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MG Midget and Sprite Technical - Can i tell if I have a Straight Cut Gearbox?

My 1966 midget is fitted with what appears to be a standard rib-case gearbox, but it makes a lot of noise even though it works perfectly with good synchromesh on the upper three gears. A pal wondered if it might be fitted with straight cut gears. Is there any way of telling without removing it and opening it up?
Mike Howlett

this subject is again in the Archives

I think you'd be in no doubt if you had straight cut gears in my one experience of them

topping up or better still doing a thorough hot drain of the oil left to empty out as long as possible might help a little

in my old g/box my mate said I'd got the loudest 1st gear he heard he he grew up with non-synchro 1st gears but it wasn't like the sound of higher straight cut gears
Nigel Atkins

Not sure if this is what you meant, but on a rib-case it is possible to remove the side access cover with the 'box still in the car. Access is a bit restricted, but enough space to get a look inside. Drain the oil first though!
Guy W

I've just had a thought (went dissy and had to sit down)

if you find a video of a racing Spridget/Minor/Mini/A30/A35 any thing with a straight cut g/box and hardtop filmed from inside preferably you'll hear what a straight cut sounds like even over the engine and exhaust
Nigel Atkins

Nigel, you say it's in the archives. All I can find is problems with first and reverse gear noise. Mine is noisy in all the gears, particularly on the over-run. I just wondered if a straight cut gearbox has any external identifying feature.
Mike Howlett

hey, you know how Searches go sometimes you find the right words or phrase straight away and the next time you can't even find what you found before

AFAIK (which isn't much) if its an original box it'll be be internal and I don't know of anyone that makes the boxes - but there could be some as I don't follow racing, I struggle to be able to afford to keep mine on the road let alone rip through engines, gearboxes, tyres and cars on a track

IIRC(?) someone has a straight-cut box in a road going car, I'm sure once you've heard what they sound like you'll know if yours is, if you can still your r/axle whine and tappets then you've probably got a standard box

have a look for those vids
Nigel Atkins

Nigels correct

If you had a straight cut box it would be loud to say the least. You would hear it outside and inside the car, inside it would drown the sound of the engine. If you can't hear it with the hood down then it is a standard box. All boxes have a bit of noise with the hood up worse if you use a hardtop.

Ed
Ed H

My own experience of racing with a straight-cut 'box is that it wasn't particularly loud, but it was a very distinctive sound.

I once bought a Midget from a guy who said he thought it might have a straight-cut 'box, but a quick drive in it established that it was just a very noisy standard box.

With regard to identifying it...there is nothing external. As Guy said, the easiest way to check is to drain the oil and pull the side cover. Make sure you don't lose the two springs for the detent plungers.
Dave O'Neill2

I've had another idea - two in one week

Mike record the noise of your gearbox for Dave to listen to and I think even I could recognize the sound

I think Dave put that info in the other thread I was on about because I probably put the ones I've heard are quite loud but the loudest was when I was a passenger in my mate's road going Mini that had perspex windows but the box wasn't as loud as the two ticking (internal?) fuel pumps
Nigel Atkins

Im sure it is a ribby straight cut gear box, there very.common on daily drivers with stock engines, brakes, and suspensions

On an unrelated note... I crap hersheys chocolate candy bars, there all brown with a nice smooth velvety texture

Prop

Prop and the Blackhole Midget

This chap is running a straight cut box.
http://www.youtube.com/watch?v=X-ofUWFEoe4
F Pollock

Yup, that's the nice noise :-)
Paul Walbran

Ah, thanks for the Youtube link Fergus. I hear the high pitched noise the SC box makes. Mine isn't like that at all. I would record the noise mine makes, but being a bit of an electronic Luddite, I have no way of doing that.
Mike Howlett

I could listen to that for hours.
Growler

"Mine is noisy in all the gears, particularly on the over-run."

Mike, that's not straight cut, that's worn out -- almost ;). I have a 1275 box living in my loft that makes exactly those noises. That's why it's in the loft, supplanted by a Type 9.
Lawrence Slater

I'm sure you are right Lawrence about my box being worn out. Damn! I have spent a small fortune on building this car and don't want to spend large extra sums changing the gearbox. While a 5-speed would be nice, to fit one has become very expensive now that Ford type 9s are in shorter supply, plus I am not keen to hack the chassis rail on my new Heritage shell. Even a reconditioned rib case is in the high hundreds of pounds.

If I strip it myself and replace what's necessary, what components do I need to change? The synchromesh works well, so I guess that's alright. From what I have read it seems as though the layshaft bearings and end float is the most likely problem. Any tips, gents and ladies?
Mike Howlett

As long as it still goes, and doesn't jump out of gear, and as long as you aren't too bothered by the noise, I'd leave it.

On the other hand, a couple of bearings and bushes now, might save a lot more wear later. I think you can buy a Kit. Guy rebuilt one I think. Guy?

As for T9's being scarce and expensive, not neccessarily so. They come up all the time on Ebay, and you can also ring around breakers yards and ask. You can get a good one for less than 200 quid and less than 100 if you look enough. Probably cost more for the bell housing and slave cylinder etc. But some people have done it pretty cheaply on a diy basis and it's worked well for them. Rob/bob and Guy?
Lawrence Slater

rebuild cost = where the noise is from.

so, is it different with the clutch in/out?

noise connected to road speed or engine speed?

noise change when driving along with engine disconnected?

noise in neutral?


>>Mine is noisy in all the gears, particularly on the over-run<<

this makes me think diff rather than gearbox.
Rob Armstrong

It never ends...thus the title ... The black hole, no currancy can escape...cash, credit cards, gold, stocks, bonds...the midget dosnt care...it just demands a finacial sacrfice to be paid and often

Mg is my religion, but it is one selfish god for sure

If the ribby is cheap enough on your side of the pond...maybe buy a spare and rebuild it to like new with fresh gears and guts at your leisure as money, time, and parts avialability permits


Prop
Prop and the Blackhole Midget

Oh don't I know it Prop. My MGB V8GT (which is the car I shall keep) has cost more than double its value. I had hoped the Midget would be a bit cheaper - some hope. I shall probably sell the Midget before too many months are up, but a potential purchaser isn't going to want to hear a noisy gearbox, is he. It's such a pest as everything else about the car is terrific, with a new shell and all the bits renewed.

Rob, thanks for your pointers but it is definitely the gearbox. You can play tunes with it by pressing the lever this way and that.
Mike Howlett

Mike,
A gear box that can play tunes? That's got to be a feature!
For what its worth, I somehow can't imagine someone who's willing to pay for a Heritage shelled Midget with the near guarantee of rust free bodywork from here on in is going to baulk too much at a slightly noisy gearbox, if they even know the difference. "Its part of the car's character and they all do that sir"
Matt1275Bucks

Lawrence, yes I rebuilt my gearbox, - but it is a type 9
I gave my ribcase box away as I couldn't ever imagine wanting to put it back in. Slight regrets now as it would have done for my frog!

My type 9 conversion cost me 220. But a long time ago when T9 boxes were 2 a penny (actually, 2 for 20, and I did as much of the fabrication as possible rather than buying the bits. But times they are a changing and this really isn't relevant.

Talking about changing times, back in the days of my youth a noisy gearbox on a car that you were selling was easily cured with a handfull or two of sawdust. Mike, I guess you could do that and claim it as a genuine 1960's period modification!
Guy W

>>You can play tunes with it by pressing the lever this way and that.<<

well that definitely sounds like a gearbox problem!

>>I somehow can't imagine someone who's willing to pay for a Heritage shelled Midget with the near guarantee of rust free bodywork from here on in is going to baulk too much at a slightly noisy gearbox<<

that's true :), and I would have suggested sawdust but Guy beat me to it.

I do have a tired and whiny type 9 in dad's garage with it's nose cut off, it was in my K. Bellhousing'd be the most expensive bit of the conversion.
Rob Armstrong

Yeah... The saw dust trick does work for a while... But if i where the new owner, revenge would be the rule of the day... I wouldnt, its just bad form...not that i belive that was ever a real intended suggestion...

Another opption that is similar to the saw dust trick is lucas oil treatment.. about a 5th of a bottle and it will quite down the box by 1/2 or more... I did it in my old ribby before the datsun 5 speed and it was a definate improvemnt but its not recommened ... Not sure why but there was a good reason not to... Id change the oil then add the lucas oil treatment, then tell the new owner the tranny flud was just changed and good for 50,000 miles... By that time your well in the ethical clear

Prop
Prop and the Blackhole Midget

Since the rest of the car is so good, I'd just tell all potential buyers, --

"the g/box is a bit noisey but otherwise works well in all gears, and that's why the price isn't higher. If you want a quieter g/box, I'll fix it for you, but I'll have to put the price up. Sorry "
Lawrence Slater

That's certainly an option Lawrence. I'll do nothing this side of Christmas anyway.
Mike Howlett

Oh ... Great idea lawerance, and no wrenches to turn
Iike that idea...esp better then the saw dust trick

Prop
Prop and the Blackhole Midget

This thread was discussed between 22/11/2012 and 24/11/2012

MG Midget and Sprite Technical index

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