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souster4

Member Since: 11 May 2014
Location: West midlands
Posts: 153

Very weird brake problem! Help please

Hi all

I wondered if you could help me, I'm posting this as I'm out of all options, and literally at the end of my tether with it. Anyway, I have a 1995 defender 90, which when I bought it, the brake system was in a very sorry state.
So since owning it its had a complete overhall on the brake system and everything is new including:

New OEM servo x2 & master cylinder x2
New vacuum pump
New AP Calipers
New mintex / ferodo pads
New goodridge stainless hoses x2
New timken bearings in all 4 hubs
3 new stub axles

Now, my problem. I'm having an issue with the pedal travel when braking after turning or when I'm off road. The travel doubles on the press following a turn, but mainly sharper turns. And off road it's awful.

So, you maybe thinking it's pad knock back due to play in wheel bearings. Which is what I was told, after many hours of research. There is zero play when rocking each wheel; I must have been into each hub at least 5 times to check or change my adjustment. And this week i decided to tighten the bearings to 40Nm to see if I still had the problem. And i did!

I've done some testing this week with the vacuum pipe off on private land. If driving in a straight line forward or reverse the pedal is perfect. If I rock the steering and turn from lock to lock while stationary no issues either. But when I turn and drive forward the travel increases. But if I remain turning for instance going round in a circle in first gear, the pedal will be fine. But when I reverse in the same circle, the pedal travel doubles again.
And it appears the same for both left and right hand lock, off road and corners driving normally (not quite as bad).

Has anybody got any ideas please, because as you can see from my list. I've replaced a lot of things now, and a lot of things twice. Any help would be massively appreciated.

Thanks for reading

8th Feb 2016 11:02pm

Mash

Member Since: 09 Feb 2015
Location: Guernsey
Posts: 1674

Never had a problem like this, as you said you have private land to drive on could you make some blanking plugs (I use old brake lines crimped and soldiered) and isolate each wheel station to try and isolate the problem to narrow your search. 90 wolf - Jasmin http://www.defender2.net/forum/topic39408.html
90 V8 - Maggie http://www.defender2.net/forum/topic42564.html
110 TD5 - Buggsy http://www.defender2.net/forum/topic59029.html
52HG25 lightweight https://www.defender2.net/forum/topic72342.html
D3 Hse - Fiona
Capri 2l S - Anna

Think I might have a problem............

8th Feb 2016 11:32pm

souster4

Member Since: 11 May 2014
Location: West midlands
Posts: 153

Thanks for the reply mash.

I forgot to add in my post, last week I changed the existing stainless flexi hoses for goodridge, as I thought they were failing and they were the only options I had left.

Before doing so, I clamped 1 front flexi at a time, and the pedal was better. I would say the pedal was 90% improved, with just a very very slight increase in travel when turning, which could have been my imagination . Both sides had the same results when clamped.

This then forced me into tightening the bearings up to 40nm as I was convinced it was to do with the bearings. No luck!

8th Feb 2016 11:49pm

excossack

Member Since: 22 Feb 2012
Location: North West
Posts: 5842

1999 Defender 110 Td5 SW Caledonian Blue

A mate had a weird issue with his brakes on a E reg 110.
He would get a leak at the rear wheel cylinder on one side. Replace it and would OK for a while and then leak again.
After lots of hunting/replacing he found there was a pressure valve/bias valve and this was causing the issues.
Located on the bulkhead area if memory serves ( think it T off to the rear brakes and might have has a sensor on it?) 1999 Defender TD5 110

Regards
John M0VAZ
Econet Station 48 no clock

9th Feb 2016 12:52pm

excossack

Member Since: 22 Feb 2012
Location: North West
Posts: 5842

I think it was a PDWA switch:
E04.040 FRONT - REAR DRUMS ('110"', LESS ANTI-LOCK BRAKING SYSTEM TO (V)HA901219 OR '130" WHEELBASE', LESS ANTI-LOCK BRAKING SYSTEM TO (V)HA901219)
VALVE ASSEMBLY BRAKE, PDWA SWITCH, WITH FRONT DISC-BRAKE/RR DRUM BRAKE, LESS FT AND RR VENTED BRAKE DISCS
Part number: NRC7871 1999 Defender TD5 110

Regards
John M0VAZ
Econet Station 48 no clock

9th Feb 2016 12:59pm

rallysteve

Member Since: 10 Feb 2014
Location: Cumbria
Posts: 2222

2002 Defender 110 Td5 DCPU Keswick Green

Presume your wheel bearings are correctly set (endfloat/preload)?

Can you not put the front axle on stands and take the wheels off to have a look at the calipers whilst turning the steering lock?
A feeler gauge should give you a good indication of the pad clearance and if they are travelling back when steering. I have had similar issues with pedal travel due to caliper seals perishing and sticking to the pistons which causes pistons to retract too far when releasing pressure.

Steve 02' 110 TD5 Double Cab Rebuild Thread

9th Feb 2016 2:22pm

souster4

Member Since: 11 May 2014
Location: West midlands
Posts: 153

excossack wrote:
A mate had a weird issue with his brakes on a E reg 110.
He would get a leak at the rear wheel cylinder on one side. Replace it and would OK for a while and then leak again.
After lots of hunting/replacing he found there was a pressure valve/bias valve and this was causing the issues.
Located on the bulkhead area if memory serves ( think it T off to the rear brakes and might have has a sensor on it?)

Thanks for the reply mate. I've also replaced that valve too, granted a few things haven't been replaced just due to this issue, the brake system was in a terrible state when I bought it. But a lot have too!

9th Feb 2016 4:43pm

souster4

Member Since: 11 May 2014
Location: West midlands
Posts: 153

rallysteve wrote:
Presume your wheel bearings are correctly set (endfloat/preload)?

Can you not put the front axle on stands and take the wheels off to have a look at the calipers whilst turning the steering lock?
A feeler gauge should give you a good indication of the pad clearance and if they are travelling back when steering. I have had similar issues with pedal travel due to caliper seals perishing and sticking to the pistons which causes pistons to retract too far when releasing pressure.

Steve

Thanks Steve. I've tried that with no luck. The reason being the issue doesn't show up when the wheels are stationary. So I think I'll have to do your suggestion, with all four wheels on axle stands and get the wheels moving. To see if I can see a problem, I'm hoping something will show up.

9th Feb 2016 4:46pm

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