Brakes locking up

[Shaun_E]

After repeated hard braking the pedal "pumps up" and the front brakes stay on - causing massive drag. Once they cool down a little then the pedal becomes spongy for a while but braking returns to normal.

This only seems to have occurred since I moved the pedals back (to the position nearest the driver) and I was worried when I moved them that I had not adjusted the brake pedal correctly.

Is there some knack to adjusting the stirrup on the brake pedal or is something else wrong? I thought that mabe the brakes need bleeding (or even replace the brake fluid).

Help - I've only just got the car and don't want to book it into a service agent if there is something simple that I can do.

Shaun

 

Yellow SL

 

Additional info: Car is 1997 SL with 4 pot calipers up front (Caterham/AP I think)

 

Edited by - Shaun_E on 21 Jul 2002 20:21:35

[F355GTS]

Shaun

 

sounds exactly like the problem I had on mine when I upgraded the master cylinder. In effect by moving the pedals closer you have increased the angle from the end of the pedal arm to the Master Cylinder. As you brake the shaft going into the master cylinder is wedging against the top edge of the bore, If you check the shaft you may see small scratches, you might have to remove the dust cover to see.

 

Simple solution and worth a try (worked on mine!), YOU WILL NEED ONE NORMAL M8 (13MM) NUT. Remove the pedal box cover, Slacken by about 15mm the lower M8 (13mm) bolt that holds on the master cylinder. Remove the nut and bolt off the top bolt holding same. Now assuming the bolt is long enough (if not get a longer M8 Bolt)

Pass the bolt through the master cylinder flange, thread the new nut onto the thread between the flange and the back of the pedal box then pass the bolt through the pedal box and tighten the original nut. tighten the lower nut and bolt to suit.

 

does that make sense? by using a 13mm nut to create a gap between the master cylinder flange and the pedal box what you are doing is making the master cylinder lower at the rear so reducing the angle of the shaft

 

If it doesn't make sense then post here, I'll take a picture of mine and e-mail it to you!

 

Mark

[sjwb]

Yup, you've got the m/c push rod adjusted incorrectly. The piston MUST be at the rearmost of it's travel, ie against the circlip. You have partially pressurised the system and with the brake off the port to the reservoir is masked.

 

Steve B

[Shaun_E]

Mark/Steve B,

 

thanks for that - I'll try re-adjusting the brake pedal first and if I can't get it right I'll try the extra nut idea - makes sense to me but if I go this route then a picture would help a lot.

 

Cheers,

Shaun

 

Yellow SL

[F355GTS]

Steve's solution sounds very feasible and much easier to try first as you say, it wasn't the case with mine as the piston was at the circlip hence the 'bodge'. I had always intended to get a piece of Aluninium machined to create the wedge but never got round to it, still it works fine!.

 

 

let me know if you need the pic

 

regards

 

 

Mark