pstirz
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| posted on 14/11/13 at 03:43 PM |
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IVA fail (brake bias help needed?)
Hello All,
Well my first attempt at the IVA fail today on a few simple things (I hope).
Digital speedo calibration (now fixed).
Rear brake light connections need some waterproof covers (shrink wrap on the way).
Brake bias (rears just locking before fronts) I'm on standard sierra discs front and drums back with no bias valve.
Can anyone help me with this?
I have just bought a ford Mondeo inline bias valve (part number #1113275) on the internet for £20 and intend fitting this in the rear brake line.
Has anyone any experience of this working?
The tester noted that he had seen ford valves used before. He also warned me to stay clear of the aftermarket adjustable ones as he wasn't keen
on the adjustment side of things.....
If I fit the valve it might be tricky to test if its worked or not.
Any help will be appreciated
Other than that, I think the test went well. Thanks again for all the pre IVA photo comments.
Paul
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daveb666
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| posted on 14/11/13 at 03:48 PM |
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Are the discs/drums all of the same age and condition?
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ashg
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| posted on 14/11/13 at 04:03 PM |
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i know of someone taking an angle grinder to his brake shoes to reduce the surface area to pass sva but its not a proper fix. the best bet is to fit
a smaller cylinder in the rear drums. i think adrianH documented this quite extensively http://www.tamarisktechnicals.com/pages/iva.html
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ReMan
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| posted on 14/11/13 at 04:04 PM |
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Good fail 
Re the brake bias, whilst he might not be keen on an adjustable valve, it's got to be better than fitting one that's not designed for your
car and can be adjusted to give an appropriate bias (whatever that is ) and then locked/covered to prevent fiddling about with.
As mentioned, are your brakes bedded in and functioning properly with appropriate pads as I could guess that drums would probably work beth in this
scenario, hence the rear lock up you have
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davidimurray
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| posted on 14/11/13 at 04:37 PM |
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As per ashg's post have a look at Adrians blog and check your rear drum size. I did the same as Adrian and downsized to 19mm and sailed through
iva.
Gallery 1 http://www.facebook.com/media/set/?set=a.116893465324.130778.601005324
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britishtrident
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| posted on 14/11/13 at 04:56 PM |
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I don't anybody that has used one but the Mondeo valve should do the job, the tester has valid reasons for suggesting you avoid an adjustable
valve.
Once you fit the valve test it on a good clean dry road surface at very low speed, then if you are sure the front brakes are locking first repeat
at a slightly higher speed.
You should test that the fronts lock first on a clean dry road because in these conditions you can apply more braking and stop with higher
deceleration therefore more weight is transferred from the rear to front wheels so the front wheels are less likely to lock before the rears. In
wet/slippery conditions there is less front to rear weight transfer so the front brakes will always lock more easily.
Some of the the adjustable valves sold by aftermarket custom brake manufacturers would not actually have much if any effect on your car because they
are designed to work at higher hydraulic line pressures than generated in your car.
Other alternate vlves bulders have used include the Vauxhall Corsa and Fiat Uno/Rtmo/Strad/Lada Riva valves, the latter can be made adjustable.
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renetom
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| posted on 14/11/13 at 05:46 PM |
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Hi
We had exactely the same thing on our IVA
rears drums locking up before front wilwoods .
The examiner told us to fit one of these on the rear line.
 
Description
which we did , but come the re-test it was still close
so he made us drive round the centre with our foot on the brake.
came back & it was fine , he said new pads need bedding in.
good luck
René
You don't need smaller cylinders just fit the bias valve & bed in the disc pads.
On no account fit an adjustable valve, this is a big no no ,I asked our tester about them , his reply was under no circumstances are these allowed
even if the adjustment has been welded up.
Another small neat bias valve is from Range Rover.
[Edited on 14/11/13 by renetom]
[Edited on 14/11/13 by renetom]
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pstirz
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| posted on 14/11/13 at 05:56 PM |
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Thanks for the advise.
The front and pads are new and rear shoes are new (old drums).
I like the idea of 19mm diameter rear cylinders.
Does anyone know where to get them or what model ford they are from?
Paul
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davidimurray
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| posted on 14/11/13 at 06:25 PM |
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Brakes international sell the 19mm cylinders.Adrian might have the reference on his blog. I think they were escort ones.i might have the part number
in my build file but won't be home until sat to check.
Gallery 1 http://www.facebook.com/media/set/?set=a.116893465324.130778.601005324
Gallery 2 http://www.facebook.com/media/set/?set=a.245243755324.181913.601005324&l=a9831a9319
Gallery 3 http://www.facebook.com/media/set/?set=a.440671625324.232627.601005324&l=3f0d42c523
Gallery 4 http://www.facebook.com/media/set/?set=a.490098255324.297598.601005324&l=efb083b7df
Gallery 5 http://www.facebook.com/media/set/?set=a.10150244028550325.366987.601005324&l=583fd5cd3a
Gallery 6 http://www.facebook.com/media/set/?set=a.10150550640070325.430417.601005324&type=3&l=fe779b358c
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Dusty
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| posted on 14/11/13 at 08:44 PM |
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You could try the effect of upgrading the fronts rather than reducing the efficiency of the rears. Set of mintex m1144 pads on the front and properly
bedded in should increase the front stopping power for a given pedal pressure. Depends on how great the imbalance is currently.
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pstirz
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| posted on 14/11/13 at 09:45 PM |
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Thanks for the advise.
The brake bias to the back is only very slight and the fronts will probably get better with bedding in.
I'm going to fit the Mondeo bias valve and pay a visit to Brakes International on Saturday morning to get new 19mm rear cylinders.
Hopefully that will do the trick for my retest.
Paul 
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Daddylonglegs
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| posted on 15/11/13 at 08:49 AM |
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I had the same thing on my first test. Fitted the Sierra tilt-valve in the engine bay in the rear brake feed and mounted it at about 15deg. Worked a
treat, and it was easy to try on our drive 'cos it's gravel so showed the results fine. I think it's mounted a lot steeper in the
Sierra, but then the car is much lighter so needs to be.
HTH
It looks like the Midget is winning at the moment......
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johnemms
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| posted on 15/11/13 at 11:15 AM |
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rear cylinders ..
http://www.locostbuilders.co.uk/viewthread.php?tid=167246
cylinders link
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davidimurray
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| posted on 16/11/13 at 01:44 PM |
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Just checked my receipts and I used BWC5079 on my rears
Gallery 1 http://www.facebook.com/media/set/?set=a.116893465324.130778.601005324
Gallery 2 http://www.facebook.com/media/set/?set=a.245243755324.181913.601005324&l=a9831a9319
Gallery 3 http://www.facebook.com/media/set/?set=a.440671625324.232627.601005324&l=3f0d42c523
Gallery 4 http://www.facebook.com/media/set/?set=a.490098255324.297598.601005324&l=efb083b7df
Gallery 5 http://www.facebook.com/media/set/?set=a.10150244028550325.366987.601005324&l=583fd5cd3a
Gallery 6 http://www.facebook.com/media/set/?set=a.10150550640070325.430417.601005324&type=3&l=fe779b358c
Duratec Engine Swap https://www.facebook.com/media/set/?set=a.10152527759580325.1073741828.601005324&type=1&l=40aae5e72f " target="_blank"> https://www.facebook.com/media/set/?set=a.10152527759580325.1073741828.601005324&type=1&l=40aae5e72f
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