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MG Midget and Sprite Technical - It jumps out of first

When I bought the wreckage of my Sprite Mk 1, the vendor may have said something about the gearbox. I forget, but then he hadn't driven it for more than 25 years, leaving it to rot in his garden, so I probably would have been sceptical about his comments anyway. Just in case, though, I had a good look at the gearbox during the rebuild, and replaced the layshaft and a couple of bearings (It's that smooth case gearbox with the close ratios that was fitted to the Mk 2s - not the original, but he'd had it fitted in 1962 and I've got the receipt).

After a number of last-minute hitches, which I've griped about on this forum - including losing the keys for a few weeks - I took it out last night for its first road run since the 'completion' of the rebuild . 18 miles there and back to our local club meet, only to find that it jumps out of TOP gear. Otherwise it's a nice quiet gearbox (except possib;y in reverse, which whines a bit). I suppose now that I'm going to have to hoik the engine and gearbox out again before I can start to enjoy it, but can anybody suggest what I must have missed? I've had gearboxes that jumped out of gears before, but not top gear, and I am at a loss. Any suggestions would be welcome.

G
Gus Gander

Hi Gus

I rebuilt my 1275 box back in 1981. (Never a problem after, in case you wondered...)

Anyway... there are a number of possible causes; I can think of two:

1. The selector forks need to be repositioned slightly, that is the shaft is not moved far enough to engage fully with the gear selection.

2. There are a couple of springs and bullets that slot into a cut-out in the selctor shafts to semi-lock the shafts in place, when a gear is selected. They provide the box with its 'feel'. Maybe these are missing, or similar...

I think that either of these is likely to be a box-out job...

I hope someone has more info...

A
Anthony

A couple of more possibilities are that the teeth on the synchro hub assembly are worn (or the corresponding teeth on the input shaft) or the shims that locate the input and output shafts need to be thicker. If these aren't correct, the shafts are too far apart causing the synchro hub not to engage fully.

Anyway you look at it, it looks like it's an engine out fix.

Martin
Martin

The easiest and first thing to check is to see if you're getting full travel of the lever relative to the hold down plate and that the brass or nylon bushing is making full contact with the selector. If you look at the AH Spares website it's the O ring, button and spring that needs to be in good nick, otherwise you can get lost movement. Also check the gear lever is not fouling the rubber gaitor and housing.
f pollock

Gus.

The worst wearing part of the midget or Sprite gearbox is usually the first gear on the main shaft and lay gear. Sadly the Mk2 C/R box is not easy to buy replacement parts for, so I would follow the advice above and also check that the detente springs and plungers are good and seat properly and you are getting full and correct selection.

If you are stuck, I still have a small selection of 'A' type gears and MAY have what you need, but I can't promise....

Call me if you would like to discuss more.

Mark.

07889 799033
Mark T. Boldry

Thanks for the suggestions. I am on my way out to check on the lever and the remote linkages, though I seem to remember that these were OK. The gears SEEM to select OK, and even on top I can convince myself I can feel the detent engaging. After this, I can run for a while in top, but it jumps out when a bit of wellie is applied.
The pity is that next weekend I was going to attend a show at the Tilford Rural Life Museum near Farnham, in order to show off the finished car to the vendor, who lives nearby. Short of running down there in 3rd, or holding the lever in top all the way (about 200 miles,which I suspect won't do the selector forks any good), I don't think I'm likely to make the date as promised. Getting the engine and box out, correcting the fault and putting it back in would certainly take me all week, especially as I remember it took about 15 months to assemble enough family members to help me put the bonnet on.

Is there anybody in the Bristol area who could lend me an engine crane for a little while? Please? I'm on 01179 677606, or at gusganderATblueyonder.co.uk

G
Gus Gander

Just to update: I lifted out the engine and gearbox (with just the strength in my arms) and had a quick look at the gearbox. All the detent balls and springs seem present and correct, so that just seems to leave a fault with the selector fork, or wear in the gears. I shall strip the box further to look. but at about this point I remembered that some time ago I had bought a used but 'Gold Seal' rib-case gearbox, so I have attached this to the engine ready to fit. I realised that I should need an engine crane to refit, in order to achieve the necessary degree of precision and to avoid damage, but found I couldn't hire one locally this week. As I wanted to make the weekend outing, I got on to Machine Mart to BUY a crane. My local branch hadn't got any in stock and didn't seem disposed to help, but I found that the Gloucester branch had one of the 500kg type. Checking by phone that it was definitely all there and available, I set off yesterday morning to collect, banking that I could make the trip in the morning and get the engine in yesterday afternoon. On collection I explained the urgency and checked again that the packages contained all the bits, and had this confirmed. By now you can guess the rest. When I got it home I found all the fasteners, chain and hook missing. Their customer services people wouldn't talk to me, and the branch staff were adamant that they would only refund my money if I undertook to take the parts I had back to the Gloucester or Bristol branch. This despite the fact that I was already out of pocket to the tune of a return trip to Gloucester. So much for Machine Mart, who I shall certainly avoid in future.

All this to and fro stuff has now meant that I shall certainly be unable to complete the job by the weekend. I shall have to obtain another crane after all. I am at present leaving the whole job for some days until I feel better about it. All very disappointing.

G

Gus Gander


Sorry to hear about your problems with Machine Mart, but I think they are gaining a reputation for "jobsworth" employees and a unhelpful service.

I brought a trolly jack from them, collected it myself, a 3 hour round trip. First time I used it, it failed! Leaving my car in the air on this jack, the only helpful suggestion Machine Mart could make was " take it back to the shop" yes, but it's got a car on it, "not our problem" was their response!

Went to Halfords brought a jack and have used it for 6 years now and will never step inside a Machine Mart shop again.

Didn't take the other jack back, I know the bloke I talked on the phone would have ended up wearing it!

Andy
a borris

Gus,

Sorry to hear about your problems with Machinemart, personally I have had good service but maybe haven't challenged them enough. I have had good results from their spares department including spare worm and wheel for their 4x6 bandsaw which I had purchased about 7 years earlier, and other items.

BTW if you want to borrow a engine crane drop me an email at djb[ at ]metal-arts[ dot ]co[ dot ]uk .
David Billington

Gus, I'd hazard a guess that if you're strong enough to pull an engine and gearbox out single handed you can certainly put it back in on your own. In fact I find it easier if anything. I use 2 lengths of wood. One forms a ramp up to the steering rack and a shorter piece sits on a trolley jack in the engine bay ready to take the sump. If you grab the engine at the mounts the only hard part is the lift over the rack to the front crossmember. After that the jack carries all the weight and you can just slide it back in.
f pollock

You won't want to be getting in and out of a Midget with a slipped disc though will you! I know all of these things are possible (I lifted an MG metro engine and box out by hand many years ago) but its not really a good idea. £75 for a first appointment at a chiropractor and probably 4 or 5 shorter visits after that,that would buy a lovely engine crane!

Carl
C Bintcliffe

Well, I've decided to abandon the trip to Tilford, Farnham, for tomorrow, and give myself time to do the job properly, and in a better mood. I shall do without an engine crane (thanks anyway to David in Bath) and sort out a system of sled and lever, with the aid of a strong piece of angle iron and some bits of wood, as suggested by Mr Pollock.

For the meantime, I have decided to have another look at the gearbox that was jumping out of top, with a view to putting this back in after all. Noticing that the rib-case gearbox had a different clutch fork also influenced this decision. At present I have the gearbox stripped and on the bench. I had been through it before, and a second examination shows that, by and large, it's in pretty good condition. Layshaft float is well within tolerance at about .002" and none of the gears show signs of wear. It had a new layshaft and needle roller bearings earlier in the job. The outer case is still in 'Gold Seal' paint, and has the number AEA 3021 stencilled on it. This number also appears on a small alloy disc riveted to the top of the bell housing.

All this must mean that the wear I see on the selector fork rods must be enough to cause the problem (the selectors themselves seem OK). I've attached a photo. The 3-4 rod is closest, and the 1-2 rod is further back. The reverse rod shows NO wear at all. I think I shall need to replace these rods, if anybody can help. The number of the 3-4 rod is 2A 3347. There may be a 'B' or '8' on the end of this number. The 1-2 rod (which I may not need as it works OK in these gears - for the time being at least) is also numbered starting 2A 3??? but I can't read the rest of the number. If anybody needs it to identify a set, the reverse rod is numbered 22A 198 (again with a possible 'B' or '8', but this rod doesn't need replacement. I'd be happy to pay a reasonable price for these rods, and any gaskets for the reassembly.

By the way, any clues as to how to get the tailshaft oil seal off? This has taken some damage and is now distorted. I'm presuming it just presses on, but am wary of just taking it off with a chisel if there's a better way.

G


Gus Gander

Gus,

I've helped a mate with getting the engine out of his Caterham with a wooden beam, lashed up A frame and blocks on his bench etc, etc. It worked but I took my crane down when we put it back in and he admitted it was so much easier. He had previously done it before, in and out, with the aid of his wife with the beam assembly.

David Billington

David: I will, after all, take you up on the offer of the loan of the engine crane, and thanks. I have put the whole issue on the back burner for a couple of weeks while I explore the possibility of obtaining new or better selector rods, or maybe of getting the existing ones built up (by metal spraying and regrinding?).

I'll be in touch soon.

G
Gus

I decided to bring this thread up-to-date, as I feel rather jubilant at present. I have just finally identified what has caused the problem, and I really can't think why I hadn't noticed it before. The internal teeth in the synchro hub for gears 3-4 are very worn. I've attached a phot which clearly shows the 'one-sided' nature of the wear which has caused 4th to throw out. The selctor rods, which I'd been blaming, are nothing to do with the problem.

I've arranged for a replacement 2nd hand syncro assembly from those nice people at 'Mirabelle' who have been so helpful, but if anybody's got a new or very good condition one of these, I'd like to hear of it, and probably buy that as well. The part number appears to be 2A 3226. Just the outer moving sleeve would do. The ring on which it moves is fine, apart from my losing a couple of the balls during the rather sudden dismantling.

There appears to be no collateral wear on the first motion assembly, which is puzzling.

G


Gus Gander

Wow! I got one right (post no. 3). That's what mine looked like. Thanks for the update and glad it's sorted.

Martin
Martin

Gus, sorry I just haven't had time to look through all my gearbox parts yet....

Mark.
Mark T. Boldry

This thread was discussed between 11/09/2008 and 01/10/2008

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