Brake balance

[zulublue]

I have just fitted a 93 Disco rear axel to my Defender Truck Cab. All brakes are working fine but due the weight difference (I Think) the rears lock upbefore the fronts do.

Is this just the way it is? Is it dangerous? Is there anything I can do if needed?

p.S. It is not been used for comping, just general on road use and more off road set up.

[Gromit]

Is this just the way it is?

No.

Is it dangerous?

I would think so.

Is there anything I can do if needed?

I think there was a thread on this recently. Rear brakes binding or fronts not doing their job properly.

[zulublue]

fronts not doing their job properly.

the front locked up first with the drum brakes on, as you would imagine and the rears only lock up under very heavy braking, not normal day to day braking.

I have had them tested in a MOT testing station and they said they were very good front and rear, but obviously they only test fronts and rears separately.

[T1G UP]

I've recently done a drum to disk axle swap but i did the front axle as well,why not go to vented disks on the front? My 90's brakes are spot on now.

[Les Henson]

Have you got the compensator valve on the O/S chassis rail inside the engine bay? I've experienced your problem before and the valve was the problem. I bypassed it with brake pipe and it sorted the problem.

Les.

[T1G UP]

Didn't have one on my b reg 90 Les.

[Les Henson]

The one I did was on a G-reg 90, perhaps they started to use them after a certain period.

Les.

[zulublue]

Thanks Les,

I will look in to that, its a J plate 92 model so hope its there.

[gruntus]

Hi Zulu,

I have the same concerns that this will happen to my build when it is ready to go on the road (1986, 90 drums on the rear now converted to 93 RR axle).

I have heard both removing and using the compensating valve to stop this so its going to be hit or miss for me and will try going with the valve fitted first.

Les, my 1986 90 2.5TD has a compensator valve fitted so not sure when they were or were not fitted?

Anyway just to add something worth while to this thread that is related you can buy adjustable compensation valves that are used on kit cars (£20-30 off fleabay).

I would think that you would need a nice straight (abandoned!) bit of road to get the brakes right ....... ........

At least you have options that aren't too expensive to fix your problem and get them just right.

Please let us know how you get on as it will help lots of peopl (including me ) in the future.

All the best

Cheers

G

[western]

the valve depends on VIN/chassis numbers as below -----------------

vented front disc/solid rear disc no abs

upto VIN LA939975 valve nrc8215 NOT 90 vehicles

from VIN MA939976 valve 29 PRF 43 part number anr1415 NOT 90 vehicles

from VIN LA930456 valve 40 PRF 24 part number ntc8836 90 vehicles

front solid disc/rear drum brakes

valve part number nrc8215 was fitted to 90's [hardtop body] upto VIN KA930455

hth

[JST]

my '86 90 has the compensator fitted and i have done a drum to disk conversion no problems with rear locking etc. i also fitted a disck axle to both a '89 110 and a '88 90 and '89 90 and none of them had issues either.

Les - how long do the pads last after by passing the compensator, i think Jase had problems with his when he bypassed it, rear pads went far too quickly.

Plus i thought the compensator reduced the force to the rear to stop the locking up first if you bypass it wouldnt the rears be more prone to locking first?

[BLACK CAB]

This is a really interesting thread.

I too am just about to swap out my 92 drum axle for a 94 disc one.

My truck started out as a Hard top and has the compensator valve fitted.

Referring to my Micro Cat, as Ralph has already stated NRC8215 was fitted to 90 Hard Tops up to KA930455 but also to 90's with vented fr / solid rear LA930456 to LA939975.

As the vented disc's main purpose is to reduce fade I can not see why it should not work with solid disc's all round.

Adjustable valves are no problem, if I was fitting one I would re-route the pipework through the cab and mount it to the front of the seatbox.

[Les Henson]

I bypassed the valve because the brakes were rubbish. I had rebuilt the master and the calipers, checked all pipes and fitted Goodridge hoses. The rear cylinders were new and the brakes were still rubbish, so I did this as a final test. The valve is there to prevent rear brakes locking up. You can take the thing apart, but I couldn't find any information on them, so just left it off. The brakes were better, but still not as good as I would have expected. Rubbish pads perhaps.

Les.

[B reg 90]

My B reg90 locked up it's back brakes after fitting a disco back axle. I fitted 110 front calipers to re balence the brakes. Added bonus is reduced pedal effort. Also gives higher braking torque to compensate for bigger tyres.

Adrian