CTLeeds
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 posted on 28/1/19 at 08:24 PM |
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IVA Fail
Sadly my car failed the IVA test last week but then I kind of knew it would. In all honesty I'm not too despondent as it failed on five points,
three of which are easy fixes and two of which less so but not insurmountable.
1. Radiusing of exhaust clamp. Inspector would be happy if it was wrapped. Easy.
2. Interpretation of electric handbrake activation rules not agreed between parties regarding "inadvertent use". My EPB module has a delay
which means you have to press and hold the button for three seconds before it activates the park brake which to my mind prevents "inadvertent
use". The inspector disagreed. He would be happy if the switch had a cover meaning a two stage action required to activate the brake. Easy fix
if I can find a cover for the switch that meets radius rules.
3. A bolt on the lower steering column UJ had become loose. It turns out it has stripped the thread. New bolt required. Easy and very happy they found
this!
4. Emissions! High Lambda figure causing a fail. I believe this is caused by a lean AFR condition. I think/hope my failing fuel pump maybe the cause
of this and will test again locally before retesting. If the new pump doesn't sort it then I'll have to revisit the drawing board?!?
5. Brake balance. Front to rear. Rear locking way before the fronts. This may also be a symptom of the rear park brake modification as I had to use
larger electric calipers from a 5 series BMW to accomplish this but the smaller 3 series front brakes remain. No amount of bias bar tweeking would
bring it in. I think the only solution will be to go bigger (and heavier) up front.
The inspectors (3!) were very good and definitely fair and a couple of issues I was concerned about sailed through inspection. They commented on the
quality of the build positively and seemed genuinely disappointed that they had to fail me. Looking forward to retesting in a month or so all being
well.
Regards
Chris
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owelly
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| posted on 28/1/19 at 08:30 PM |
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That's a fairly good fail...
For the rear brakes, could you reduce the contact patch on the pads? Fire up the angry grinder and see what happens.
http://www.ppcmag.co.uk
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paulc
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| posted on 28/1/19 at 09:48 PM |
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If you have twin master cylinders (sounds like you have) you can move the bias forward by using either a smaller diameter master for the front, or a
larger diameter for the rear, or both.
Do you know the cylinder current diameters?
Paul
[Edited on 28/1/19 by paulc]
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CosKev3
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| posted on 28/1/19 at 11:24 PM |
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You haven't got the master cylinders the wrong way around?
Been done plenty of times before! 
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gremlin1234
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| posted on 29/1/19 at 12:23 AM |
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quote:
You haven't got the master cylinders the wrong way around?
or the bias bar tightened so it doesn't move properly.
I did see one 'post' (I think on the westfield forum) that suggested wd40 on the rear shoes for the test, please don't do this, it
might pass on the day, but rears that lock before the fronts is a disaster waiting to happen
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hughpinder
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| posted on 29/1/19 at 09:12 AM |
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For the brakes I'd look at the master cylinders too. The force on the pads is proportional to the area of the master cylinder, so for example,
if you have 2 19mm cylinders and change to a 22 rear and 16 front the bias will change by a factor of 1.89 which is pretty significant!
Good luck,
Hugh
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Bigboystoys
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| posted on 29/1/19 at 11:08 AM |
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I had to swap my master cylinders around on my rush after I fitted hi spec calipers front and rear for the exact problem you have.
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rusty nuts
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| posted on 29/1/19 at 11:35 AM |
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Check your exhaust system for leaks as they cause high Lambda readings , even the smallest of leaks!
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killerferret666
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| posted on 29/1/19 at 02:59 PM |
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thats a good fail,
Can i ask which Ebrake did you go for?
Building DDR GT4
Miami Gt4 Blog - Click Here
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dunk3
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| posted on 29/1/19 at 05:27 PM |
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Not a bad fail that. How did you lock the brake bias off and where did you take it for Iva.
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CTLeeds
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| posted on 30/1/19 at 09:36 AM |
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quote:
Originally posted by owelly
That's a fairly good fail...
For the rear brakes, could you reduce the contact patch on the pads? Fire up the angry grinder and see what happens.
Ha! I like you're style! I'm gonna try for something a bit more conventional before resorting to this method though.
Thanks
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CTLeeds
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| posted on 30/1/19 at 09:48 AM |
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Thanks for all the replies. To answer questions posed...
Car was tested at Beverley near Hull. This is the nearest test centre to me being based in Leeds.
I do have twin master cylinders. I started with a pair of 0.575" cylinders to which no amount of bias bar adjustment would bring the balance in.
I then replaced the rear cylinder to a 0.625" which I was assured would reduce the pressure the rear circuit. It did, but not by enough to bring
the balance in. I've now bought some second hand BMW M3 front brake calipers and carriers which includes "run in" discs and pads. If
these don't sort it out then nothing will and a visit to the drawing board will be required (again...).
The Ebrake system is a bit of a hybrid, but by design. The calipers are from an F series BMW 530. The module that controls them is from Simtek
Motorsport near Rochdale. It's a dead straight forward system and just works.
The custom exhaust is leaking at the rivets on the silencer. I need to seal them to see if this is causing the issue. I'd thought that the
exhaust would always be at positive pressure meaning it wouldn't allow gases in but I guess this isn't the case?
Thanks again all.
Chris
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MikeRJ
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| posted on 30/1/19 at 11:26 PM |
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quote:
Originally posted by hughpinder
For the brakes I'd look at the master cylinders too. The force on the pads is proportional to the area of the master cylinder
Inversely proportional. Bigger master cylinder = less force on pads for a given pedal pressure.
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