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MG Midget and Sprite Technical - SORRY! But yet another T9 installation question

I have been trawling for hours and hours through the archives for clarity on this question but I'm more confused than ever!

As previously stated, I am going to be fitting a Type 9 5 speed to my 1275 A series. I have bought an MMC bellhousing and a later type 'box from a Morris Minor owner.

I plan to install a concentric clutch setup with probably a 7.5" clutch (from Avenger/Escort?), with the flywheel modified as necessary.

My query is with regard to the Spigot Bush. I have seen reference to this bush being fitted within a steel sleeve that is fitted from behind the flywheel and in fact the seller of my bell housing has sent me a diagram indicating as much.

Also, I have found on Ebay this item being offered as a supposed necessary part of a conversion http://www.ebay.co.uk/itm/311140308702?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT.

From what I can see of the 1275 midget engine design, this steel sleeve is not fitted in the standard setup and I can't see how/why it can be fitted as part of the 5 speed conversion.

I appreciate that a new, different sized oilite bush will have to be obtained and fitted, but can someone please explain the need (or otherwise) for the accompanying steel bush?

Thanks
Glynn
Glynn Williams

The Type 9 gearbox 1st motion shaft when fitted to the correct adaptor bellhousing is too short to locate in the original spigot in the crank ( its the wrong size as well ) This Ebay adaptor fits inside the flywheel to locate the new Type 9 spigot, So the steel is just an adaptor to take the new sized bronze bush. There you go , clear as mud!
R Mcknight

Ok, I understand I think... I need the adaptor to extend the location of the spigot towards the 'box? I already realised the ID/OD's were different but assumed that the design of the bell housing would position the input shaft in the right position along the length of the car :-/
???
Glynn Williams

Glynn,

One issue is IIRC that some crankshafts don't have a large enough spigot bore to fit a bearing large enough for the type 9 input shaft. The A series used a 1/2" input shaft end and that of the type 9 is 15mm. I'm not sure which engines had what but mine had a 5/8" bore for the spigot bearing to fit into and I don't think an oilite bearing is made thin enough that would allow a 15mm ID to be fitted into a 5/8" bore with a sleeve.
David Billington

The shorter gearbox input shaft will end up (when engine/box all bolted up) just short of the bore of the crank where the original spigot bush is. So the conversion needs a spigot bush 'carrier' that sits in the internal bore of the flywheel and extends slightly forward towards the crank.

The new bush carrier needs to be an interference fit in the flywheel and the oilite bush also needs to be an interference fit in the carrier. From experience this isn't always easy to achieve when buying the bush carrier, I had 3 from Frontline that were a loose fit and even after loctite and centre punching they still came loose. In the end I had one made a few thou bigger so it was a really good interference fit. Frontline couldn't seem to grasp that removing a thou or two to make them fit would be a lot easier than making them grow a thou or two!

So make sure it's a really good hammer in fit, use loctite on the carrier to flywheel and also on the bush to carrier if possible. Another thing I've just remembered is that the bush is better to be too loose than too tight on the input shaft, on my first install the bush was too tight and seized onto it causing the bush to turn in the carrier. I think I relieved the bush a bit with emery cloth.

On about the third try it was all fine!!

I'd definitely try and get the concentric slave sorted, the other options aren't brilliant.

Not sure I'd bother going for a bigger clutch unless you've got a real fire breather under the bonnet. I'm still on my original clutch from Frontline (10 years ago) and it gets some serious hammer with no probs so far.
john payne

Thanks John - that all makes a lot of sense. I might just get one "made to measure" then based upon your experience and then source an appropriate sized Oilite bush to suit.

Regarding the clutch, I had just picked up on the threads of other installations that going for a larger clutch at the same time was just "the done thing". If my existing clutch looks in good order when I dismantle it, I might well leave it alone and re-fit as is.

Cheers
Glynn Williams

Hi, that's my item on eBay. This is what you get from David Manners who do these for Minors and Midgets.

As R McKnight pointed out the type 9 input shaft is too big a diameter to allow a spigot bush to be in the same place as an A series gearbox. The hole is smaller that the input shaft. So, the solution bellhousing manufacturers came to was to put more distance between the gearbox and flywheel. In this position the input shaft is within the larger hole in the end of the crank so allowing an adapter with oilite bearing to be fitted to carry the input shaft.

The reason I am selling this is because the type 9 GB I have has a long input shaft from a V6 type 9 GB. This needs to be shortened to be the same length as a 4 pot type 9 input shaft. BUT, with the longer shaft shortened, the splines are so close to the end of the input shaft that they fouled on the spigot bearing carrier from David Manners.

So I had to remove it and make other arrangements, hence why it is on eBay.

BTW, the spigot adaptor sits within the recess in the flywheel and is meant to sit flush with the flywheel face.

In the end I had to buy an oilite bush that was 22mm OD to fit inside the larger (outer) hole in the crank.
There is something important about the holes in the end of the crank. The outer does not have to be accurate. The inner must be an accurate size to provide an interference fit for the proper 1275 spigot bush.

The outer hole can vary quite a lot in diameter and I was lucky enough to find mine was almost exactly 22mm diameter. It's nominally, 7/8 inch but as pointed out above does not need to be accurate.

There is no reason why you shouldn't do the same. In the end I had to mount the 22mm bush on a mandrel and reduce it's diameter very slightly to give an interference fit. Obviously, the 22mm I had measured was not very accurate and I believe the bush was on it's oversize side of manufacturing tolerances.

If you look at the David Manners website (good luck with the search facility, it's cr*p) you will see they have 2 spigot bushes for the type 9 to 1275 conversion, for the reason I pointed out before, the lack of accuracy of the outer hole. In fact, you may end up having the spigot bush carrier outer diameter reduced to make it an interference fit.

If you need any more advice please ask away. I'm just about to fit the engine and GB this weekend after a long and tortuous type 9 conversion, mostly due to not taking the well tried and tested route.

Rob
Rob aka MG Moneypit

I did this drawing to show how the spigot bearing and carrier sit.

The original spigot bearing is not shown in this diagram but is to the right of then new carrier.

NOTE this is only a problem when using a cut down long input shaft type 9.

Rob




Rob aka MG Moneypit

I should have said "to the left".

Rob
Rob aka MG Moneypit

Thank you Rob for the detailed explanation. I have attached my version of what I think you describe/draw - is this correct?
If it is, I still don't understand (because I'm thick!) why the "spigot adaptor" and the spigot itself can't be made from one single piece of Oilite material, fitted into the flywheel and crankshaft? Is it because the steel adaptor needs to be a TIGHT fit in the flywheel and crank?

Glynn


Glynn Williams

Hi Glynn, almost correct. The blue part marked spigot bush sits within the flywheel so it's face is flush with the recess in the flywheel. Also, the diagram shows the input shaft protruding too far into the crank. A friend of mine found that when he did his he had to remove the original spigot bush because his input shaft was just touching it. Sometimes due to production tolerances this happens when bellhousing and backplate are near minimum and crank flang is near maximum.

I think the answer to your question is it can be one piece because that is what I ended up doing. My bush was 22mm OD x 15mm ID x 16mm long (which is not a common oilite bush size). The larger (outer) hole in the end of the crank is not very deep (15mm at least, 16mm at most) so not a lot of bearing surface. Using a carrier you can add the thickness of the flywheel recess (about 6mm) giving a bearing surface about 24mm long. Also, a more common (and hence cheaper) oilite bush is probably available to fit this carrier.

The longer bearing surface is ok for the short type 9 input shaft. Due to mine being a shortened long input shaft I only had about 15mm before the splines. In my case I also needed to grind the splines back by a further 5mm but it left a surface not suitable to run in a bearing.

Mine has a SAAB 9000 Concentric slave only because the bell housing I used was drilled for it. The usual is the Burton Concentric but a bit expensive for me. (I bought the SAAB 9000 for 45 complete with release bearing off eBay). SAAB 900 has also been used by some. It depends how handy you are with a lathe (or if you know someone with a lathe). I didn't need either as I was lucky to find which slave fitted my bellhousing. If you can get bits made up then there are very cheap concentric slaves. (Cheap in the sense not expensive but good quality as currently used on production vehicles)

Rob



Rob aka MG Moneypit

Cheers Rob.
When I get my current engine/box apart, I'll have to make some measurements of the crank, the flywheel and the type 9 input shaft and go from there I think.

Regarding the Concentric clutch setup, my plan was to probably have to buy the Burton mounting plate, about 60:( but then use a Fiesta or similar slave cylinder with an appropriate sized spacer that I'm hoping I can get turned on a lathe by a mate...

I'll let you know how I ge on over the course of the project!

Thanks
Glynn Williams

You cant beat a good assemble then measure up. I did it many times before getting to the install part.

Rob
Rob aka MG Moneypit

Glynn,
I presume that the Burton Mounting plate that you mention holds the input shaft oil seal, and replaces the T9 nose piece.

I used the base part of the T9 nose piece and cut the nose extension off it, retaining the part that has the oil seal in it. I then machined a spacer/ mounting piece with a slightly concaved rear face so it fits snugly onto the domed front of the base plate. Then a Fiesta type concentric slave (abt.30) bolts directly to that. No expensive Burton Power parts needed.
Guy Weller

Now that sounds like my sort of price Guy! Did you find that you needed a spacer between your machined nose piece and the slave to get the position of the release bearing correct? If so, how big was that approximately?
Glynn Williams

This is where the assemble and measure up is invaluable. The fingers move toward the gearbox as it wears so you need to provide a clearance to allow this to happen. In my installation I have about 10mm although many say 5mm is sufficient. I have 10mm as that is what I ended up with after several assemble and measure sessions using bits and pieces I already had.

You should be able to find the maximum extension for a particular concentric and ensure you have less else it might pop off.

Rob

Rob aka MG Moneypit

This thread was discussed between 24/10/2014 and 25/10/2014

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