Brake Balance Bar

Technical Area for all the problems you have in the garage
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andyg
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Brake Balance Bar

Post by andyg »

I have the dual brake master cylinder set up with a balance bar. My understanding for SVA is that the front wheels must lock slightly before the rear and when you have achieved this, the lock nuts and bar must be fixed - drilled and roll pinned. How do you set up the balance bar to achieve the required setup? I understand it is something to do with adjusting the threaded rod but not sure how to do it correctly. It appears that the threaded rod should be parallel to the clevis pins under braking. Applying the brakes and seeing if the bar is parallel however seems to be a bit of an art as I cant apply the brakes properly and have my head down by the footbox at the same time!

Andy.
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clive
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Re: Brake Balance Bar

Post by clive »

Hi Andy,
What brake set up are you using? I have the Princess 4 pot front and Jaguar inboard rears. Because the rears are more powerful than the fronts, the bias has to be fully to the front. It does take a bit of working out but easy once you know how.

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Cheers, Clive.

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andyg
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Re: Brake Balance Bar

Post by andyg »

Clive,

I have the Jag IRS with the inboard rear discs, but the front is 4 pot AP Racing calipers with 12" discs. May just be a case of jacking the car up and having the brake pedal pressed to see what locks first and taking it from there?

Andy
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Roger King
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Re: Brake Balance Bar

Post by Roger King »

With the Jag rear and Princess front (which I wouldn't imagine to be any different to yours, ultimately) you need the whole bias to the front. The Jag brakes are way too powerful really.
With the XJ40 rear outboard calipers, which are single-pot and much smaller, the problem goes away.
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Re: Brake Balance Bar

Post by SJ »

What about for MGB brakes I have the V8 discs and calipers to the front and mgb drums to the rear? Any different?
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Roger King
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Re: Brake Balance Bar

Post by Roger King »

No idea, sorry - but I wouldn't imagine MGB rear drums are anything like as powerful as Jag discs, so I'd think you'd need something pretty neutral. I know nothing about MGs, but are yours a standard setup? That is, you say your discs are BV8 - did they use the same rear drums as you have on the BV8? Because if they did, there was no bias control so they should be correct with everything setup neutral, i.e. to work front and back brakes the same.
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richmixture
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Re: Brake Balance Bar

Post by richmixture »

if you set up the bar so that you have about 70% on the front then you should be ok. If your running MG gear, set up your rear drums so that are fully adjusted, then adjust the bar so that the bias , i.e the amount of travel is greater on the front, you can do this, you might need to swear for a while, then possible become so annoyed that you start selfharming, but it will come when you see what is happening. you need to get you head down to look at what is happening when you press the stupid thing down.

You ideally need to drive it forward, put the brake on and see if the back wheel lock up before the front, if that happens, - well, its not right, you need to move it to find it hits on the front, or get the MOT guy to test the brakes for you on the rolling road, then you can minor adjust it.

with the drums and V8 discs and pads you should stop on a sixpence
Kris
andyg
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Re: Brake Balance Bar

Post by andyg »

Hi All,

I am still struggling with my balance bar!

I have one supplied by Gerry which also came with two spacers. They apparently thread onto the bar before the clevis and are a failsafe mod.
My only problem then however is I have very limited (1/16") adjustment of the brake bias. Did anyone else use the spacers or is this a more recent mod by Gerry. The picture shows the bar with a neutral setup, the correct spacing for the clevis 2.5" - to match the master cylinder spacing, with the spherical bearing in the middle. You can see the limited adjustment available - if yo go to far the spacer locks the clevis at 90 degree to the adjustment rod, which apears to defeat the purpose of the balance bar.

What am I missing?

Thanks,
Andy
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clive
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Re: Brake Balance Bar

Post by clive »

Hi Andy,
Not the easiest of places to photograph, but I have the same setup.
As you say there is 2 1/2" between clevises but mine seems to work fine.

Image

Image
Cheers, Clive.

(If I'm not here I'm in my workshop or on the golf course!)
andyg
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Re: Brake Balance Bar

Post by andyg »

Clive,

Thanks again for the info.

They certianly appear to be the same bar. I was expecting to have more adjustment on the bias than there seems to be. My understanding is that I have to screw the two spacers onto the rod as close to the bearing as possible. Then thread on the clevis for the front m/c and screw it as close as possible to the spacer, but not actually touching it. Put the bearing into the pedal and then put the other clevis on adjusting it to give the 2.5 " spacing. I was expecting the adjusting rod to sit at an angle when the pedal is at rest, but with the clevis so close to the spacer it has to sit fairly square. Your pictures seem to indicate that what I have been doing was just about correct, but as I said, was expecting to be able to get more adjustment. I thought I would be able to adjust the spherical bearing from one side of the pedal sleeve to the other - the spacers prevent this. I will put it in as described above and see how I get on. I appear to have the front m/c clevis 1/4" closer to the spherical bearing which, according to the Tilton instructions, should give 60/40 bias to the front, but with the balance bar remaing square to the master cylinders and not cocked like the instructions.
All very confusing, but hopefully I am getting there.

Andy
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