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MG Midget and Sprite Technical - 1500 gearbox story

I have finally got around to pulling my 1500 gearbox apart. When I had the car running many moons ago first gear made a sort of clattering/clicking sound.( like a loose bearing ) Also the clutch bearing would scream if I tried to pull away anything other than carefully. ( more of that anon - will post separately)

So today I managed to get the mainshaft and layshafts etc out. The state of the reverse idler - which engages when you select first or reverse is quite something - absolutely every tooth is chipped - most don't have a discernable apex to the tooth form at all.. - the other gear amazingly doesn't look too bad !

Lets see if the pic comes out - doesn't show just how bad it is..


So new reverse idler gear and reassemble !

Lots of swarf attached to the magnetic drain plug !!



John Barber

Keep us updated John! I am thinking about refurbing my 1500 'box sometime soon. I took off the top panel and mine looked in a similar state! I would be interested in knowing about what parts and things you replaced.

Cheers,
Malcolm
Malcolm Le Chevalier

For those interested I am putting some pictures of the relevant bits and pieces of me gearbox and clutch rework story. mainly just the parts for now - I may try to see if I can explain my way to assenbly/ dis-assembly later..

anyway see at this link

http://s1136.photobucket.com/albums/n484/drjrbarber/midget/gearbox%20and%20clutch/?albumview=slideshow
John Barber

not sure that link worked - try this one..

http://s1136.photobucket.com/albums/n484/drjrbarber/Midget/gearbox%20and%20clutch/
John Barber

John,
I don't think this site likes the spaces in the link (shown as 20%)

a computer guy told me not to put spaces in file names for reasons I forget

so 'gearandclutch' instead of 'gear and clutch'
Nigel Atkins

Mine sounds exactly the same in 1st... I've bought a second hand box... so that I can rebuild that and stick that in in a single weekend... means I can keep the car on the road a bit longer.

I will let you know what my reverse gear looks like when I get it off.

C
C L Carter

managed to get my desk camera to focus a little better..

I am going to replace my thrust washers and the neddle rollers which are cheap. The main bearings are about 18 a pop.... With the reverse idler at about 36 the whole repair shpuld amount to about 80 with gaskets etc..

I will try to remember to take some pictures as I reassemble it...

let me know how you get on with your C..

Did you find the pictures okay then after correctly the spaces Nigel?



John Barber

Hi John,
no I copied and pasted the link into address bar at the top of the scren and it got me there eventually but I ran out of patience want for the photo to resize

I really meant you need to rename the file or copy it and put it under a second file name without spaces

is it just your intials or are you a Doctor as I have some photos I'd like a doctor to see :)
Nigel Atkins

Okay understand the problem now try this link..

http://s1136.photobucket.com/albums/n484/drjrbarber/Midget/

This should like to photobucket pic's of my part restored midget - you can then navigate to the sub directory which has all the gearbox stuff in it.. ( called funnily enough 'gearbox and clutch' )

Nigel Its not initials so by all means send pictures (I could do with a laugh if its something embarassing) - but I won't be giving any opinions on any medical matters over the net. As a professional engineer I don't think this would be ethical and besides you probably won't like my prescriptions.!

cheers
John Barber

as it happens John some of the medical matters probably need engineering solutuions :)
Nigel Atkins

Hi John,

Keep me updated - have looked through your photos. I'm keen to know how hard it was to strip out the internals. Did you use a bearing press? Would be great if you could share what order and how you accomplished it?

Are you replacing all bearings and seals as well as the reverse idler?

Where are you getting parts from?

I've bought a spare box from eBay, i've cleaned it up and painted it. Replaced gaskets, and mounted it on my lathe and listened to how it runs is all gears. Sounds fine so i'm tempted to wack this one in and then rebuild my one when it comes off.

Keep me updated!
C L Carter

Hello again, have stripped out all the mainshaft and gears synchros etc washed them off and taken a detailed look. I followed haynes Manual basically - I managed to get the speedo drive gear off the mainshaft by using the mainshaft bearing which you lever out of the casing - using something sharp /flat behind the split washer which is mounted in the bearing outer race in a groove... Once you have the bearing free from the shoulder on the shaft - you can use it as a drift against the speedo drive gear - I just used the weight of the bearing to tap against the speedo gear and it gradually moved down the shaft and off...

I have posted a load more photo's on the photobucket link above for those interested in gearbox strip and repair. next step is to order them and annotate with step wise info. Reassembly shouldn't be too tough just need to work out the thrust washer size ..

I will post when I have it all done.

Intend to renew needle rollers as I have rock in the mainshaft to input shaft and in the layshaft also. main input bearing and output bearings and gaskets thrust washers etc.

John Barber

I am going to put in the new box, and then strip down the original when it comes out. I can't wait!

Isn't it amazing to think that those gears have spun round millions of times and they've transmitted quite a bit of force too!

Gotta love real engineering!
C L Carter

Carter, I could not have said it better! So much more interesting than my engineering desk job. Snooze! Ha ha

Malcolm
Malcolm Le Chevalier

Malcolm, it sure beats my accounting desk job!
C L Carter

This has inspired me to start my gearbox overhaul.

Hit a problem already tho... How do you get the output flange nut off? Is there a smart way to lock the 'box to get this off?

Box is out the car sat on the floor seperate from engine.

Cheers,
Malcolm
Malcolm Le Chevalier

I didn't have too much a of a problem with this - you can try putting something through the prop flange bolt holes to lever against the tail casing...
John Barber

Malcolm,

I'm not familiar with the 1500 box except it seems similar to many Ford boxes. If John's idea doesn't work then I would have tried putting it into a forward gear and reverse, obviously after the interlock mechanism has been removed. With the top cover removed that should be a simple matter of engaging a forward gear then sliding the reverse idler into engagement which should lock the gearbox output shaft.
David Billington

Thank you for this find it very interesting. I just pulled my engine as I thought the clutch release bearing was going however the bearing looks fine do think the gearbox is coming out and a rebuild.might be needed. Toying with the idea of doing it myself or a professional rebuild but think the limited funds will mean I am doing it.
C Carter

Started dismantling my box at the weekend. Looks pretty easy really. (Famous last words)

Couldn't lock it as suggested to get the flange nut off. So did it the red-neck way and wedged a spanner inbetween the case and one of the gears... *whistles innocently*

Cheers,
Malcolm
Malcolm Le Chevalier

Malcolm,
I've not had the 1500 box apart but it should be similar to others. The objective is to lock the gears on the output shaft. On a transverse mini box this is done by forcing the two syncro hubs in to gear, thereby locking the box. Then you only need to worry about stopping the whole box rotating ;o) I recommend sitting astride and riding bareback (Rach'll now what I mean) lol
M McAndrew

I tried following Davids advice but without removing all the selector forks and gubins I couldn't figure out how to manage it.

And you can't seem to get these bits out without getting the output flange off so it seemed a bit chicken and egg...

Admitedly I didn't give it a huge amount of thought/effort before giving up and using the wedging method! I'm sure there must be a 'proper' way but it's too late now.

Malcolm

P.S. Yes, I then had to mount the box horse/camel/greased pig style in order to stop it flailing about the garage floor.
Malcolm Le Chevalier

Malcolm,

Shame about the chicken problem. I realised later in the day I posted that comment that putting the gearbox in any 2 gears is sufficient as M McAndrew mentions. So practically you need to engage 1st or 2nd and 3rd or 4th by sliding the synchro hubs into engagement, thast'll have the effect of locking the gearbox.
David Billington

No worries David, no harm done!

Thanks all the same.
Malcolm Le Chevalier

Hello, been a bit slack on the follow up - have ordered a host of bits and pieces to come for this weekends re-assembly bonanza. Key thing is the reverse idler gear. new needles and seals etc thrust washers still reqd which I am having trouble getting. Measured the selective washer clearance and found all okay so it can all go back together now. I will post a reassmbly process in stage by stage pic's when done.
Sorry you had trouble getting the flange off Malc - really was not an issue on mine as I say either - use screwdriver through the flange and lever on the casing or use two screwdrivers through two opposite holes and long lever between them to work against the spanner on the flange nut. (if that makes sense)..

So far I really can't see too much here to be frightened of - really not much more difficult than an engine rebuild I would say.. However I will confirm once its all back and spinning in each gear !
John Barber

Have my rebuild kit and just bought some circlip pliers. Here's hoping for a jolly weekend of gearbox rebuilding!

I will let you know how I get on.

Malcolm
Malcolm Le Chevalier

This thread was discussed between 28/12/2011 and 26/01/2012

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.