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Brakes Help Before I Go Mad


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#1 miniman86

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Posted 08 January 2019 - 07:26 PM

Hi guys and girls, got a really strange problem. On my 1975 998 auto clubman estate, I've recently changed the front backplates, as the adjusters on the original ones were knackered. Swapped them over for a decent pair of back plates, adjusters work nicely, not siezed but nice and tight. Bled brakes with an easy bleed, and a visibleed on the wheel end. Bled in the correct sequence until there was just fluid coming out from all four bleed nipples. Now have awful brakes, comparing it to my 1970 estate with drums all round, the pedal feels awful. All the way to the floor. I've adjusted the fronts in the correct way (the way the wheel would go when travelling forward) but still no luck. Even left the pedal depressed overnight in case there was any air left in that i couldn't get out. Still no luck. Is this just a case of keep adjusting them until the shoes are re bedded into the drum correctly, or have I missed something out? Any help is great fully recieved!

Alex

Edited by miniman86, 08 January 2019 - 07:27 PM.


#2 sc-em

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Posted 08 January 2019 - 08:07 PM

Have you checked the rear wheel cylinder just in case you have one of those leaking.



#3 spraybeater

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Posted 08 January 2019 - 09:00 PM

Have you refitted the beehive shaped! retainers, between the wheel cylinder pistons

and the shoes, and make sure their are no leaks any where and all adjusted properly!

Drum brakes do work perfectly well if looked after.



#4 Norris73

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Posted 08 January 2019 - 10:14 PM

Having just had a similar nightmare with my '79 Clubman Estate, I would suggest tightening all 4 front adjusters fully up - locking the wheels (turn in direction of wheel forward rotation). If you then have a good pedal at top of movement you know that you have no air in the system and that the issue is adjustment. Also when bleeding I found having the handbrake off helped get the last of the air out of the rear circuit.

 

I have given up on drums, as they just require too much adjustment and have always squealed like mad after a handful of applications.

 

Good luck hope you get it sorted, I finally gave in after 8 days of playing with the drums and bought a Cooper S disc brake conversion kit (back plates were knackered on the drums)


Edited by Norris73, 08 January 2019 - 10:18 PM.


#5 Moke Spider

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Posted 09 January 2019 - 02:13 AM

If you have some Brakes, sometimes with Drums after a rebuild like this in particular, going for a short drive on quite streets and a few hard applications of the Brakes settles them and breaks them in a little, then try adjusting again.

 

This tends to be the case where a solid peddle feel is present, but just a very low peddle.

 

If it feels spongy, then there's still air in the system.



#6 miniman86

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Posted 09 January 2019 - 07:10 AM

Thanks for the advice. Yes the beehive shaped retainers are on the shoes. I will lock the fronts up tonight and see if I have a good pedal. Also I'll whip off the rear drums and check the cylinders, but there is no weeping externally that I can see, and they were fine before. Also, I put the easy bleed on without any fluid initially, and put some air through, couldn't hear any air leaks so I'm thinking that I have a sealed system...

Alex

#7 Boycie

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Posted 09 January 2019 - 09:13 AM

I don't know why, but it always takes me so long to get a good pedal with an all-drum setup.  When I recommissioned my City last summer, I totally rebuilt the whole system and then spent two days trying to get it bled out properly!

 

Some things to try-

Turn the front adjusters up so the drum is solid and then try bleeding again.  Do one wheel at a time, starting with the furthest away from the master cylinder.

Do it the old fashioned way, ie someone in the driver's seat operating the pedal.  Get your glamorous assistant to get any pressure they can on the pedal, hold it down and then you crack the bleed screw.  When you undo the bleed, keep thumb pressure on it to minimise air leaking back in, past the threads.  Nip it up and ask your assistant to raise the pedal slowly.

Do all four corners.

If you get any sort of pedal, slacken off the adjusters so the wheels move and as suggested, get some heat into the brakes.  I don't know why this can help, but it does.

Luckily you should be without the FAM valve on the bulkhead as a 1975 car should still be the single circuit brakes?

 

I went through many litres of fluid on mine and finally I got a solid pedal that bites right at the top of its travel.  But I'll admit, I almost gave up at one point!



#8 Rorf

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Posted 09 January 2019 - 12:32 PM

Do the experts here advocate using the small springs which connect the brake shoe to the cylinder piston on the front drums.



#9 Boycie

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Posted 09 January 2019 - 06:18 PM

I'm no expert but mine doesn't have them and my drums are excellent now.



#10 Rorf

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Posted 10 January 2019 - 06:03 AM

I'm no expert but mine doesn't have them and my drums are excellent now.

 

Good to hear as I have often wondered what their actual purpose is, and they are not cheap. Mine were removed about 20 years ago but currently doing a full rebuild and wondered if I should get them.



#11 spraybeater

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Posted 10 January 2019 - 10:59 AM

OK, as the first person on this thread to mention the Beehive retainers! here is my take on  their fitment.

The twin leading shoe front drum brakes are adjusted by snail cam adjusters! so when they are adjusted

properly the shoes lift (albeit] slightly from the wheel cylinder piston seat, so when the brake is operated

that slight gap has to be taken up by pedal travel! So the Beehive retainer is fitted (in the pre drilled holes)

they inturn hold the piston hard against the shoes and they also retain the shoes to the back plate keeping 

the shoes in alignment.

We see time and time again sorties and questions on here about getting Drum brakes to bleed/work properly

as I said in my first post properly fitted and maintained Drum brakes do work.My first Mini back in 1966 ish

had drums, and we ran a successful Autocross/ Rallycross Mini on Drums in the seventies, the hubs were

specially machined to take 1100/ADO16! CVs, we could not afford fancy disc set ups then and they were

as good as if not better than the disc brakes that were available form early Coopers.

My current classic Mini has Drums and will retain them.

I await the views of others! these are mine as a retired, Body repairer, mechanic,MOT inspector, HGV fitter

work/shop manager and still working on and restoring Classic Minis.



#12 Rorf

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Posted 10 January 2019 - 12:09 PM

Thanks Spraybeater you have convinced me to install them, your explanation makes total sense and I can definitely see the potential problems of the piston pulling back from the shoe and causing that long pedal.






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