Mercedes-Benz Forum banner

1 - 18 of 18 Posts

·
Registered
1977 450SL
Joined
·
3 Posts
Discussion Starter #1
77 450 SL is pulling to the left when I apply brakes - the higher the speed, the more sever this issue is. I recently put all new tie rod ends on this car as there was lots of play there, it helped - but I still have this issue.

My thoughts are leaning towards either air or blocked passenger side brake line? visibly it looks as if the caliper is fine and moves when pedal pressure is applied.

Any help greatly appreciated!

Tom
 

·
Registered
1965 230sl (euro spec,48k), 1979 450sl (200k)
Joined
·
392 Posts
Perhaps one caliper has been replaced at some point with a different brand/slightly different size?
 

·
Registered
Previous: 1989 190E 2.6, 1997 E420, 1985 380SL, 1975 450SLC
Joined
·
747 Posts
One of the two caliper pistons in the weaker side could be seized. That would show some motion during brake pedal pressing yet still not stop the car well. Wheel off, brake pads out to check (see if both pistons be forced back into their cylinders by squeezing each individually with large Channel Locks pliers.)

To rule out air in the hydraulics do a power flush of your brake fluid with a Motiv power bleeder or similar.. something you should be doing every year or two, regardless. There's lots written here on how to do it.
 

·
Premium Member
1975 450SL
Joined
·
2,440 Posts
It's been noted before that the flexible brake lines from the frame to the calipers can swell on the inside with age, acting like a one-way valve. If this is happening, the caliper piston will not return, effectively leaving one caliper still "on". If you don't know how old the lines are, you might be ahead to change them out, they're not expensive.

The brake system flush with a power bleeder would be part of this job, so you could get two birds with one stone.

Just a suggestion,
Scott
 

·
One of the BW Old Guard/R129, W204 Moderator
1997 SL500- 40th Anniversary
Joined
·
7,166 Posts
77 450 SL is pulling to the left when I apply brakes - the higher the speed, the more sever this issue is. I recently put all new tie rod ends on this car as there was lots of play there, it helped - but I still have this issue.

My thoughts are leaning towards either air or blocked passenger side brake line? visibly it looks as if the caliper is fine and moves when pedal pressure is applied.

Any help greatly appreciated!

Tom
I suspect right front brake (could be back, but more likely front) brake is not applying, or not effectively applying... causes already mentioned.
 

·
Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500se+500slAMG +250seStkW108 350sl4spdX3 500secEuro
Joined
·
22,563 Posts
Brake hoses and a system flush should likely be less than $50 in parts ($40 for hose and about $10 worth of fluid).

If the problem persists, then replace the Pads and rotors. If one of the rotors was cooked up, that could cause the problem. I cooked up one of my rotors on my 73 and it pulls slightly now, possibly due to worn pads, but more likely due to the rotor glowing red hot and then being smoothed out by the pads when I drove the car home with a caliper seized on the rotor due to a brake hose acting as a one-way valve.

So now that I rebuilt the caliper since the internal rubber all melted due to the heat, and replaced the the brake hoses and fluid (as I should have when I first got the car) I still have to replace the pads and rotors which I might not have ever needed to do if I just did the hoses first. I got lucky with it only being a several hundred dollar mistake. Someone. Oils have done the same with your car, and like me, not yet replaced the pads and rotors.
EDIT: Possibly you have done the same with your car, and like me, not yet replaced the pads and rotors.
 

·
Registered
Previous: 1989 190E 2.6, 1997 E420, 1985 380SL, 1975 450SLC
Joined
·
747 Posts
I changed all four rubber brake hoses on my 85. The two rears came off their steel brake lines fairly easily after an overnight soak in Kroil. Quick job. The fronts were a completely different story, both being seized and resisting all methods recommended here and elsewhere. What finally worked for one side was V-jaw vice grips on the flare nut. On the last (worst) side I ended up having to hack off the flare nut fitting which (naturally) trashed the steel brake line, forcing me to bend my own brake line replacement. Not fun.

If a caliper isn't releasing its pads when you take your foot off the brake pedal then there's going to be heat build-up while you're driving on that wheel. If you're able to drive your car any distance at all, feel both front wheels when you complete your trip. One side should be noticeably warmer than the other if it indeed has a stuck piston.
 

·
Registered
1986 560 SL
Joined
·
7,355 Posts
Someone. Oils have done the same with your car, and like me, not yet replaced the pads and rotors.
Someone. Oils = someone else??
Are you using a voice translator to post? How does it know to put things in brackets?
 

·
Registered
1984 380SL
Joined
·
330 Posts
Are your brake pads M-B or aftermarket? Before I did anything else I'd install new M-B pads. Mine did the same until I did just that. My old pads were from O'Reilly's; M-B pads made all the difference. It stops fine now.
Ned
 

·
Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
Joined
·
10,213 Posts
Are your brake pads M-B or aftermarket? Before I did anything else I'd install new M-B pads. Mine did the same until I did just that. My old pads were from O'Reilly's; M-B pads made all the difference. It stops fine now.
Ned
Is that because of the MB supreme pad quality or is it because the reseated pistons are in a new part of the bore?
 

·
Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
·
29,512 Posts
Since it's after post 10 and the question has been answered, albeit, with some additional questions, may I suggest you enter your car into oval racing.
 

·
Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500se+500slAMG +250seStkW108 350sl4spdX3 500secEuro
Joined
·
22,563 Posts
Someone. Oils = someone else??
Are you using a voice translator to post? How does it know to put things in brackets?
I was on the iPhone. I think I meant to write "possibly you" , or "Maybe you". I don't know what that iPhone was thinking. I fell asleep right after the post. So maybe I was half asleep already. Oops!
 

·
Registered
72 350SL
Joined
·
14 Posts
It's been noted before that the flexible brake lines from the frame to the calipers can swell on the inside with age, acting like a one-way valve. If this is happening, the caliper piston will not return, effectively leaving one caliper still "on". If you don't know how old the lines are, you might be ahead to change them out, they're not expensive.

The brake system flush with a power bleeder would be part of this job, so you could get two birds with one stone.

Just a suggestion,
Scott
Can someone direct me to the thread about the swelling? I note this is an older thread - couldn't find the swelling reference with the search function. Thanks in advance,
 

·
Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500se+500slAMG +250seStkW108 350sl4spdX3 500secEuro
Joined
·
22,563 Posts
Can someone direct me to the thread about the swelling? I note this is an older thread - couldn't find the swelling reference with the search function. Thanks in advance,

The point is that the brake hoses are only about $10 each, and the brake fluid is supposed to be changed every two years regardless of mileage. Spend the extra $40-50 while replacing the brake fluid, at least if you don't know when the brake hoses were last replaced.

I had the one-way valve happen to me on my 1973 450sl when I first bought it. It was the night of the glowing rotor. Then I had to rebuild the brake caliper because I cooked up the internal caliper seals.

Swelling brake hose: lots of pressure pushes the hose wider when braking and fluid gets around the bits if disintegrated hose in the center that are clogging it. Then you let off the brakes, and the hose comes back to normal size, and the fluid can't return from the caliper because the hose is now clogged because there isn't any more high pressure on the booster side making the hose swell. Make sense?




Sent from AutoGuide.com App
 

·
Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500se+500slAMG +250seStkW108 350sl4spdX3 500secEuro
Joined
·
22,563 Posts
I'm actually not even in PA, but less than 30 minutes from Downtown Philly. I prefer not to have too distinct information in an online forum where I have no control over what happens to the information after posted.


Sent from AutoGuide.com App
 
1 - 18 of 18 Posts
Top