Poor front brake performance

[Rissy]

Hey folks. During my MOT, for the first time highlighted, the front brakes were very poor, and should in fact fail the MOT (it didn't though - nudge nudge wink wink)

The performance of these seems to be right down on last years performance. The overall brake performance is still sufficient to be able to stop the car (hence why the guy let it go....for now) but it was suggested that this could be a sign that the old rubber seals in the master cylinder could be on their way out, meaning a new master cylinder to replace the old. This would then hopefully bring back the performance to new again. Basically just looking for some input to this theory. Is this theory sound, or is there any other theory out there?

God I wish I had someone to help me with this stuff!

[Chris Williams]

Possibly, if it were me (depending on what has been done/replaced by MartinG) would be to replace the flexi hoses as these may be expanding, and go from there perhaps a complete refresh is in order?? new/refurb'd calipers and pads, and a new M/Cylinder. To give you an idea, when I recently did mine I bought new calipers new discs green stuff pads and S/Steel flexi pipes all came in at around £220 for the front. A new M/C from Ed is about £100 if needed.
Chris

[Rissy]

OK, thanks Chris. I'll see what Martin says then (hear that Martin, i'm waiting for you :wink: ) I'm now down in Rugby again, so can't look at the car until Xmas time now to be able to try and assess what has been replaced, at least as far as visible items like the hoses... As far as the less obvious items, i'm sort of at the mercy of Martin on this one, otherwise it'll be a HUGE spend on replacing EVERYTHING!

[Rissy]

Nudge nudge Martin. :wink:

I think LEX has stainless brake lines (front AND back?) But has she also had a new master cylinder fitted? Could the servo cause this issue?

[Chris Williams]

I would have thought (and I'm sure someone will correct me if I'm wrong) but I would have thought that if the M/cylinder was on it's way out that if you pushed the brake pedal down then it would 'creep' down as far as the pedal can go.
Chris

[Rissy]

you could be right Chris. Truth is, I don't know myself. I'm not an expert. It's also weird that the back brakes *seem* to be working fine whereas the fronts are somehow lacking in performance?? Maybe it's pads? I should have a look. Or maybe BOTH front calipers are somehow jammed, or suffering high resistance to fully gripping??!!

[Chris Williams]

If the backs are ok then it does point more to the fronts rather than the M/C. Martin may have changed the flexi lines with the ones he had made up, but in reality the cost is not great to get the calipers refurb'd with new pads. gotta be the cheapest option after the flexi pipes. discs are cheap but the hubs have to come off to change them and then you 'probably' need new bearings as they sometimes fall apart on removal. :roll: Best bet is Martin to let you know what he's done.
Chris

[Guinney1971]

pads are dirt cheap, around £12 as they x-ref to a 1981 Capri from memory.

When I had rubbish brakes on my 1989 Cavalier, changing the caliper for refurbed
ones sorted it, they were about £40 each on an exchange basis, but this was about
6 or 7 years ago now.

[stunned_monkey]

Lex had refurbished callipers, stainless flexis and new (almost certainly NOS Saab 50/50) master cylinder while in my posession. Check the colour of the pad back plate. You *might* have EBC redstuffs but I genuinely can't remember if I ever fitted them to my own car. Probably just has good quality Mintex pads.

First step for me would be a fluid change. It should be flushed every couple of years so it's probably getting on for 10 since it was last done. On the plus side, the fronts are standard cortina and very inexpensive to get on exchange if they are getting sticky and a doddle to change (2 bolts each, the bleeding's the hard part!). Weirdly the fronts do get sticky more than the rears.

BTW general bleeding advice after a full overhaul is to bleed the brakes as best you can one day, then leave for 24 hours and repeat. The second time around will result in a little burp from each corner, then you're good to go.

[dave t]

Hi
agree with the above post....

in the MOT did you get the efficiency values? 56% service brake required for pass...is it one side that's giving trouble??
what values have you??

this is what Id do.
remove wheels...check brake pad pins (sticking), pad condition, are the pads tight in the calliper? (common mistake), bleed the brakes out completely running fresh fluid through.
If still poor remove the pads have an assistant gently press on the brake pedal checking for sticking pistons & piston condition (don't over do it pistons will pop out). ....If all ok then change the master cylinder.

50/50 master cylinder http://www.partsforsaabs.com/product_in ... ts_id=2566
OR http://www.psautoparts-store.co.uk/inde ... th=159_162
Delphi master cylinder 50/50 also can be got from any motor local motor factors using the Saab numbers in link.
shouldn't cost more than £80. If fitting pads or Discs I use Apec Braking on Beamers ,Mercs etc in fact all the cars we fix here.

If you need bits ...Cylinders can be 'very' cheap...eg clutch slave £25 ...use a good motor factors with good knowledgeable guys they'd be glad to help out.

Best of luck let us know how you get on.
Dave

best of luck
Dave

[Rissy]

Cheers for the responses guys. I'm nowhere near the car (again, as usual) so can't look at things like brake pads etc until next year.

Not sure of the overall performance figures from the MOT for the brakes (can't remember them - can only remember the guy saying "oops! This aint good, you're gonna have to get this sorted for next year") It's BOTH front brakes. Both are equally bad i'm being told.

The guys used a traffic light system resistance tester on the brake and clutch fluid, which I was wanting to replace this year, and the tests for each came up green, meaning no need to change the fluid yet. Based on this tester's results, the garage told me not to waste my money and leave the existing fluid in there for longer. Do you think these testers are not worth their weight in reliability?

Dismantling the calipers or changing the master cylinder, bleeding etc is not something i'm going to do. If it doesn't go well, and i can't manage to get the car back together again within the same day or the next, then i'm up a gum tree. While the car lives away from me, i really don't have much choice but to let the garage do these types of jobs.

[Chris P]

hi Chris,

I must admit to be very remiss when it comes to changing fluids. It the tests say its Ok i'd believe them.

The main problem I have had with the normally reliable braking system, is sticking callipers/ pads due to rust/ lack of use. I'd certainly try levering them open, then applying the foot brake and see how easily they move. A very small amount of copper grease on the piston, under the rubber dust cap was worked for me.

i'd certainly try this before spending any money!

[Rissy]

Chris P Wrote:hi Chris,

I must admit to be very remiss when it comes to changing fluids. It the tests say its Ok i'd believe them.

The main problem I have had with the normally reliable braking system, is sticking callipers/ pads due to rust/ lack of use. I'd certainly try levering them open, then applying the foot brake and see how easily they move. A very small amount of copper grease on the piston, under the rubber dust cap was worked for me.

i'd certainly try this before spending any money!

I may next year in the spring time, build up enough confidence to take a proper look in the way people are recommending for caliper seizing. Just as a note though, I wouldn't use copper grease near anything rubber though, as this breaks down the rubber and causes it to perish and rot. I'd use silicone grease. It's more expensive, but it wont rot the rubber.

[stunned_monkey]

Please use the proper stuff for brake pots and seals. Here's one example.

http://www.ebay.co.uk/itm/MILLERS-OILS- ... 43adc781e0