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MG Midget and Sprite Technical - Type 9 GB in 1275 Midget Question.

Anyone doing this now that can measure the distance between the Type 9 gearbox face and the bell housing face?

I'm doing this now using a slightly none standard route but my measurements suggest I have a 15mm discrepency somewhere.

Rob
Rob aka MG Moneypit

Which gearbox do you have?

I'm led to believe that some type 9s have different length first motion shafts.
Dave O'Neill 2

The ratios suggest a Sierra 2ltr but the input shaft looks to have been shortened but protrudes about 5mm out of the bellhousing face so may have been a long input shaft. No idea why.

The bell housing is an Antec racing alloy originally meant for fitting a Midget 1500 gearbox to an A series engine. I have a Canley Classics adaptor (1500 to Type 9) to go between the bell housing and the gearbox.

Rob

Rob aka MG Moneypit

Dave
you are correct. I'd have to search out paperwork to be able to give the different lengths.
Alan
Alan Anstead

I know there are two lengths. 208mm and 175mm.

I'm sure this box has a shortened long input shaft but the first gear I measured at 3.65:1. Long input shafts were fitted to Diesel, Pick-up and V6 engines but having a 3.65:1 first gear means it is either a standard Sierra or Early V6. Also, this gearbox has the later hexagonal and lower oil capacity so that rules out the early V6.
This gearbox seems to be a standard Sierra, but fitted with the long input shaft that has been shortened. Very strange.

Anyway, It won't fit my 1275 engine for a number of reasons that I cannot reconcile. If anyone knows the distance between the bell housing face and gearbox face I can rule out one of the variables involved.

Rob

P.S. I have Daniels excellent book, hence the above info.
Rob aka MG Moneypit

I thought I ought to measure my input shaft. It measures 175mm but it has definately been a shortened long shaft.

The very end has been chamfered crudely and the splines have been parred back a few mm.

Also, the distance from the face of the GB to the face of the bell housing is 170mm leaving the input shaft protruding by 5mm.

Rob
Rob aka MG Moneypit

Rob,
I have a scanned copy of a magazine article on the T9 box which is quite useful in identifying the several variants. I could e-mail it if you provide an @ddress.

As far as I am aware the longer input shafts are matched to a deeper CI bell housing, so as to give clearance for a more bulky clutch assembly. So when the gearbox is then used with a replacement alloy bell housing, the longer shaft extends too far forward. It then either needs swapping out for the shorter version, or more commonly it is simply shortened with hacksaw or cutting disk.
Guy Weller

Hi Guy,
I think I have enough info on the type 9 itself, just wondered if anyone was doing it right now who could give me a measurement. Thanks for the offer.

If anyone has bought an alloy bellhousing from Frontline, MMC or whoever, I would be interested to learn how deep it is.

Rob
Rob aka MG Moneypit

I think I can probably reach into the engine bay or get underneath, and get you the measurement you need a little later today Rob, if nobody has a loose one laying around.

As it happens though, won't the depth be the same as the original cast iron ford bellhousing? The shaft has to penetrate the crank spigot, so I'm guessing the depth of the bellhousing is the same. I have 3 of those spare, and can measure one of them. Or maybe not, as the A series crank, and the Ford crank are of course different. :(. But I'll measure it anyway.

Lawrence Slater

Thanks Lawrence.

I seem to remember reading somewhere that the input shaft should be flush with the bell housing face.
In my setup it is proud by about 5mm or maybe a little more.
When I first offered it up it fouled on the old spigot bearing which I removed and it seemed to be ok.
Then I put the clutch on and tried again and the splines fouled on the fingers of the clutch. Then I started measuring and realised I may have a problem!!!

Rob
Rob aka MG Moneypit

A bit too much rain today to get a decent look. I'll have a go tomorrow.
Lawrence Slater

Rob,
When I did mine I remember that I had to remove the 1275 spigot bearing from the end of the crank and drill it out oversized to suit the ford input shaft. Therefore if you attempted to fit it to the standard spigot, it would of course foul on it. In my case I was using a V6 gearbox with the longer shaft and I therefore also had to lop about 20 mm off the end.

Although one might assume that the alloy bell housings are the same depth as the Ford CI ones, this isn't necessarily the case. The bell housing depth must be determined in each case by the clutch cover plate etc that it needs to house, and this will likely be different from the Ford original.
Guy Weller

Forgot to add, my bellhousing is 180mm from the gearbox face to the flange that bolts up to the '1275 backplate. I hadn't posted this before as firstly mine is a fairly early MMC one and I know that the design was subsequently changed, so this measurement may not match their current offerings. And then you were also talking of using a different version anyway, weren't you?
Guy Weller

Thanks Guy. Some good info there. I did a more accurate measurement on my setup. My bellhousing depth is 174mm and my input shaft is 181mm long. So I too have a long shaft that has been shortened.

Did you enlarge the smaller or larger orifice in the end of the crank?

When I offer it all up to the engine and get it as far forward as possible I have a gap about 7mm wide between bellhousing face and engine backplate (this is with the flywheel fitted but no clutch cover). Looking into the bellhousing I can see the splines touching the larger orifice in the end of the crank.

If I put the clutch plate on the splined part of the input shaft and do the same again I can see that the plate centre (the splined part) overhangs the splined area on the input shaft by about 5mm.

So, it looks like I could do with about 7mm more bellhousing depth. Bum!!!!

Rob


Rob aka MG Moneypit

Rob,
I measured the bell housing depth by reaching under my car (its not been raining today here up north!) so that 180mm measurement may not be spot-on, so it needs to be considered as =/- 2mm

I have a spare box which has a standard input shaft. This measures 177 mm, taken from the face of the CI gearbox housing (i.e. not from the face of the big circlip). On that shaft the nose section is 30mm long, and behind that is the splined section which is another 45mm in length.

Looking back through photos I find one of the spigot bearing that I used. I thought I had made it but looking at the photo this looks like a bought in one. Memory playing up, it was about 15 years ago!

Guy Weller

That looks like the MMC centre doohickey Guy

But you may well have made it instead

Rob is the engine out of your car now?

I would like to help but the photos I used before to illustrate my measuring set up have vanished in the dross inside my hard drive...

Its gone kinda floppy

The pictures may still be in the archives though

Braver men than me have trawled through them to find missing gems

bill l

Hi All. Had another tinker tonight. I loosened the bellhousing to gearbox screws enough to place 3 nuts between to gain an extra 6.5mm. I can now attach the gearbox to the engine without the input shaft fouling the crank end flange.

I have some 8mm ally plate so could make a spacer. I have a choice of putting the spacer between bellhousing and gearbox or between bellhousing and engine. Which one I choose will depend on release bearing clearance which I have yet to determine.

Putting the spacer between bellhousing and engine will gain me an extra 8mm clearance if I need it but will involve making a big spacer. If I don't need any extra clearance I will put the spacer between bellhousing and gearbox, it will be a lot easier to make such a spacer.

The Antec bellhousing has been drilled (before I got it) for a concentric slave which I have found out has the same 3 point mounting as a SAAB 9000 concentric slave which I have also purchased and trial fitted. Just need to put it all together to check clearances which I will try to do tomorrow.

Thanks for all the help. I will report back when I can

Rob
Rob aka MG Moneypit

Hi All, got some time on the problem. I cut the middle out of the 1275 clutch cover and reassembled (including a new friction plate) but without the concentric slave. Drew a line around the input shaft where the diaphragm fingers reached. Dismantled everything, fitted the concentric clutch to bellhousing to reveal no clearance. Infact it's about -2mm clearance.

So I need to make a spacer about 8mm thick to go between the bellhousing and backplate.

Oh well, out with the jigsaw, drills and pencils.

Rob

Rob aka MG Moneypit

Well, at last, after about 4 hours hard work I finished the spacer. I made it out of 8mm Alli plate. See attached. Next step is to check clutch release bearing clearance. Hope I've got it right now.

Rob

Rob aka MG Moneypit

Nicely made backplate spacer Rob.

"to reveal no clearance. Infact it's about -2mm clearance." - My concentric operates by being in constant light contact with the clutch fingers. That's how it is designed to work.
Guy Weller

mine too

You might find the hydraulics push the working gubbins out if you have to move the bearing that far before the clutch operates

I reckon on about 12mm movement inside the cylinder, off to on, if my memory serves
bill l

If my figures are correct I should have about 5mm clearance. The cylinder hasn't had any fluid in it yet so the clearance is with a virgin cylinder so is as far back as it's going to go. From what i have read on t'internet, you should allow for about 5mm due to clutch plate wear. As the clutch gets thinner the fingers move toward the release bearing so if you have insufficient clearance you find the clutch slipping before before it's worn out. I had this on a frog that used a 1098 gearbox and clutch release with a tin 948 backplate. The clutch slipped before it was half worn. Very inconvenient.

Took a while to do the spacer. I only have a battery drill and powered jigsaw and a set of old files. Many jigsaw blades were sacrificed!!!, and I spent hours filing everything down. I could really do with a drill press because some of the holes I drilled were not very square, but they aligned enough to allow the backplate screws to be fitted.

Next is (yet) another trial fit, then dismantle and plumb in the hydraulics.

I went to a local steel suppliers and got a 2 ft length of 60mm square tube with 2.5mm wall to strengthen the cut cross member. Must have caught them on a good day. it only cost me 2 in the charity box.

Rob
Rob aka MG Moneypit

I worked mine out starting from a measurement of the concentric slave with it extended to the forwards limit of its travel. Then subtracted the 12mm needed plus a couple of mm clearance. That left me around 8mm to accommodate clutch plate wear. I then used these figures to work out what thickness to make the mounting block to hold the slave in the right position relative to the flange of the bell housing.

The bit that surprised me was that the standard 1275 master cylinder moved just the right amount of fluid on a single pedal stroke to achieve the correct movement on the slave. Coincidence? Or is there an industry standard, in which case why?
Guy Weller

Got everything sorted and got about the correct clearance with a new clutch plate. Need to plumb in hydraulic lines to somewhere on the box and fit flexi pipes and some way to bleed system.

Will post image soon.

Rob
Rob aka MG Moneypit

Got the hydraulics at the clutch end sorted. See image. I have two terminations, as seen, for the small unions used on a Frogeye. One will be a bleed point and the other will be the connection to the MC via a flexi direct from the MC. It's long enough so I can have the engine and gearbox next to the drivers door and still have it plumbed in so I can try it before fitting into the car. The last thing I want is to play hokey-cokey with the engine and gearbox.

Rob




Rob aka MG Moneypit

This thread was discussed between 24/08/2014 and 23/09/2014

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