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BigJimny Meet 2019 (17 May 2019)

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20TH OCTOBER 2019

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Noggin and Natter - pre-event chat - Old Bell at Grazeley (part of hotel) 7:30pm 19th October

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Re:Re:Jimny Front Brakes Seizing

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19 Aug 2019 15:40 #212304 by Witzend
Hello all – I have been a reader of this site for years, but have just registered as I am stumped by this. I had my last Jimny 10yrs, did 132,000miles and it never gave me any problems, but I replaced it a couple of years ago with a 2012 SZ3, and months ago the front brakes started binding soon after setting off on the first journey each day. I have freed off the callipers, cleaned and re-greased the pistons, polished and re-greased the sliders and replaced the pads.
After reading just about every post on here about brakes, I see that some others have experienced similar problems, but nobody has confirmed what the cure was. Following suggestions made in these posts, I have run it with the servo disconnected; with the fuses removed from the ABS pump and with a replacement (2nd hand) ABS pump all with no change. The problem appears to be a build up of hydraulic pressure, but does not seem to affect the rear, only the front, backed up by the unchanged rear shoes still being in good condition, but the new front pads already being worn down. When they seize, there is very little travel in the pedal, and it always affects both sides, suggesting it is not a flexi pipe issue. Relieving the pressure by cracking a nut on the ABS pump instantly releases both callipers, suggesting the callipers are working correctly. As I don’t get increased pedal travel and it only affects the front, it suggests the master cylinder is working OK. If there is a problem with the ABS pump, it would mean a problem with both the original and the replacement, and is still an issue with the fuses removed, so I am guessing it is not this, either. It still happens with the servo vacuum disconnected, suggesting the servo is not the cause.
The front brakes get very hot and seize so much that hills are a problem, the top speed is reduced to 40mph and the mpg is down to less than 2/3 what I used to get. When stationary, it is impossible to push it or roll it downhill, yet when left standing with the engine off for an hour or so, the brakes have released and the same journey can be done with the brakes working perfectly with no seizing or heat build up, no matter how much I pump the brakes. Also, it can sometimes release itself during the journey – you can feel the performance increase and the pedal travel return to normal. There is a connector/splitter (pressure differential balance valve?) between the master cylinder and the ABS pump that I am thinking of replacing as I cannot see what else can cause this, but I am really clutching at straws – any ideas (especially from those who had this problem in the past)?
Thanks for reading.

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19 Aug 2019 18:07 #212316 by Lambert
Welcome to the forum. I haven't had this myself on Dreadnaught, just the usual slider seize problem occasionally. So somehow you're getting excess pressure in just the front system? I'd expect a fault code if it were abs related. Have you examined the hard lines forensically from master to caliper for and sign of deformation or damage including the fittings?

Dreadnaught (black 2011)

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19 Aug 2019 18:19 #212317 by Witzend
Thanks, Lambert. It's as if there is a sticking valve, allowing pressure to build up in both front callipers but not releasing it. I've looked at the pipes and they're all in good nick. The only part of the system with any corrosion is the around the outside of the aforementioned splitter (bolted to the inside of the n/s wing just below the ABS pump). I've ordered another, but if this is just a connection block with no valves inside then I can't see it being that.

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19 Aug 2019 20:14 - 19 Aug 2019 20:14 #212329 by mlines
Has one of the flexible pipes collapsed internally, acting like a one way valve

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Martin

2003 M13 early KAP build.
3" Trailmaster lift with 1.5 Spacers on front
Customised winch bumper and roll cage
235/85R16 Maxxis Bighorns on 16" Rims, 4:1 Rocklobster, Rear ARB locker and on-board air
Corrected arms all-round, rear disks, Recaro seats and harnesses
Last edit: 19 Aug 2019 20:14 by mlines.

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20 Aug 2019 05:03 #212341 by CC Baxter
I had this problem on a 2009 Swift. I suspected the master cylinder so got a used one from ebay and a new seal pack ( total cost about £60). Never any trouble after that.
Chris

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20 Aug 2019 06:56 #212344 by RainerK
What would be the position of your breaking pedal in each case?

It sounds like the break is applying pressure without pressing the pedal.

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20 Aug 2019 07:12 #212346 by kirkynut
I think I'd be replacing the front flexi hoses as Martin says first as they're cheap and are likely due for renewal anyway. Then if that doesn't solve it, the master cylinder.

If it's definitely both sticking on I might be tempted to do the master cylinder at the same time as you've got to do a load of bleeding anyway.

Kirkynut

The underdog often starts the fight, and occasionally the upper dog deserves to win - Edgar Watson Howe.

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20 Aug 2019 07:51 #212352 by sniper
Same issue started on my 05' car and I replaced both front callipers with a pair from Germany £58 ea. I can't remember the retailer but it was from eBay.

I remember laughing at myself, new callipers a performance mod...... well the car was quicker...... :laugh: :laugh: :laugh:

I did the flexi hoses first as kirkynut suggests.

sniper

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20 Aug 2019 08:20 - 20 Aug 2019 08:21 #212365 by Jimx5
Check that you have clearance/free play between the brake pedal and master cylinder push rod.
Seen this problem many times where someone has over adjusted the push rod or the push rod lock nut has come loose.
Last edit: 20 Aug 2019 08:21 by Jimx5.

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20 Aug 2019 18:55 #212409 by Witzend
Martin, thanks. From previous posts on here I also wondered about this, but as it affects both front brakes at the same time, I ruled this out. Also, when it clears itself, it clears both. It has never affected just one of the front brakes, so I was looking at something before the pipes separated.

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20 Aug 2019 19:01 #212410 by Witzend
RainerK, thanks for this. The pedal gets progressively harder up to the point that the brakes seize. If and when it clears itself, the pedal travel returns to normal, suggesting to me a gradual build-up of pressure each time I apply the brakes. I don't think that the pressure is building up without depressing the pedal, but I can't rule this out - I will try just using the handbrake for a run around some quiet roads and see if it happens without the brake pedal being depressed.

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20 Aug 2019 19:17 #212413 by Witzend
Thankyou CCBaxter. Someone on a previous post suggested changing the master cylinder, but I couldn't see that there was a way this could affect the front brakes without also applying pressure to the rear. There are 2 pipes coming from it, but on an exploded diagram I found, it names them as primary and secondary. They go to a connector/compensator/pressure differential valve (not sure which) and the 2 pipes coming out are then described as Front and Rear. I've got another one of these connectors on it's way and I'll have a close look at it and decide whether it's worth a try but if you say your Swift had a problem with just the front brakes seizing, I'll look at changing the master cylinder instead.

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