So straight to the point... I failed on 1 item which was the brake bias. I was given time to adjust it, but no matter where I moved the bias bar, it made no difference, the rears were grabbing too much. The setup is Wilwood 4 pots front and sierra discs rear with 0.625 master cylinders on both. Before I begin, can anyone suggest a solution? Incorrectly setup, worn out bar or replace the front master cylinder with a bigger one? Unfortunate that this is something you cannot test at home!

Anyway, after being a little gutted (mainly at having to return to the test centre for one thing) I've realised that it's a very good fail and should be easy enough to sort as the brake power and efficiency is there. I need to find the solution and get the re-test booked asap (will need an hour slot apparently).

On a happier note, most of the things I was worried about were fine.. After some problems with the machine, the emissions went through first time (Caterham sports cat, standard engine map) and the noise test came in at 91db! (Straight through silencer/cat in to standard zx12 silencer with a db killer for good measure). Lights were not too far out after using the garage wall either.

Massive thanks to Ian from here for trailering my car and coming with me, hopefully yours will fly through soon. Dennis at Norwich test centre was also a great help and made us feel very welcome and relaxed which was great. He explained most of the test and reasons behind them which made the whole thing quite enjoyable!

James

I used a 0.625 on the front and a 0.7 cylinder on the rear with discs all round. Bias bar not far off central. Think that's a pretty standard combination.

All in all not a bad result well done.

Less pressure on the rear !

Change the rear cylinder, 0.625 is fine for fronts but too much for rear discs

Replacing the front M/C with a larger one is likely to make things worse , replacing the rear with a larger one would reduce the pressure in the rear brake circuit . I would try a 0.700" master cylinder .

usual problem with bias bar is they are set up too close, so don't allow the bar to swing.

but as others have said, well done!

Nice and small fail,well done

You can test the brake balance on axle stands if you've got someone decent that can help and press the brake pedal nice and slowly and hold the pressure when told to!
Turn a front wheel by hand whilst your helper presses the brake pedal down slowly,once the front wheel cannot be turned tell them to hold the pedal where it is.
Go to a rear wheel and you should still be able to turn it,then tell your helper to push the pedal down more and the rear wheel should lock up then too.

OK thanks, nice tip on testing it out, I'll give it a go.

The only thing that made me think against changing the master cylinder was that I think these are the cylinders that came from Spire in the brake kit. Either way, it sounds like the larger cylinder should have the desired effect.

Bigger bore cylinder on the rear also make sure the yokes on the bias bar have enough side clearance to work ie they are not hard up against the tube that goes through the pedal

I have same set up, but 0.7 for rears, passed recently.

Before you go and buy new parts make sure you have the bias bar setup correctly. Both myself and a friend had the two arms to close to the pivot point so the bar itself couldn't swing. If you tried altering the bias and it made no difference then the bar itself isn't working properly.

Thanks for all the advice, I think I may have sussed it and learnt a valuable lesson... Don't trust other peoples work! The bias bar was one of very few parts I didn't check/rebuild when I bought it part built, but tonight I discovered the balance bar was in the wrong way meaning that the bias was set to the rear. No wonder I ran out of adjustment.

Hopefully I'll be able to get someone to help me test it tomorrow evening and if all is good, ring the test centre on Friday. The front cylinder certainly looks like it is moving a lot more than before. If all is not good, 0.700" master cylinder on the rear.

At least you haven't got too far to go for the retest.

Not far to drive... Long wait though 22nd June

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Originally posted by Jamesc
Not far to drive... Long wait though 22nd June

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Originally posted by gremlin1234

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Originally posted by Jamesc
Not far to drive... Long wait though 22nd June

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time to get the reg forms from dvla

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IVA PASSED!

It's been a long wait for the re-test, but it sailed through this time with balance bar assembled correctly...

Now just to pay the £472 insurance!

£472 is ridiculous.

Your either young or need to shop around

I'm 27. A lot of places won't insure drivers that haven't had a kit before unless they are over 30.

It was £265 until they realised it was a bec. But I agree, ridiculous!

Congrats!!!!! What was wrong with the brake bias?

Thanks mate! Er, well, er, the balance bar was put in the wrong way. Not originally assembled by me, but I should have checked really. Hindsight and all.

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Originally posted by Jamesc
IVA PASSED!

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congratulations on the pass just a short step to get registered and then enjoy

So I posted the registration application (for a new plate) off on the 23rd June. I was on holiday last week and checked my e-mails/bank account to find nothing.

However, I came home yesterday to find all the documents I sent and a V5 sitting on the floor. They were dated 6th July, so not 100% sure when they came but decent turnaround in my opinion and no fuss about documents etc.

I'm now the owner of a 16 plate. Just need to wait for the rain to bugger off!

Nice one!

Take it easy out there. These cars bite and the roads are greasy at the moment