braking/handling problem?

[gtirjoey]

right jus had a scary moment in the r!
giving it some down country roads and had to brake hard from about 120mph(no slower)
the back end of the car almost felt as if it were trying to leave the floor and the car was trying to pull sideways(no brake lock) bit hard to explain hopefully you will get what i mean! has any one else had this problem and what did you do to overcome it?
i am running wilwood front and standard rear brakes. with standard shocks and lowering springs any ideas please help much appreciated

 

[davey red.r]

your discs may be out of true,
joey you had it set up lately ie tracking laser allighment?

davey

 

[johnsy]

all your braking power is up front , have you got the same pads on the back as the front? maybe look into a rear upgrade to try balance the front rear bias

 

[gtirjoey]

had the front wheels tracked but thats all it seems to handle fine cornering or on power etc.. jus the heavy braking at high speeds. like to get it sorted as im going cadwell next week

 

[gtirjoey]

all your braking power is up front , have you got the same pads on the back as the front? maybe look into a rear upgrade to try balance the front rear bias

yellow stuff pads front on 4 pots. standard rear pads.

 

[Shaun]

I had this with my Wilwoods,every time i braked from high speeds the rear of the car always felt twitchy so i've upgraded the rear disc for a GodSpeed 300mm big disc kit which evened up the braking perfectly

 

[johnsy]

problem solved

 

[pulsarboby]

not all to do with the brakes joe.
its weight transfer;-) basically under hard braking at speed your transfering all the weight from rear to front of car which in turn causes the rear end to get skittish and lighten right up! now this is mainly because you have standard struts and they are weak.
what you need is uprated struts and springs such as coliovers or adjustable gabs and set them so they are hard on damping to absorb the weight transfer under harsh braking.

the fronts on my car are at max and the rears are around midrange setting, and you know what thats like under harsh braking lol

 

[GTIR-LOZ]

how are you finding the brakes did you get the discs sorted?

 

[gtirjoey]

gtir-loz..yeah got them sorted spot on cheers mate glad a grabbed a bargin!
bobby..you got anything to help my cause??

 

[fubar andy]

its weight transfer ;-)

basically under hard braking at speed your transfering all the weight from rear to front of car

mainly because you have standard struts and they are weak.
what you need is uprated struts and springs such as coliovers or adjustable gabs and set them so they are hard on damping to absorb the weight transfer under harsh braking.

This man has made a good point.

Another way to avoid this shifting of weight (before going to Cadwell) is to remove as much interior as possible. That way when you’re braking the mass of the car has been reduced and therefore the shifting of weight is reduced.

What Wilwood kit are you using?

I’d also service your Wilwoods and make sure that not of the pistons are not sticking.

Junk your yellowstuff pads :roll: and buy something better, whether it’s CarboTech XP8’s DS2500’s (3000’s if needed for track – not for road use) or some Mintex 1144 or 55’s.
Install braded brake lines (if not already) to your rear (and front – if not done) brakes and opt for some decent brake fluid.

When I used to have my Wilwoods (280mm kit) under hard braking the car would nosedive to the right and feel quite unstable at high speeds

Not only that since your doing 100+ on back roads :roll: I’d also pay attention to the road surface, this can also have a detrimental effect on braking. On track the surface if smooth and flat, normal roads can be quite different and you might find that at Cadwell your braking issues might not appear.

 

[gtirjoey]

i am using 310mm discs and wilwood four pots i dont believe they are very old so dont think the pistons are sticking.
i also thought it would be an issue with front shocks being to weak. i will remove the back seats parcel shelf etc for cadwell if its gonna help matters
know what you mean about country roads there not the best for fast driving(and to be honest was going a bit over the top)

 

[azboy]

all your braking power is up front , have you got the same pads on the back as the front? maybe look into a rear upgrade to try balance the front rear bias

couldent say it better my self, pull ur hadbrake when driving the back end sinks iff all ur braking power is on the front the front will nose dive cousing the back to go light REAR BRAKES ARE VERY IMPORTANT if u have good front brakes u must sort out the back this is just common sense forget the shocks ect sort ur rear brakes out this way the front wont nosedice as the back will also sink keeping a even balance.

 

[pulsarboby]

bobby..you got anything to help my cause??

sorry joe ive got nothing in at the moment, the ledas off the other car i broke are being picked up tomorrow and they were the last set i had of uprated struts.

tbh andy im not sure that removing the weight from rear would help at all as these cars are already nose heavy. actually by stripping more weight from the rear you could well magnify the problem when you think about it, unfortunately its the front that carries most of the weight and its that which causes the dive on the front and the rear to go light.
perhaps strapping a big bloke in the rear may helpreggers::lol: :lol:

i can however think of a temporary bodge though which il tell you about tomorrow and it will only cost you a few quid;-) thats assuming you cant get hold of any uprated struts at least for the front

 

[gtirjoey]

okay i will give you a bell in morning mate

 

[fubar andy]

tbh andy im not sure that removing the weight from rear would help at all as these cars are already nose heavy. actually by stripping more weight from the rear you could well magnify the problem when you think about it, unfortunately its the front that carries most of the weight and its that which causes the dive on the front and the rear to go light.

Do you know what? I was thinking that after I posted it... :doh:

 

[pulsarboby]

couldent say it better my self, pull ur hadbrake when driving the back end sinks iff all ur braking power is on the front the front will nose dive cousing the back to go light REAR BRAKES ARE VERY IMPORTANT if u have good front brakes u must sort out the back this is just common sense forget the shocks ect sort ur rear brakes out this way the front wont nosedice as the back will also sink keeping a even balance.

how can you say forget the shocks:shock: :shock: im shoxed lol.
you surely know how important these are to the handling and braking of a car!
they will cause all sorts of problems on the track if they are weak (which joe knows his are)
im still running standard rear stoppers and although uprated would be better my car has minimal dive and thats with 8 pots on the front, big rear brakes will not compensate for dodgy springs and struts! its a sure fire way to end up embedded in the armco barrier if they are not sorted out.

also the proportioning valve is diagonally split from front to rear and unless you have some sort of bias valve to alter the bias i dont think you will gain a great deal there.

you said it yourself 'that by pulling the handbrake, watch the rear dip' well if it does that on handbrake then the rears are working ok anyway! go too much and the rear end will be swapping places with the front on a track.

 

[fubar andy]

I've got no experience with actual brake biases but in simple terms if you uprate your brakes whether is the pad coefficient, bigger disc's, bigger pistons you have increased the front bias so it could be more like 90% 10%

However if you also change the rears for better pad coefficient, bigger disc's or bigger pistons this will help counteract the front bias restoring it to similar settings and also giving you better braking for the track/road.

"Perfect brake bias is obtained when the front-to-rear balance of the brake system exactly matches the front-to-rear weight balance of the vehicle"

 

[pulsarboby]

not disputing that andy, and it does make sense, although ive not bothered with it, i just have uprated pads!
but its absolutely ludicrous to say 'dont worry about the shocks' when they are one of the most important factors to do with handling and braking, if they are weak and your steaming into a bend and need to be hard on the brakes then no amount of rear braking is gonna help the balance and control of the vehicle, the car will be wallowing all over the place.

 

[Major_Sarcasm]

perhaps strapping a big bloke in the rear may helpreggers::lol: :lol:

Rob?