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Front Drum Brake Adjustment


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#1 kiwimike01

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Posted 03 July 2019 - 07:48 AM

Hey guys I am trying to adjust the front drum brakes for a warrant of fitness (New Zealand version of MOT, I think) but as im turning the adjustment screw in the forward rotating direction of the wheels as suggested by the haynes manual it just keeps spinning without the pads binding. The wheel can keep spinning freely. Am I going the right way on the screw and if so why will it not bind to lock?



#2 smurfomatic

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Posted 03 July 2019 - 07:58 AM

Take the drum off and look t the adjuster - see if the "wedges" are moving properly when you're turning it. Might be that they've seized or they're too worn to adjust any further.



#3 Moke Spider

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Posted 03 July 2019 - 09:12 AM

The Front Brakes adjust on a Cam mechanism rather than a Screw and Wedge, like the Rears.

 

When the Shoes and / or the drums are well worn, the adjuster will spin over as you are finding.

 

There is 2 Adjusters on each wheel (so 4 in all for the fronts). One is fairly easy to see the other is hidden behind the Steering Arm.



#4 kiwimike01

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Posted 03 July 2019 - 09:28 AM

Thanks for the quick reply. I will take them off tomorrow to have a look and let you know how I get on.

#5 smurfomatic

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Posted 03 July 2019 - 10:00 AM

The Front Brakes adjust on a Cam mechanism rather than a Screw and Wedge, like the Rears.

 

When the Shoes and / or the drums are well worn, the adjuster will spin over as you are finding.

 

There is 2 Adjusters on each wheel (so 4 in all for the fronts). One is fairly easy to see the other is hidden behind the Steering Arm.

 

Oops - missed the first word of the thread title! Thought the OP was adjusting rears...



#6 Norris73

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Posted 03 July 2019 - 04:48 PM

Another thing worth checking with the front drum adjusters is that they are securley pressed into the back plate. Remove the drum and give the adjuster a wiggle from the back of the backplate, if the adjuster cam moves up and down relative to the backplate it is loose and will never hold adjustment. Unfortuntley replacement means complete new backplates.


Edited by Norris73, 03 July 2019 - 04:49 PM.


#7 kiwimike01

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Posted 06 July 2019 - 12:48 AM

OK I've pulled the drum off and the top adjuster spins and makes the pad go up and down. The adjuster is wobbly and a very thin broken washer did fall out of where the it comes through the back plate... I put the drum back on but it still won't lock the wheel at full adjustment. Also when I wind it up fully the shoe pops out of the piston assembly thing and sits on top of it instead of in the groove, not sure if this is an issue. The shoes are worn down to about 3 mm too so maybe there isn't enough meat left to bind to the drum.

This is only the left front, the right front adjusted and binded no worries.


Edited by kiwimike01, 06 July 2019 - 01:50 AM.


#8 imack

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Posted 06 July 2019 - 05:49 AM

Have you got the springs fitted that attach the shoes to the wheel cylinder pistons?

#9 kiwimike01

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Posted 06 July 2019 - 08:50 AM

There was just the 2 long springs that hold the shoes together. Are those the ones you are talking about or is it missing something else?

#10 Boycie

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Posted 06 July 2019 - 09:36 AM

All good advice here. I'd also add- check the shoe metal part where the adjuster cam contacts it. Any obvious wear here means you won't get the adjustment necessary for a good pedal. I've fixed that issue on my car and it fixed 'the dreaded long pedal' instantly. This was after days of bleeding the stupid thing first!

#11 Rorf

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Posted 06 July 2019 - 11:21 AM

Brake linings when new are 4mm thick. I would check your drum inside diameters too - more than 180mm and they are very worn. If the adjusters turn without resistance then you need new back plates. Also yes you need the small springs which hold the shoe to the brake cylinder piston.

 

Check these parts diagrams on the suppliers websites such as Somerfords or MinSpares.



#12 imack

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Posted 06 July 2019 - 05:00 PM

There was just the 2 long springs that hold the shoes together. Are those the ones you are talking about or is it missing something else?



No these, they attach to the shoe and then hook into a small hole in the end of the wheel cylinder piston preventing it retracting away from the shoes. Can't find a picture if them fitted.

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#13 A-Cell

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Posted 06 July 2019 - 07:11 PM

These 27H3753 front brake shoe retaining springs were only fitted to mk2 mini 1967 on along with larger bore GWC126 and GWC127 (0.9375 inch) wheel cylinders which have holes in the piston to attach the retaining springs to.
Mini spares http://www.minispare...ic/27H3753.aspx

#14 kiwimike01

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Posted 06 July 2019 - 07:52 PM

Ok thanks guys. I will replace the backplate as I think the adjuster might be too loose. I don't really know the service history so will also put new shoes on both fronts and add in the little retaining spring which is missing from both. I'll check the inside drum diameter too just to rule that out before I put my parts order in. Also is it worth changing the pistons to new ones at the same time? When i was trying to refit the shoes there was a fluid leaking out of one when i touched the rubber seal on top, not all the time just when i moved the seal.

My answer to this may be a while because funnily enough the supplier in New Zealand is out of stock with the front left hand backplate but not the right.


Edited by kiwimike01, 06 July 2019 - 07:56 PM.


#15 Rorf

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Posted 07 July 2019 - 06:21 AM

While you are in there I would definitely replace the front wheel cylinders, they are cheap enough.

 

Do the rears also and strip the master cylinder too.

 

I am sure the hydraulics in the clutch system will be in a similar condition. Brake/clutch hydraulic fluids should be changed every 2 years but the majority of owners never do.

 

Oh and replace all the hydraulic rubber hoses.

 

 

Never cut corners with the brake system, especially where front drum brakes are concerned - disc brakes are much more forgiving when it comes to maintenance.






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