dangerousbrian
|
| posted on 25/3/15 at 03:57 PM |
|
|
Rear brake force
Hello
My current brake setup is basically sierra all round, so sierra front calipers, rear drums and I presume master cylinder.....
I don't think their is a great deal of effort going to the rear brakes, for example, when driving on the road I never feel confident with the
brakes. I can lock the fronts with medium/firm pedal pressure but at that point it doesn't feel like their is any braking coming from the
rear.
I've had the rear of the car jacked up and can lock the rears if I literally have my whole weight on the pedal but at lighter/medium pressure
their is virtually no braking effort.
is it an easy job to convert away from the tandem? master cylinder I currently have to a single cylinder with adjuster lever for the rear circuit?
On track once tyres are warmed up etc I don't seem to lock the fronts half as much as I would on the road and the car does seem to stop better,
but it still never feels like it has great brakes.
Cheers,
Bri
|
|
|
|
|
ianm67
|
| posted on 25/3/15 at 04:12 PM |
|
|
Are you using the Sierra brake compensator jobbie? I remember that my Tiger CatE1 used one with the standard Sierra disc / drum set up. The brakes on
that car were epic.......
Always biting off more than I can chew.....
|
|
|
adithorp
|
| posted on 25/3/15 at 04:21 PM |
|
|
quote:
Originally posted by dangerousbrian
is it an easy job to convert away from the tandem? master cylinder I currently have to a single cylinder with adjuster lever for the rear circuit?
A tandem master (from Sierra) IS a single cylinder... it's just double acting. You can't legally or safely use a single, single-acting
cylinder to feed both front and rear brakes. Any fluid loss would leave you with no brakes. Both a tandem and twin system ensure you have some brake
left (either front or rear the way kits are piped up).
You can either, alter your current system, by changing the rear slave cylinder to a larger size for instance. Changing the master for a smaller size
(from a non-servo donor) would give you more brake effort (but not effect the F/R balance).
Or, convert to a twin master cylinder and balance bar set-up.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
|
|
|
dangerousbrian
|
| posted on 25/3/15 at 04:35 PM |
|
|
Cheers adithorp,
I don't like the sound of almost all of those suggestions!  I'd like a twin cylinder setup but i was working away A LOT last year and
all the car did was 2 silverstone trackdays, so this year i'm wanting to put it to some use on track more so i don't really want to have
it in pieces in the garage.
I wouldn't say at the moment i need to reduce the braking effort so to speak, it's been that way for 3 or 4 years i've had the car
and effort wise seems ok, i'd just like a an increased rear braking effort so may try the change in rear slave cylinders since it's not a
massive job to do.
|
|
|
Barksavon
|
| posted on 25/3/15 at 05:05 PM |
|
|
I've just fitted a floor mounted pedal box with seperate brake cylinders for front and rear brakes to my car you - would do it in a week. First
test of the brakes this weekend but pedal feels fine. The amount of extra leg room the floor mounted pedals give you is worth the effort alone!
|
|
|
Dingz
|
| posted on 25/3/15 at 07:22 PM |
|
|
Odd because the usual problem with Sierra brakes is the rears locking first hence the compensator thingie. not that it is much use on a 7 style as it
relies on inertia and body pitch change. Are you sure there is not just a problem with the rears? What size drums are they 9 or 8 inch?
Phoned the local ramblers club today, but the bloke who answered just
went on and on.
|
|
|
gremlin1234
|
| posted on 25/3/15 at 07:26 PM |
|
|
I suspect the rear brakes may need adjustment, in that the front are acting immediately, and stopping the pedal going down any further, before the
rears have started working.
so check adjustment, and re-bleed fluid, and see what happens.
|
|
|
britishtrident
|
| posted on 25/3/15 at 07:28 PM |
|
|
Changing the rear wheel cylinders is the obvious move but if the car has a any kind of limiting valve that could be the issue. The Sierra
valve is sensitive to the angle it is mounted at.
One question nobody has asked is what size rear drums you have fitted 8" or 9" ?
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
whitestu
|
| posted on 25/3/15 at 07:35 PM |
|
|
Like others have said the problem normally tends to be the other way round.
There is nothing wrong with a standard Sierra disc / drum set up on a 7 when working properly.
When you say you don't lock the fronts on track half as much as a road car then it sounds like things are working OK.
|
|
|
adithorp
|
| posted on 25/3/15 at 07:59 PM |
|
|
I think you need to check the rear brake line for a compensator valve first.
If there is, just removing it may give you too much rear brake (not nice) so replacing it with an adjustable valve might be the answer.
If not then larger rear cylinders could be the answer but again may go too far so again adding a valve at the same time could be a good idea.
Both solutions assume the brakes are actually working/adjusted correctly.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
|
|
|
dangerousbrian
|
| posted on 28/3/15 at 04:16 PM |
|
|
No sign of any valve that I could see in the rear circuit, they are 9" drums. I've had them off today and adjusted them to be sure.
I'll give them a good bleed and see where they are afterwards.
|
|
|
rusty nuts
|
| posted on 28/3/15 at 06:26 PM |
|
|
Check the Pistons in the wheel cylinders are not seized , if they are I would sort that out before doing anything else
|
|
|
.jpg)
