Bleedin Brakes :crap:

[Ashy]

Yo, just after some ideas with this one...

Been trying to bleed the brakes today after the rebuild... For info the servo has been replaced but the master cylinder is the original (which worked when removed). All the brake lines remian unchanged, I've fitted new 4pots upfront, new rear compensator, all bleed nipples work as they should.

So started off by using my 1 man bleed kit to pressurise the system and push the fluid around without pumping the pedal to prevent any damage to the master cylinder. Once flushed through a couple of bleed nippes were a bit slow so we started with the up - down - up - down method... Now we bled it about 3 times as above until absolutely no air was in the system.

The problem is they just aren't right, the pedal does go hard when pressed but you can press through it and eventualy the pedal will hit the floor...

Whilst Mark pressed the pedal I was going round checking all possible leak points and couldn't see anything dripping...

Any ideas chaps?

Cheers Ashy.

[car.crash]

Did you push the bias valve open whilst bleeding the rears?

[Ashy]

Did you push the bias valve open whilst bleeding the rears?

Yup...

[Matt Cole]

Can be a ******* marrow when the system has been drained.

It must be air, sometimes it pockets at the master cylinder. Might be worth cracking each connection off to see if theres anything there. I rememeber using a stack of fluid years ago trying to bleed the red 5's brakes.

I had an ax also years ago that did the same. Turned out to be the mc seal had perished.

[michael tierney]

i had a prob years ago but i could'nt get fluid out of the front o/s caliper....turned out the front piston in the master was stuck down!!!
if u can get a hard pedal and start the engine with ur foot on the brake and the pedal eventually goes to the floor then its more than likely its the master cyl....worn

[Brigsy]

Probably needs a new mastercylinder mate, the seals dry up when dry for a period of time making the pedal poor

[Ashy]

more than likely its the master cyl....worn

Feck, I hope not...

[michael tierney]

well at least they,re not that expensive...tough part is getting them outkeep us posted,when u remove it take it apart and check

[old skool turbo power]

i had a simmilar problem myself ,at 1st i was bleeding the brakes as normal but then still getting the feeling air was in the brakes,untill i read up that the rear bias valve helps if was kept open so i did that with cable ties and after a good while later all was ok.
i know it takes alot brake fluid to bleed out the brakes and i mean alot,a pain in the arse as well tbh(having to do all round the car)
cheapest way mate id carry on bleeding them,id still say air is still the system though
each line that i blead id carry on untill i can see fluid flowing from the tube free from bubbles.(tube submerged in brake oil)that way you know for sure.
if not then the master cylinder,that was quite tricky to change as well.

[GTphil]

I go with the mastercylider also.

One thing that came to my mind was a little issue my mates old man had, when he fitted some uprated brake calipers to his mini, somehow he had the calipers either on upsidedown or on the wrong side and the bleed nipple was at the bottom of the caliper and not the top, hence no matter how many times it was blead the pedal just wasn't right.

Funny one really we never had a leg to stand on when it came to taking the piss out of him because the pair of us didn't spot it after pissing about with the brakes for almost an hour

[Ashy]

The calipers are deffo on the right way round!

I'll have another go at bleeding them tomorrow, might crack the connections off the MS as Matt suggests and also at the rear bias valve... See if we can't find any more air.. If not then i'd best order a new MS.

[Pete@Backyard Racing]

Are you bleeding the callipers in the right sequence as per the Haynes manual???

[Ashy]

Are you bleeding the callipers in the right sequence as per the Haynes manual???

Good question, never checked that, I just use the old school method of working from the furthest caliper away from the MS to finish at the closest.... I'll check the haynes before having another go today....

[Ashy]

Good question, never checked that, I just use the old school method of working from the furthest caliper away from the MS to finish at the closest.... I'll check the haynes before having another go today....

Haynes says:
1st - LH Rear,
2nd - RH Front
3rd - RH Rear
4th - LH Front

I'll give that a shot...

[newbstar*]

Master cylinder would be my thoughts on this! The calipers wont be the problem ash.

[RussellT]

My experience with the HiSpec 4 pots is that you have to increase the size ofthe master cylinder. The 19mm one just doesnt move enough brake fluid. The next one up ?22mm is essential. Because of the lack of fluid movement you get unequal flow to the caliper pistons and then the pads wedge and it feels like air in the system.

When bleeding tapping the caliper with a spanner can help release some air. I use a clear plastic tube off the nipple so you can see the air bubles coming out. I also do the outer pistons first then the inner ones but I dont know if that is essential.

[philg]

My experience with the HiSpec 4 pots is that you have to increase the size ofthe master cylinder. The 19mm one just doesnt move enough brake fluid. The next one up ?22mm is essential. Because of the lack of fluid movement you get unequal flow to the caliper pistons and then the pads wedge.

Sorry to hijack but since my 4 pots have been fitted if I jump on the brakes from say 70 mph, my car always dives to the left, I have been through everything, I'm going to try bleeding again, but maybe it is uneaven pressure to the front brakes.

[Ashy]

My experience with the HiSpec 4 pots is that you have to increase the size ofthe master cylinder. The 19mm one just doesnt move enough brake fluid. The next one up ?22mm is essential..

I've re-bled them and its still the same, no idea what it would be like on the road?

Anyway, i'm gona whip the MS off and replace it... Whats the 22mm one off Russ? Just thinking if i'm gona replace it I might aswell upgrade it.

[Ashy]

IWhats the 22mm one off Russ? Just thinking if i'm gona replace it I might aswell upgrade it.

Looks like a 172 cup should fit.

[old skool turbo power]

Sorry to hijack but since my 4 pots have been fitted if I jump on the brakes from say 70 mph, my car always dives to the left, I have been through everything, I'm going to try bleeding again, but maybe it is uneaven pressure to the front brakes.

id guess that its un even brake balance and one problem can be that the piston is not fully working(right one)so the left piston is doing all the braking.easy way to check it just do a quick drive.....plenty of boost of course some hard braking here and there get out of the car (say a min later)and see if the disc is still warm,if not then you know capiler isnt working fully.

[philg]

id guess that its un even brake balance and one problem can be that the piston is not fully working(right one)so the left piston is doing all the braking.easy way to check it just do a quick drive.....plenty of boost of course some hard braking here and there get out of the car (say a min later)and see if the disc is still warm,if not then you know capiler isnt working fully.

going to give them another bleed then give this a go

[Ashy]

Just taken a £100.00 punt on a clio 200 master cylinder which is bigger again...

Reno 5 - 19mm
Clio 182/172 - 22mm
Clio 200 - 24mm

So fingers crossed, if it fits it should make considerable difference, if not its non returnable so it will be an expensive paper weight.

[newbstar*]

How much pressure did you put through the easy bleed????

[markey b]

Just taken a £100.00 punt on a clio 200 master cylinder which is bigger again...

Reno 5 - 19mm
Clio 182/172 - 22mm
Clio 200 - 24mm

So fingers crossed, if it fits it should make considerable difference, if not its non returnable so it will be an expensive paper weight.

Golf rallye is 26mm IIRC.. fitted one to mine and pedal is like a new car!

[markey b]

correction, its 22.2 on the golf G60/rallye one

[Big Steve - Raider]

Clio 200 - 24mm.

look forwards to seeing how this goes...!?

You could be the first guy to do a Endo in a 5 Ash!?

[Ian S]

Isn't in one of the articles about using a bigger master cylinder? With part numbers from about 2004.

There was a 22mm used on a Peugeot if I recall correctly, not a huge price, same make as 5GTT OE.

Tom TK had one.

[RussellT]

Obviously the bigger the MC the harder you have to push to get the same effect so the pedal does feel much harder. Bear that in mind you can go too big.

I also rec standard road pads save your DS2500 for track days as I found with the bigger brakes they done get enough heat into them during ordinary road use or speed events.

[Ian S]

Russell, what pads are you using for road use?

[RussellT]

HI Spec sent me EBC Ultimax. Only £15 and very effective

[Ian S]

What advantage is there is 4 pot callipers over the 5GTT original equipment?

I don't mean in theory, but in practice

[Alastair]

Ashy, ive just seen this and you should have a read of my 'brakes' / build thread, i had the same issue with 4 pots:

Nothing (including 2 new standard 19mm M/C) could get them to work right. (I know some people have used Hi Specs with 19mm M/C fine but i couldn't - perhaps they had a 21mm one and they didn't know).

Uplifted to a peugeot 24mm M/C and wahey they are fixed after a decent bleed. M/C was expensive though.

24mm M/C is amazing for pedal feel when racing but you need a big leg - try a 22mm one first. 24mm gives you very strong rear breaks and you need a decent proportioning vv to overcome it. I popped a wilwood and a Tilton... buy AP first time and be done with it.

Also - hard pads are a pain with a 24mm M/C until they get hot, i now use Mintex 1155. Dont go harder than DS2500 untill youve tried them. Also avoid EBC pads, they are arse.

Make sure you connect each pair of ports diagonally with a bigger M/C otherwise you will lock the rears too early. Rear left and front right to the front ports and then vice versa.

I now have perfect, controllable breaks but still occasionally consider a smaller M/C when the rears cause a bit of a squirm when i haven't adjusted the proportioning vv for cold breaks before a run!!!

Any snags drop me a pm and ill give you my mobile number and we can chat through the other options i tried.

[Alastair]

What advantage is there is 4 pot callipers over the 5GTT original equipment?

I don't mean in theory, but in practice

Ive cooked a few standard set ups, but only in extremis...

99% of peeps should be fine with a quality disk and Ferrodo DS2500, DS3000 set up and decent mineral based fluid. (mineral fades gradually, not suddenly like synthetic fluid).

Alloy 4 pots are lighter (with proper disks) and offer a progressive feel. More resistant to fade etc etc. ill dig out a previos thread that details loads of really useful info, i think i had Hi Spec in the title - was some time ago!

[Alastair]

Lots of good stuff here Ashy

https://www.rtoc.org/boards/showthrea...ht=spec+brakes

[Ian S]

Should have been a brakes article. Maybe there was one. I forget. I really want back the articles in the style of the old site. Been four years nearly.

[Matt Cole]

Ashy has a larger servo to compliment the new MC. Should eliviate some of the extra pedal leverage.

[Matt Cole]

Obviously the bigger the MC the harder you have to push to get the same effect so the pedal does feel much harder. Bear that in mind you can go too big.

I also rec standard road pads save your DS2500 for track days as I found with the bigger brakes they done get enough heat into them during ordinary road use or speed events.

Russ if i remember correctly, the pads that fit the hi spec calipers are from a Volvo 740?

You would need to check, but i'm sure its a Volvo.

[Ashy]

Ashy, ive just seen this and you should have a read of my 'brakes' / build thread, i had the same issue with 4 pots:

24mm M/C is amazing for pedal feel when racing but you need a big leg - try a 22mm one first..

Cheers mate, I've found out that the 24mm clio 200 MS only has 2 ports, duff info off Cliosport

Looks like I need to speak to my guy at Reno in the morning see if I can cancel the order or I'll be messing around with tee pieces.... I might change the order to a 172 cup MS which will suit the clio cup servo that I have and its 22mm as you suggest!

[Matt@CodeRedMotorsports]

The 200 has abs, that's the reason for only two ports, 172 cup is non abs so will have 4 ports, you still using a gtt bias valve, or an in car adjustable valve?

[markey b]

Cheers mate, I've found out that the 24mm clio 200 MS only has 2 ports, duff info off Cliosport

Looks like I need to speak to my guy at Reno in the morning see if I can cancel the order or I'll be messing around with tee pieces.... I might change the order to a 172 cup MS which will suit the clio cup servo that I have and its 22mm as you suggest!

golf G60 is a direct fit and £40-50 brand new

think hispec pads are volvo 340 iirc, there was a post a while ago as the 285mm discs are lancia delta

[Big Steve - Raider]

golf G60 is a direct fit and £40-50 brand new

think hispec pads are volvo 340 iirc, there was a post a while ago as the 285mm discs are lancia delta

You fitted one of these to a GTT Servo?

What's the benefit if you do? Better brake feel, stronger brakes??

[philg]

Make sure you connect each pair of ports diagonally with a bigger M/C otherwise you will lock the rears too early. Rear left and front right to the front ports and then vice versa.

Alister is this the best way only when upping the m/c, what is the correct factory way?

Im going to check mine over tonight make sure mine are the correct way round, im a bit worried about the veering to the left when heavy braking especially with knock hill round the corner

[Sparkie]

golf G60 is a direct fit and £40-50 brand new

gsf p/n = 652vg0250 = £34.40 + vat
or 652vg0251 = £42+vat (better make)

[markey b]

You fitted one of these to a GTT Servo?

What's the benefit if you do? Better brake feel, stronger brakes??

i've got 325mm hispec's and the OE m/c wasn't shifting enough fluid. brake pedal is alot more 'normal' now

[Big Steve - Raider]

i've got 325mm hispec's and the OE m/c wasn't shifting enough fluid. brake pedal is alot more 'normal' now

What would be the effect of putting that Master Cylinder with the standard brakes???

[markey b]

What would be the effect of putting that Master Cylinder with the standard brakes???

i have no idea.... standard master cyl is fine with standard brakes

[Ian S]

What would be the effect of putting that Master Cylinder with the standard brakes???

You have a hard pedal that travels a lot less and, at first impression anyway, doesn't move far enough to have adequate pedal feel and braking control. I've tried it; 22mm, drove TK's car briefly.

[Big Steve - Raider]

Thanks for your answers guys, I was just wondering what the next steps would be to try & improve braking performance on a car with 13's.

Guess it's just a case of making sure everythings in good condition & some funky pads?

[Ian S]

Has your braking got noticeably worse?

Have you ever changed the fluid?

You already have DS2500 don't you? And on the rear? The rear makes abut 20% of the braking, if that's not working or in correct proportion with the front you'll notice it.

Still got the original rubber brake lines? The steel over braided PTFE lines can make for sharper braking. Less pedal movement to lock the fronts is what happened to mine.

Discs wearing evenly or unevenly?

One way vales working fully? Servo? Rear compensator? Master cylinder? Still on the front and rear callipers that came with the car?

Someone recommended the better Brembo discs to me, said they really gripped the (standard, IIRC) pads compared to the OE discs they'd replaced. Standard sized Brembos they were. I did some Googling, people quite liked them. They might have been called Brembo Max.

[Big Steve - Raider]

Has your braking got noticeably worse?......

Sorry Ian, I should have mentioned this is for my 11 and somthing else on the Horizon...

But every recommendation you make I'm sure would make a difference to the 11.