeder
If wheel then frees , replace hose ... if not, possible stuck caliper.

[PK]

I just went through this with help from the forum about five weeks ago. Left front froze on the return from buying our '64. I went ahead and replaced all four hoses and all but the line running front to back. The eye opener was blowing low pressure air throuh the calipers and looking at the "black toothpaste" that came out. You don't say how long you've have the car, have you gone through the brakes? Going is good, stopping is critcal.

[ted280sl]

JalkL,
  Rotors are cheap. If in doubt change them. Remove the wheel and turn the rotor by hand. If you feel a cruchy action or the rotor can jiggle about then your wheel bearings need replacing. If you can turn the rotor, then it is unlikely your caliper is frozen. I agree with the experts in the problem we face in our flex houses gumming up. These hoses tend to become clogged and will hold pressure on the caliper which can lead to your symptons.
Ted
1969 280SL
Great day in New York for a ride!

[jakl]

Many thanks to ted280sl, PK and A Dalton, you guys responded and your advice was spot on!  This past weekend I performed test, replaced brake hoses and pads on both front wheels.  Rotors look okay.  Car stops great!
Couldn't have done it without this web site.  Until my next problem...
Cheers,
jakl

[Cees Klumper]

Reviving an old thread - I had the smoking front brake this evening; the left front brake froze up after some intermittant freezing, and after one mile the rotor was literally red hot. Onto replacing the hoses first; if it cures the problem fine, if not, then need to replace the calipers as well. Although upon inspection after cooldown, the pads could be pushed in quite easily, so the pistons are not stuck in the calipers. Will report back when I am done replacing the hoses.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[rmmchl]

check the brake hoses-----they look normal, but if they are old they clog up-this happened to me-very common on these cars--replace them all-they are very inexpensive-originals at buds benz

[Cees Klumper]

Geronimo!


On the nose RMMCHL,

Replaced the brake hose this morning; the outside looked good, however the inside I could not blow any air through! Completely clogged up. After replacement, the problem was completely gone, what a relief. I won't replace the calipers for the time being, as the braking is just fine. The front ones took maybe a half an hour each to do, a surprisingly easy job. For bleeding the brakes, I used a Mityvac pump set-up that I bought on Ebay for, I believe, around $60, which made bleeding the system a very easy job.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[J. Huber]

Hey Cees, how long had it been since you changed the hoses? Just curious... Thanks and glad you quit smoking.

James
63 230SL

[Cees Klumper]

Hi James. That smelly smoke, and the sight of a red-hot brake disk glowing behind the wheel, was very unnerving to say the least - when I stopped to inspect, there was a small flame of dried out grease at the front suspension steadily burning - oh great!. I have experienced this only once before, with my second car I ever owned (this was in 1978, a Jaguar sedan 4.2 liter that had red-hot glowing front brakes after we took her all the way to top speed on our first drive, which was around 200 KPH)

Since I bought the Pagoda, in the summer of '99, I had not replaced the hoses. So that's 8 years and about 35K miles that I've put on since. Moreover, I replaced the brake fluid for the first time (I know ...) last year. No telling when the hoses were last replaced by a PO (Previous Owner). Then again, it's just not something that you think needs replaced every X miles or years, and to my knowledge there is no replacement frequency in the BBB, Haynes Manual etc.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[Shvegel]

ATE caliper are known for sticking the pads in the caliper. Remove the wheel, remove the small pins that go through the top of the pads with a hammer and small punch from the outboard side and see if you can pry the pads away from the rotor. If you can the pads are just stuck and you can wiggle any pry them out, clean up the areas where the pads sit on the caliper with a file(carefull of the rubber boot around the piston) and put it back together with a new rotor and pads using some form of antisieze on the edges of the pads where they contact the rotors.

If the piston is stuck you will have to remove the bolts that retain the caliper to the hub and somehow slide it off the rotor(hammer,pry bar, cusswords, etc) buy a rebuilt caliper, a rotor and a new hose and put it all back on again.

Speaking as someone who has enough experience with ATE calipers to own the Saab factory tool that winches the pads out when they are stuck, the custom file that is used to clean the caliper and the special extra long punch for punching out the pins(about $250 total)
I rebuilt all four calipers, replace all the hoses and lines and replaced the master cylinder on my car when I bought it and I have never had to worry on a long trip about something letting go.

Remember hydraulics are going to fail when the pressure is the highest which is when you need them the most unless of course you are at a drive thru in a 65 Pontiac Gran Prix and you stand on the pedal when you reach into your back pocket for your wallet, blow a hose and crash into the car ahead of you.

[graphic66]

Just a quick correction, I believe Shvegel means to put antisieze on the metal edges of the pads where they contact the calipers, not the rotor. Fitting new pads to your calipers with a file is important to help stop the brake squeel also. The pads should move freely in the caliper with no binding. Every set I have installed in my Mercedes has needed filing to fit perfect.

[Shvegel]

Yup, not on the rotors.

[Ben]

My car drives dead straight but pull violently to the right when braking. The hoses look fine so I think I will just fit new pads and since I have a caliper rebuild kit I will just clean everything up and order new hoses anyway, since I dont know their history !

Most likely this is a sticky caliper right ?

Regards,
Ben in Ireland.
'64 230SL 4sp.

[al_lieffring]

quote:Originally posted by Ben

My car drives dead straight but pull violently to the right when braking. The hoses look fine so I think I will just fit new pads and since I have a caliper rebuild kit I will just clean everything up and order new hoses anyway, since I dont know their history !

Most likely this is a sticky caliper right ?

Regards,
Ben in Ireland.
'64 230SL 4sp.

Maybee not

The restriction (constriction) on a bad hose is on the inside so it isn't visible from the outside.

A simple test if the calipers are sruck when you try to retract the pistons; open the bleeder valve, then if the piston moves freely the hose is bad if the piston is still stuck the caliper is bad.

Replace brake parts in pairs, and if the calipers are stuck replace the hoses too.

Al Lieffring
66 230Sl
Jones'n for a new gas tank

[Cees Klumper]

Ben - my car pulled heavily to the right upon braking, because the left brake hose was constricted. Both my front hoses looked fine, as Al points out you can't see the deterioration from the outside. So if I were you I would replace the front hoses (costs maybe 20 pounds) and odds are that that will solve your current problem, as well as prevent the more serious one where the left front brake seizes up, like on my car.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[Ben]

Yeah I have ordered a complete set of rubber hoses, since I dont know their history, safer to chage all !

Ta !

Regards,
Ben in Ireland.
'64 230SL 4sp.