w110 pulling to the left on braking

[zbethem]

I have a 67' w110 200d. Recently, I've been dealing with a pull to the left under braking. From what Google's been telling me, I should suspect a sticking caliper.

What are the steps for diagnosing such a thing? A few hits on youtube, but the comments give me caution in trusting the blokes.

If they are stuck, what are the steps for replacement? I'd like to avoid some ubotanium replacements due to cost if I can help it.

Thanks! Back to my searching too..

[KCM]

Hey there zbethem,

Sticking calipers are not uncommon with older vehicles due to corrosion and gunk build-up in the system. But there are other causes too. You may have a problem with one side sticking as you think, or maybe it is the other way around and the other side is not applying enough.

To check for a stuck piston in the caliper, jack the wheel up that you think is sticking. Apply the brakes and then release the pedal. Try to spin the wheel. If it is dragging really hard, then that wheel definitely has a problem. But before you condemn the caliper, open the bleeder valve. If the wheel is still tight, it is the caliper. If the brake releases, then you likely have a partially plugged hose to the caliper. I had a case like yours where it turned out to be the hose. With age, pieces of the rubber will fall apart inside and act as a one-way valve.

If you apply the brakes and the wheel still turns freely, then you might have the case where the other wheel is not applying enough. This could also be due to a stuck piston in the caliper or a plugged hose to that wheel. Diagnosing this is a little more difficult, but if you have a friend pump on the brake, hold the pedal down, then open the bleeder, fluid will shoot out if the piston is stuck, but likely will not with a plugged line.

As far as fixing a stuck caliper, you could replace the entire unit with a new or rebuilt one, but that will likely be big bucks if you can find one. The other option is to take the pistons out and clean them and the bore with a very fine emery cloth, then clean it very well with brake cleaner and a cloth. Probably should mark the orientation of the piston with the bore in case there is there is a slight distoration in the piston to make sure everything assembles correctly. Do not disassembly the two halves of the caliper, just remove the pistons. Compressed air at the line connection will blow them out, but be careful as they come out with force and can do serious damage to a body part in the way. Best to reinstall with a new rebuilt kit, which is simply a new boot and o-ring per piston. Coat the bore and o-rings with brake fluid to aid in reassembly. Be very careful to get they piston and bore parallel when pressing the piston in (by hand) or the piston will wedge in the bore.

Hope this helps and gets you started on the right track.

[zbethem]

Great information KCM! Thanks.

I'll start checking things as you described. I might just start with new hoses as that should be a cheap deal and they are most likely old and neglected.

Thanks again!

[Carpenterman]

KCM's info is all good. If needed, rebuilt calipers for this chassis are still available. I think I paid around $65 for one.

I found mine online, but you should try your friendly local chain parts stores first. They have good availability for stuff like this. Shipping a core back gets pricey.

[zbethem]

Just wrapping up this thread. I went out and got a replacement caliper for $59 (+$35 core). The braking has improved tremendously. There's still a slight pull, but not scary like before.

I'm thinking the slight pull is because I didn't change pads. So the stuck caliper's pads were a bit uneven. It feels like they are starting to even out though as the pull gets less and less. OR, perhaps that's false hope.

Much better all around though. Thanks all!

[ScooterABC]

Assuming you have ATE calipers, rebuilt are inexpensive, as are the hoses. If it's pulling to the left when braking then the right one probably has a stick piston and you are only getting part of the brake action on the front right wheel.