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R32 Brake Problem After Conversion - Pedal Goes To Floor

gts25
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gts25 Rising Star

gts25

Posted
Posted

Hi Guy's,

Currently having a problem with my R32.

I have completed a conversion from 4 stud hubs and non-turbo brakes to 5-stud and GTS-T brakes.

I have done the following:

- replaced front hubs, fitted new rotors, pads and calipers. Replaced brake fluid with new DOT 3 fluid. Bleed the brakes

and beeded in the brakes with no problems. Pedal travel felt fine and brakes pulled up with no problems

- I then replaced the rear hubs, rotors, pad and calipers. Replaced brake fluid and bleed brakes. Now when pressing pedal, takes a few pumps to build up pressure. When car is running the pedal goes to floor and I cannot build up pressure with the pedal.

Found out that I bleed the brakes in the wrong order and bled them again - RL, RR, FL. FR. Bleeding the brakes the second time did remove some more air and I am confident that there is no air is left in the lines. At no stage was the brake fluid resoviour emptied completely.

Is it possible that in pushing the pedal completely to floor when bleeding could I have possibly damaged the seals in the master cylinder causing loss of pressure or could it be that I still have air in the line?

Thanks in advance

Jason

br3ndan Mentor

br3ndan

Posted
Posted

I would think u still got air in your brakes lines...

I always push my pedal all the way down to bleed the brakes, and nvr had any problems.

Give it another bleed and see how it goes...

twogtrs Newbie

twogtrs

Posted
Posted

suggest you check your resiviour

levels and make sure it is not dropping if it is then you have a leak and need to search for it. best bet start at the rear since this is where the last work was done. However if there is no drop it the levels then there must still be air in the line or air getting in so check all the lines for tightness and bleed again

hope it helps

ps why dot 3 and not dot 4

Hi Guy's,

Currently having a problem with my R32.

I have completed a conversion from 4 stud hubs and non-turbo brakes to 5-stud and GTS-T brakes.

I have done the following:

- replaced front hubs, fitted new rotors, pads and calipers. Replaced brake fluid with new DOT 3 fluid. Bleed the brakes

and beeded in the brakes with no problems. Pedal travel felt fine and brakes pulled up with no problems

- I then replaced the rear hubs, rotors, pad and calipers. Replaced brake fluid and bleed brakes. Now when pressing pedal, takes a few pumps to build up pressure. When car is running the pedal goes to floor and I cannot build up pressure with the pedal.

Found out that I bleed the brakes in the wrong order and bled them again - RL, RR, FL. FR. Bleeding the brakes the second time did remove some more air and I am confident that there is no air is left in the lines. At no stage was the brake fluid resoviour emptied completely.

Is it possible that in pushing the pedal completely to floor when bleeding could I have possibly damaged the seals in the master cylinder causing loss of pressure or could it be that I still have air in the line?

Thanks in advance

Jason

gts25 Rising Star

gts25

Posted
  • Author
Posted

thanks for your thoughts guy's

I will check if fluid levels drop but I believe it does not and we have checked for leaks.

Could we be bleeding incorrectly? We used the method described in the workshop manual - open bleeder nipple, attach clear hose immersed in jar of fluid, press brake pedal and release, wait 3 secs, repeat until most of reservoir is empty, top up reservoir. We are only getting fluid coming through the hose and no air

I have used DOT3 as this is recommended for use on the top of the reservoir cap

Jason

blind_elk Grand Master

blind_elk

Posted
Posted

Did you bleed the master cylinder?

I normally have some pressure in the system before opening the bleed nipple. Hold the pedal down while re-tighten bleed nipple, then let pedal up.

Beer Baron Grand Master

Beer Baron

Posted
Posted

you should be doing:

hold pedal down. open nipple. pedal goes to floor. keep it on the floor, close bleed nipple. now let the pedal up. pump it up a bit and hold it, open bleed nipple, pedal goes to the floor. close bleed nipple, let the pedal up. etc etc. don't be just pumping away at it with the bleend nipple open as each pump will suck up some air.

Trav33 Mentor

Trav33

Posted
Posted
you should be doing:

hold pedal down. open nipple. pedal goes to floor. keep it on the floor, close bleed nipple. now let the pedal up. pump it up a bit and hold it, open bleed nipple, pedal goes to the floor. close bleed nipple, let the pedal up. etc etc. don't be just pumping away at it with the bleend nipple open as each pump will suck up some air.

I think its actually more like

pump pedal about 3-4 times to build up pressure, and hold pressure on the pedal.

second person opens bleed nipple, when the pedal just about hits the floor, #2 person yells "floor".

#1 person tightens nipple and yells "pump",

and repeat the process x number of times.

BHDave Grand Master

BHDave

Posted
Posted

once you have a tube full of brake fluid you aren't really going to suck anything back in but brake fluid if you have a decent seal. Thats why the manual states to immerse the end of the tube in a jar of fluid. Once you pump the pedal twice you've blown all the air out of the tube and you are at worst sucking up a bit of old fluid. By the time you flush all the new stuff through until you are seeing clean fluid you are only sucking back clean fluid. Not saying to try it but in theory you could bleed your own brakes this way with no one opening and closing the nipple.

Everyone's got their own variation on it. Whats the point of pumping the pedal to get pressure in the system btw? as soon as you crack the bleed nipple it's gone and so when you depress the pedal it's just like you didn't pump it at all.

I do a bit of a mix of both. It works, i'm sure all of the other ways you guys do it work as well. It's not rocket science to get the bubbles out if the system is up to scratch.

Back to the OP's concerns, has anyone considered the master cylinder may not be up to the task of bigger calipers all round? I could be totally wrong but i have no idea of the relative sizes of the cylinders.

gts25 Rising Star

gts25

Posted
  • Author
Posted

Hi Guy's,

Good news - I have fixed the problem - almost embrassed to say what it was. I installed the rear calipers on the wrong sides

(left on right side of car, right on left side of car). Whilst the calipers are exactly the same and fit on either side regardless, installing them on the incorrect side puts the bleeder valve on the bottom of the caliper. The bleeder valve needs to be at the top of the caliper assembly. Although I have bleed the calipers numerous times a pocket of air was being forced to the top of the caliper...

Once installed the correct way round and bleed again, pedal is back to normal - wohoo :)

Btw - existing master cylinder and booster seem up to the task for the larger calipers

Thanks guy's for all your suggestions

Jason

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