Brake Force Regulator

[n/a]

My first try at this but here goes.  I am now the owner of my dads 68 280 SL that we have owned since '71.  Very low mileage car (26k original miles) that spent most of its life in the Pittsburgh, PA area.  

Anyways, after storage over the winter, I noticed what appears to be dried brake fluid near the left rear wheel.  I took the wheel off to have a look and the brake line appears fine but I think the brake force regulator (?) may have leaked or failed.  Other symptoms include a low reading in the brake fluid reservoir that serves the rear wheels and a left rear caliper that does not seem to be fully released from the rotor (the rotor turns but not freely).  Any thoughts on this situation are welcome as well as where to find a new part.  Thanks and regards.

[jeffc280sl]

Congrats on the purchase.  I'm sure you will enjoy the car.  I've been working on the brake force regulator or proportioning valve on my 1970 280SL.  I understand they are reliable and when failed have a tendancy to prematurely lock up the rear wheels in a panic brake situation.  Some of the best advice from this group concerning brakes is the change the rubber brake hoses.  The tend to block up over time and act as a check valve.  High pressure will push some fluid out to the caliper but the fluid does not flow freely the other way causing the calipers to not fully retract.  I'd start there and as you bleed the system get all of the old brake fluid purged.

Jeff C.
1970 280SL 4-speed

[Dngalura]

Dan is my name.  A new member. Not sure, but I hope I'm in the right place for posting.
I came across Jeff280 sl  posting in 2005, re: brake force regulator. I'm wondering any new thought about this unit.
I believe  this is my issue. During, routine maintenance, I noticed my rear hoses are old and are blocked and dry and also no fluid in both calipers . I replaced the hoses with new ones. I noticed also, no  fluid coming out from the brake force regulator. Tried to pump the brakes hoping it will open the regulator, but no luck. I checked the brake line from the master cylinder, and there is fluid.
Now, my question: any current advice how to deal with  this issue, beside replacing the regulator? This  is an expensive unit, isn't it? I want to explore any option, before replacing it. Or someone had done something that had worked. Thank you.

[garymand]

Have not heard of the reulator going bad.  Possible water n the fuid could do it but then you would hav frosen calipers too.  seems to me there are only 2 hoses to replace one at the regulator going to the diver's side and one near the passenger side.  fuid should flow freely out of both sides just with gravity.  Usually the problem is just swollen hoses after 40 years of exposure to the alcohol in the fluid.

[Dngalura]

This is Dan again. Thanks for the reply. Anyway,I want  to share my unexpected  result re: brake force regulator. After I posted my concern, I put of f the project for awhile, but in the meantime, I researched all the thread about the issue. Few days ago, I finally decided to tackle the regulator, with a planned approached . Just my lucked,  I noticed brake fluid seeping out  of the metal tube connection to the left rear hose, which  was dry before, so, I checked the bleeder nipple, and there was free flow of fluid, again, none before. So, I checked the right side, also fluid present. After removing the wheels, I went ahead and inspected the brake pads, rotors and calipers and pistons. It appeared that  the rear brakes were not working for the longest time. After cleaning , lubricating, the pads, calipers ,pistons, and bleeding, I tested the function of the pistons . Happy to see that, everything is working. This saved me from taking the regulator  out.  Lesson learned:  after replacing both rear brake hoses, maybe, just give time for things to correct itself. I continued to drive the car around, knowing only the front brakes working, maybe, with continued  pressing of the brakes, this eventually opened the  " brake force regulator " .

Next project:  my ac compressor is making a loud noise and it's very irritating, it takes out the fun of driving around. I took out the aircon a while ago, and I don't have any  used for the compressor. I know this will be a huge project , but if I get the right guidance, I can tackle this.
If anyone has the experienced or have done this , I would appreciate hearing from you. What is the first step, and then next.... Thank you!

[Peter van Es]

Dan,

Please can you not reply to really old threads anymore?

And secondly, please start a new topic on your AC compressor in the Electrical and Instruments section as this thread is about Brake Force Regulators.

Thanks

Peter