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Model specific boards => Golf mk2 => Topic started by: leeroy20vt on 23 August 2010, 21:25
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as some of u may know im in the middle of building a mk2 track car with mk3 running gear (widetrack)
we have put mk3 disks on back and a willwood bias valve but took it for a quick drive up road today to test brakes after they were bled and the rear is locking even with the bias valve wound right off
what can i do to further reduce fluid to rears i have some reducers out of a mk1 cab is this a possabillity if so where in the system should i put them ?
posted this in trackdays as well but then thought might not quite be the rite place
cheers lee
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If you've closed the rear bias - then they shouldn't operate at all. Methinks you haven't plumbed it properly.
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apperently they only do 57 % from what ive read there was only a few old wilwoods that shut off completly
lol not being funny but its one line in one line out how could u not plumb in properly ?
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apperently they only do 57 % from what ive read there was only a few old wilwoods that shut off completly
lol not being funny but its one line in one line out how could u not plumb in properly ?
Well it should be 2 lines (front corner -> rear corner), and if you've put the valve in backwards (depending on design) it might cause unpredictable behaviour.
The rears should only account for about 30% of braking (with no additional weight on the rear axle).
All I can go off is what you have described, you're saying if you shut the valve totally - they still lock up - that screams something is fatally wrong.
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this is the valve i got 2nd one down as u can see it only does upto 57% which i thought would be enough
http://www.wilwood.com/MasterCylinders/MasterCylinderValves.aspx
i have spoke to loads of people and have run one line for rear and one for front so its diagonal as it was every one said this would be ok only reason it run diagonal is for brake failure reason ?
when i had on brake roller fronts were 250 ft/lb and rear were 100 ft/lb at there lowest settings there were all very balanced to
i have just put the reducers in so shall see in abit what that does
im sure i put in the rite way as it has in and out on it goin to doulbe check tho lol
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I'm confused.
You said you've run 1 line for front and 1 for rears - then said you've used a diagonal split system, you are contradicting yourself :(
It should be 1 line for front left and rear right, and another line for front right and rear left, so 2 lines going to the rear in total - meaning 4 pipes in the bias valve (2 in, 2 out).
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opps soz that did come out wrong i have a 2 pipe mc one does front one does rear
rear tees off at the back in the centre off car
like i said spoke to loads of people and they all said this would be fine as its not a road goin car hmmm
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I've never put a track toy together, so maybe the consensus is as you say, but if it were me, I'd have a diagonal split system - track cars should be even safer than road cars :rolleyes: Best waiting for someone more experienced to interject though :)
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I've never put a track toy together, so maybe the consensus is as you say, but if it were me, I'd have a diagonal split system - track cars should be even safer than road cars :rolleyes: Best waiting for someone more experienced to interject though :)
Depends on how you look at it though. Excellent maintenance together with new parts is generally safer imo
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i assume what he means is the 2 front brakes are still on a diagonal split, its just the 2 rear lines that are joined together to run thru the bias valve yes? if so id say that should be safe enough as since rears dont do much anyway loosing them both wouldnt be such a big deal.
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no m8 master cylinder off a mk3 16v only has 2 outputs so 1 is front and one is rear hope that makes sense im crap at explaining things soz
just taking it up road again and with reducers fitted the rear did not lock up and its peeing hard here so seems ok
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mk2s only use 2 outlets on the mc as well, what they have are 2 T pieces to split into 4 lines for each corner. i agree with ben, at least split the front brake circuit across the 2 mc holes for safty sake, i.e. run pipe from frotn outlet to 1 sidfe, and pipe from rear outlet t'other
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would that know the balance off fronts out tho ?
as u would have 2 rears 1 front on one and 1 front on other or am i not getting it :embarassed:
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No, your rear bias should have 2 in and 2 out, it keeps the 2 circuits separate and regulates flow through each independently. So whatever you adjust it to, will apply to both left and right circuits.
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that would mean buying another bias valve :sad: hmmmmmmm
even rally design said it would be ok the way it is :angry:
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that would mean buying another bias valve :sad: hmmmmmmm
even rally design said it would be ok the way it is :angry:
There is nothing functionally wrong with your set up (ie. it shouldn't cause the imbalance you are seeing), assuming its not in back to front.
Diagonal split systems are pretty much a standard with any braking system, it is the recommended set up for safety, and if I were throwing myself round a circuit - the last thing I want is the car to pop a nipple and loose both front callipers and cause the car to endo!
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cheers ben i understand were ur coming from i do and yer safety is number 1 not just for me but others
the complete set up is all new so fingers crossed will be ok for saturday will not be pushing the car as only just put it together
i put those reducers in and rears are not looking up now till u wind the bias valve to more brake and even then there only just trying to
i will have to try and get another valve and replumb
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To fit a brake bias valve you need to have your brake system split front to rear as you have done. You cannot split it diagonally and fit two bias valves - you will never get the two sides set up the same.
As far as safety is concerned you have two circuits so if one fails you have the other to fall back on. It isn't an ideal situation with having one circuit fail and whether the circuit remaining is diagonally front and rear or just the front or rear it is going to give you a worrying time. Having one diagonally opposite circuit working is truelly awful with one strong front brake and one weak rear brake working you will be lucky to keep the car in a straight line, at least with a front rear split you will have equally performing brakes working at one end of the car.
Stick with what you have.
If you had a three port master cylinder you could run the rear brakes off of one port and each front brake off of its own port.
Going back to your problem I know some master cylinders have a higher proportion going to the rear port (closest to the operating rod) but I think this is for cars with a front rear split so I doubt VW ones would be set up this way.
Paul
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paul ur a diamond dude just what i wanted hear thanks bud
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Your set up is fine, the issue is that you're struggling to get the pressure to the rears down enough. The measures suggested in the track section are fine.
The problem in here is a lack of understanding (Paul excepted) regarding what you've done and why.
The ports on the MC are all the same volume displacement. Talk to a specialist supplier to see which bias valve reduces the pressure the most.
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cheers dh i was reading some where that all modern bias valves only do a certain % now so u need to get the rear system down to roughly the correct pressure then the bias is just fine adjustment
i set it up thsi way for the fact that i only wanted one bias valve and was the only way i could see on getting round that i did speak to a lot of people to ask advice on that set up and said would be fine so went ahead and done it
just a few people on here that been out on track and done various conversions have comfirmed it ok to run like that :smiley:
i have put the mk1 cab reducers in and even in the wet it doesnt lock up with it wound rite off and u can feel it just starting to with it wound on so i think im there thank god
so looking forward to saturday now first track day in the beast well first time i have really driven it other than up the road and back lol
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Good skilz :cool:
Have fun!