Lotus Elan

MCT75 to Elan Sprint

PostPost by: worzel » Wed Apr 04, 2012 8:04 am

Hi

Having (almost) arrived at the point when I can actually fit the box I've come up what might seem a relatively stupid (mundane) problem.

For those of you out there with a MT75 box fitted- exqactly how did you attach the prop to the output shaft of the gearbox?

Why do I ask a question the answer to which is b******g obvious? Well, unless the prop I've had made is using some odd sized yolks I can't actually physically get the bolts thru the holes in the prop flange because the yolks are preventing this.

So- 2 questions

Is it technically permissible to thread the bolts thru the gearbox flange, loctite them into place then simply use nuts and lockwashers on the prop flange (I can't think of any sound reason why this shouldn't be a good idea but enlighten me please if I'm wrong). Or-

Do Ford use something like socket headed hexagon drive setscrews. I guess the smaller heads on these would enable them to fit past the prop yolks. Unfortunately I don't have access to something like a Ford Scorpio works manual to clarify the last point.

Many thanks in anticipation

John
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PostPost by: bcmc33 » Wed Apr 04, 2012 10:20 am

worzel wrote:[/b] Is it technically permissible to thread the bolts thru the gearbox flange, loctite them into place then simply use nuts and lockwashers on the prop flange [/b]

John,

Most inadvisable to use a screw in this application. Special bolts are made with a short plain section to match the thickness of the unthreaded flange.
Maybe, if you have the facilities, you can machine out the threads in the flange and use a bolt with a plain section to match the thickness of the two flanges - just like the standard Elan method.
Thinking about it - reaming the thread out would be the most effective method as you would easily maintain the positional integrity.
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PostPost by: stugilmour » Wed Apr 04, 2012 2:29 pm

John, mine uses socket head screws; pretty sure they are threaded into the flange on the transmission shaft. They are the star type socket fastener with shoulders on the head. I believe they are metric sized. Can't recall if they had threads all the way to the head or not. Like Brian mentions, they appear to be purpose made or purpose selected fasteners. Tried a pic of mine for you but it is too confined to get the camera to work correctly. The screws, flanges, and complete prop shaft were all supplied by Spyder.

Gerry posted a mod to his flange that removed portions of the flange to allow it to fit easily in and out of the tunnel with more clearance.

The MT75 (rear drive) and Scorpio manuals are on-line at this site. If I am reading the pics correctly, the Scorpio stock set-up used hex fasteners at the transmission output flange and at the diff. There is a parts reference drawing somewhere on the site as well but I can't seem to find it right now.

http://www.fordscorpio.co.uk/

Down left side menu select: Servicing/repairs - Transmission - Manl Gearbox Manual

http://www.fordscorpio.co.uk/mantrans.htm

http://www.fordscorpio.co.uk/manual/man ... DOHC8V.pdf

Your progress is shaming me! I have to pull my engine and transmission in the next month to repair the fastenings to the bell housing we discussed, but have been too busy to get to it. I should have it all out in the next three weeks or so if you need more detailed photo's.

HTH
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PostPost by: worzel » Fri Apr 06, 2012 8:57 am

Hi Brian and Stu

Brian- re your point about reaming out the threaded flange. Are you in fact saying that on your car the prop flange is attached to the diff input flange by nuts and bolts?

On my car which I bought in '78 the input flange on the diff is threaded (and I'm pretty sure the first owner of my car wasn't the type to get his hands dirty and alter things) so I'm guessing the way these parts attach on my car is the std, factory method- or am I wrong?

Stu- Again thanks for the info. I've since bought the "special" bolts from Spyder (a very quick service from them I should add with next day delivery). These have what I'd describe as an integral flat washer as part of the bolt. Two questions about these-

Do I need to fit split/shakeproof washers and-
I notice that the prop flange has machined round recesses around where the bolt heads sit. Are these simply metal saving devices to save Ford some money (?) or do the bolts pass thru some type of larger washer that fits snugly into these recesses to prevent any "looseness" under load? Might make sense if this is so but on my car at the diff end of things the diff and prop flanges both merely clamp together so I don't see why the front attaching fittings should be any different.

Any views on this?

Regards

John
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PostPost by: bcmc33 » Fri Apr 06, 2012 9:15 am

worzel wrote:Brian- re your point about reaming out the threaded flange. Are you in fact saying that on your car the prop flange is attached to the diff input flange by nuts and bolts?

Sorry, John, I seem to have misinterpreted the thread - I thought we were talking about the prop to gearbox flange not prop to diff. Yes, the diff flange is threaded.

Regarding the cut-outs - these are spot faces to ensure square application of the bolt head.

If the bolts you have are flange headed, then the flange acts as a washer face. Don't forget to lubricate the flange to achieve the correct torque setting.
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PostPost by: RichardHawkins » Wed May 23, 2012 7:19 pm

Dear John,
I have just read your problems with the MT75. I think you need to speak with Clive Cox at Bailey Morris. I had a conversation with Clive some years ago and I think I remember him saying that they have the adapter you need for an MT75.

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PostPost by: worzel » Thu May 31, 2012 8:19 am

Hi Richard

Thanks for that info- I've not replied to your posrt before now as I've only just returned from holiday.

regards

John
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PostPost by: c42 » Thu May 31, 2012 12:31 pm

Hi John
I am just having a propshaft made at the moment, which end have you got the problem with - gearbox or diff?
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PostPost by: worzel » Thu May 31, 2012 8:40 pm

Hi John

Problems!- still a few but I'm sure they can be resolved. Problem one is the depth of the bellhousing I intended to use. I need one that has a Type 9/MCT fixing pattern but with a depth of 175mm inc the thin spacing plate. This is because the splines on the MCT box are an exact match for the std 4 speed box in terms of positioning for the clutch drive plate. the bellhousing I have is a Rocket to BDa one but- I've discovered that it's deeper by 10mm than a std one so the clutch swplines will be overhanging at the front of the input shaft- not good!.

Problem two- if I modify the bellhousing (not keen on this idea) and reduce the depth by the requisite 10mm it means that the gearbox output shaft will foul the beginnings of the centre box section. This is more easily solved but would require modifying the MCT output flange to accept a much smaller diameter flange. Do-able though. Problem still centres around the bellhousing. One possibility is to modify a cast iron 4 speed bellhousing so it bolts direct to the box but opinions on the viability of successfully welding cast iron are pretty varied. Once this problem is resolved it's all systems go. The car is still on the road anyway so no panic-yet!. I'll post the outcome- any suggestions welcome.

Regards


John
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PostPost by: c42 » Thu May 31, 2012 9:22 pm

Hi John
After giving you advice on a previous thread not to join gearbox shafts I feel obliged to show you this thread from another forum that I visit every now and again.

http://alpine.forumup.com/viewtopic.php ... rum=alpine

I must add that I still do not think that it is a good idea though.

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John
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PostPost by: worzel » Fri Jun 01, 2012 8:30 am

Hi John

thanks for that info- all I can say with regard to the article about modding the input shaft is mmmmmmm! I'm more confident about altering the output flange simply because the diameter is that much greater so it's more akin to the technology behind making up a custom prop. We'll have to see.

Regards

John
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PostPost by: RichardHawkins » Fri Jun 15, 2012 7:28 pm

John,
I was looking for an MT75 speedometer drive and stumbled across something that may be of interest to you. Apparently Morgan have used this gearbox at some time. sites.google.com/site/morganatica/04-transmission/ford-mt75 shows photographs of a morgan fitted with an mt75 showing the type of prop shaft coupling that you are looking for. hope this helps.

Regards,
Richard Hawkins
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PostPost by: worzel » Fri Jun 15, 2012 8:15 pm

Hi Richard

Thanks very much for taking the trouble to post the info. If the diameter is small enough that will solve the problem without going to the expense of having a one-off made.

Again- thanks.

I'll post te result of my enquiries with them.

regards

John
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PostPost by: RichardHawkins » Sat Jun 16, 2012 9:39 am

John,
I also stumbled across this web site www.super7thheaven.co.uk You will find reference to the MT75 in a LDV van! www.super7thheaven.co.uk/images/documen ... v-mt75.pdf This also shows the type of drive flange that I think you are looking for.

Hope this helps,
Richard
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PostPost by: worzel » Fri Jun 29, 2012 12:39 pm

Hi and help!

Could I ask any owner out there who has fitted a MCT75 to a 2 seater using a standard chassis to measure something concerning where the box output flange ends up in relation to the centre spine of the chassis. I know some owners have the MT75 fitted but the problem with using measurements from this box is that because the bellhousing is integral the overall length of a std MT75 might differ from a MCT75 attached to a Rocket bellhousing.

Alternatively do any owners know the exact overall length of a MT75 using measurements taken from the engine mounting face of the bellhousing to the outer edge of the box output flange (the 6 bolt round version) and, importantly, if there is any difference between the versions of the MT75 unit. A definitive answer would mean I'd be able to compare my gearbox with the bellhousing fitted to one actually fitted in a 2 seater and then determine if the output flange would cause any problems.

Many thanks in anticipation.

John
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