Slow braking

[synthium]

Hi everyone, I'm new to the forum but have recently bought a 1997 defender 300tdi dualcab. Loving it so far but find the braking is quite slow-essentially if I didn't down gear it would take quite a while to stop. The discs look fine but not sure of the pads yet. When I put the handbrake on I can actually rock the car slightly back and forth to a point. Anyone have any idea if the rocking and slow breaking are related?
Thanks for your help.

[rick130]

Hand brake is a drum transmission brake at the rear of the t/case ;)

When you say slow, is the pedal 'hard' and high, or long ? (like a Japanese 4WD)

If long, the brakes need bleeding, if high and hard it may be a booster problem.
These things have a common problem of cracking the booster near the M/C, which obviously does wonders for the vacuum assistance.

There's a valve in the booster that can give problems too apparently, or the vacuum pump can be cactus.

[synthium]

Hi rick130 Thanks for the response! It is high and hard. If I slam on them it does stop faster but if I press slowly it reached a hard point where it does not seem to really respond.

[synthium]

Are there any simple tests to assess if it is the booster or vacuum?

[justinc]

booster sounds like it has no vac supply, or is split where the master cyl bolts to it, a common defender tdi problem. to check for vac, you need at least 15"Hg at idle at the pipe where it enters the booster, also check the pipework for leaks/ rubbing marks.

jc

[synthium]

Thanks jc. I will have a look at it when I can ( at work for 12 hours tomorrow :( so hopefully time on Thursday!

[ajge]

Are there any simple tests to assess if it is the booster or vacuum?

Hi
With the engine running pull the vacuum hose out of the booster. There should be vacuum (air sucking in the pipe). If there is then I would be looking at the booster. Otherwise the pump has failed. I'm on my 4th pump in 400K.

Regards
Andrew

[synthium]

Thanks for that. Seems simple enough to do. Hopefully will have it worked out and resolved soon. Brakes are rather important.

[nedflanders]

Quick test is with the engine off put your foot hard on the brake, keep your foot on the brake and start the engine, the pedal should sink about an 1" if the servo is working, if not either a servo or vacuum pump issue.

[synthium]

I have taken the vacuum pump hose out of the booster while it was running and found there is suction, which pulses slightly. It is enough to suck onto my hand but easily pulled off. Unfortunately I do not currently have anyway to measure the "Hg. Does this seem too weak or do I really need to get a tool to actually measure the suction.
I also did the test suggested by nedflanders and found that the pedal did not noticeably depress once I turned on the engine. Does this seem to be the booster? Anything else I should try?
Thanks for all the help
JP

[rick130]

You'll probably need to get a vacuum gauge and check.
460cixy checked and tested a pump for me last week just so I knew what vacuum to look for on mine and it surprised us both by pulling 24" at idle.

Also have a really good look around the booster where the m/c bolts on, and with the engine running listen for any hisses.

Get someone to jump on the brake pedal HARD and look for deflection where the m/c bolts on at the booster.
This will indicate a crack too.

[synthium]

Ok - have found hairline cracks in the servo. Looks like the problem has been identified.
Thanks everyone for your help!

[rick130]

Ok - have found hairline cracks in the servo. Looks like the problem has been identified.
Thanks everyone for your help!


Really, really common.

Make sure you buy a TRW (genuine manufacturer) version, there are other aftermarket ones around that aren't worth a pinch of the proverbial.
One of the members here posted a video of a cheap one he bought and the flex at the M/C had to be seen to be believed.

[synthium]

Great thanks for the advice. I have ordered one from British Offroad.

[synthium]

Just to bring the thread to completion - I put in the new servo and braking is 100times better. Thanks all