Spongy brakes off-road (Def 300tdi)

When off roading (low range box 2/3rd gear type), I found my brakes were very spongy, sometimes requiring two pushes on the pedal before working. This is nothing like having wet brakes. However, back on the road they behaved normally.

Any ideas please?

Guy

Reply to
Guy Lux
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Sounds like the Vacume pump isn't supplying a great enough vacume. We had this recently on Mrs D's Rangie, a quick inspection revealed a perished hose which had been prompted to fail by a mamouth commute. Sorted in our case with 10 seconds use of a stanley knife to cut away the worn hose.

Lee D

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Reply to
Lee_D

On or around Mon, 5 Jan 2004 09:44:06 -0000, "Lee_D" enlightened us thusly:

erm...

lack of vacuum is normally the opposite symptom, pedal gets hard.

Reply to
Austin Shackles

Sometimes when off road the extra vibrations and wheel movement can move the pistons back into the caliper slightly. Even with a couple of mil on each of your four caliper's pistons will be a greater volume of brake fluid is needed to bring the pads back into the action. This produces the soft feeling in the brakes and even the double tap required to brake. Motor cyclists who have had a "tank slapper" or severe front wheel wobble observe the same phenomenon

Reply to
News

Well I suppose it's down to your perceprion of hard , stiff floppy and level of pumping required ;-)

On the Rangie the pedal went from firm and High to low and lacking, once the vacuum was restored firm and High was again the norm. Whislt the pedal could be described as firm even when low the sensation elsewhere in my body when realising that the brakes weren't braking was not firm to say the least.

Again in our scenario pumping the pedal increased the efficiency but pumping the pedal and sheer panic aren't naturally at one with each other unless your well trained or super human.

Lee D

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Reply to
Lee_D

Guy Hi and Happy New Year,

I would suggest you check the endfloat of the axle bearings and the swivel locating pins and bearings.

Take care Pantelis

Reply to
Pantelis Giamarellos

Thanks News, sounds like a plausible explanation. Am going to check for bearing wobble on the back of this. Will also check the vacuum hose area just in case.

Guy

Reply to
Guy Lux

Hard or soft pedals, I'll check the hoses.

Cheers

Guy

Reply to
Guy Lux

"> I would suggest you check the endfloat of the axle bearings and the swivel

Indeed, i would check your bearings. I had a very small amount of play in my back left wheel bearing and when offroad it would take a full pump of the pedal to get any feel back into it, same happened when i hit speed bumps or took corners vigorously - both encourage the wheel to wobble with the free play. On normal road driving down motorways and stuff it was fine Changed the bearing and now the brakes are as good as gold all the time.

Nick C D90 300tdi csw

Reply to
Nick C

On or around 5 Jan 2004 10:13:24 -0800, snipped-for-privacy@hotmail.com (Nick C) enlightened us thusly:

all this talk of brakes reminds me that I should adjust the drums on mine sometime. Seems to be more travel than there used to be. Not as bad as Sister's BF's Series 3 which is used as a farm hack, on which the brakes take about 1.7 strokes of the pedal to come into play.

Reply to
Austin Shackles

Remembering my own experience last spring, if the adjuster doesn't seem to make a difference -- you should be able to lock the wheel with the adjuster -- you need to fit new shoes.

Reply to
David G. Bell

On or around Mon, 05 Jan 2004 19:15:22 +0000 (GMT), snipped-for-privacy@zhochaka.demon.co.uk ("David G. Bell") enlightened us thusly:

shoes are OK I think. They were replaced not *that* long ago. Looks damp here this morning, so it can wait...

Reply to
Austin Shackles

You're not bloody kidding!!! I had one once at about 60 while I was overtaking a bus on a road that had quite a lot of ripples on its surface. Accelerating makes the front go light which can help the tank slapper start. In my case it was low front tyre pressure that was the cause.

*Very* scary, makes you ride slowly and sensibly for a while after.
Reply to
Simon Barr

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