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MG Midget and Sprite Technical - Brake Sticking On

Over the past few days/weeks I have been getting a nasty shudder from the front left area when pulling away from a stop at at junctions etc.

A bit of investigation shows the caliper seems to be binding on. Everything else seems in order, so I assume this is the cause.

Can anyone shed any light on the cause and remedy for such a situation?

Malcolm Le Chevalier

Yeah.... ive had this and seen this several times on the bbs

if your lucky its the hose brewking down inside but i think you have replaced yours not to long ago

the next common problem is the caliper piston is made from mild steel... most or stainless or chrome so the issue is moisture has made contact with the piston and its rusting

some times you can use compressed air (40 to 60 psi) and wd40 or other rust cutter ...and just keep working the caliper piston back and forth and hope it cleans its self up... if not then its ither a rebuild or a replacment...

On mine i just replaced it and took all the risk out of me doing the rebuild just wasnt worth the risk of saving $25

Check and see but i think denatured alcohol will help to clean out any brake fluid residue ... you can find D.A . at any home paint store

Prop and the Blackhole Midget

This is not uncommon Malcolm. As Prop said it can be the flexi hose liner acting as a non-return, but that's less likely where the hoses are good quality and good condition as I'm sure yours will be.

Very often just unbolting the caliper, popping the pads out and giving everything a really good blast out with brake cleaner will sort it out. Nearly all calipers I see when I do disc and pad changes (on moderns) need a serious clean and it's surprising how often I see evidence of brakes dragging.

Hopefully it'll be something simple like that.

Ah... brake cleaner

i wish i had thought of that....your a genius grey


Prop and the Blackhole Midget

A test to check if it is degraded rubber hoses is, when the pistons aren't easing off, crack the bleed nipple open. If the cause is to do with the hoses, then the fluid will be held under pressure and this will become apparent when you release the bleed nipple. If fluid just weeps out gently, then the hoses are probably fine.

Certainly in the majority of cases I have seen of the caliper binding, it is the piston seized within the caliper body. Moisture/crud gets in - usually via a damaged boot - and the ensuing debris/rust fouls the return of the piston. The usual symptom is a hotter disc than normal after a run.

The simple remedy is to remove the wheel, pads and caliper, push the boot back as far as possible, and very gently press out the piston as far as it will go without popping it out of the caliper. The offending surface area of the piston is usually somewhere which is normally unexposed and hidden within the caliper itself - hence the requirement to push the piston out.

Thoroughly emery paper all the exposed outer surface removing all rust/crud, smear with silicon grease, and push the piston back - piece of wood and a G clamp or something. Fairly easy job. However, invariably the problem returns, in which case replace piston and seal - cheap enough.

hadn't thought about the hose, so thanks. had a look at the caliper this evening. I think its a sticky piston.

stupidly though, when taking the caliper off, I hooked a spanner on the first thing I found (bit dark in the garage and not paying proper attention) and cranked it undone. shame it was the brake banjo! what an idiot! need to bleed caliper again now.

Malcolm Le Chevalier

Probably a wise idea to bleed afterwards anyways - if pushing the piston out and back.

bite the bullet and replace the caliper seals. just been through this very problem with the 356. The seal must have swollen ever so slightly and was gripping the piston just a tad too much. New seals and bingo.

Suggest you try very helpful guy and prices better than i could find elsewhere for the black beast :)

best of...
M McAndrew

New callipers at 40 GBP a shot would be the safest option
dominic clancy

You could also try this company
Kelly Hughes

stainless steel pistons are available from minispares. fit them then forget forever.
Rob Armstrong

Dammit - it must be infectious.

Took the midget out for bit of a blast this afternoon and returned to find the nearside brake dragging and VERY hot. Smoke coming out of the wheelarch and all.

It already has stainless pistons, according to the POs notes so I've ordered new seals. I've run out of brake cleaner so I thought I'd go out in the GT6 and get some and give the Triumph a bit of exercise at the same time.

Over-choked it and flooded it, so had to muck around a while sorting that out, then completely forgot how low it was on fuel.


A nice 2 mile walk to get the spare can from the Midget and a two mile walk back. By the time I got back the place I buy brake cleaner was closed and tomorrow's Sunday. B+gger.

Had enough for the day. Tomorrow I'll pull both calipers ready for the new seals.

How did you get on with yours Malcolm?

BTW Dominic - where did you see new calipers for 40?

Will be interesting to see what's dragging, my money's on pads sticking in the caliper rather than a corroded ss piston.
Rob Armstrong

I agree Rob. But my fear is that it might have got hot enough to damage the seals so as a precaution the plan is to change them anyway. I like to be confident about brakes!

I had planned to take the car for a blast to Oban and back tomorrow (180 miles round trip) so I guess I'll be cutting the grass instead :-(

Welcome to my avg. life grey....haha

i worked today....i spent half the day painting this basement rec room lots of trim and crap to move and deal with... it was a 2 part color...not alot of paint just 2 gallons ...just really complex lots of cutting in work

Guess what happened....yepp...wrong paint on the wrong walls

so i get to redo it all agian tomarrow

Prop and the Blackhole Midget

Greybeard...Seen a nice late 74 GT6 on the web. Looks to be in very good nick. Thoughts welcome as to whether it is overall, superior to a Midget....



I had a GT6 before my present Midget. The GT6 is a different type of car to a Midget.

Strangely a GT6 cabin feels more cramped than a Midget's. I had the Mk3 that has a slightly higher windscreen but it adds very little more room and I'm only 5' 6", though I know those six foot or more own them.

They are ovens in the summer even in moderate summer weather.

The 2.0 litre six is smooth enough but no real powerhouse, in standard tune at least.

Having a separate chassis and the (standard) suspension set up on mine made the body feel like it wanted to go in one direction whilst the chassis and suspension wanted to go in two others - I'm exaggerating but it's nothing like a Spridget.

The rear window means what's in the 'boot' is on display and subject to 'solar gain', even more so than in a BGT (which was my first classic in the very early 90s).

I know you're a very long way from them but I can recommend John Yarnell of JY Classics and can recommend you avoid Jigsaw Racing (in Corby, Northants).

The Triumph Sports Six Club is near where a friend lives so I've visited a few times and been a member of the club, I wouldn't dissuade you from it but again wouldn't recommend it.

Parts and books and info are in good supply but not quite as much as for Spridgets.

They do look very good though - of course you can't drop the top to let all of that heat out or fresh air and sunshine in.

In this photo do bear in mind I'm only 5' 6" and whilst overweight I'm not massive.

Hope some of this helps.

Nigel Atkins

Hey Greybeard,

I pulled off the caliper, pumped out the pistons most of the way and cleaned and lubed them up. Worked them in and out a bit more, then reassembled. It seems to be better, but I have not been able to give them a proper test.

This is because I took one of the wings off to paint. Wifey and I are off to a wedding using wedding cars sevenoaks on Friday, I was told we can only take the car if I finish the paintwork. Apparently one wing in red oxide primer is not an acceptable finish for a car going to a wedding! ha ha.

Malcolm Le Chevalier

But if it doesn't work, or sticks again I might get new calipers. I don't know if I can be bothered rebuilding them again.
Malcolm Le Chevalier

Oddly enough we talked about this not too long ago. I'm in agreement with Nigel for the most part. They are a bit cramped, even for those of us who are vertically challenged. (I'm 5'7"). And they are pretty noisy inside IMO. That said I don't know how people who are significantly taller than me can live with Spridgets, but they seem to manage. My seat is all the way back on the runners and I fit just fine.

I'm not sure when the change happened but earlier Mk3s had the Rotoflex couplings (as did late Mk2s I think) and were reckoned to handle better than earlier cars. Later Mk3s had the similar "swing spring" arrangement as the late Spitfires. That had some advantages in that it was lighter and simpler, but most critics reckon the Rotoflex cars have the edge IF the couplings are in good condition. A car with knackered doughnuts wil steer like a Tesco cart, but many have been upgraded to CV joints, which is the business. The front end starts to get a bit floaty and vague at high speed, which is disconcerting, but can probably be fixed with a spoiler.

The engine is the big sister to the 1500 of late midgets and shares some compromises. Avoid a car with noisy bottom end bearings for the same reason as you would on a 1500. Rocker gear can be pretty noisy too, but it's cheap and easy to replace with upgraded (bushed) rockers. I've heard the thrust washer can do the same dropping out trick that the 1500s can, which wrecks the engine pretty comprehensively.
The bottom end weaknesses can be fixed in a similar way to the 1500, by uprating the oil supply, or so I understand.
The engine was basically intended for a big squidgy saloon car, but I find it a reasonably lively performer in the GT6. I've always had a liking for them - I've had several of the saloons as well as a Mk2 GT6, but they don't really like to be thrashed. Mine stuck a conrod out of the block in the end.
They do sound good though, especially as they will all have aftermarket exhausts on by now - the original chimneys rusted out in no time.

The gearbox is much better than my 1500 and usually have a J type overdrive fitted, which is excellent. I wouldn't buy one without it.

I can't say objectively if it's any better than a Spridget because for one thing I have almost no experience of 1275s. They are different in character. Personally I like them. I think it's a hell of a nice car to drive, but I wouldn't want to press my luck in it. The engine is pretty heavy and can lead to pretty scary understeer. They don't weigh too much more than a 1500 and the understeer can to turn to oversteer very quickly which is not good, so you have to learn it's foibles. It's a "slow in/fast out" car as someone put it recently.

If it were to be my only car I'd choose the Triumph over the Midget, but not otherwise. In the end it's up to you and your own taste. I think they look great and they are super-easy to work on. Plenty of spares and no more expensive than Midget bits for the most part.

Sorry Malc - crossed in the post. Good luck with the caliper and painting.

Here are the callipers at 43

I think the deal for the whole rebuild kit is a steal! Callipers, discs, pads and hoses for 110, and if you spend another 10 you get free shipping.

dominic clancy

I'd forgotten about the gearbox on the GT6, not a very nice change and slightly offset gear lever alignment on top gears (IIRC). No where near as nice changes and layout as an A-series Spridget g/box, I don't know about 1500s as I can't remember having only driven one once (I think).

I personally don't much like overdrives as you have to keep your foot on the accelerator pedal for in and out selection of o/d, not the same as lifting off and down-changing from a higher gear, but o/d is a good idea on the GT6.

As for fitting in a Spridget or GT6 a person's leg and body length makes a difference, I've short legs and longer body so in both cars the seats are almost all the way forward. All the cars I've driven always have room behind my seat.

The cabin noise on the GT6 can't be lost like in a Spridget by putting the roof down.

Despite its size a GT6 seems to me to better compared with a BGT rather than a Spridget, tourers rather than sports.
Nigel Atkins

Nigel is spot-on about the slight offset between third and fourth, but it's easy to get used to. I guess individual gearboxes vary - the one I drive is pretty nice. I have next to no knowledge of the various A series Spridget boxes, but I'm told they're sweet devices.

Personally I love the O/D. It makes a huge difference to the useability of the car and if I could lay my hands on a single rail Triumph box with O/D I'd have it in the Midget in a heartbeat. It makes the car a practical proposition as a daily driver I think. I know there are people who use Spridgets as workhorses and respect to them, but for me it's less a car than a kind of mechanical pet.

Also Nigel hit the nail on the head saying that the GT6 is more a sporting tourer than an out-and-out sports car. In that sense it is indeed a competitor to the BGT. Once Triumph had mended the wayward handling on the early cars, which used to tuck in the rear wheel cornering, they were a much better car IMO than the BGT. I drove my Rotoflex Mk2 to Greece and back twice but I wouldn't honestly fancy it in the 1500. Plus at the time it was my only transport and the Midget isn't (except when the POS Ford is laid up lol).

The car you're looking at Mark probably has the last variation on the rear suspemsion theme, inherited from it's sister the Spittie. Not necessarily a bad thing - it works well - but a Rotoflex car is reckoned to have the edge. I say that because it's a 74 and production ended in December 73 although some cars were not registered until 74 so it must be very late. Don's car is a Rotoflexer but my Midget runs rings round it in twisties, then the Triumph leaves me for dead on the A roads. Depends on what you want the car for really. After I blew mine up I had a Mk3 Cortina. It was a far better daily driver TBH. I'd like another right now in fact.

At the time I had mine I worked in Aberdeen and sometimes had to drive on snow. Not an experience I'd like to repeat. And they are a serious handful in the wet by the way, but then so is my 1500.

Nigel; like you I'm a shortarse with short legs but I have very long arms. I can touch my knees without bending! Maybe it's the angle of the seat back making the difference?

Soz for the thread hijack Malc. I'll try to post something about brake calipers soon. In fact here it is.....

Thanks Dominic for the link. That's looks like a real bargain to me too.

No worries, hijack away! The brake issue is done and dusted and I too like a GT6. Great looking car and I do fancy owning a car that has more than four cylinders for once.

I have also pondered transplanting a GT6 engine (or 2.5 litre) into an MGB. Sacrilege to some maybe, but in my mind a way of replicating an MGC without the awkward MGC suspension and lardy C series lump.

Malcolm Le Chevalier

I like the idea of a fifth gear, indeed I have one on my Midget, and o/d provides this but it's not as good for me as cogs on the down-changes.

But the o/d on third gear is very handy for quick up-changes.

I don't have long arms but even if I did my knees are far too close to the ground to reach.
Nigel Atkins

Sounds like a gt6 would be up for a more modern engine and trans upgrade
Prop and the Blackhole Midget

after riding in (and driving a little bit) a Spitfire with the improved transverse spring where it was bolted to the diff, the last thing it needed was more power...
Rob Armstrong

An update - and back to the caliper woes.

The new seals haven't arrived yet so I thought I'd just pull the pads and clean everything up squeaky clean, just to see what difference it made.

Answer - none at all. It was okay for a couple of miles then started dragging again and got pretty hot again. But I did discover that the pistons are not stainless after all. So far as I can tell the PO paid for St/St but whoever did the work just cleaned up the old ones and put them back. Wouldn't surprise me if they reused the old seals too. The PO when I met him was a retired architect in his early 80s and a delightful gentleman. I'm really disappointed to think that someone would rip off a lovely bloke like him in that way. I could never do that to anybody.

Moving along, I decided to just get on with stripping the calipers for the new seals, making a mental note to buy pistons too. I started with the left caliper which was the one giving trouble and by pure luck I spotted a crack in the lower mounting lug. It doesn't look recent, it looks like it's been cracked for a while but it made me decide on the spot to forget about pistons and seals and just buy calipers. Can you imagine hitting the brake and the lower caliper mounting coming adrift? Yikes....

I've never seen this before, but I'll be very careful to look at any calipers I work on in the future.

Oh well - I'm doing oil and filter on the Triumph tomorrow then I'll take it out and wring it's bloody neck for half an hour. What's the betting the clutch finally gives up?

"a way of replicating an MGC without the awkward MGC suspension "

The reason the MGC had torsion bar suspension is because the original crossmember wouldn't fit with the longer engine.

Will a 6 cylinder Triumph fit in the available space?

What I would like to do is fit a 3.2 litre V6 from a Vauxhall Omega into an MGB.
Dave O'Neill 2

Yeah, I am aware why the suspension was changed. I don't know if it would fit or not but the C-Series engine is known to be a bit of a biffer and 1000cc bigger in it's internal size hence I ponder that the Trump six would just squeeze in.
Malcolm Le Chevalier

I can get some measurements for you if you like Malcolm. Personally I've wondered about the Ford V6 in the Triumph. (Essex or Cologne). There's oodles of space in there....

Maybe not on reflection. I think it might be too tall.

surely has to be a KV6 - keep it in the family (sort of)

p.s cheeky b****r with the non-ss pistons. V poor. Reminds me of the person who has 'restored' my P6 for it's first owner (and only owner before me) at a pretty high cost, and appears to have done nothing but put another skin on everything...
Rob Armstrong

>>surely has to be a KV6<<

Weren't they notorious for HGF?

There's the V8 Stag engine if you want to keep it in the family. They ate their HGs too IIRC. My late uncle Pat had a world of pain with his until he got a Rover V8 fitted (aka small-block Buick). ISTR that was a common conversion at the time. I wonder if modern gaskets ever cured the problem. Probably. I expect Google knows, but I'm too tired to go and look.

The KV6 was a pretty solid engine. Unfortunately it got wrongly tarred with the K-Series head gasket blowing brush!
Malcolm Le Chevalier

And the Stag engine wasn't as bad as people made out either. It was one of the first engines to have alloy heads. Poor maintenance meant the alloy heads would corrode, blocking the waterways, causing it to overheat. Head gasket blows, garage changes HG, but didn't tackle route cause.

Or that's what I believe to be the real truth anyway...

Malcolm Le Chevalier

no hgf for KV6 engines. And, when properly designed cooling systems are used and engines are kept an eye on, no hgf problems with a 4 pot K.

Rob Armstrong

I believe the Stag engine problems were sorted, eventually.

Another popular fitment in the Stag was the V6 Essex engine.
Dave O'Neill 2

Going back to topic, I don't think it was front caliper at all. It was certainly a tiny bit sticky, and a clean up sorted that, but I don't think it was the actual cause of the juddering etc.

It was much simpler in that the back brake was adjusted a bit too tight.

Malcolm Le Chevalier

The back brake was adjusted to tight

uuHHHHHmmmm... NO !

Malc buddy friend brother...drugs like Herion and LSD may seem like a good idea at the moment all things considard but just say no haha

i dont think its possiable to tighten the rear brake shoe and drum and overtightening is just a fantacy

Prop and the Blackhole Midget

ha ha, no, scrap that idea actually. I thought it was the back brake a bit tight and/or maybe not releasing properly.

As usual, I was too quick to post... I just didn't release the hand brake properly when playing about earlier!

I shouldn't be let loose with spanners :-)
Malcolm Le Chevalier

Don't put that on your CV ;o)
Dave O'Neill 2

This thread was discussed between 07/08/2016 and 17/08/2016

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