[moved] rear brake bias valve

[JusVR6 0]

I'm getting too much rear braking on my VR6. Its has been lowered by the previous owner and I dont know if the rear brake bias vlave has been adjusted to compensate. Can anyone tell me if it needs to be and how?

[ Edited ]

[acf8181 0]

it would theoretically need altering, but i think its a dealer only job.

doesn't the abs catch it?

[acf8181 0]

just to add to my above comments...if its locking up cause you've disconnected the abs, it could mean theres nothing worng with it, some cars that have abs are dsigned to have a lot of rear bias (as it'll enable the car to stop quicker, but you won't have probs with loosing it under braking cause the abs scoops it up)

[vwcaddy.com 0]

I recently gutted 2 VR's and niether had a proportioning valve :? ABS sorts it out as acf8181 saiz.

What make you think you are get to mch rear braking ?!

[JusVR6 0]

On two occasions I have had interesting!!!! moments while under braking.

Once downhill round a corner under slight braking at low speed (in wet) 20 - 30 mph the rear end just came loose requiring quick correction.

Second time at speed into faster corner I applied moderate brakes and the car's rear end seemed to twist dramatically putting it out of balance.

Maybe I'm asking too much of run of the mill road car?

I cant say I have total confidence in it at the moment.

[jte 0]

could this be the rear axle bushes wearing out? i hear if they get too bad they allow the rear wheels to steer a bit.

[acf8181 0]

er...you're not supposed to brake hard and turn at the same time really.

its physics...when you brake the centre of gravity goes to the front of the car, thus making the rear end 'light' if you then turn the rear will of course then step out as theres proportionally loads more front end grip than rear.

every car will do it. your abs will catch it before you spin, but you will get a certain amount sideways before it does...just as if you lock the fronts and turn it would understeer a bit before the abs kicks in. if they set up the abs so it doesn't allow any lock up the car would be impossible to stop in snow (the fiat punto is like this - and its sooo scary i can tell you). the optimum braking is to have the wheels slightly locking, just as the optimum accealaration is to have a fraction of wheelspin.

there's nothing wrong with your car, you just need to adjust your driving. you're braking too hard whilst cornering, and the tyres can't keep grip. brake as hard as you want in a straight line, ut progressively release the pedal as you enter a corner if you need to turn...its a racing technique called trail braking.

[ Edited Fri May 21 2004, 04:45PM ]

[VRmonster 1]

good explination.. heres another one thrown in the mix. when braking severely hard, and abs kicks in ie. about to hit someone who jus pulled out in front of you, why would the front end seem to move slightly from side to side. its as tho my cars made of jelly. lol. i know the fishtailing will probs be because the weight is at the front of the car so the rear is light. as acf explained. the brakes are already definately warped btw, as i can feel the judder under light braking.

[acf8181 0]

it'll moves from side to side at the front because the roads aren't perfect and one tyre picks up grip (or looses some grip) at one point, where as the other doesn't and vice versa.

so the abs is constantly adjusting and compensating for it.

[VRmonster 1]

cheers acf, i was thinking roads, but it does feel very much more like a suspension problem, i was thinking about arb or a strut brace. but probs wouldnt change anything with me having coilovers, anyway, i blab on. lol

[JusVR6 0]

Thanks for the driving lesson - I realise its not ideal to brake whilst cornering but its a reality that happens to everyone - I'm not talking hard braking anyway. I've driven many different cars over the past 20 years and I know when something aint right.

[ Edited Sat May 22 2004, 07:21AM ]

[Eat this 2]

r u sure the front pads/disks r ok i sometimes brake hard in corners (just 4 a laugh) and its suprisingly stable u hav to really giv it som to get the back end to come round exact opposite of a punto theyr dangerous lol

[JusVR6 0]

Yeah new pads front and back - discs ok too.

[kilokilla 0]

Im having same prob at mo have got all new suspension and brakes but i havent replaced brake fluid yet and mine is pretty grotty black colour so im gonna try bleeding em up next and see if this makes any difference was just wondering jusvr6 wot is your fluid like (brake fluid that is)he he

[JusVR6 0]

really interesting you mentioned that - I changed the brake fluid 2 days ago, its was like watery gravy do you think it could have been that? Havent tried it out yet tho.

[kilokilla 0]

let us know how it goes cos i know bad fluid can cause brake fade and its possible its fading 1 brake more than another and making the car pull to side under braking.

[JusVR6 0]

Brake blead has worked but have got wishbone bush probs that can't have been helping.