450SLC dragging rear brakes

[brycedunn]

Hello ozbenz,
I've noticed a squeaking sound from the rear of my SLC which gets worse when the brakes are used.

After a longish drive (40 mins), the alloy wheels are HOT to the touch on the rears, but ok on the fronts. Both rears are hot, not just one.

My assumption here is that I have dragging brakes. If it was on one side it would be easy - start with the flexible hose and if not that, the caliper. However, with both sides, I'm not so sure.

There is also quite a bit of brake dust on the rears (more than the fronts!)

Any suggestions?

[tsharkey]

I had this on one of the W123's

www.ozbenz.net/viewtopic.php?f=5&t=25855

Replaced the master cylinder and all has been well

[Bartman4800]

Replace the hoses when they have dry cracking or when they are older than 15 years.

The calipers could be grabbing because the pistons are stuck. Happens when there is the tiniest bit of rust on the caliper body just underneath the dust cap.

Bring them to your brake specialist to have them rebuilt. You can do it yourself but only if you are sure what you are doing.


Bart

[brycedunn]

Thanks!
Good suggestions.
I might start with the flexible brake hoses. I checked my history file and I last changed them in 2003. Even if not the culprit they are old enough that they really should be changed.

Then i can do some tests to try and see if its master or calipers.

Bryce

[Bartman4800]

Yes.

Easiest is to take off a caliper and see if you can easy retract a piston, either with a caliper tool or a clamp from Bunnings.

https://www.bunnings.com.au/craftright- ... p_p5860086

If pistons do not retract easily, open the bleed screw (and bleed into a jar with a small hose). If that makes it better, the hose is your culprit.

Bart

[CraigB]

I hate bleeding brakes, so for my money, if i was changing hoses, for $30 or so for a caliper kit, and while i have it all partly dismantled, I would pop out the pistons, check for corrosion, fresh rubbers and dust caps and then bleed it. Usually the pistons are ok I have found and corrosion is in the body or the caliper usually combined with a disintegrated dust boot that has let moisture in. You can clean that up with emery without affecting the rubber to piston seal. Or you can get the calipers rebuilt but its fairly straightforward. I remember JG saying how he had a few cars in a row that had leaks between the caliper halves and recommended always splitting the caliper. I've never split a caliper and never had a leak - but my sample of cars is a lot less than JG, so not going against his advice. Still, if it is an even effect on both sides, less likely that both calipers would lock equally and more likely Tsharkey's suggestion .... I reckon!

[Bartman4800]

The front calipers on my Finnie rusted evenly on both sides

But yeah, Craig has made some great suggestions.

Bart

[John Green]

Thanks! Good suggestions. I might start with the flexible brake hoses. I checked my history file and I last changed them in 2003. Even if not the culprit they are old enough that they really should be changed. Then i can do some tests to try and see if its master or calipers. Bryce

I would start with the hoses. ATE have a recomended service life of 10 years for brake hoses, so they are due to be changed anyway. if that doesn't fix it, do the master cylinder.

[brycedunn]

I would start with the hoses. ATE have a recomended service life of 10 years for brake hoses, so they are due to be changed anyway. if that doesn't fix it, do the master cylinder.

Yes, this seems to be a good place to start since they are a service item in any case.