Rear Brakes Locking After Fitting 288mm to front. HELP!

[Philuk 0]

Right here comes the story. Changed the front calipers to 288's from a sharan and they are a fair size to be fair! got everything fitted, left rears as standard caliper as there fine.

Black diamond front and rear discs and fast road pads.

 

Got the car back from my mate who fixed my bleeding issues and it was properly arse happy!. like seriously scary arse happy.

 

Took it back and we knocked the compensator valve right off to stop as much power going to the back as possible. but it still locks the back up before the front.

The rear tyres arent awesome and the weather isnt exactly brilliant either but it never did it before with the standard front calipers and knackered discs and pads. The abs doesnt work but hasnt for a while but i was wondering if it was anything to do with this. The only other thing my mechanic friend can think is changing the master cylinder to make the front brakes work harder as such but im not sure this will work?

 

Any Ideas?

Edited February 5, 2012 by Philuk

[Philuk 0]

anyone. any ideas at all?

 

someone must have had this issue before?

[boost monkey 0]

if it was me, I would have fixed the ABS before shelling out on upgrades.

 

If you've adjusted the bias valve and the rears still lock up first then I doubt a new MC will fix it. What pads are on the back?

[16VG60 0]

ABS fault needs to rectified, as this is an integral part of your cars braking system, and to mention the legality / insurance issues. Secondly are you sure your compensator valve is working. These valves regularly are found to have seized, as they rarely become get moved (Corrado being predominantly not loaded sufficiently to bring it into play) you may well have backed off the compensator arm, but is this influencing the internal valve? Your problem very much sounds like brake pressure proportioning fault.

 

 

Sent from my iPhone using Tapatalk

[Philuk 0]

The abs has NEVER worked properly on this car. Everytime i came for MOT the light was on and they would get the light off and then maybe a month back into driving it would come back on and not go off again till the following year. trying to find out what was wrong was getting tedious to be fair! Its now throwing up. all 4 Abs sensors and engine speed sensor.

 

its got standard size discs and pads on the rear just black diamond upgrades. it didnt do it before with the standard size on the front so all i can think is that the load compensator is jamf inside. o well thatll be another new one of them then. second in 2 years. Im at a loss of what to do with the abs. i dont wanna shell out for 4 sensors but i just dunno where to look. Lad who did it is gonna plug it in when i go back to see him and see if anything different is thrown up. If i can pinpoint one thing being wrong then ill change it. Im not arguing that it needs fixing but its an expensive game to be chasing a lost lead....

[8vMatt 1]

I had to fit a new brake regulator as the old one seized. Fitted it and drove the car, oof scary rear locking. I had help on here about adjusting the position to just over half way sorted it completely. You might need a new one.

[Philuk 0]

Ive knocked it right off to see if it did anything but it still locks? did yours do the same until fitting a new one?

 

Someone has mentioned maybe needing a new master cylinder but I cant see why it would need it? People running 312mm on standard one so why wont this work. its getting well frustrating! lol!

[8vMatt 1]

No, mine only locked up after I fitted the new regulator. It must of been set up wrong from the garage. There's a sliding scale of where the bolt is tightened up. Mine was about a quarter way up from the bottom. Moved the bolt up to just over half way. I couldn't get the rear to lock however I tried to make it happen. Nice again now.

[VWVW 1]

If you are looking for a new brake compensator for your VR6. Eurocar parts is selling an OEM ATE branded one for 69.30 delivered using discount code brake25. They normally retail for 92.40. So its a bargain if you need this part.

Edited February 5, 2012 by VWVW

[8vMatt 1]

If you are looking for a new brake compensator for your VR6. Eurocar parts is selling an OEM ATE branded one for 69.30 delivered using discount code brake25. They normally retail for 92.40. So its a bargain if you need this part.

 

Thats where I got mine from. TPS wanted in the region of £180 :bonk:

[VWVW 1]

Thats where I got mine from. TPS wanted in the region of £180 :bonk:

 

That is a crazy price from TPS!!!

[swiftkid 1]

have to ask guys, why would the bias valve break as a result of fitting new front brakes? I know my rear brakes started locking up after I lowered it but backing it off solved that issue.

 

Just been chatting with Phil and I reckon putting the old 280's back on and seeing if it makes a difference is the first step and then we can eliminate the front brakes as a cause of the problem. After doing a little research, the standard sharan master cylinder is larger which would make sense seeing as the actual caliper/pad is bigger but still 288mm. What I think COULD be wrong is that the front brakes are not functioning properly (they require a bigger m/c) so having to press the pedal harder which in turn causes the back brakes to lock up. But we shall be testing that anyway!

 

I can't see how ABS would affect just rear braking, I'm under the impression that the ABS system in the corrado isn't clever enough to unlock individual wheels? Its either all wheels getting the ABS treatment or none. Or am I mistaken?

[Philuk 0]

I work in parts so its not getting the bits but just the spending to find out what if! - Ive knocked it right off all the way to the top so it shouldnt do any braking at the rear unless is paggered inside...

[8vMatt 1]

That is a crazy price from TPS!!!

 

I know, I was gutted when I heard it as I didn't think there would be a chance to save anywhere else.

[Philuk 0]

I think i have sussed the problem.... The standard vr calipers have a 53.9mm piston. The mk3 golf ones have a 53.9mm piston. 312 have 53.9mm piston. Do we see something happening here? The sharan ones have a 56.9mm piston. So thats 3mm per side so 6mm in total more piston to push. The corrado master cylinder is 22.2mm and the sharan one is 23.8mm. So the long and short. i fluffed it up!

 

ARSE

 

need to get some golf calipers now!

[Abdul 0]

Woah you just saved me a load of hassle.. Was just chatting to Kev about fitting passat calipers with 57mm pistons!

 

Bad idea then!

 

Hope you get it sorted mate...

[Philuk 0]

Gonna get some golf 3 calipers. The sharan calipers needed a 1.5mm washer behind each bolt of the carrier to space it enough, The ONLY advantage to em is that you can use standard corrado hoses but they just dont work. I rekon if you fitted the sharan master cylinder and a manual bias control valve it would work... or just buy golf calipers :) lol

[Abdul 0]

Which hoses will you be using for the mk3 288's?

[Philuk 0]

i got black diamond to make me some up and they did it for me :) just ask them for a corrado hose kit with banjo fitting! :)

[Abdul 0]

i got black diamond to make me some up and they did it for me :) just ask them for a corrado hose kit with banjo fitting! :)

 

Cool, do you know if any of the oem hoses will fit? Ie factory mk3 hoses or something?

[Philuk 0]

I have no idea mate, i would presume that mk3 golf ones would fit. but its just length?, the hose is still gonna be a m10x1 fitting should think they would fit. i needed new copper front hoses as mine were goosed! so be prepared to change them aswell :)

 

are you going for standard hoses or aftermarket hoses?

[Abdul 0]

I have no idea mate, i would presume that mk3 golf ones would fit. but its just length?, the hose is still gonna be a m10x1 fitting should think they would fit. i needed new copper front hoses as mine were goosed! so be prepared to change them aswell :)

 

are you going for standard hoses or aftermarket hoses?

 

I want standard mate as I had a set of braided hoses give up on me in the past without warning, which wasnt much fun...

 

I'll probably mock up some OEM mk3 hoses and see how it goes, if all fails then braided it is.

[Stonejag 10]

Doublecheck your banjo sizes before you buy any hoses, some of the 288/312 calipers are M10x1 and some are M10x1.5. Ask me how I found out! :bonk:

 

Stone

[Abdul 0]

Doublecheck your banjo sizes before you buy any hoses, some of the 288/312 calipers are M10x1 and some are M10x1.5. Ask me how I found out! :bonk:

 

Stone

 

Doh! I thought all mk3 calipers were m10x1.5?

Edited February 11, 2012 by Abdul

[Stonejag 10]

Thread a normal bolt with each thread pitch in? Off the top of my head I think normal M10s are 10x1, you can measure with digital/Vernier calipers (well worth investing in, they aren't dear and come in really useful!).

 

If you buy from C&R they'll send you new ones if you get the wrong kind by mistake. Or I can post you some if you like ;)