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Location:
sydney
Registered:
May 2002
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brake problem... i think i've tried everything...
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Tue, 02 July 2002 08:37
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ok,
so far to resolve the problem i have rebuilt master cylinder, pulled down calipers and reco'd them. bled whole system, adjusted handbrake, checked that im gettin vacuum from brake booster. but yet as soon as i turn on the car after bleeding the pedal goes softish... not hard enuf i think!
but if i drive it and press it down far enough it stops well.
it's in my 86 and i have vented fronts and drum rears.
any ideas?
thanks
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I supported Toymods
Location:
NE Melbourne
Registered:
May 2002
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Re: brake problem... i think i've tried everything...
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Tue, 02 July 2002 11:36
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did you do any brake modifications? i mean is the the braking system totally stock, or have you upgraded you brakes in any way.
if so larger calipers and no bigger master cylinder will mean that your brake pedal will feel spongy. tell me more and i'll try to help you out if i can...
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Location:
sydney
Registered:
May 2002
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Re: brake problem... i think i've tried everything...
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Tue, 02 July 2002 11:50
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the only thing that i changed was put some vented calipers and discs from a jap spec sprinter, but i stil feel that they are a bit too soft... all rest is standard.
might have to take it somewhere to look at it,
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I supported Toymods
Location:
NE Melbourne
Registered:
May 2002
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Re: brake problem... i think i've tried everything...
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Tue, 02 July 2002 12:17
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well, if the vented calipers have a bigger bore size then the master cylinder will be a miss match and can cause you to lose pedal feel. next i have to ask, did this occur as soon as you did the conversion, or did it occur later?
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Location:
sydney
Registered:
May 2002
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Re: brake problem... i think i've tried everything...
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Tue, 02 July 2002 12:48
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well, i put it all together b4 i rebuilt the calipers and master cylinder and was ok for a while but then the cylinder started to leak, so i rebuilt it and while i did it i pulled the calipers down, and they were filthy. so thats the only thing i can think of, they weren't returning fully
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I supported Toymods
Location:
NE Melbourne
Registered:
May 2002
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Re: brake problem... i think i've tried everything...
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Tue, 02 July 2002 12:52
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i assume you know what you were doing during the rebuilds so i'm going to count that out for now... however, if there was something that you did wrong, i cannot pin point it from here. sorry i cannot help anymore. all i suggest is wait on the forums before you go anywhere and spend more money and see if soemone else can come up with something.
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Location:
Sydney
Registered:
May 2002
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Re: brake problem... i think i've tried everything...
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Tue, 02 July 2002 13:15
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Barbel
Just a shot in the dark.
Did you put bigger cams in at any point or change cam timing?
I had a similar problem when i put Group A cams on a previous car - the pedal went soft and only really felt comfortable at high sppeds. Something to do with loss of pressure in the head/under the cam cover or something as a result of the high lift/duration of the lumpy cams.
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Location:
newcastle
Registered:
May 2002
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Re: brake problem... i think i've tried everything...
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Tue, 02 July 2002 15:05
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another shot in the dark is it leakin in the rear drums as new front seals could increase pressure in the rear causing the rear to leak therefor a spongy pedal until theres no fliud left ops no brakes?
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Location:
sydney
Registered:
May 2002
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Re: brake problem... i think i've tried everything...
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Tue, 02 July 2002 22:16
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no cams yet, and there is vacuum from the inlet manifold as when i took the hose off i heard the pressure release.
not loosing fluid anywhere yet either. and i dont think that the caliper bore is that much bigger, maybe someone with vented fronts on a sprinter could verify how there's feels...
thanks
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Location:
sydney
Registered:
May 2002
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Re: brake problem... i think i've tried everything...
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Thu, 04 July 2002 22:26
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Something i noticed last nite...
i spoke to a friend and he said sme thing, when he put vented on the front it felt a bit spongy.
but last nite i took it for a drive and the longer i had the car on and drove it the harder the pedal got, and i wasnt necessarily braking much, alot was just cruising along. and it got very hard, slightest touch would cause braking...
any ideas on this one?
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Location:
Perth WA
Registered:
May 2002
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Re: brake problem... i think i've tried everything...
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Sat, 06 July 2002 12:06
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Barbel,
2 things that MIGHT have gone wrong. I had this similar problem when I had my master cylinder o/hauled.
1. The actuator rod behind the master cylinder, the one that actually pushes on the mater cylinder, might not have enough clearance. I had to linish/grind mine down about 2-3mm for adequate clearance. Make sure that the rod doesn't 'push' into the master cylinder when you bolt it back in. Before this modification, my brakes would start to 'grab', with an extremely hard pedal. And the only way of 'relieving' this brake'grab' was to release the pressure in the master. Please read point 2 before checking...
2. The removal of the actuator rod in the vacuum booster can cause a few problems. If the rod was removed without securing the reaction disc, then this 'disc' could fall out of place, causing a similar 'grabbing' problem, but the brakes would not lock on. Pedal would sometimes feel spongy. Unfortunately, the only fix for this would be to send it out to a very good brake specialist, and have him fish around the inside for the disc, and to put it back in its proper spot. Keep in mind that most brake ppl will tell you that a new booster will be needed, and this is not needed if the booster is not leaking. If the actuator rod was removed or disturbed when the master cylinder was out, then this might also cause part of the problem.
I had this happen to me about 6 months ago, and I was pulling my hair out over the whole thing..!! The reason that I can think of for the pedal getting harder as you drive along is that the booster might be activating the brakes. If the actuator rod is too long (without adequate clearance), the vacuum in the booster will be pushing the rod into the master, and that will cause a harder pedal.
Take a look at your master cylinder, and it should tell you the size of the internal bore. I know that the local AE86s and the import AE86s have a slightly different bore diameter. As Dorikiin would have said, the spongy pedal is because of a mismatch of calipers and master cylinder bore size...
Email me if you have any questions....
Hope this helps!
And sorry about the longish post!!
Cheers!
Zack.
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