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Isuzu MU 1994 rear Disc brake

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Isuzu MU 1994 rear Disc brake

Postby IsuzuMU1996 » Sun Nov 18, 2012 11:16 pm

I'm back again with a question.
My Isuzu MU 1994 is equipped with disc brakes in the rear. The hand brake does hardly brake. It's not the cables from the handbrake until the callipers. I haven't opened the callipers yet but I assume that there is a handbrake-operated piston in the calliper? Would anybody have a repair manual on those calliper? I first would like to see a drawing before I dismantle them only to see that the spares won't be available here in Malawi.
Thanks, Martin
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Re: Isuzu MU 1994 rear Disc brake

Postby geeves » Mon Nov 19, 2012 4:22 pm

easy things first.
I assume you have the 2.8 engine and the handbrake that works on the disc not the one with the separate inner drum.
The cable adjuster is in the end of the piston and adjustment is by an allen key under the 12mm bolt on the back of the calliper.

Make sure the cables are free running in the outers. If they bind at all they force the caliper out of adjustment
Take the calipers off and note that the calliper slides directly on one bolt and on a sleeve for the other bolt The bolt and sleeve must be free moveing.
Refit calipers and adjust till they bind on the disc then back off till they stop binding.
Refit cables and adjust cables so you have 0.5mm between the endstop and the cable lever with the brake off.
These steps fix 85% of problems with this handbrake but they were never a good handbrake
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Isuzu MU 1994 rear Disc brake

Postby IsuzuMU1996 » Mon Nov 19, 2012 9:38 pm

You assume right, 2,8TD and no drum.
Thanks for your detailed instructions. Will only find time next weekend to work on them, but it would be really great if it could be solved like this without dismantling the callipers. It is very likely that the mechanics working on the car previously didn't know that.
Will let you know the results next week. Martin
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Re: Isuzu MU 1994 rear Disc brake

Postby geeves » Tue Nov 20, 2012 2:29 pm

one very serious problem that mechanics that dont know what they are doing can cause is by forcing the piston back the same way as the front will destroy the adjuster inside the caliper. These are a pig to work on and you have to make the parts
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Isuzu MU 1994 rear Disc brake

Postby IsuzuMU1996 » Thu Nov 22, 2012 3:47 am

A pity you can't see me smile. I took the afternoon off today and followed your instructions. Very clear and the handbrake is working now. Thanks! I discovered a typical african problem. Someone has damaged the front of the piston with a hammer. Now it's not square anymore and presses only on a small portion on the pad, probably the reason for the brake binding on that side ... sooner or later I will have to dismantle this calliper and repair the piston.
Thanks and good night.
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Re: Isuzu MU 1994 rear Disc brake

Postby geeves » Thu Nov 22, 2012 2:36 pm

Someone has damaged the front of the piston with a hammer

????????????????? Remind me not to go to that mechanic
The pistons can seize but that is not the way to free them
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Isuzu MU 1994 rear Disc brake

Postby IsuzuMU1996 » Fri Nov 23, 2012 8:32 pm

Most people here have either not the knowledge or not the tools and some of them even not the attitude. Still they try to do the job and that can end badly. When working on a car which was used and serviced in Africa you must be prepared to discover strange things. Like this brake piston.
The workshop manual which I downloaded earlier this month does not contain a chapter on the rear axle/differential. Would you know where to get one? On my MU the right wheels turns harder than the left wheel (with callipers off).
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Re: Isuzu MU 1994 rear Disc brake

Postby geeves » Sat Nov 24, 2012 7:14 am

grab what you want from here
viewtopic.php?f=12&t=4123
The TFS series and the kb series cover 95% of the Mu
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Isuzu MU 1994 rear Disc brake

Postby IsuzuMU1996 » Thu Nov 29, 2012 3:56 am

Got it thanks!
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Re: Isuzu MU 1994 rear Disc brake

Postby MuZILLA » Tue Feb 28, 2017 7:28 pm

I am doing a rear caliper overhaul on my 91 MU 2.8td. Brake piston out and most of caliper is now unseized. Im down to the 4mm Allen head adjustment bolt on the back of the caliper. This was seized. Soaked in wd40 and applied a bit/lot of heat. That freed up without much force at all after this method. Now turning this adjustment bolt does NOT turn the thread that the piston screws onto. Im pretty sure its supposed to. Am i wrong or would the threaded shaft be seized or is there teeth inside the housing which are no good?

Could someone please share some light on this before I light everything I have here on fire. :lol:
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Re: Isuzu MU 1994 rear Disc brake

Postby turnturn » Tue Feb 28, 2017 7:36 pm

Probably the teeth are shagged.
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Re: Isuzu MU 1994 rear Disc brake

Postby MuZILLA » Tue Feb 28, 2017 7:58 pm

Oh right. Thankyou for your pictures. Im struggling to get the little circlip out on the threaded shaft to have a look. But f*** that really sucks. :'(
When i do get it out of the housing and most probably will see a more eaten set of teeth. Would you know if i am able to get replacement parts for it or do i have to hit up an engineering shop? The caliper seal kit was hard enough to find in Western Australia. And second hand calipers get snatched up so quick they are pretty much non-existent here.

:? I think its time for a beer break.
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Re: Isuzu MU 1994 rear Disc brake

Postby MuZILLA » Wed Mar 01, 2017 4:38 pm

Ok, after a few beers, a bunch of swearing and a crapload of heat to melt the o-ring around that splined and threaded shaft. I finally got that shaft out along with the pin without much damage. Can't see much chance of getting the adjustment bolt out past the thread of the thin cover bolt. Unless you've got any ideas.

The teeth on the adjustment bolt don't look sheared from what I can see. Fingers crossed. But there was enough gunk in the teeth to make a smooth surface, probably letting the two sets of teeth to skip over each other. In the process of cleaning it out now.

Image
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