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MG Midget and Sprite Technical - Slow starter when clutch depressed

I have a frogeye with a 1275 engine. When I press the clutch to start the car it turns over very slowly. When I lift the clutch the car turns over faster and starts fine. Engine was rebuilt with new clutch less that 2,000 miles ago.
I have a new frogeye slave cylinder but I did have to lengthen the pushrod.
M D Brittain

You are placing extra pressure to the flywheel which will slow the starter. It is recommended to start the car in neutral without depressing the clutch.

Cheers

Gary
79 MGB
gary hansen

I've just lost my post.

I'll just put the links instead of the blurb now to save my typing finger, how's your battery, main cables and connections and earths, if not in good condition extra strain on them can make a difference.

Perhaps you could do a video of both starting methods to see how things seem - but as Gary has put and see video below.

video about clutch - https://www.youtube.com/watch?v=d173K60GSU8

info on 1275 - http://www.spridgetguru.com/DriversHandbooks/AKD7355_4thEd.pdf

and later 1275s - (Ref: 0057) - https://mgownersclubstore.co.uk/catalog/Online_Catalogue_Handbooks_5.html

AH Sprite MkI Driver's Handbook from July '58 - http://www.spridgetguru.com/DriversHandbooks/97H1583B.pdf

Nigel Atkins

" When I press the clutch to start the car..."

Don't.
As Gary said....
David Smith

Thank you

I have been starting the car with the clutch disengaged except when I forget. My modern daily driver won't start without the clutch depressed.

I was just worried something was wrong. I think I am probably ready for a new battery and the cables checking.

Thanks again for your help.
M D Brittain

Though I agree you should not press the clutch when you start it should not have a significant impact on the cranking speed.
I would suggest employing an assistant to press the clutch and look at the crank pulley for excessive movement indicating thrust washer wear
O K

Sorry to be thick but am i looking for end float movement in the crank pulley at the timing cover when the clutch is depressed?
M D Brittain

M D,
don't change the battery until you have checked the battery thoroughly, the battery is one of the most oversold unnecessary replaced parts on a car.

Disconnect it and remove from the car to check and clean it particularly the posts as even a small bit of crud on the posts can restrict starting ability. Modern batteries do not need the posts to cable clamps protecting with anything.

Check the electrolyte level in each cell and top up if required.

Slowly fully charge the battery, over 24 or 48 hours if required, don't use a higher amperage quick charge.

Whilst the battery is off the car check all the main cables and wires, the cable clamps and all earths are clean, secure and protected. Particular check the main earths and their connections from the battery to body and the engine earth lead.

Also check the main lead to the starter and that the starter is fitted securely, the ignition switch wires and connections.

Even if these are not the cause of this particular problem it is always worthwhile having checked and cleaned were required anything electrical starting at the battery to all the way through yo the end components.

A battery with low charge or in poor condition or with connections in poor condition can be the cause or part cause of many problems and a hindrance to solving problems - but that doesn't necessarily mean it needs replacing (see more of the John Twist videos on this subject).
Nigel Atkins

I'm not technical or mechanical (I do know about the importance of the battery and electrical connects though) but I wonder if Onno is thinking of the (Triumph) 1500 engine rather than the A-series engines - but I could be talking rubbish to put it politely.

I was thinking of that clutch thrust bearing being excessively worn or perhap air in the hydraulics.

The post I lost was going to ask you if you'd fairly recent tried the clutch pedal feel on any other Spridget or only know of your own as last week a lad thought his clutch pedal feel was light when in fact it was very heavy, which he realised when trying mine and mine is slightly heavier than standard as it's a different type.

Also is your engine souped up and higher compression than standard which might take a bit more effort to start especially when new (2,000 miles)?
Nigel Atkins

Thanks. I will try a full charge on the battery before replacement and will double check the cables at the same time.

I did have problems bleeding the new slave cylinder but I think its OK now. As I said in the original post I did also have to lengthen the pushrod on the frogeye slave cylinder. I haven't had the opportunity to try another spridget clutch.

The engine is mildly tuned I think. Rolling road showing 61 BHP at 5438 revs. But if that was partly the issue why does it spin over very quickly with no clutch depressed?

Are we talking about the clutch release bearing possibly causing a problem?
M D Brittain

When the engine is idling, what effect does depressing the clutch have on idling speed? If the revs drop significantly, you u could could have a problem.

If the crank is moving, the problem will be with worn crankshaft thrust washers.

With regard to your question, yes you should be looking for movement at the front pulley when depressing the clutch.

Please don’t think you are being ‘thick’ by asking a question. If you aren’t sure, that is the best way to find out.

Although we learn from our mistakes, it is often better to learn from the mistakes of others and then not repeat them.
Dave O'Neill 2

@Nigel,
Not thinking of a 1500, 1275’s have thrust bearings as well and they can wear/fail though it is not a normal maintenance item like on a 1500 ;)

@MD
Preferably you will be looking at a lack of movement ;)

All expecting a good starter an battery off course, as any problems there will enhance other starting issues
O K

61bhp doesn't suggest a higher compression engine, did you get the reading on Peter's rollers.

As I put I'm not technical or mechanical, there are others on here that know about these sort of things but length pushrod suggest a mix and match of parts/components/system from which gearbox to 1275 engine and then which clutch and set/mix of hydraulics.

There's lots on here in the Archives on these subjects.

In the post I lost I put more info on your particular car would help in sorting what might be -
. what clutch (from what model)
. what bell housing (from what model)
. what master cylinder (from what model)
. what slave cylinder (from what model)
. what other changes from standard Frogeye do you have

You can put up a 'Vehicle profile' and may it viewable which some will look at to get an idea of your vehicle as there are thousands of variations on even the standard models over the years.

Any photos of the clutch and/or starter you can put up can help otherwise wrong assumptions can be made.

Somethings have quick answers but very many do not and require investigation, research and diagnostics but it's not always too painful.

Big things is get the battery and connections checked, the number of times a good battery in good condition and fully charged with all connections good have resolved or help with, even long term, issues is a lot more than many imagine.
Nigel Atkins

The rolling road tune was done at Noble Motorsport in Chesterfield.
I will look to post some vehicle details but to answer you basically:
-I fitted a 1275 clutch thought I needed same as engine
-Mk1 sprite smooth gearbox and bell housing
-new dual master cylinder (for disc brakes MK2 sprite?)
-frogeye slave cylinder
Otherwise standard more or less.

Depressing the clutch with the engine running makes no difference to idle speed.

I'll progress the battery first and see how things go then
Thanks again
M D Brittain

Sorry Onno, I did say I might be talking rubbish again, it's far to hot here to think straight, even if I could.

M D,
as DaveO put questions are good and often need from both sides.

Being able to compare with other models that are in good running condition (and not just shiny) can be very useful, perhaps a club meet or another local owner.
Nigel Atkins

What engine backplate did you use? Thick 1275 or thin (pressed tin) Frogeye?

It's normal to use thick 1275 back plate and 1275 slave cylinder with 1275 release bearing. If you used thin back plate and Frogeye slave cylinder I'm wondering if you have too much throw?

Check the crank endfloat at the timing chain end when the clutch is depressed. Excessive endfloat and worn thrust bearings can produce the problem you are seeing.
Rob
MG Moneypit

I'm pretty sure it was the 1275 backplate that was on and I used the 1275 release bearing.

I think I couldn't use the 1275 slave cylinder because it was a larger bore and would necessitate changing the master cylinder.

When I first put it on the road the clutch pedal was firm but the gear change was notchy. Hence I added some weld to the pushrod. Gear change is now fine. But perhaps I added too much?

Would excessive endfloat cause oil leaks because that's another problem.
M D Brittain

You can't easily fit anything other than a 1275 backplate to a 1275 engine, as the earlier ones don't clear the oil pump. Ask Bernie!
Dave O'Neill 2

Throw wouldn't be determined by which backplate you used anyway. Thow is purely a function of the hydraulics, especially the relative sizes of master and slave cylinder. Similarly, lengthening the pushrod doesn't actually effect the overall throw, but does impact on the start and finish positions of the slave cylinder piston and may have been necessary in getting the release bearing 'at rest' position correct for your particular combination of parts.

Are you using the original, unmodified bore, MK1 master cylinder?
GuyW

No I am using the later disc brake version GMC 112

Disc brakes (c) H-AN6 to (c) H-AN7, (c) H-AN8, (c) G-AN1 to (c) G-AN2, (c) G-AN3, 1098cc

The car has later midget type disc front and drum rear brakes.
M D Brittain

I am not sure of the change over dates, but if you are using a later, 3/4" bore master cylinder, but matching it to the earlier frogeye slave, then wouldn't you be getting too little throw on the clutch?

Adding weld to the pushrod doesn't extend * the throw of the clutch. What it does do is move the actuating travel of the slave cylinder further up the barrel of the slave, but the actual throw remains the same at around 1/2" But if you are using a small bore master, then you pump less fluid down to the slave which moves corespondingly less than it would have done with the original MK 1 master.

* This may be necessary to make up for the shorter offset of the release bearing carrier for a 1275 clutch.
GuyW

Use a bar or length of timber to press against the front crank pulley by levering against the front cross member. This is to push the crank back as far as it will (should) go. Then watching the front pulley closely, get your Attractive Assistant to press firmly on the clutch pedal, right down to the floor.(engine not running) You should see little, or better, no movement at the pulley. Sometimes you can judge this better by feel, resting a finger to touch both the pulley and the front of the chain case cover. Eccessive movement suggests worn crank thrust washers. And seriously warn washers cause the conrods to align badly which increases load on the engine so that the revs drop.
GuyW

M D,
two points I'd like to point out -

a) for others to address - "Would excessive endfloat cause oil leaks because that's another problem."

b) I have a few decades of experience with MGs in this - rolling road tune - I don't know Noble Motorsport in Chesterfield they could be excellent but I bet Peter Burgess could possibly improve and I'm just about certain it would be at lower cost but (much?) better value, and in your neck of the woods, he knows the odd bit'n'bobs about A-series engine too.

https://www.mg-cars.org.uk/peterburgess/

Rolling road tuning is most effective of course after full service, maintenance and repairs have been done.

Certainly see if the starting improves are dealing with battery and connections and let us know if it improves or not as far as starting goes.
Nigel Atkins

Thanks Guy
I'll try that and report back
I think the slave cylinder is the same from 1958 to 1966 which covers both the 7/8" and the 3/4" bore model.
M D Brittain

Nigel
Thanks for the link to Peter Burgess. Didn't know about that and so nearby.

Just waiting for the Attractive Assistant to turn up and will update.

Thanks everybody.
M D Brittain

MD, I thought you said you were using a 1275 clutch? The 1275 diaphragm clutches (post 1966) certainly use a different slave to the earlier cars. The earlier slave will result in clutch overthrow which eventually distorts or breaks the clutch fingers. I don't know, but could imagine that overthrow could also be causing your drop in engine revs.

I would still do the crank movement check to test for worn thrust washers, because it's quick and easy. But mis-match of clutch parts could still be your problem.
GuyW

Another recommendation for Peter Burgess. Such a great bloke and I doubt there is anyone in the UK who understands BMC A and B series engines as well as he does. Don't be put off by his somewhat unkempt premises, he is the real deal.
Mike Howlett

...don't forget to take the donuts...
David Cox

I always thought that you need to start classic cars with cluth depressed to remove rotation resistance of the gearbox from the starter... So I have been mistaken for so long ? :o

I do loose about 200rpm at idle between depressed or not... How much do you guys loose ?
CH Hamon

MD, when I put the 1275 clutch in my 998 engine I initially got clutch overthrow. Try starting with clutch pedal partly depressed. Problem disappeared when I fitted the correct slave.

Les
L B Rose

Cedric,
where does it say to do that in the Driver's Handbook, take a look at the video. You have the information given to you at your fingertips but you do need to access it and take it onboard - you can lead a cheval to water but you can't kick it's a*se to get it to drink, they're too big. ;)

video - https://www.youtube.com/watch?v=d173K60GSU8

Nigel Atkins

I am a French horse, why you lead me to water ? :)

The extra pressure added on the flywheel is not compensated by less torque consumption from the gearbox...?
CH Hamon

MD, you can get an adaptor so you can use the 1275 slave. The adaptor is screwed into the master cylinder to accept the bigger pipe diameter of the pipe used by the 1275 slave.
On an early spridget pipe flexing between slave and master cylinder is taken up by the pipe being coiled a few turns. On later cars it's taken up by a flexi pipe between a bracket on the chassis and the slave cylinder.
This bracket is missing from a Frogeye.
You can coil the thicker pipe as well, which I did, but it's quite tough, but doable.
Rob
MG Moneypit

In over 50 years driving I have never pressed the clutch to start any car, and that includes an MGA, three Midgets, two Bs, a couple of Cortinas, an Anglia 105E, a Triumph Vitesse, a Triumph Dolomite, two Imps and a brace of Minis ..... until we bought a new VW. That blighter won't start at all unless you do press the clutch.
Mike Howlett

The new cars require the clutch pedal to be depressed to keep people who don't know what they are doing from starting while in gear. Just another example of people who "know better" protecting us from ourselves.

A few years ago some G.M cars also needed to be in reverse to start the car. Never did understand the logic of that.

I've also never started my cars with the clutch depressed unlike my wife's new car.
Martin

We had a vauxhall that needed a foot on the clutch to start. I was told it was to prevent kids from starting it. It made me wince every time to think of the release bearing and crank thrust.
I looked into rewiring it to the nanny switch under the seat but it looked like a nightmare with the CanBus wiring so I didn't take it on.
My ride on mower was the same, but I've disabled most of the nanny systems on that.
Personally I thought if anyone is dumb enough to start in gear they deserve what's coming to them. It's a Darwin thing...
Greybeard

Greybeard,

I never leave my car in gear but I know many people who do ostensibly in case the handbrake fails it'll likely prevent it rolling away, I guess they're aware it'll be in gear and depress the clutch or take it out of gear before starting. I rarely drive others cars these days but in case I do I check whether it is in gear before starting.
David Billington

A lot of modern automatics require the brake pedal to be pressed before starting, although they're only supposed to start in 'park' or 'neutral'.

My modern has that many sensors and safety systems that it should be able to prevent any foolishness by itself.

Having said that, it did give me a strange message yesterday, suggesting that I wasn't actually in the car...


Dave O'Neill 2

Quite right David, and maybe I was being a bit harsh.
I confess I've long been in the habit of leaving the car in gear because I worked away at sea for decades and more than once came home to find the handbrake stuck on.
The current modern (Volvo) has a magical transmission so no clutch pedal, but does require a boot on the brake. Even so I always thought the foot on the clutch thing is a monumentally stupid design. There are any number of better ways to achieve the same benefit without the attrition it must cause.
Sigh...
Greybeard

Dave, it didn't suggest you weren't in the car, only that it didn't consider you go be the driver! Maybe it knows something we dont!

Trev
T Mason

Good grief Dave. Why the absolute f@@@ if it thinks there is no driver would it bother flashing a message to the driver?
I think stop/start systems are actually dangerous in some circumstances. I nearly got torpedoed when a car just cut out on me at a junction in London. And Lane-keeper assistant (?) almost got me killed in a rented Toyota when it decided to abort an overtake manoeuvre.
I know these things can be switched off, but in that instance I didn't even know it existed until it tried to kill us all.
Greybeard

I think I do everything you think is bad :
- Depressed the clutch to start classic car
- Keep the car in a gear (same as greybeard - my Alfa GTV rear brakes use to stick after a cold night, whatever was the handbrake lever position)

I adapted to RHD, I can adapt to your habits too I guess :)
CH Hamon

Dave,
Are you on diet ? Eat more cheese and the car will see you again :)

Greybeard,
I had a brand new XC90 with a lot of options (somewhere close to full I would think) as rental car a year ago in Spain. I was alone, driving on highway (getting bored...) so I started to play with all the automatic driving : auto-cruise, auto-steer, lane keeper... Weather was warm, sun was shining : great weather with "water puddle effect" on the road. The car could see them, and didn't know how to interpreted them : she started to go a bit left, then a bit right, left again, right again - changing direction faster and faster ! Hard on the brake, shut her brain off and put mine back on.
Later in the week, night was falling and a big storm with heavy rain arrived. Just by curiosity, I tried to put the auto-drive back : she refused, too complex for her ! Easy answer...
And by the way, in the storm, headlights was a good as the genuine Midget ones...



CH Hamon

Sorry for the delay in getting back on this.

I have done the crank end float test and thankfully there is no movement when the clutch is depressed.
The engine revs do not drop when the clutch is depressed.

Having given the battery a full charge I did try starting the car with clutch depressed and it turned over reasonably quickly (but not quite as quick as with no clutch).

I think the conclusion above that it's to do with the clutch and the slave cylinder sounds most likely. As lengthening the pushrod seems to have given me a decent gear change I'm inclined to leave it for the time being.

I have other issues which may need the engine out but I'll start a new thread for those!

Many thanks again for all the advice.
M D Brittain

Thanks for reporting back.

Always pays to have your battery and all connections and earths in a good condition and battery charged as much as possibly, helps with lots of problems and prevents other problems and often solves some problems.
Nigel Atkins

This thread was discussed between 24/07/2019 and 26/08/2019

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