problem getting rear disc back on

Rick-sta · 26th December 2018, 16:05

Hi all,

Been replacing the brake discs and pads all round on the ZT-T today, front two went on easy as usual, however the rear one I've started is being a nightmare.

I've got the hold disc off, but when I fit the new disc I can only rotate it about 75% way round before it seizes completely and is impossible to turn by hand. The handbrake is off and I've also tried loosening off the handbrake shoes right down using the adjuster and the disc still seizes.

No idea why it keeps doing this even with the handbrake adjusted right down, the only thing I noticed is the handbrake shoes seem to have a fair bit of play/movement. I can move both handbrake shoes around together, sliding them side to side, up and down etc by about 3-4mm. I don't remember being able to do this on the other 75's and ZT's of ours I've changed the rear discs on previously. The shoes look like they could move enough to touch against the inside of the brake disc whilst the disc is turning.

The caliper is off whilst doing this.

Should the handbrake shoes be able to move at all? If not is there a way to tighten the handbrake shoes to stop them from moving so much?

Cheers
Rick

DMGRS · 26th December 2018, 16:11

Which shoes are they?
I remember Jules has had lots of issues with poorly-fitting aftermarket shoes over the years.

marinabrian · 26th December 2018, 16:12

The handbrake shoes should not cause the problems you describe Rick, and if the shoe steady springs are secure in the backplate then there will be no excessive movement.

Are the shoes centralised on the backplate??

Brian

Rick-sta · 26th December 2018, 16:24

No idea what make they are, could well still be originals looking at them. I'm only changing the discs and pads so the shoes I haven't changed.

I'll try and get a video of how much play there is, I centralised the shoes every time I try fitting the disc, but as soon as I turn the disc the disc jams.

marinabrian · 26th December 2018, 16:33

Quote:

Originally Posted by Rick-sta

No idea what make they are, could well still be originals looking at them. I'm only changing the discs and pads so the shoes I haven't changed.

I'll try and get a video of how much play there is, I centralised the shoes every time I try fitting the disc, but as soon as I turn the disc the disc jams.

Do the shoes look like the ones in Artic's picture Rick, especially the location of both the pull off springs, and the shoe steady springs?

If the adjuster is wound fully in, the pull off springs correctly fitted and the shoes are secured to the backplate, it simply isn't possible to have the web of the shoe jam against the drum.

Can you rotate the hub without the disc fitted?? ie the brake shoes aren't fouling the rear face of the wheel bearing

kelvo · 26th December 2018, 19:51

only one disc or both sides?

Does it matter which way you turn the disc?

Does it always do it in the same spot - perhaps rotate the hub 180 deg and put the disc back on and see how far it can turn then?

Have you tried putting the old disc back on?

If it didn't do it before you changed the discs then can't really see what else could cause it - there is a bit of movement on the brake shoes as they are only held by spring pins?

Rick-sta · 26th December 2018, 22:13

Yes mine looks pretty identical to the one in Arctic's pic.

The two springs which are mounted to the back plate are in, although they do move a little bit.

I can rotate the hub freely without the disc fitted yes.

It's only the offside disc, haven't started the nearside rear one yet.

Doesn't matter which way I turn the disc, clockwise or anticlockwise after turning more than 180degrees the disc kept jamming as if the handbrake was on. I recon it's definitely something to do with the shoes as the disc goes on easily (i.e not tight against the shoes), but when the disc jams it's really difficult to remove, it gets jammed on and has to be knocked off with a mallet.

oddly enough I went out again earlier as I was going to see if I can take a video but funny enough I centered the brake shoes and fitted the disc again and it's now spinning freely. Typical. I'll check tomorrow in the daylight if it is just me not centering the brake shoes well enough of if the issue is still there.

Many thanks for the replies by the way all, really appreciate it.

RoverP480 · 27th December 2018, 08:12

The brake is a duo servo type ,brake works as two leading shoes type the same forward or backwards The shoes are designed to float in use but the springs should keep them in position when the brake is in the off position. You trouble seems to be caused by the shoes grabbing the drum and self servoing on. Recheck the pull off springs and their location in the shoes plus the shoe retainers to the back plate. Its possible that the new drum is actually eccentric to the centre and the disc part!

slovcan · 27th December 2018, 13:28

Quote:

Originally Posted by RoverP480

The brake is a duo servo type ,brake works as two leading shoes type the same forward or backwards The shoes are designed to float in use but the springs should keep them in position when the brake is in the off position. You trouble seems to be caused by the shoes grabbing the drum and self servoing on. Recheck the pull off springs and their location in the shoes plus the shoe retainers to the back plate. Its possible that the new drum is actually eccentric to the centre and the disc part!

I was thinking about this last night. Is it possible that the shoes sort of keep themselves laterally centred in the drum when they are correctly adjusted? Conversely, when they are very loose by having the adjuster backed way off to the point that the upper and lower springs are not under tension, with the locating springs not providing any lateral support, can the shoes fall to the side and snag the side of the drum?

Just a thought,
Glenn

Edit: I guess this idea is sort of a counter-point to MarinaBrian's. Still, you've all had the up-close-and-personal looks at this setup.

macafee2 · 27th December 2018, 14:02

Quote:

Originally Posted by RoverP480

The brake is a duo servo type ,brake works as two leading shoes type the same forward or backwards The shoes are designed to float in use but the springs should keep them in position when the brake is in the off position. You trouble seems to be caused by the shoes grabbing the drum and self servoing on. Recheck the pull off springs and their location in the shoes plus the shoe retainers to the back plate. Its possible that the new drum is actually eccentric to the centre and the disc part!

forgive me, how can they work as two leading shoes (is that twin leading shoe?) The shoes are only operated at one end via the handbrake, the other end is basically still and only moves then the adjuster is manually moved.
is twin leading shoe where both ends of the brake shoe are moved towards the drum?
twin leading shoe has more brake materiel in touch with the drum then single leading shoe

macafee2

26th December 2018, 16:05	#1
Rick-sta This is my second home MG ZT 2.0 CDTI+ in Typhoon, MG TF 135 in Typhoon & Rover 75 Connoisseur CDTI SE in Pearl Black Join Date: Oct 2012 Location: Norfolk Posts: 7,534 Thanks: 2,718 Thanked 2,827 Times in 1,462 Posts	problem getting rear disc back on Hi all, Been replacing the brake discs and pads all round on the ZT-T today, front two went on easy as usual, however the rear one I've started is being a nightmare. I've got the hold disc off, but when I fit the new disc I can only rotate it about 75% way round before it seizes completely and is impossible to turn by hand. The handbrake is off and I've also tried loosening off the handbrake shoes right down using the adjuster and the disc still seizes. No idea why it keeps doing this even with the handbrake adjusted right down, the only thing I noticed is the handbrake shoes seem to have a fair bit of play/movement. I can move both handbrake shoes around together, sliding them side to side, up and down etc by about 3-4mm. I don't remember being able to do this on the other 75's and ZT's of ours I've changed the rear discs on previously. The shoes look like they could move enough to touch against the inside of the brake disc whilst the disc is turning. The caliper is off whilst doing this. Should the handbrake shoes be able to move at all? If not is there a way to tighten the handbrake shoes to stop them from moving so much? Cheers Rick __________________ How to retrofit Cruise Control on a diesel with no OEM wiring in place: Link How to retrofit heated electric memory seats with no OEM wiring in place: Link How to operate FBH and ATC via text Link How to restore cloudy projector headlights Link

26th December 2018, 16:11	#2
DMGRS Discount MG Rover Spares Rover 75 CDTi, 2x MG ZS180 Join Date: Jun 2011 Location: Hythe, Southampton Posts: 11,320 Thanks: 456 Thanked 3,377 Times in 2,027 Posts	Which shoes are they? I remember Jules has had lots of issues with poorly-fitting aftermarket shoes over the years. __________________ Your trusted MG Rover specialist! Tel: 02380 001133 / Email: [email protected] We now have a 'chat' function on our site for even quicker replies. Give it a try! Remember - discount code FORUM5 for 5% off

26th December 2018, 16:24	#4
Rick-sta This is my second home MG ZT 2.0 CDTI+ in Typhoon, MG TF 135 in Typhoon & Rover 75 Connoisseur CDTI SE in Pearl Black Join Date: Oct 2012 Location: Norfolk Posts: 7,534 Thanks: 2,718 Thanked 2,827 Times in 1,462 Posts	No idea what make they are, could well still be originals looking at them. I'm only changing the discs and pads so the shoes I haven't changed. I'll try and get a video of how much play there is, I centralised the shoes every time I try fitting the disc, but as soon as I turn the disc the disc jams. __________________ How to retrofit Cruise Control on a diesel with no OEM wiring in place: Link How to retrofit heated electric memory seats with no OEM wiring in place: Link How to operate FBH and ATC via text Link How to restore cloudy projector headlights Link

26th December 2018, 22:13	#7
Rick-sta This is my second home MG ZT 2.0 CDTI+ in Typhoon, MG TF 135 in Typhoon & Rover 75 Connoisseur CDTI SE in Pearl Black Join Date: Oct 2012 Location: Norfolk Posts: 7,534 Thanks: 2,718 Thanked 2,827 Times in 1,462 Posts	Yes mine looks pretty identical to the one in Arctic's pic. The two springs which are mounted to the back plate are in, although they do move a little bit. I can rotate the hub freely without the disc fitted yes. It's only the offside disc, haven't started the nearside rear one yet. Doesn't matter which way I turn the disc, clockwise or anticlockwise after turning more than 180degrees the disc kept jamming as if the handbrake was on. I recon it's definitely something to do with the shoes as the disc goes on easily (i.e not tight against the shoes), but when the disc jams it's really difficult to remove, it gets jammed on and has to be knocked off with a mallet. oddly enough I went out again earlier as I was going to see if I can take a video but funny enough I centered the brake shoes and fitted the disc again and it's now spinning freely. Typical. I'll check tomorrow in the daylight if it is just me not centering the brake shoes well enough of if the issue is still there. Many thanks for the replies by the way all, really appreciate it. __________________ How to retrofit Cruise Control on a diesel with no OEM wiring in place: Link How to retrofit heated electric memory seats with no OEM wiring in place: Link How to operate FBH and ATC via text Link How to restore cloudy projector headlights Link

27th December 2018, 08:12	#8
RoverP480 Gets stuck in None at the moment Join Date: Jan 2018 Location: Hereford Posts: 501 Thanks: 1 Thanked 165 Times in 146 Posts	The brake is a duo servo type ,brake works as two leading shoes type the same forward or backwards The shoes are designed to float in use but the springs should keep them in position when the brake is in the off position. You trouble seems to be caused by the shoes grabbing the drum and self servoing on. Recheck the pull off springs and their location in the shoes plus the shoe retainers to the back plate. Its possible that the new drum is actually eccentric to the centre and the disc part! Last edited by RoverP480; 27th December 2018 at 08:15..

26th December 2018, 16:12	#3
marinabrian MG ZT Join Date: Jan 2011 Location: Newcastle Upon Tyne Posts: 20,151 Thanks: 3,565 Thanked 10,837 Times in 5,718 Posts	The handbrake shoes should not cause the problems you describe Rick, and if the shoe steady springs are secure in the backplate then there will be no excessive movement. Are the shoes centralised on the backplate?? Brian

26th December 2018, 19:51	#6
kelvo Gets stuck in MG ZT 190 SE Join Date: Oct 2017 Location: Chatham, Kent Posts: 569 Thanks: 22 Thanked 163 Times in 135 Posts	only one disc or both sides? Does it matter which way you turn the disc? Does it always do it in the same spot - perhaps rotate the hub 180 deg and put the disc back on and see how far it can turn then? Have you tried putting the old disc back on? If it didn't do it before you changed the discs then can't really see what else could cause it - there is a bit of movement on the brake shoes as they are only held by spring pins?