Soft brake pedal.

[BillyWhizzz2002]

Hi all,

I have had trouble with a soft brake pedal since getting the car at xmas. So i set about bleeding the brakes (two man method so i could see any air coming out).

Got a big bottle of of DOT4 so i could completley change all the fluid. Which we did but still had a soft pedal. So set about bleeding again with all pistons pushed back in.

While watching for air bubbles ( odd couple came out) i noticed some thick bits in the nice clean fluid coming through. they look like tiny bits of set silicone. Pedal still soft.

Worried now that the system has had DOT5 in at some point   , what do you guys think? and what should i do now?

and i got a track day only a couple of weeks away.

[pistonbroke]

Not certaqin but I doubt dot 5 would be the cause of the lumps , you sure there not bits of silicon rubber seal which have gotten in from somewhere ,

you dont say if disks fitted all round , drum rear , 4 pots or whatever ?

I would check for any leaks and try flushing the system again

edit to say Ive had rubber bits enter the resavoir due to a perished cap seal (not on me wessy though) so worth checking that  

[BillyWhizzz2002]

std disc setup all round with floor mounted pedals. With the lumps looking like clear set silicone i thought it may have had silicone brake fluid in at some point. But not sure what happens if you mix the two.

[peterg]

Can synthetics be mixed where DOT 5 silicone was used or is it recommended that the rubber be replaced when changing back?

Silicone is an inert substance, this is why it is safe for breast implants. Technically it should not damage the rubber parts.

Polyethylene glycol based fluids (conventional or synthetic) will not mix with silicone fluid (DOT 5). It will lump together somewhere in the system. Also, they will not react when it is mixed. So, if you perform a good flush, the rubber parts and the system should be OK..

I'd keep pumping DOT4 fluid through until you don't see any bits in it, also have you tried taking the rear calipers off and turning them so the bleed nipple is right at the top, this can aid bleeding air from them (depends which calipers are fitted too)

[chris7273]

How soft ? maybe it's just the "non servo" feeling... did you compare with other Westfields with the same setup ?

[BillyWhizzz2002]

was comparing with my old westy that had drum rears , pedal was always rock hard. This new westy the spongy pedal dose nothing for for first half of travel then starts to work but still feels soft. I can lock up the front wheels but i have to stamp on the brakes very hard, i would say with twice the pressure i had to than in old car. And by this time the peddle is nearly on the bulkhead.

[pistonbroke]

bung some more fluid through as said and if there sierra calipers (odds on they are)  turn the calipers  upside down while bleeding as they are fitted upside down on westfields .

You will need to put some plywood or similar between the pads when they are off the disks .

99.9% says its air in the rears , very common problem with loads of stuff written if you do the search  

[a4gom]

I'd keep bleeding them through till its clean, I've not had too much problem with the westfield but with other cars I've had issues with the alignment / bends in the pipe retaining air when bled by foot. Have a look at the pipes, any nasty bends? A series of quick full pumps usually shifts pockets but I have had to jack some cars into some daft positions in the past.

Also as Peter says depending on the set up you may find the bleed nipple isn't at the very top of the calliper void so some air is retained. Take all the callipers off put some old pads in or something solid which will allow the pistons to come out to the max without popping out, this will prevent the pistons trapping any air, then bleed with the caliper in your hand, this way you can move it about and make sure the nipple is at the highest point.

i don't have disks on the back of mine but from previous posts it sounds as if thats where you should start.

[Dave Eastwood (Gadgetman) - Club Chairman]

Other tricks to Westfield brake bleeding include using a block of wood, braced off the chassis cross-member to keep the brake pedal pressed in over night. gentle tapping of the callipers while bleeding, with a soft face mallet can help tease the bubbles through. I didn't actually take the rear callipers off on mine, but I did follow Westfield's advice to jack the rear end of the car up as high as I could before bleeding. (I seem to remember leaving the back end of the car on the build stand!)

[BillyWhizzz2002]

cheers all, a few things to try there over next few days.

[John Loudon - Sponsorship Liaison]

As already stated by A4GOM, the rear calipers are sensitive to trapped air at the top of them. removed the calipers and suspend as high as possible with a block of wood between the pads and rebleed

Also, if you have a bias pedal box, you will need to bleed the fronts and rears simultaneoulsy

[BillyWhizzz2002]

Here is a pic of my rears, the bleed nipple is at top. But do they still need removing and lifting to bleed. By the way any idea what sort they are?

[stephenh]

Your bleed nipple looks to be at or near the top of the caliper to me?

[Dave Eastwood (Gadgetman) - Club Chairman]

There's still probably benefit to removing though, or at least getting the backend of the car as high as possible. (The second option worked fine for me   )