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MG Midget and Sprite Technical - Brake pedal not coming back fullyh

Hi,

Looks like I wrote too fast about the car behaving great...

During a test drive yesterday, I realised that the brake pedal is not coming back fully, so the brakes are always a bit "ON", except if I pull the pedal back up with my feet. Feels like it is since I greased the pads because they were noisy...even though I am not sure why it would trigger that.

I did the obvious to me, but might have miss something or did them incorrectly:
- bleed the brakes
- rear brakes adjusted
- removed caliper and greased the pads again
- Put some GT85 on the "pedal axle"

Front caliper are fairly recent (few years), brakes lines too (Goodyear from MGOC I guess).
I don't know how to check the master cylinder...

Any suggestions? :)
CH Hamon

...and the pedal spring is alright :p
CH Hamon

I would think it is most likely that the pedal has seized at the pivot. You may find that the bolt is turning with the pedal. I know you have tried GT85 on it but you need to hold the hexagonal head of the bolt still while you move the pedal up and down a bit to get the GT85 to work its way along into the bearing.
GuyW

I'm not sure what you mean by "greased the pads again" but I was always taught that grease is a no-no anywhere around brake pads or shoes. Could the grease have melted and is now fouling the caliper piston or accumulated dirt and causing them to stick?
Stan Kowznofski

No problem Guy! As I said, if the problem is still there, it is either because I missed something, either because I didn't correct it properly :p I will give a second look to the pivot.

Stan, I apply copper ease on the back of the pads (contact area with the piston) and on the "ears" (not where you can grab them, but where they "slide" on the caliper). I though it was good practice... I did notice that on both caliper, on piston move easier than the other one (when no pad and pushing the brake pedal, or to retract them).
CH Hamon

It certainly sounds like the pedal pivot bolt.

I’m not sure how effective GT85 is. You may need to dismantle and clean/lubricate.
Dave O'Neill 2

I agree it's more likely the pedal pivot, but not long ago I had a caliper dragging and found that the piston had corroded. I had of course used red grease on assembly, but there was a small patch of corrosion that caused the piston to stick and not return fully. New piston cured it.

Les
L B Rose

It goes without saying that you've change your brake fluid and thoroughly bleed two or three times now within your ownership of the car.

What about the master cylinder pushrod and it clevis pin ridge(s) wear in one or both?


Nigel Atkins

Thanks a lot for your feedbacks!

I had some time for the midget this evening, so had a second look at the brake pedal area as you advised: look like you were right!
I think the seals and tape in this area are pretty old, maybe the same age as the car, and they are now really perished. They disintegrate, create dust and particules, which "clog" the pedal pivot.

I did remove and clean a bit, but the two screws at the back are pretty annoying... I am now facing a dilemma:
- do I finish to clean, re-lubricate correctly the pivot and keep the full disassembly (of the pedal box) and cleaning for the next rain period,
- or this is too poor work: i disassemble everything now, taking the risk that some parts will be difficult to remove, need repainting, and then have the car stuck one or two weekend (with this amazing weather)?

I am off to bathroom now: "someone" reminded me that my duties doesn't stop wonce I am back inside, apparently... Who would have guess? :p






CH Hamon

Sorry Cedric I am lost as to what you mean by the two screws. Reservoirs are replacements. I think I am totally distracted by the Jean-Luc rolls of string red wires with connectors.

I might be wrong but the battery cable to the starter solenoid looks exposed (bare) and possibly a bit off colour?

I was wrong about pushrod and clevis pin.
Nigel Atkins

That is not a problem Nigel, I came to gather more ideas and judgment than mine, which is what people kindly did :)

If you have the book of Grahame Bristow, which of course has been recommended to me here, a good summary of my last days of ownership is at the end of page 64.
The screws I am talking about are page 69: the two top screws which are holding the pedal box. If I am not mistaken, to clean and lubricate properly the pedal axle, I need to remove the pedal bolt, which means I have to remove the pedal box....(which is opening the can of worms :D)



CH Hamon

Cedric, I replaced the pivot bolt on my Sprite recently without removing the pedal box. I used a Dremel to grind a semi-circular cut out in the pedal box frame which allowed me to extract the bolt.

Guy W suggested that grinding one of the flats off the bolt might also give you the clearance you need to remove the pivot bolt.

Check the amount of 'slop' or play the pedals before you remove anything and, when it's out, inspect the bolt carefully for wear. It might be a good idea to replace the bolt and pedal bushes as a matter of course. The original bushes aren't available but 1275 spigot bearings will fit, though they are a bit shorter. You could also consider fitting grease nipples as per Jeremy Mk III's photos in the recent Clutch Dragging thread that I started when I had a pedal problem: http://mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&mode=thread&access=&subject=97&source=T&thread=202103291933309480.
C Mee

Sorry Cedric my fault, I get even more brain fade with heat. I've not got that Grahame Bristow book but I think I know the one you mean.

Personally, if you are not driving your Midget in this weather when would you(?). Me I would spray with something thin like GT85 to flush out crud, wire brush, spray again to lubricate, then after a day or two lubricate with a light oil, both times working the pedals. The easiest and more enjoyable way to work and ease the pedals is to use them by driving the car. On good Spridget roads you will be using the clutch and brake pedals to loosen them and work the oil in.

When the time comes that you are using the Midget less you could then consider more involved work if you need to. Not using the car highlights and exasperates these kind of issues whereas using the car regularly on reasonable length journeys can ease things.

You know which end of the farting-about-with-the-car to driving ratio I prefer. (did you get that video link?)

Anyway you will not have to worry about any of this if you have an electrical fire and claim the insurance for a MX-5 BBR supercharger performance upgrade.😁
Nigel Atkins

Thanks Colin, that is really helpful! Both for the technique of removal, and the bearing/nipple solution!
I was thinking of cutting to prevent dissassembly of the pedal box, but I was also wondering why it was designed like this... If some people did it here, then I feel confident doing it too :)

Nigel, I am more thinking of a 2.5L swap, so I can practice pulling in and out engine, hopefully before I need to change the clutch on the Midget :P Still, baby steps! (otherwise, I will be left alone rusting with my cars... :D)
(Yes I did receive it - sorry for not replying yet...)
CH Hamon

Cedric,

So glad you are putting 'Bristow' to such good use !

As I know you are working outside I would limit the work to what is required to get it working well and leave as much insitu as possible.

If you do try taking out the p/box the screws you are talking about are No3 pozidrive - as they are likely to be well corroded I would soak in release fluid and then tap the screwdriver head with a hammer to get it seated well and then give a harder bash - my large pozidrivers have a flat or hex on them so I can attach a wrench to get leverage while I push as hard downwards, if that fails do you have an impact driver ? (its a handtool and by hitting it with a hammer it converts the force to a rotary force that turns the screw /bolt etc - use with respect as can easily shear bolts etc - not very expensive.

With the pedal issue, first check that the pedal is not turning the pivot bolt when you work the pedal - if not its just stiff and needs lube - add good penetrating oil or 'Ferrosol' (Bilt Hamber again) you must get some ! even smells nice !

https://www.bilthamber.com/ferrosol

You may find it possible to get more movement with the pedals to 'work them' and get the lube to flow in better if you pull out the clevis pins from the master cylinders.

Keep up the good work mon ami

R.


richard b

Thanks a lot Richard for your encouragement, and I know you are my best ally when it comes to buying....euh hum...needing some new tools :) I should stop using the drill (see pic), especially for someone as ham-fisted as me :p

Concerning making a flat, it would not have work on my car (or i didn't understand properly), as even the shaft would not go out from the inside of the care...(second pic)

Anyway, by lifting the pedal box about an inch or two (I become soooo British :D), taking care not putting stress on any component or hydraulic lines, and extended use of Plus Gas, I finally got the shaft out from under the bonnet!






CH Hamon

I was surprised to see that the pedals'bushings are in pretty good condition, not ovalised and same diameter across them... The shaft, pretty dirty, is also not ovalised and with constant diameter... I cleaned them and they are now drying under the sun, while thinking what I will do next...Any suggestion? :)

Also, I wanted to give a small clean to the brake and clutch master cylinder shaft as the saw some dust: which product would you use to do so?

Have a nice sunny weekend in your Midget, while mine is sunbathing :p






CH Hamon

It might just be the angle of the photo but your clutch pedal *looks* slightly twisted even allowing for outward bend, but if it's not causing uneven wear don't worry about it and I could well be wrong.

For cleaning, use the least abrasive material you can that removes the roughest of the rust reducing to finer as the rust goes and on less rough areas to end with a fine grade of material. You only want to remove the rust to get a level smooth surface then you can apply something like Kurust, leave to dry, wash off excess, dry again.

A wheel in a drill, or shoe buffing action with strips of material whilst the shaft is held steady probably easiest and quickest.

Others will probably have better ideas.

Basically, as which much servicing, maintenance and repairs you've just cleaned and lubricated, unless the clutch pedal needs sorting or anything you have bust not much sexy engineering.

Leaves plenty of time to sort the wiring. 😁
Nigel Atkins

Cedric

If it were mine I'd remove all the rust from the bolt with wire wool / emery/ whatever you have to get it smooth, grease it and the bushes and re-fit. Clean up the pushrods similarly and lightly grease to stop rust.
Bill Bretherton

I agree with Bill. A good clean and reassemble. The shaft is unlikely to seize if well assembled and lubricated!
Bob Beaumont

Give you something to do rather than driving the car, you could adjust the screw at the pedal shaft end to take up a little bit of the slack - subject to the cable not being frayed or twisted on route and having a little slack both ends.


Nigel Atkins

Yes as others clean up the shaft with Emery cloth - try to get a best surface where the bushes are.
Check for a nice easy slide fit into the bushes with no dragging. Grease up the shaft and bearings with plenty of wheel bearing grease - should last for years - I doubt it had much grease applied on the assembly line !

R.
richard b

Back on weekend duties, thanks to you: merci :)


(small club meet on Sunday morning in Hemel Hampstead)


CH Hamon

That is a small club ! (Billy no mate's type of club !)

Looks very nice - like your house !

R.
richard b

I would get the servants to park their cars round the back, out of sight. And anyway, Cedric, from that line of cars it looks like you are paying them too much.
GuyW

Way too many bathrooms to clean Richard! I am not going to fall in this trap ;)

I am too generous Guy :) Still, I would not exchange my Midget for any of theirs... Amazing how you feel like everybody has the wrong car when you are driving a Spridget :)


In all honesty, I was too busy talking to other owners (it takes some time to get use to my accent ;)) and when everybody left, I realised I didn't take any picture... Anyway, lucky me and lucky you, the cutest was still there :D
This one was made by the organiser (sorry for the - lack of - quality of the picture). If you fancy joining, there is some "breakfast meetings" organised in Surrey, Hertfordshire and Kent few times a year. Nothing fancy :) (don't pay attention to the E-types, they didn't stay long anyway :p)



CH Hamon

This thread was discussed between 30/05/2021 and 14/06/2021

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