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MG Midget and Sprite Technical - Gearbox oil

Does anyone know if refilling the gearbox with lighter oil would stop my gearbox from grinding on downshifts?
So far I have replaced; master cylinder, clutch line, and slave cylinder. None of these changes has had any effect on the terrible grinding sound.
I have checked the clutch arm pivot bolt. It seems to have been replaced with a bolt at some point. The actuating rod does not move up and down, it does however move back and forth by a few inches.
Could the syncros have gone?
This problem has been around for almost half a year and I have no idea how to fix it. I'm really worried that at some point it will strip a gear.
Thanks, Ben
(Its a 1977 1500)
BH Harvey

Nope... Your problem is clearly in the peddle assembly... Im surprised you can even shift with " a couple inches " of play

Id track down a good peddle assembly...

Prop
Prop

almost 99% no it wont

someone will say you might have cream-cracked your box by not always using EP90 GL4 already (and time might prove them correct)

it's a lot, lot more likely another fault

but at such a low price I'd empty out and refill with Comma SX75w-90 Semi-synthetic if you really want to try

this suggestion will upset many though

note: I've not got a 1500
I'm going fully synthetic with the rear axle next change and same in Type 9 gearbox and in engine when I've used up all my presnt engine oil - possibly only the gearbox will survive this :)

if it all falls apart I'll let everyone know I was wrong

I never used to worry about these things when I used to do 12-15,000 miles per year in my daily classic and I know of at least one that went on to do many miles for many years with the next owner

ETA: Prop posted as I was typing
N Atkins

You might look into double shifting ... I think thats what its called... Without using the clutch You slip it out of gear, blip the gas, and slide the shifter into the next gear...without ever using the clutch... Ive never done it on the midget....it just takes some fenies.

Prop
Prop

known as double-declutch over here (using the clutch)

often practiced with the non-synchro a-series engined Spridgets
N Atkins

Hey BH,

I may have misread your post....

On the clutch peddle look where it pivoits, there is a clivis pin that when it wears out it will be oblong, and wont allow the peddle to fully activate the clutch master... Thud causin the grinding condition because the master isnot fully depressed....sometimes it can be so bad the peddle assemble is worn out along with the clevis pin


Prop
Prop

Thanks nigel

Im now thinking we call it double clutching not double shifting...is it doable on the stock trans


Prop
Prop

yes if you want to
N Atkins

Thanks, but the play is in the actuating rod which connects to the clutch arm, not the clutch pedal (which also has a few inches of travel before biting).
I have replaced the clevis pin to reduce play there though.
I will buy some new oil tommorrow, the Haynes guide recommends 80 for refill 90 for top up. Does anyone know why?
Prop, I have not got the driving skill to double declutch, all my attempts have ended out of gear with a screaming engine.
BH Harvey

Ahhh ...the play is in the fork... I got you

Try finding some similar rod stock at a hardware store and cut it a little longer to take the play out of the fork.

That said... I think this can be done..thats basically what riverate does with its 5 speed conversion other wise you have to weld a small extention on the end of the clutch slave rod
Prop

Aka... Sorry... What im ref. Is the clutch slave push rod is to short... Probably worn out graiter around the fork in the trans hole
Prop

The play is in the release arm (fork?).
I've added a diagram for clarity as each of these parts seem to have at least 5 different terms.



BH Harvey

The play is at #76 meeting #64 ???

Yeah, you might need to add an extension to take up the slack, it dosnt appear you can just put in a longer push rod

Prop
Prop

The play seems to be in #64 itself. I don't know what this signifies -if anything- though.
BH Harvey

Im not sure what to say... I dont have any experiance with the 1500...but i think once you loose the play you should be in good shape...basicqlly the fork issnt getting fully extended..

Just another thought.. have you bleed the clutch recently, might try tha for grins
Prop

Nigel, he's not referring to double de clutching... he means not using the clutch at all. I do this in some much older vehicles, 1916-1926... it means the clutch doesn't get worn out... it means other people can play with the clutch spring settings and not confuse my timings for changing gear... however, get it wrong and a huge force is transmitted to the gear teeth... which = bad things happen. Tis a useful skill to learn if your clutch ever fails you can still change gear (although getting into 1st from stationary is a bit tricky and can be painful for your starter motor - best to use the clutch there - unless you've got a passenger willing to push).

If anyone who wants to give it a go and can already double de clutch, here's the best technique.

1. Getting the car out of gear - needs to have no force on the gear teeth - so this is the point between which the gears and transmitting engine force to the road and transmitting road force to the engine (engine breaking)... best way of achieving this is to lightly come off the gas and as you come off pull it out of gear.

2. Getting into the next gear is the same as double de clutching, only you have to wait longer for up changes (a LOT longer) and you have to get the down change just right... if you rev up and just gently guide the gear lever it will pop in at the right speed... (this is bad for your synchro though... better to judge the speed right.

Good luck - NB... best to practice on your dad's transit van first!

Chris
C L Carter

Clearly there should be as little play in the clutch operating system as possible. If there is play around the release arm you need to find out what is causing that. I know little about the 1500 but I have read on this BB that there is a pin that provides the pivot for the relase arm and this can drop out. If so the release arm will flop about. People who know 1500s better than I can explain and tell you how to replace it.
Chris H (1970 Midget 1275)

The first thing I would try is bleeding the clutch properly, because if it's got any air in the system, no amount of changing rods, oil etc is going to help. Borrow or buy an Eezi bleed, connect it up according to the instructions, (on a 1500 you may have to make a cap to fit by modifying an old cap, as I'm not sure that there is one in the kit that fits. The 1500 one is very big compared to most). Then disconnect the slave cylinder push rod and push it as far back into the cylinder as you can and secure it there while you bleed the system. At least when you've bled it you'll know that the hydraulic part of the clutch is OK as you've already replaced the two cylinders.
The other thing that springs to mind is the play in the arm. Could the release bearing have collapsed?

Bernie.
b higginson

<< I have checked the clutch arm pivot bolt. It seems to have been replaced with a bolt at some point. >>

If your clutch lever pivot pin has been replaced with a bolt then someone has been fiddling about under your car, so:

<< The actuating rod does not move up and down, it does however move back and forth by a few inches. >>

If by actuating rod you mean the slave cylinder pushrod, is it possible someone installed the shorter rod from a pile of Spitfire 1500 parts (part #76 in the above pic)? This will give you limited disconnect when fully engaging the clutch pedal, also the symptom you describe above, "the clutch pedal (which also has a few inches of travel before biting)".

Richard
Richard Reeves

BH,
the Haynes sometimes has errors, what's it got in the original factory (available as a reprint) (owners) Driver's Handbook

if you search the Archives there was great debate on on EP90 fairly recently

Chris, Prop,
aplogises about double declutch, I did put in brackets - using the clutch

I've never driven a vehicle older than late '50s

not using the clutch we'd have called crashing the gears, I've only had to do it on a Fait that lost its clutch cable

I was taught the method of getting onto a non-synchro (such as first on a-series engined Spridgets) using the clutch and it was known as double-declutch

possibly I was told wrong and missunderstood future references to the word or meanings change as the years and generations pass

a tonneau means something different to verteran/vintage/anceint car enthusiasts to what it means to classic car owners I learnt many years ago
N Atkins

As suggested above, I'd start with a good bleed of the clutch slave cylinder. You can do it with the slave in place, but according to what I've read, it's best to remove the slave from the clutch housing, leaving the hydraulic line connected. The pushrod will stay in the clutch housing, so what I'd do is get a bolt or some such, stick it into the cylinder through the dust boot until it contacts the piston, push the piston back, and then hold it there with a clamp of some sort.

Now hold the slave at an angle with the bleed port up, get a lovely assistant to depress the pedal, crack the bleeder, etc. etc.

Once any air is out, remove the clamp and re-install the slave.

That said, a lot of the above applies as well, RE: wear at the clutch master pushrod clevis, wear at the pedal pivot pin, etc. The 1500 slave pushes a rod directly into the clutch release arm, meaning there's no clevis just outside the clutch housing as is the case with earlier models.

Best of luck! Clutch bleeding can be a real trial.

-:G:-
Gryf Ketcherside

I've tried bleeding the clutch normally with an gunson pressure bleeder. It was definatly easier than the traditional method, but gave little improvement.
Richard, Looking at the Moss catalogue part numbers shows that the spitfire and Midget share a release arm, but not a pushrod. The spitfire push rod is shown as being much shorter than the Midgets.
Does anyone know the rough dimensions of a Midget push rod?
BH Harvey

Thanks chris for the shiftng without the clutch info...

i only had to do this briefly as well in my youth when the clutch went bad...honestly, i think its something everyone should try once if they are into old cars...you never know when your 300 miles from home and loose a clutch cable.

Nigel... Not a problem, i think i own most of the blame for not knowing the correct term for shifting without a clutch...tbh, im still not sure what the correct word is.

And good luck on the clutch system... But i still dont think changging the oil will correct the gear grinding noise...its never that simple...lol

Prop
Prop

cheers Prop

when I was a kid we just knew it as crashing the gears as you'd only have to do it if you had a clutch fault
N Atkins

Midget 1500 pushrod length: 3 1/4". Spitfire pushrod (IIRC) 2 7/8". HTH
Richard Reeves

Just dug thru my spares and found my 1500 Spitfire armature and pin: pin is just shy of 2 1/2".


Richard Reeves

Ben,
I have recently fitted a rebuilt gearbox and I filled it a mixture of EP80/EP90 oil that I had in in 2 half used bottles, the result was an awful gearchange really tight and hard not to crunch the gears. after some searching i found that halfords do some EP75w/80 GL4 oil, which made the gearchange far better, not perfect but a big improvement.

http://www.halfords.com/webapp/wcs/stores/servlet/SearchCmd?srch=gear+oil&department=165744%7CCar+Maintenance&action=search&storeId=10001&catalogId=10151&langId=-1

You did mention play in the release arm, and you included a link showing the arm, what the links does not show are two 'top hat' type bushes, shown in this diagram:

http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=1323

Item 18,
not very clear in this diagram, but they fit around the release arm pivot pin item 65 in your link, if these are worn they could be contributing to slack in the movement of the release arm, however, they can only be changed with the engine separated from the gear box.

I have just had look in the garage, and i cant find my Midget relase arm and push rod to confirm the length. I will have another look tomorrow.

HTH
Alan
A Pritchett

Ben,
Just had another rumage and found my Midget push rod,anf the length is 3.3 inches end to end and 3 inches from the centre of the eye to the end.
I have also discovered that the Midget slave cylinder is not the same as the Spitfire one, so this could be something else for you to check,Moss list the Midget one as GSY 107 and the Spitfire as GSY 103. A quick look on Ebay shows some selling the right one for the car and others selling them for both cars.

HTH
Alan
A Pritchett

Is the release bearing ok?
James B

crashing the gears is something women do... why do you think synchromesh was invented?

crashing just means you haven't matched the engine speed to the road speed and hence the gears aren't spinning at the same speed and hench they "crash" into each other... a clutch helps you achieve this, but isn't always necessary... you can still change gear without using the clutch and without crashing them...

Anyway... tis somewhat irrelevant to this thread now... so sorry to clog it up with nonsense gear changing maguff
C L Carter

I thought that to downshift without the clutch you first put the car in neutral, brake with the left foot, gently push the stick towards the lower gear while raising the rpm. The gear stick SHOULD slot in, when the road speed and engine speed match. I've never had a reason to try it though.
My push rod is just over 3 inches, which rules out the easy fix. Thanks to all those who gave measurements though.
While I as under the slave I did notice some yellow, bubbly residue, along with some clear brake fluid around the adaptor (I had to make an adaptor to connect the pipe to the slave cylinder). Could this indicate a leak which is allowing air into the lines?

BH Harvey

BH - you are right...that's what I said in my first explanation. You don't need to brake with left foot - its quite hard to control your left foot... better to let the car slow down to a reasonable speed for the gear you are about to select and then raise the revs... you may need to brake if you are trying to downchange going downhill - but why would you be doing that.

The otherway round... upchanging while going up hill... is almost impossible... because by the time the engine speed has dropped down to a reasonable level to slip it into 2nd... you have stopped (or worse going backwards).

Hands up if you're now really confused! Come drive our 1916 Dennis Fire Engine and you'll soon get it =]
C L Carter

Why are all fire engines and old bin lorries called Dennis. LOL.
b higginson

lol

interestingly thats a different DENNIS to the Dennis who made fire engines back during the war... different company.
C L Carter

This thread was discussed between 06/11/2011 and 09/11/2011

MG Midget and Sprite Technical index

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