Brake proportioning valve needed ?
907 - 8/3/15 at 05:15 PM
Hi All
My car failed IVA on uneven braking, front to back and left to right, so this weekend I have given it a bit of a refurb.
We are talking Cortina front discs with M16 callipers, Cortina tandem master cylinder, and Sierra 9" drums on the back.
Haven't touched the M/C as this was originally bought as a recon unit.
I have stripped, cleaned & re-sealed the callipers. I have fitted new 20.6mm (13/16"
slave cylinders to the rear.
I have done a vacuum bleed and put 1-1/2 lts of fluid though to flush the system.
My first question is, has anyone passed IVA with this or a similar set up ?
I took the car up the farm track and even on the dusty gravely spots couldn't lock the fronts first. It really dips the
front suspension but still locks the rears first.
My second question is, should I fit a brake proportioning valve, either non adjustable or adjustable ?
If this could be the answer then recommendations please.
My intention is to pay for an unofficial MOT / rolling road brake test before going back for an IVA re-test.
( now who do I know that works in a garage? )
Thanks in anticipation,
Paul G
[Edited on 8/3/15 by 907]
adithorp - 8/3/15 at 05:44 PM
What size were your previous rear cylinders? You could try smaller ones.
Not sure adjustable proportioning valve is allowed for IVA. The MOT brake test is done in a different (simpler) way to the IVA one but it should give
you L/R balance and F/R
907 - 8/3/15 at 06:07 PM
quote:
Originally posted by adithorp
What size were your previous rear cylinders? You could try smaller ones.
Not sure adjustable proportioning valve is allowed for IVA. The MOT brake test is done in a different (simpler) way to the IVA one but it should give
you L/R balance and F/R
I took the old ones out first and measured them before ordering new ones.
I did come across bigger ( 22.2mm 7/8" ) ford slaves but nothing smaller.
The 20.6mm are even used on Fiesta's and I dare say their drums are a lot smaller than a Sierra.
I thought I had read on here that adjustable's could be locked (wired, welded, pinned) once set.
Cheers
Paul G
britishtrident - 8/3/15 at 07:38 PM
MOT roller tester is absolutely useless for front rear balance.
The availability of smaller bore wheel cylinders depends on type of system you have Girlng or ATE (Teves)
For the Girling system 17.8 mm cylinders were fitted to some mk3 Escorts.
The left right imbalance indicates a problem Cortina front callipers are notorious for seized pistons and the pads seizing in the calliper
SPYDER - 8/3/15 at 07:50 PM
I'm not sure whether it would make any difference on your setup but are the connections on the master cylinder the right way round? Could there
be an inbuilt bias inside the master cylinder that is working against you?
Google images shows some tandem cylinders to have equal diameter chambers whilst others have differing diameters for the two outputs.
907 - 8/3/15 at 08:19 PM
quote:
Originally posted by britishtrident
MOT roller tester is absolutely useless for front rear balance.
The availability of smaller bore wheel cylinders depends on type of system you have Girlng or ATE (Teves)
For the Girling system 17.8 mm cylinders were fitted to some mk3 Escorts.
The left right imbalance indicates a problem Cortina front callipers are notorious for seized pistons and the pads seizing in the calliper
Regarding the MOT rollers I'm just trying to save a 2 hour drive (to Norwich) and a £90 retest fee.
I believe that the re-seal of the callipers and replacing the rear slaves will have solved the right left balance problem.
They push with just thumb pressure now.
It's just front to back now.
Cheers
Paul G
907 - 8/3/15 at 08:26 PM
quote:
Originally posted by SPYDER
I'm not sure whether it would make any difference on your setup but are the connections on the master cylinder the right way round? Could there
be an inbuilt bias inside the master cylinder that is working against you?
Google images shows some tandem cylinders to have equal diameter chambers whilst others have differing diameters for the two outputs.
I have the connection nearest the foot pedal going to rear brakes.
Connection nearest the front to the front discs. (No crossover of pipes)
I haven't stripped the master cylinder to check diameters.
If I have to add a valve I will have a look.
Cheers
Paul G
CosKev3 - 8/3/15 at 09:22 PM
The only adjustable bias allowed for IVA is balance bar type pedal boxes,you are not allowed any type of in line adjustable bias device even if you
lock it out.
Some Fords have little valves screwed into the mc ports, which are restrictors.
These are allowed as they are not adjustable, got mine off a Fiesta.
CosKev3 - 8/3/15 at 09:26 PM
http://m.ebay.co.uk/itm/331468749935?nav=SEARCH
You can see them in the bottom ports of the pics in that advert.
Have fitted one to my rear line, but I'm running discs all around, it deffo restricts the rear line as I've had someone press the brake as I
turned the wheels.
When front locked I went to rear wheel and I could still turn it.
coozer - 8/3/15 at 09:32 PM
Sounds to me you need to refurb the calipers (electrolysis) new pads, new cylinders shoes and drums (electrolysis). And a sierra proportion valve in
the back..
Some red or yellow pads may help as well.
[Edited on 8/3/15 by coozer]
CosKev3 - 8/3/15 at 09:55 PM
quote:
Originally posted by coozer
Sounds to me you need to refurb the calipers (electrolysis) new pads, new cylinders shoes and drums (electrolysis). And a sierra proportion valve in
the back..
Some red or yellow pads may help as well.
[Edited on 8/3/15 by coozer]
I thought I read on here sierra valve is no good for iva?
As it only works with the force of the car moving, so on rollers it doesn't do anything?
renetom - 9/3/15 at 08:44 AM
Hi
"We had the same problem on our Indy failed IVA
The examiner recommended one of these which is an
automatic valve. did the trick and worked fine.
Adjustable valves are strictly no no for iva
Instant fail even if locked.
Good luck.
Description
907 - 9/3/15 at 12:19 PM
quote:
Originally posted by renetom
Hi
"We had the same problem on our Indy failed IVA
The examiner recommended one of these which is an
automatic valve. did the trick and worked fine.
Adjustable valves are strictly no no for iva
Instant fail even if locked.
Good luck.
Description
Where do you find a Rover part nowadays? I've searched but no joy.
Cheers
Paul G
CosKev3 - 9/3/15 at 12:55 PM
quote:
Originally posted by 907
quote:
Originally posted by renetom
Hi
"We had the same problem on our Indy failed IVA
The examiner recommended one of these which is an
automatic valve. did the trick and worked fine.
Adjustable valves are strictly no no for iva
Instant fail even if locked.
Good luck.
Description
Where do you find a Rover part nowadays? I've searched but no joy.
Cheers
Paul G
It will do exactly the same job as the Ford ones I've linked too earlier.
britishtrident - 9/3/15 at 01:58 PM
quote:
Originally posted by 907
quote:
Originally posted by renetom
Hi
"We had the same problem on our Indy failed IVA
The examiner recommended one of these which is an
automatic valve. did the trick and worked fine.
Adjustable valves are strictly no no for iva
Instant fail even if locked.
Good luck.
Description
Where do you find a Rover part nowadays? I've searched but no joy.
Cheers
Paul G
Not exactly difficult to find with Gogle/Ebay search but pricey unless you can find a scrapper.
As already said Ford Mondeo or Vauxhall Corsa B valves are cheaper and do the same job.
Do an ebay search on FORD MONDEO BRAKE VALVE.
THe Rover 25 and 45 also have valves which are dead easy to get at in the scrappies but because they are double circuit valves the plumbing would
not be an easy fit on a live axle car.
JAG - 9/3/15 at 03:40 PM
Smaller rear drumbrake cylinders will work.
The Girling one's come in 17.8, 19.05, 20.64, 22.2 diameters.
I have M16 front calipers and 8" rear drumbrakes with 22.2mm wheel cylinders.
Your car will work fine with 9" rear drumbrakes but smaller cylinders; either 19.05 or 17.8 would be enough.
renetom - 9/3/15 at 04:44 PM
Hi we had 4 pot wilwoods on the front & drums on the rear.
When we went for the re-test the examiner told us to do about 10 laps of the test centre
with our foot on the brake to bed in the new pads
Then watched us whilst we did emergency stop.
Only 2 years ago.
There is another valve which is from an old Range rover that will do
but you will have to put yourself out and go to a breakers.
Good luck
907 - 9/3/15 at 04:53 PM
Having trouble with my internet.
Have found a Mondeo valve but will try Fiesta mk4 17.5 cylinders first.
Cheers
Paul G
[Edited on 9/3/15 by 907]
JAG - 10/3/15 at 09:28 AM
Not all valves are the same.
They are supplied with different cut-off pressures.
adithorp - 10/3/15 at 10:25 AM
quote:
Originally posted by 907
Having trouble with my internet.
Have found a Mondeo valve but will try Fiesta mk4 17.5 cylinders first.
Cheers
Paul G
[Edited on 9/3/15 by 907]
That should do it.
Slight thread drift... Has anyone seen a stepped master cylinder like SPYDER mentions? In all my years in the trade I've yet to come across one.
SPYDER - 10/3/15 at 10:46 AM
I saw these images ...
They look like different chamber diameters. The top one is from a BMW site.
The bottom one has the chambers labelled up for a diagonally split system though, so the pressures must be the same. I'm confused.
Edit: Looking at it again it isn't a one piece piston rod with two different diameters. The pedal will generate pressure in the first chamber
which will create, via the second piston, the same pressure in the second chamber.
As you were.
[Edited on 10/3/15 by SPYDER]
matty h - 10/3/15 at 11:12 AM
PM sent regarding valves.
Matty
britishtrident - 10/3/15 at 11:27 AM
quote:
Originally posted by adithorp
quote:
Originally posted by 907
Having trouble with my internet.
Have found a Mondeo valve but will try Fiesta mk4 17.5 cylinders first.
Cheers
Paul G
[Edited on 9/3/15 by 907]
That should do it.
Slight thread drift... Has anyone seen a stepped master cylinder like SPYDER mentions? In all my years in the trade I've yet to come across one.
I
Istr Vauxhall/Opel used them on some RWD models, Ford never used them as Ford like most manufacturers always used a diagonal split.
britishtrident - 10/3/15 at 11:29 AM
quote:
Originally posted by adithorp
quote:
Originally posted by 907
Having trouble with my internet.
Have found a Mondeo valve but will try Fiesta mk4 17.5 cylinders first.
Cheers
Paul G
[Edited on 9/3/15 by 907]
That should do it.
Slight thread drift... Has anyone seen a stepped master cylinder like SPYDER mentions? In all my years in the trade I've yet to come across one.
I
Istr Vauxhall/Opel used them on some RWD models, Ford never used them as Ford like most manufacturers always used a diagonal split.
907 - 10/3/15 at 01:29 PM
quote:
Originally posted by matty h
PM sent regarding valves.
Matty
Yes please, But my internet won't let me reply to your u2u
Paul G
edit
Just tried from my phone.
Send a text to 07779 561613
[Edited on 10/3/15 by 907]
Dick Axtell - 10/3/15 at 01:57 PM
quote:
Originally posted by SPYDER
I saw these images ...
It may have come from a BMW site, but its still an old Girling mcyl design, (TV/CV = Tipping valve/Centre valve), as used on the early Ford Escort
(Mk1). And possibly on the Mk2 also (I think!).
[Edited on 10/3/15 by Dick Axtell]
Dick Axtell - 10/3/15 at 02:05 PM
quote:
Originally posted by SPYDER
I saw these images ...
This one was used with servo booster, as you can see from where the mounting flange is positioned. Its clearly a non-simco (non-simultaneous cut-off)
type, and was used for F/R split brake systems. Used on older model Mercs.
Dick Axtell - 10/3/15 at 02:10 PM
quote:
Originally posted by JAG
Smaller rear drumbrake cylinders will work.
The Girling one's come in 17.8, 19.05, 20.64, 22.2 diameters.
I have M16 front calipers and 8" rear drumbrakes with 22.2mm wheel cylinders.
Me too, although I also fitted a PCRV (pressure-concious reducing valve) in the rear brake circuit. Another suitable valve could be one from an
earlier Fiesta (not sure which vintage). These were fitted into the Fiesta mcyl outlet ports.
adithorp - 10/3/15 at 02:44 PM
I've seen those pictures before, just never actually seen one.
However I'm not conviced how they work. Bear with me as I don't think it's actually as obvious as it first seems.
Smaller cylinder creates more presure than a larger... but in this case, the secondary piston is floating so the presure either side should be
equalised.
