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MG Midget and Sprite Technical - Fitting new brake calipers

Am fitting new brake calipers to my 1970 midget.
The pistons in the calipers are pressed right in.
I have also got green stuff pads.
When I took the old caliper off the pads had anti squeal shims, which I will refit with the new pads.
The pads came with a small sachet of lubricant and 4 rubber self adhesive square pads about 1" square

1) Do I need to put any lubricant onto the pistons in the caliper, as I can't see how to extract them off the car.
2) Do I put a bit of lubricant onto the anti squeal shims ( I assume I do)
3) what is the purpose of the 4 square pads? I assume they should be stuck on the back of each pad, but then it would foul the shims, which would not then sit flush.
Geoff
Geoff Mears

Sorry,
Point 1) I mean "extract them with the calipers off the car"
Geoff Mears

Hi Geoff,

Are there not instructions with the pads?

My memory is hazy, but I have vague recollections of cutting the rubber to match the back of the pad and sticking it to the pad. I think I ditched the shims, they seemed fairly pointless to me!

The lube might be slider pin grease (is it silicon grease?) which maybe gets chucked in with every set of pads regardless, but on the Midget is not needed. I am guessing...

Malc.
Malcolm

I don't recall any rubber pads. Certainly I have never had any. I do use the shims though, it helps prevent squeal along with some anti-seize compound such as Copper slip. The lubricant is also a bit of a mystery. can't see why its needed. my green stuff pads are fine and were installed 'dry'.
Bob Beaumont

Geoff. I am not completely clear on what you are saying. You post of new calipers and new pads. Are you replacing both?

New calipers should have had the pistons lubricated at the factory and rebuilt units should have been lubricated when they were rebuilt. The inner sections of the pistons (the part that sits inside the caliper) would have been lubricated so that they would slip into the rubber seals more easily.

Originally, the disc brake pads were fitted directly against the discs in the caliper. The "anti-squeal" shims were a later development and I do not remember ever using them "back in the day". I do know that none of the factory disc brake pad sets came with either lubricant or shims. The use of the shims and lubricant is a more modern convention and, if the pads require the use of the shims, lubricant, paper pads, etc. it should be noted on the instructions (if any) included with the pads. If there are no instructions, the best thing to do would be to contact the technical services section of the manufacturer and ask their advise on what to use and how to use it.

When BMC introduced disc brakes onto the various sports cars, the vast majority of automobiles were still using a drum based system on both the front and rear axles. MG was one of the first factory vehicles, at least here in the US, to offer front disc brakes--later an industry standard. But, MG went out of production. Other vehicles adopted the innovations pioneered by MG and have continued to perfect them. Thus, a call to the tech support at Moss Motors, the manufacturer of the parts, or something like one of the owner's clubs might provide some very useful information that you can bring back to us about how we can best set things up today. Yesterday's advise, which is all we can give, might be as obsolete today as the practices were decades ago when the cars were new. Or, the original methods might be best on the vintage cars. A tech support section would be the best place to find out definitively.

Les
Les Bengtson

Hi Malcolm.
Yes there were instructions but don't cover my questions. The rubber items are clearly meant to be stuck to the back of the pads. There was no info on those, so I just need to decide whether to stay with the anti squeal shims or try the pads. The last lot of green stuff pads that I had didn't come with the rubber pads. I'll probably go with the shims again.
The lube is slider pin grease, so I will ignore.
Bob, I've not got any copper slip - any other suggestions as alternatives? Otherwise will just clean the shims up.
Les, Yes I'm fitting new calipers and new pads.

And finally, I've got some Mini front drum brake linings which are identical to Midget ones except they are wider. I have cut the leading edges to match the Midget ones and am reliably informed they will fit inside the drums. I'm assuming extra lining on the drums will stop me better.
I expect there will be a reason why I shouldn't do it???
Geoff Mears

Geoff I used the wider mini brake shoes on my '71 car. They work ok, but TBH I couldn't really tell the difference. The only explanation I could come up with is that although you get a greater surface are of contact, the mechanical advantage of the pedal lever and hydraulics remains the same. Result is a lower contact pressure per unit area. What you gain on contact surface, you loose in contact pressure! Someone will now tell me that friction doesn't work quite like that, but that is how it seems to me.
There may be other factors at work. The 'servo' effect of twin leading shoe brakes with wider linings? Better heat dissipation? . ... ...?
GuyW

No worries if you haven't any copper slip. The shims clened up will be ok. The slip is just another anti squeal preventative.
Bob Beaumont

The rear shoes are only there to stop the pistons popping out the rear cylinders. They don't actually help to slow the car down! Ha ha ;-)

Guys experiences and explanation sounds plausible.

Malc.
Malcolm

Geoff
Well, I don't know where to start---------
Each to his own and I'm all for enthusasts working on their own cars------BUT
Honestly, if you don't know what you're doing fitting something as life dependant (yours and others) like brakes ,maybe it's not such a good idea to be doing it yourself

To try and answer your questions and try and get you working properly----

First off the pistons should be pushed right into the calipers when they come and need nothing done to them--leave them alone
If your greenstuff pads are green on the backs, then clean and fit your original anti squeal shims without any extra goop
If the pads have a metal or heatproof shim attached to the rear of them then you won't need the shims
What the stick on rubber pads are is beyond me, if they're rubber they'll just burn up if they're on the pads---in the bin they go--if they're rubber
Coppercote is crap on pads, it melts and runs everywhere---If you're going to use anything(which you shouldn't need to with shims)use something that firms up like CRC Disc Brake Quiet
And please, if you aren't 100% sure of what you're doing get someone that does to have a check of what you've done

Have you read the literature with your pad kit
ONe little item you might have missed---

"When replacing brakes of any kind please remember how important brake safety is to your own well being and either have a professional mechanic install your new brakes or if you are a qualified mechanic use the EBC installation DVD as a guide in support of your vehicle owner’s manual."

willy
William Revit

Make sure that the brake pads edges are smooth and round where they touch the calipers, so they cannot stick.
Sometimes the edge of the piston has a cutaway part. It must be assembled at the lower end of the caliper. (Photo is in the MG A)

Flip


Flip Brühl

Willy
Well said. You have probably stated what many think but hold back on actually saying.
Alan
Alan Anstead

GuyW is correct about wider rear shoes. Infact it also applies to disc pad area and tyre width. Where there is a difference is with wear rate. The bigger the area the longer they last but definitely no increase in braking force.
Rob
MG Moneypit

I know Willy is right, but replacing these parts is not difficult and with care and methodical work it is quite within the capabilities of most DIY owners. Geoff is rightly asking questions and getting good advice to enable him to proceed safely. The dangerous ones are those that faced with a problem just carry on regardless, or omit items difficult to fit etc etc.

The fault, if there is any here, is in the parts suppliers who package up kits with components not required for the application in hand and fail to provide clear instructions about what is needed for the specific application. If the calipers are pre assembled with the pistons and seals in place there is no need to include the rubber lubricant and why include sliding pin lubricant for calipers that don't work like that!

There are tips and advice that experienced folk here like Willy can give and that is the way to learn how to work on these cars. Better still is to find someone who knows the job and who can come and help, show you how it is done. MASC contacts can be particularly helpful and reliable for this.

Incidentally, the rubber squares don't sound like anything that could be used an brakes liable to get hot. Are you sure they are not just part of the packaging?
GuyW

I am sure I have seen and used what Geoff is talking about, they are a bit more sophisticated than common or garden rubber.

I am beginning to doubt if it was on the Midget though... it may have been another car... I can't remember! Even at my fairly young age, I have done enough brake pad swaps on various vehicles that they are all blurring into one another!

Getting old!

Malc.
Malcolm

Like these things (it doesn't tell you what they are actually made of though)...

http://www.amazon.co.uk/Brake-Anti-Squeal-Backing-Universal-fitment/dp/B07QBCGP17

And a similar discussion on a much lesser motoring forum...

http://www.tr-register.co.uk/forums/index.php?/topic/12714-anti-squeal-shims/

Malc.
Malcolm

Geoff,
if you still need help I can give you a contact at EBC to email, he's asked for a photo of the contents of the box to be certain.

I don't like to give out names on the open web but you can email me so I can pass on details to you.

Cheers.
Nigel Atkins

ISTR I had the self adhesive strips with my green pads but I didn't use them.

I think this is what is being refered to :-

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=253775735694&_sacat=0

EBC brakes parts and sold by MGOC for the 'B' so do others use them?

I smear just a tad of coppercoat onto the back of the pads - as was taught by my local garage owner in the late sixties (BMC trained) when I helped ? out a bit. Also just a tad of white grease on the rear brake shoe pivot points.

On a Spridget its very important to keep the rears well 'adjusted up' as it really seems to effect the performance more than other cars i've had.

R.
richard b

Also, I assume new copper washers will be fitted to the banjo connectors. I've had slight seepage with these and was told by the good folks here to anneal them first so they crush better. You also want a smooth surface between inner washer and caliper, maybe better with paint removed.
Bill Bretherton

Yes carefully remove any paint between mating surfaces as they should be machined flat.
richard b

"between mating surfaces" including between caliper and hub carrier, where it bolts on, and both sides of the guide bracket that holds the flexible brake hose at the correct position, using the same 2 caliper mounting bolts.
And, assuming you have bought a pair of calipers do make sure they go on the correct sides! Bleed nipple at the top. They will fit perfectly on the wrong sides but it is somewhat annoying to find at the final hurdle that they then won't bleed properly! BTDT!
GuyW

Thanks to everyone for your helpful comments. I am awaiting an order for new bolts, washers and locking tabs so I can replace everything with new parts. I think that some of the “extra” items that I received with the green stuff pads are just put in automatically.
I do like this BBS as there is always someone willing to offer their advice.I have owned Spridgets on and off for 50 years, and sometimes like to get other people’s thoughts on specific jobs. I rebuilt my current Midget into a Heritage shell back in the 1990’s.
Attached is the pack of rubber received.



Geoff Mears

Geoff,
did you see my post at 14:54, no problem if it's not wanted or needed.

Don't bother with the lock tabs from the likes of the usual suppliers as they've not enough tab to them and are flimsy, use split washers and/or threadlock instead.

For the wider shoes to rear, depends on material as to if they're better, all explained to me a couple of year back, all in Archives now. You will need to clean up the existing drums to allow for the areas where the extra width will go. New drums, just usual, and perhaps their quality.

Just cleaning the drums and fitting new shoes correctly and adjusting them correctly will probably give improvement over old shoes especially if they needed cleaning and or adjustment.

Also bear in mind the tyres are a great influence on braking (and steering, road holding, handling and ride comfort and noise) so if you retain tyres gone hard from lack of use and/or age (regardless of tread depth left on them) you won't be getting best braking performance, negating the pad upgrade.
Nigel Atkins

Hi Nigel
Thanks for the kind offer but am ok thanks. My rear drums are in good condition - will get round to cleaning them up when I’ve sorted the front. Tyres are about 3 years old. Car normally gets used regularly so tyres in good condition.
Geoff Mears

Geoff

When I fitted Mintex front pads I do not remember getting extra bits that I did not need to confuse me! The advice on making sure the rear brakes are adjusted properly is good. And wheel cylinders not leaking.

What shoes are in the back as going for EBC Green Stuff on the front sounds like a bit of upgradeitus, would standard set up in good condition including all lines and hoses and good quality standard pads, shoes, discs and good condition OE drums, fresh fluid and well bled might be good too? (As well as dampers flushed and filled with fresh 20W Silkoline fork oil and suspension bushes not perished, suspension bolts correct torque, trunions oiled and good tyres not too old and at correct pressure.

Cheers
Mike
M Wood

Hi Mike
I have been using goodridge flexible hoses and green stuff pads, and also have frontline suspension. The back brake shoes are standard at the moment, and to be fair the overall system seemed to be reasonably good when it came to stopping. I just thought whilst fitting new callipers I’d check the whole system through, and the mini shoes seemed (to my mind) a way to improve things. I knew that they fitted ok, but thanks to more knowledgable people here it would seem that ithere is probably no difference. Whilst on the subject of stopping (when parked) I can thoroughly recommend using 1500 handbrake cable set up instead of the standard rod system on earlier cars.
I shall be putting new fluid in.
Geoff
Geoff Mears

Geoff,
no problem.

With the brake shoes it the same as with tyres really, a wide tyre doesn't necessarily get you more grip as it depends on the tyre's compound.

As with most things about setting the car up it's a matter of balance, you don't want the front braking overpowering the rear braking.

If you've got the new wider shoes you might as well fit them and see if they make any difference, depending on your existing shoes the wider ones might be better just by being newer and less worn.

The Greenstuff front pads have their own bedding/breaking in surface but with the shoes it'll be a matter of nipping up as required.

If you wanted, once out of the bedding-in (for front and rear) and adjustments as required you should be used to the feel of the brakes (and pedal feel) you'd be able to do tests to see how the braking is set.
Nigel Atkins

Others,
as Geoff had already read the instructions I went on to another novel idea for some, I rang the manufacturer to ask them.

They were great in their response.

The receptionist took details of my enquiry, my name, phone number and email and within minutes of putting the phone down I got an email response from the Automotive Product Manager and follow up emails from him to check.

Now I don't know if I got such favorable response because of my refined speaking voice and charm, which may have also hinted at my good looks, or my local telephone number, or none of these but it was simple, easy and quick.

Like most I was pretty certain I knew what the pads and lube were for but always better to ask to be certain as we all know what assume means.
Nigel Atkins

This thread was discussed between 15/02/2021 and 17/02/2021

MG Midget and Sprite Technical index

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