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MG Midget and Sprite Technical - Spigot Bush

Until I did my Toyota conversion about 10 years ago I never knew the spigot bush existed. I changed clutches and just assumed the gearbox shaft went in the end of the crankshaft as is. I therefore have no idea what the standard arrangement is, only the Toyota conversion version.

The Toyota box has an input shaft with an end diameter of about 12mm. The conversion kit includes a bush that is tapped (as I recall it needed whacking rather than tapping) into the crankshaft. The bush consisted of a phosphor bronze centre but the majority of the insert appeared to be steel.

The bronze centre has come out of the bush so I now need to get the steel bit out to replace the entire insert (with one from a Datsun conversion but that's another story).

The standard method is, I know, fill with grease and whack a tight fitting rod into the hole. However bearing in mind how hard I recall it was to get the thing in in the first place will this really work?

If this fails then what are my other options. Presumably my final resort is to drill it out which I guess is a machine shop job.
Jeremy Cogman

Jeremy,

The standard 1275 uses an oilite sintered bronze bush, INHO a needle roller is better as it should last longer and stand upto riding the clutch, if you have something other than a grahite release.

One way to remove the steel shell piece is with a die grinder or hacksaw blade to carefully cut through the shell almost all the way, it should give up its grip when it gets thin enough.
David Billington

What David says!

Not too difficult and you are certainly capable of doing it without any problems, no need to pay for machining

You may even find that irrespective of the effort involved assembling after a while in service it will be ready to pop out using the "greasedraulic" method. Try it before worriting your self too much.

If you have a dremel type doodah you could grind gently away at it in one spot until it gets thin, then a slim screwdriver would lift the casing away to release itself

if "greasedraulicing"© the job, make sure that there is no free space behind the bearing that has no grease in it, this reduces the chance of pressure squeezing up before the work starts to happen
Bill

Is there any chance you could tap a thread in to the remains of the bush and then pull it out that way?

Carl
C Bintcliffe

Why do some crankshafts have a big wide hole for this bush? (mine, for example)

When I was rebuilding Blue's engine, I bought that oilite bronze bush, and it flapped around uselessly. Then the ancient bloke in my machine shop calmed me down, told me not to panic, and offered me what I think he said was a Morris Ital bush - pretty thing with needle rollers, which fitted perfectly.
Nick

Yup, some engines have the 5/8" bush and some use a 3/4" bush. No one has been able to give me a change-over date, it seems to wander around. My Rivergate 5-speed kit came with the 5/8" bush, but the instructions indicated that I could get the 3/4" unit if needed. The only good reason for the larger hole was to accommodate a needle bearing. OTOH, Trish's Miata uses a rather large sealed ball-bearing; talk about a pain to remove!!! Ended up dissecting it with the Dremel.
David "spigot happy" Lieb
David Lieb

I bought my kit for the Toyota box from frontline some 15? or so years ago. The kit came with a bush that was 2 sizes (different OD at either end) and you chose which way round to put it in as to what size crank you had. I used it on the small end originally and then when I fitted a Marina crank later I had to reverse it to the large end.
Bob (robert) Midget Turbo

Jeremy, an old 'trick' was to run a weld around the inside of a bearing (or in your case a bush) which would shrink it enough to fall out.... It that possible?

I have both bush and needle bearings in stock for the 1275 cranks. Like David Leib says, I don't know of a change over point either.

Mark.

Mark Boldry

Hey Jeremy,

Get what is called a blind hole puller, works like a charm, I dicovered this tool about 3 months ago....and just love it....currently Im know 5 for 5 on failing with the stick and grease method and highly jealous of those that have had sucuess on there 1st attempt....


http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95987

prop
Prop

Hi Jeremy
An easy way to get the remains of the old bush out is to tap a thread into it as Carl suggested and then just keep winding the tap in. When the end of the tap bottoms out against the end of the crank just keep winding and it will quite easily push the bush out
Gary
Gary

Thanks for all the suggestions folks.

I did wonder about the tap method but I don't happen to have a 14mm tap.

First step is to get the engine up onto the bench (too old to do this sort of thing grovelling on the floor).

Then I think I'll try the 'coat yourself in grease' method. If that fails then I'll go looking for big taps and finally try David's sawing method.

Will you let me into Spridget 50 in my Saab? It's quite old!
Jeremy Cogman

Jeremy, of course you can come to Sp50 in the Saab

I have a lovely parking spot just inside the entrance for you.

Dammit man there's nearly two months left to get it ready, come on, no shillyshallying...
Bill

I am re-activating this thread (which I found very useful) as I would like to know where I can get Marina/Ital crank spigot bushes (plain or roller bearing).

Can anybody help?

Thanks

John
John Turner (Midget & MGB)

John
I have some late 1275 needle roller bearings

midgetbitz (at) gmail (dot) com
Dave O'Neill 2

For the purposes of completeness I eventually got the bush out by tapping it with a thread appropriate to the internal diameter (I think it was 14mm) and then used an appropriate bolt and a slide hammer.

And I didn't need to take my Saab to Spridget 50!
Jeremy Cogman

This thread was discussed between 25/03/2008 and 01/02/2011

MG Midget and Sprite Technical index

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