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  #1  
Old 04-10-2004, 11:10 PM
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car pulls to the left rather sharply (420SEL)

I just put rebuilt calipers on in the front, and it still does it just as bad as ever. We had good pressure coming out the front when we bled them to get the air out. So we are pretty sure they both have good equal pressure.
After test driving and seeing that the problem wasn't fixed, we put the car on the lift and I hopped in the driver's seat. My uncle watched the wheels as I did different pressures with the brake pedal. The RR wheel was not stopping as fast as the LR. So we pulled the wheels off and the inside piston of the RR caliper doesn't seem to be doing much. The rotor looks normal on the first 2/3 of it closest to the axle. So, as what I am saying is that the outer most 1/3 of the rotor looked somewhat chipped and rusted as if the caliper wasn't making good contact, which I guess it wasn't.
So, would that one RR caliper being marginal cause the car to pull sharply to the left. It isn't just slowly or gradual, you HAVE to turn the wheel 5 or so inches to the right to keep yourself from killing someone.
The rear pads look hardly worn on either sides, and the inner and outer are worn equally. It began suddenly, about 2 weeks ago. Well, when I drove it two weeks ago I noticed, it's my mom's car so I don't know when it began and she never said anything until I pointed it out to her, so it must have started when I was driving. Please let me know what you think before I buy more parts that aren't faulty in the first place. We just want to get the car fixed so we can sell it.
Thanks
David

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Old 04-11-2004, 03:21 AM
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You don't mention whether the car pulls left when the brakes are applied or when you are on the gas, or coasting.

I am no expert (but have dealt with tons of 126 front end issues) but I would verify the front end is to spec. Any clunks under hard braking (track rod mounts)?

Is this the reason you are selling the car?
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Old 04-11-2004, 12:16 PM
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It is only on braking. No, that is not the reason we are selling. The car has more rust than we thought and they just painted over rust which is now bubbling up. The windshield, or something in the front is leaking water badly into the back passenger seat. It isn't the drain at the hinge, I've cleared that out. Although, it holds water in the right corner under the hood where the battery tray is. Shouldn't that water run out? I felt around and couldn't find any drain there.
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David
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Old 04-11-2004, 12:16 PM
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Car has no clunks and actually drives rather nicely.
Thanks Again
David
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  #5  
Old 04-11-2004, 01:27 PM
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Stick piston in the rear caliper -- also the pads got worn down and hit the spring, so that the rotor is worn funny.

Replace rotors and rebuild rear calipers.

Check the bushings on the rear control arms, and check for rustout on both -- W126 rear control arms rusting out is beginning to be a problem. If you replace the, drill a ventilation hole in the bottom and paint the inside.

Peter
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  #6  
Old 04-11-2004, 02:04 PM
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David, it's logical that if the RR caliper is not effectively stopping rotation of the RR wheel that your Mom's 420SEL would tend to go to the left as the brakes are applied. Rebuild or replace both rear calipers and install new rotors.
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Old 04-11-2004, 02:58 PM
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It pulls rather strongly to the left even on lighter braking. It was my understanding that the rear brakes don't do a whole lot except fo hard braking. I thought that the pull was too strong to be the backs, but i guess I'll get rebuilt ones and have the rotors turned. I talked t my uncle about us rebuilding them, and he said it wouldn't be much more to buy rebuilt ones rather than buying the parts ourselves, and the ones that we buy will probably have been done better than we could do. I'll go right now and order some from Autozone. That's where I got the set for the front and they are working fine, plus they're MB ones and are now shiny, which looks better I guess. Would I want to replace the rubber hose sections out of necessity? I don't want to do them if I didn't really have to, remember, we just want to sell the car.
Thanks
David
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  #8  
Old 04-12-2004, 09:39 AM
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David, if your 420SEL pulls left under light braking then the right front caliper must not be functioning properly. Did you bleed air out of the system after replacing the front calipers? If not, I'd recommend that you do so immediately.
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Old 04-12-2004, 11:11 PM
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Could this be and ABS issue? That it is releasing pressure to the RF wheel as if it were sensing a lock-up? I never hear the pump buzz or anything like it does when ABS normally comes on...
I understand about it may not be the rear calipers because it does it at low speeds, but I bled the fronts very well and it has an excellent pedal. Plus the fronts are rebuilt so those can be pretty well crossed off the list I would think. What about the rubber hoses, could those be the problem? When we bled them, both wheels had good pressure so there didn't seem to be an obstruction to the flow of the fluid...
Thanks
David
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  #10  
Old 04-12-2004, 11:33 PM
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David:

I suggested doing the rears because you have an obviously bad rotor/caliper on one side.

Yes, bad hoses will cause exactly this problem -- so will stuck calipers (as I found out on my Mom's old Dodge Aspen -- the plastic pistons collapsed and stuck, make it dive for the ditch pretty bad sometimes).

Just because you bought a rebuilt caliper doesn't mean it's not sticking. I'd test it by jacking up the front wheels and gently applying brakes. I'll bet one side spins almost free.

Peter
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1987 300D Turbo killed 9/25/07, 275,000 miles
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  #11  
Old 04-13-2004, 09:25 AM
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We did that check with me in the car on a lift with it in drive. That's how we noticed that RR wasn't as good.
Thanks
David

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