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Author: Subject: Iva fail
johnhsmith

posted on 9/12/18 at 11:21 PM Reply With Quote
Iva fail

Hi to you all.
Sorry it's been so long since I last posted, can't believe it's been 2 years!!
I read your posts all the time and really enjoy them, but I struggle with 'media' issues so find it difficult to post myself.
I've had so much fun with the build - best fun I've had with my clothes on. Had loads of issues as you can imagine with the cvh engine, and it's still running like s--t.
However, it does run on a few cylinders and I finally took it to Derby for its Iva last week.
The tester was really helpful, I think he enjoys testing these things as much as we like building them.
Headlights were a bit out of alignment but he let me adjust them and passed them after a few minutes.
My declared weights caused a few issues but he said that they would be ok on a retest.
The outside edge of the seatbelt anchor bracket was not radiussed to 2.5mm so that was a fail.
He wanted to look at the seatbelt anchor fixing to the chassis, so moved the drivers seat forward on the runner to have a look. The bolts on the back of the seat to runner were loose, and as we moved it the one bolt fell off!! What a complete plonker I am. The bolts had to be loose to locate the bolts to the floor, and I must have just forgotten to tighten the driver side nuts afterwards.
Easy to sort those and I was so pleased because I thought there would be so many other issues.
However, big fail was on the brakes. He noted that the brakes were 'a bit spongy but effective' I've bled them 5 times but can't seem to get them any better. But that was not a fail, just a note.
The major fail was on brake/weight distribution calculations. It passed on pedal pressures 1-3, but on p4 ad p5 it went the other way.
I can see that it's all to do with brake bias but I can't see how to correct it.
I've taken the brake deceleration valve off the sierra and may try to fit that as it's a brake bias control, but I understand that it's a live valve and the test is static, so that's not going to sort the problem but may help. Other than that I'm hoping to get the car on a track and give it a few miles in the hope that the brakes will bed in and that may help.
Any other thoughts would be very much appreciated.

Sent from John's iPad

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ianhurley20

posted on 10/12/18 at 09:01 AM Reply With Quote
For the IVA test I replaced the sierra rear wheel cylinders which are 2.2?cm dia with Ford Ka cylinders which are 1.7cm dia but theoutside housings are identical. No issues at all at IVA with balance - er then they fell off and the sierra ones went back on.
Because they are smaller dia they exert a lesser force on the brake shoes and there fore prevent locking up but allow a reasonable amount of braking to take place
Good luck with your retest





My build blog http://ianhaynes20.wordpress.com IVA passed 3/10/16
written off 23/9/18
Aug 2019 completed Tiger Avon with ST170 on TB's
Now restoring 1968 Ginetta G4
And - a series 1 Land Rover - don't ask why!

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JAG

posted on 10/12/18 at 01:10 PM Reply With Quote
John;

If you want any help correcting your brake bias U2U me. I do this stuff for a living (for a large vehicle manufacturer) and I'm always happy to help.

Ian;

If you really switched the rear drumbrake wheel cylinders back to 22.2mm bore after IVA then your rear axle may lock before your front axle during some high deceleration brake stops. It may work perfectly well at low to moderate rates of deceleration but at higher values the rear axle will lock before the front axle.

When/if that happens your car will spin out of control. Be very careful





Justin


Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!

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ianhurley20

posted on 10/12/18 at 03:42 PM Reply With Quote
quote:
Originally posted by JAG
John;

If you want any help correcting your brake bias U2U me. I do this stuff for a living (for a large vehicle manufacturer) and I'm always happy to help.

Ian;

If you really switched the rear drumbrake wheel cylinders back to 22.2mm bore after IVA then your rear axle may lock before your front axle during some high deceleration brake stops. It may work perfectly well at low to moderate rates of deceleration but at higher values the rear axle will lock before the front axle.

When/if that happens your car will spin out of control. Be very careful


I agree with you Justin - a good point to make for others, perhaps I should have added that I have had mine on a rolling road after the change and locking did not occurr at any brake pedal pressure, I would have passed IVA as I was I guess, I just wanted to make sure of a pass, an incomplete explanation by me - well spotted





My build blog http://ianhaynes20.wordpress.com IVA passed 3/10/16
written off 23/9/18
Aug 2019 completed Tiger Avon with ST170 on TB's
Now restoring 1968 Ginetta G4
And - a series 1 Land Rover - don't ask why!

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johnhsmith

posted on 10/12/18 at 03:45 PM Reply With Quote
Ian,
Thanks for the speedy response, and what a brilliant idea. Iíve been down to my local Andrew Page and they found one for me to check. They can get the other one in tomorrow, so for £12.00 I should be able to get that done. A bit more bleeding to do, but fingers crossed.
Justin,
Thanks for the offer, and youíre not too far away from me. It sounds like Ianís trick should work, and Iíll take your advice and leave the smaller cylinders on afterwards.
Any advice on the bleeding? Iím using the air-fed easybleed and starting at the furthest wheel, but even after doing it 5 times the pedal is still spongy. Maybe after changing the cylinders I may have some luck.
Thanks
John

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adithorp

posted on 10/12/18 at 04:46 PM Reply With Quote
Assuming you have drum brakes... Bleed the rear with the adjusters fully off. When they're adjusted, a small amount of air can remain in the end of the cylinder due to the slight angle it sits at. Alternatively bleed as normal then remove the drum, open the bleed nipple and push the pistons fully back with a couple of screw drivers, then lock the bleed. Repeat on the other side. Note this needs 3 hands.





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rusty nuts

posted on 10/12/18 at 04:51 PM Reply With Quote
Have you manually adjusted the rear brakes? Is the auto adjuster free and operating? After fitting your new rear wheel cylinders slacken off the handbrake adjuster then with the brake drum off operate the auto adjuster one click at a time refitting the drum each time until the drum just fits without binding . Refit the drum then readjust the handbrake
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MikeR

posted on 10/12/18 at 07:29 PM Reply With Quote
If it still takes it is possible to convert a automatic brand restrictor to manual, hunt the web. If you can't find anything u2u me and I'll hunt too. I think fiat Uno rings a bell for done reason.
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nick205

posted on 11/12/18 at 04:42 PM Reply With Quote
quote:
Originally posted by MikeR
If it still takes it is possible to convert a automatic brand restrictor to manual, hunt the web. If you can't find anything u2u me and I'll hunt too. I think fiat Uno rings a bell for done reason.


Fiat Uno is correct. I used one on my Sierra based MK Indy in the rear brake circuit. The Uno valve has a plunger that rises as brake pressure is applied. I made a bracket with a nut and bolt to limit the plunger travel and provide some adjustability. The car passed SVA without issue as you couldn't reach it from the drivers seat, you had to remove the bonnet and have a spanner to adjust it.


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johnhsmith

posted on 11/12/18 at 11:35 PM Reply With Quote
Nick,

I'm hoping that the Ka cylinders will do the trick, it only took 1 hour to fit them, so could be a great result. But if that doesn't work I'll be looking at all of the other options.

Is Iva different from Eva, as note 4 clearly excludes manual bias valves. Or does inaccessibility rule?

'Note 4: Hydraulic valves that only operate automatically and react to vehicle loading or braking forces are permitted (Load Sensing and Gravity valves) Manually adjusted valves (other than to permit presetting the automatic function of a valve) are not permitted to be fitted even if they are rendered un-adjustable.'

Thanks

John

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johnhsmith

posted on 11/12/18 at 11:37 PM Reply With Quote
Obviously I meant SVA. Predictive text rules!
John

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nick205

posted on 12/12/18 at 09:12 AM Reply With Quote
OK the rules appear to have changed!

SVA was quite some years ago for me and I've not had to IVA a car so not familiar with current the rules. I'm sure for SVA you were allowed adjusters, but weren't allowed to adjust the bias from the drivers seat. I believe others fitted twin master cyclinders with adjustable bias bars, but "modified" them to be unadjustable so their cars would pass the SVA. It seems the IVA has ruled this out.

I hope the Ka mod works for you and you get through the test!

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Abe

posted on 14/6/19 at 12:08 AM Reply With Quote
Thread resurrection!...How did you get on with the brakes in the end, did it pass ok? Just curious as Iím looking into options on mine at the moment.
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johnhsmith

posted on 14/6/19 at 02:16 PM Reply With Quote
Abe,

Seems like ages ago now!

I fitted the Ka rear cylinders in no time booked the retest. When I arrived at the centre the tester said that the brake equipment wasn't working and he would have to do a manual test. This involved me driving the car towards him and hitting the brakes on his signal. The front brakes locked up first so he said than was ok, passed.

The brakes still feel spongy, but are quite effective and there is no sign of creep, so all ok.

I hope this answers your question, and nice to hear from you.

John

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Abe

posted on 14/6/19 at 02:30 PM Reply With Quote
Good stuff! Thanks for the reply John.

Got an amusing picture of you running over the tester lol

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