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Got SVA date - 6th April

Posted: Fri Mar 13, 2009 12:45 pm
by Nissanman
Well, it's finally going to happen, about 2 years after I expected it to, which I supose is normal!

I'm actually pretty sorted for it, just got to sort out the brakes/balance bar which is driving me nuts as I can't get the front to lock before the back, which is a definite fail. I've re-bled the fronts and shifted the balance bar to both ends with no joy. The calipers have Green stuff pads on and I'm wondering if regular Sierra pads would be softer and come to temp quicker .... would that make a difference?

Apart from that just got to attach the seats and belts and make a steering wheel soft pad and it's done..... looking forward to it now :)

Re: Got SVA date - 6th April

Posted: Fri Mar 13, 2009 6:20 pm
by MattD
Nice one Jasper, good luck 8)

Where are you going for the test ??

I don't know much about balance bar brakes, I'll let someone who know's comment.
But presumably the master cylinder bore sizes are correct, etc ?
Are the pads bedded-in ?

Rgds

Matt.

Re: Got SVA date - 6th April

Posted: Fri Mar 13, 2009 6:54 pm
by Nissanman
Mitcham - South London, same place I went with my last one, decent guys there. Pads aren't bedded in, keep doing little trips around the block with my foot on the brake to get them there though.

I'll get my very techie mate over to help me with it, must be something obvious.

Re: Got SVA date - 6th April

Posted: Fri Mar 13, 2009 10:12 pm
by Antnicuk
it took me 4 attempts to bleed my brakes properly, i just couldnt get the air out. First thing i did is to prop a broom handle or piece of wood between the pedal and the seat, keeping a fairly decent amount of pressure on the pedal. Leave it over night and then see if the pedal is firm, if it isnt, try and bleed the fronts again. The pressure moves all the air to the end of the system. I didnt need to bleed mine afterwards but others did and said it helped. This has worked everytime for me and was advice given to me by an experienced mechanic. Some guys tried it on the Locostbuilders site and it worked.

The other thing is the bias bar. make the plunger bar going to the front brake M/C longer by unwinding it from the clevis (it wont unwind from the M/C) or make the one going to the rear shorter, you can also adjust the bias bar so the pivot is closest to the front M/C, as you push the pedal the front should then be pushed first.

HTH

Re: Got SVA date - 6th April

Posted: Fri Mar 13, 2009 10:49 pm
by stylussprinter
Nissanman wrote:Well, it's finally going to happen, about 2 years after I expected it to, which I supose is normal!

I'm actually pretty sorted for it, just got to sort out the brakes/balance bar which is driving me nuts as I can't get the front to lock before the back, which is a definite fail. I've re-bled the fronts and shifted the balance bar to both ends with no joy. The calipers have Green stuff pads on and I'm wondering if regular Sierra pads would be softer and come to temp quicker .... would that make a difference?

Apart from that just got to attach the seats and belts and make a steering wheel soft pad and it's done..... looking forward to it now :)
What calipers are you using :?: Hope you are using dot 4 fluid , you don't want that poncy ' 5 ' stuff :lol: Did you just bolt the pedal box to the floor or did you take it apart and set it up :?: Between 3 and 6 mm longer rod for the front brake cylinder , also make sure that neither rod is screwed in so that it fouls the balance threaded bar. They must be parallel too. Then each side of the ' tube ' needs a large loose fitting washer . Adjust the screwed bar all the way towards the front clevis/brake cylinder then back around two complete turns . Push a piece of rubber hose over the thread and put a dot of tipex on it so you can see if it's moved . Test it and see . If it's better but not perfect then wind back a little towards the front clevis/brake cylinder .

I forgot to say that when you put your pedal box together , take the bias bar apart then polish the tube plus pivot point and copper grease it.

Lastly use decent pads like Hawk black code M or the new W code. Shit hot brakes :)

As Tony says --- get the brakes very well bled . I use a pressure kit attached to a pumped up tyre -- brilliant every time :D

Re: Got SVA date - 6th April

Posted: Sat Mar 14, 2009 12:56 pm
by MattD
Just one other thought....

I'm sure you're aware that Balance Bar brakes have to locked in position in order to pass SVA.
The bias has got to be "permanently" set for road use, so that they are not adjustable.
Quite usual to fit a rollpin or similar.

First thing you'll drill out when you get home with your MAC certificate !

Re: Got SVA date - 6th April

Posted: Sat Mar 14, 2009 1:02 pm
by Nissanman
Yup - know about the locking thing. Thanks for the info chaps, got my head around what I need to do now, and got a nice day of weather tomorrow to do it :)

Re: Got SVA date - 6th April

Posted: Sat Mar 14, 2009 1:20 pm
by PeteC
Just a thought, when I made my pedal box, I used two different sizes of cylinder(0.6" and 0.75" I think) so be sure you have them on the correct circuits..
Good luck with the test!!
Pete.

Re: Got SVA date - 6th April

Posted: Sat Mar 14, 2009 1:23 pm
by PeteC
The bias has got to be "permanently" set for road use, so that they are not adjustable.
Quite usual to fit a rollpin or similar.
First thing you'll drill out when you get home with your MAC certificate !


Can you still get away with this or does the remaining bar require welding along it's entire exposed thread, thus rendering it non-adjustable?
Pete.

Re: Got SVA date - 6th April

Posted: Sat Mar 14, 2009 1:48 pm
by Nissanman
Nope - drill and roll pin is fine, but no good for new IVA, that does have to permanently set.

Re: Got SVA date - 6th April

Posted: Sat Mar 14, 2009 5:04 pm
by Antnicuk
PeteC wrote:Just a thought, when I made my pedal box, I used two different sizes of cylinder(0.6" and 0.75" I think) so be sure you have them on the correct circuits..
Good luck with the test!!
Pete.
^^^^ thats also a very good point,...

Re: Got SVA date - 6th April

Posted: Sat Mar 14, 2009 7:18 pm
by stylussprinter
Forgot to say that Tony :roll: I used a 3/4 for the front brakes and for the clutch ( firm pedal ). The rear brakes have a 5/8 ths cylinder , all three are Girling . With hindsight the clutch would have been better using a 5/8 ths too :wink: It's like a Formula clutch -- bloody stiff :o I'm used to it but anyone who gets in to try usually says '' bloody hell Rob '' :shock:

Re: Got SVA date - 6th April

Posted: Sat Mar 14, 2009 7:45 pm
by Antnicuk
i used the same as you rob except my clutch is a 0.7?, the same with the rear brakes. RX7's have a fairly firm clutch as stock so didnt want it any harder.

Re: Got SVA date - 6th April

Posted: Fri Mar 20, 2009 4:39 pm
by Nissanman
Still having trouble, done all of the above, wound the front mc rod right out, and the rear mc rod right in to the clevis, got the balance bar right over to the front side, re-bled the front calipers twice (left piece of wood wedged overnight) and while it's better (front brakes definitely working more) the rears still lock up first.

Spoke to a chap at Compbrake and he reconned to try a large MC for the fronts, so I'll give that a go.

Apart from that all ready for SVA in 2 weeks.

Re: Got SVA date - 6th April

Posted: Fri Mar 20, 2009 10:03 pm
by Antnicuk
There are several people on Locost builders who are having similar problems, you may find some useful suggestions on there.

What size M/C's are you using?

If push comes to shove and you run out of time, a bodge to get through the SVA that I have seen done by people who used to import some jap cars. On things like the Shoguns that required the ESVA where they couldnt get the fronts to lock first, they would grind 2 or 3 mm from half of the face of each rear pad. This will reduce your rear braking surface area by half. As soon as the 2 or 3 mm is worn down the pads will back to normal.

As said, a bit of a bodge but may get you through the sva if you cant get it fixed.