ChrisS
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| posted on 20/5/08 at 08:10 PM |
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Over efficient brakes?
Is it possible to have over efficient brakes. Obviously the car is very light weight, and the brakes are setup to lock the fronts before the rears,
but it seems very easy to lock the brakes .
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britishtrident
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| posted on 20/5/08 at 08:14 PM |
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Both wheels on one axle or is one locked well before the other ?
[Edited on 20/5/08 by britishtrident]
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ChrisS
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| posted on 20/5/08 at 08:21 PM |
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It seems possible to lock both the fronts then the rears without having to apply tons of pressure. I would expect to have to really stand on the
brakes to get it lock up.
Actually i was trying to see at what point they would lock up, but was suprosed at how little effort it took.
Then on another occasion today i was going a little to fast and needed to stop quicker than normal, which also give a quick squeal.
[Edited on 20/5/08 by ChrisS]
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nick205
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| posted on 20/5/08 at 08:31 PM |
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What leverage ratio do you have on the brak pedal?
moving the pivot point may make for better feel and travel of the pedal before reaching the lock up point.
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turbodisplay
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| posted on 20/5/08 at 08:33 PM |
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Do you have a brake servo?
If so you could remove it for more feel.
If not changing the master cylinder bore size could help.
Whats your setup ie, M/c ,calipers etc?
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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ChrisS
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| posted on 20/5/08 at 08:50 PM |
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Brakes are running through an OBP bottom mounted pedal box with with brake bias setup, locked to give front bias, with 0.7 rear and 0.625 front master
cylinders.
moving brake pivot point is not an option really as this is designed into the pedal box.
I guess im just far to used to driving the tintop with all its gizmos. Just need to learn how to drive the car properly i guess.
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britishtrident
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| posted on 20/5/08 at 09:04 PM |
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Putting another O.7" dia master cylinder on the front should improve things after that if you find you have too much rear brakes you
can't get a balance by adjusting the balance bar rathr than change the other mastercylinder I would just fit an Fiat Uno or Fiat Strada/Ritmo
brake regulator valve.
Should be easy to find a buyer for the 0.625" cylinder
[Edited on 20/5/08 by britishtrident]
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niceperson709
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| posted on 20/5/08 at 09:21 PM |
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What tyre pressure are you running? I found with my CEC that if i ran with the tyres too hard the wheels would lock up way too easy... but in a BEC
that has got to be even more of a factor , basicly harder tyres = smaller contact patch = quicker lock up....
Best wishes IAIN
life is not the rehearsal , it's the show so don't sit there thinking about it DO IT NOW
http://iainseven.wordpress.com/
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Coose
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| posted on 20/5/08 at 09:37 PM |
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I would ask what tyres?
Spin 'er off Well...
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RazMan
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| posted on 20/5/08 at 09:54 PM |
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Normally it is the opposite problem to yours (pedal too wooden)
As BT says, try a larger m/c bore to increase pedal pressure required.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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ChrisS
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| posted on 21/5/08 at 07:59 AM |
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Im running Toyo Proxy T1R's, which are meant to be good tyres. Ive tried 18psi, and yesterday 22psi.
I dont want to increase pedal pressure, i want to increase travel i think, so that the the brakes arent locking up so soon.
I think i might try winding the master cylinder connector rods out a bit.
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niceperson709
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| posted on 21/5/08 at 08:04 AM |
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I run 18 lbs in my CEC and that seems jsust about right so mabe in a BEC 18 is still a bit high.
Best wishes IAIN
life is not the rehearsal , it's the show so don't sit there thinking about it DO IT NOW
http://iainseven.wordpress.com/
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gingerprince
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| posted on 21/5/08 at 08:18 AM |
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22psi is way too high for a bec generally. 16-18psi is more like where you want to be.
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ChrisS
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| posted on 21/5/08 at 08:24 AM |
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quote:
Originally posted by gingerprince
22psi is way too high for a bec generally. 16-18psi is more like where you want to be.
Cos the car is so new, i was just trying out different psi to see what gives the best performance. But ive realised now after a few miles round the
block that the lower psi is actually better.
Iguess its all about experimenting at this stage.
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niceperson709
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| posted on 21/5/08 at 08:33 AM |
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drop them down to say 16 lbs and try it out again
with mine I started out with 28 lbs and found it was like driving on ice no grip at all , I droped it progresively down until I settled on 18, whic is
as Goldylocks says "just right"
Best wishes IAIN
life is not the rehearsal , it's the show so don't sit there thinking about it DO IT NOW
http://iainseven.wordpress.com/
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RazMan
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| posted on 21/5/08 at 08:57 AM |
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quote:
Originally posted by ChrisS
I dont want to increase pedal pressure, i want to increase travel i think, so that the the brakes arent locking up so soon.
I think i might try winding the master cylinder connector rods out a bit.
Pedal pressure and travel are pretty much the same thing in your case I think - moving the m/c rods will just move the pedal position and won't
affect braking performance unless the pedal to m/c angle is drastically off 90 degrees.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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iank
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| posted on 21/5/08 at 10:01 AM |
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As a matter of interest what brakes (calipers/discs/rears/pad material) are you using?
I couldn't see from your photo archive unfortunately).
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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ChrisS
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| posted on 21/5/08 at 10:22 AM |
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quote:
Originally posted by iank
As a matter of interest what brakes (calipers/discs/rears/pad material) are you using?
I couldn't see from your photo archive unfortunately).
Im using the sierra standard setup, drum rears and vented disc fronts. all new setup though, which i guess is why its working so well.
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britishtrident
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| posted on 21/5/08 at 06:32 PM |
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quote:
Originally posted by ChrisS
Im running Toyo Proxy T1R's, which are meant to be good tyres. Ive tried 18psi, and yesterday 22psi.
I dont want to increase pedal pressure, i want to increase travel i think, so that the the brakes arent locking up so soon.
I think i might try winding the master cylinder connector rods out a bit.
Don't touch the push rods !!!!!!
If you wind them out you will just end up with hydraulic lock up when the brakes warm up.
Only things that determine pedal travel are the mechanical advantage of the pedal and hydraulic ratio of the sytems + losses due to lost motion and
flexing of the pedal box mounting and other mechanical parts.
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