Lotus Elan

Fitting a MT75 box to a std elan chassis

PostPost by: worzel » Sat Mar 05, 2011 5:29 pm

Hi Aussie John

Sorry I didn't clarify things earlier. I do have a sprint with a modded Type 9 box fitted and it works fine but this is for a different car (it's a sort of joint project between me and somebody else).

as I said earlier I could modify a Type 9 along similar lines to mine but it's fairly longwinded and if something else would just bolt straight in I'd prefer that route (age?).

Since my own car uses a Rocket to BDA bellhousing that is basically a carbon copy of the original 4 speed item but bolts direct to the T9 and a Ford RS2000 is similar except for cable clutch operation and 2 starter positions then I'd go with either of them.

Although more costly there are no "niggles" to sort out so it's simpler in fact- (it is age creeping in I think).

Regards

John
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PostPost by: c42 » Tue May 10, 2011 9:35 pm

After browsing the archive I decided to ditch the idea of fitting a x flow to my +2 project and I have now obtained a 1.8 Zetec (Escort) and MT75 box which will be fitted to a standard Lotus chassis. I am still unsure regarding the clutch/flywheel/starter motor issues which I hope someone will have the answers for. My questions are - can I retain the 1.8 flywheel and which clutch plate/cover combination should I use if I go for a cable clutch release mechanism rather than hydraulic, also will the MT75 box allow the Escort starter motor to be used?

Thanks in anticipation

Regards
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PostPost by: chrishewett » Wed May 11, 2011 7:52 am

I have an MT75 gearbox which I have just removed from a +2, to which I am fitting a four speed box as I want to make it more original. The box was modified and fitted by another member of this forum before I bought the unfinished car. The gearshift has been altered and fits in the correct place. It also has a manufactured propshaft. This box and prop are surplus to my requirements and are for sale if anyone is interested.
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PostPost by: worzel » Wed May 11, 2011 11:55 am

Hi to all fellow sufferers!

I've just noticed the ad re the modified MT75 box being sold. I've e-mailed Chris re some info I could do with but in the meantime can anybody supply the info I need- principally-

The gear linkage- that looks similar to the Spyder system but does it have 2 rose joints on it? I ask because (and excuse my ignorance/stupidity here) I'm still trying to figure out just how a sideways movement of the gearlever becomes converted into a circular motion on the actual selector rod. The rose joint on the lever pivots ABOVE the selector rod and I can't see any sort of "crank" arrangement below the selector rod so how does it work

Second question-is the gearlever fixed to the rose joint in any way or does it slide up/down?

3rd- last one- what is being used on the output flange of the box- I know the std (!) MT75 has a pretty large circular flange and I know this can switched for a 3 eared transit one but that on the box in the picture looks smaller than both of these- if my eyes aren't actually deceiving me does anybody have any idea of its origin?

4th- (okay I lied)- the metal "box" thru which the gearlever passes (ie just below the rose joint). I know it's rubber filled and it looks like a proprietary part but none of the Ford dealers I've contacted recognise it as a Ford part. Any ideas on this one?

tHANKS jOHN
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PostPost by: GrUmPyBoDgEr » Wed May 11, 2011 1:15 pm

worzel wrote:Hi to all fellow sufferers!

I've just noticed the ad re the modified MT75 box being sold. I've e-mailed Chris re some info I could do with but in the meantime can anybody supply the info I need- principally-

The gear linkage- that looks similar to the Spyder system but does it have 2 rose joints on it? I ask because (and excuse my ignorance/stupidity here) I'm still trying to figure out just how a sideways movement of the gearlever becomes converted into a circular motion on the actual selector rod. The rose joint on the lever pivots ABOVE the selector rod and I can't see any sort of "crank" arrangement below the selector rod so how does it work

Second question-is the gearlever fixed to the rose joint in any way or does it slide up/down?

3rd- last one- what is being used on the output flange of the box- I know the std (!) MT75 has a pretty large circular flange and I know this can switched for a 3 eared transit one but that on the box in the picture looks smaller than both of these- if my eyes aren't actually deceiving me does anybody have any idea of its origin?

4th- (okay I lied)- the metal "box" thru which the gearlever passes (ie just below the rose joint). I know it's rubber filled and it looks like a proprietary part but none of the Ford dealers I've contacted recognise it as a Ford part. Any ideas on this one?

tHANKS jOHN


Gear selection on the MT75 box is done by a push/pull/ twist action on the shaft that exits the rear of the box.
The change lever is pivoted on that shaft with a cross pin/bolt to provide the twist/turn bit of it.
The lever is located & fixed higher up with a double rose jointed link which acts as a fulcrum for the lever to provide the push/pull bit & the rose joints permit it to twist.
The height of the rose joint on the lever must be fixed otherwise the lever movement would be variable due to possible changes to the position of the fulcrum.
The other end of the link has the rose joint bolted to any convenient point on the top of the box.

Errrm; dunno about the rest :oops:

Cheers
John
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Editor: On Sunday morning, February 8th 2015, Derek "John" Pelly AKA GrumpyBodger passed away genuinely peacefully at Weston Hospicecare, Weston Super Mare. He will be missed.
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PostPost by: worzel » Wed May 11, 2011 7:18 pm

Hi John from John!

Thanks for the early reply and info. I can see how by using 2 rose joints the sideways movement of the lever acts on the selector rod to produce a twisting motion and hence permits gear selection since the rose joint mounted further back allows a fair amount of movement sideways and acts as a pivot point but on the Spyder versions I've seen the single rose joint/rod end is screwed into a threaded tube which in turn is welded to a bracket that bolts rigidly to the gearbox casing. I imagined that moving the lever sideways would simply cause that part of the lever that protrudes below the rose joint and which feeds into the metal "box" below to just produce a similar sideways force rather than rotate the selector rod.

If the gearlever were to connect with a crank BELOW the selector rod then I can see how a side to side motion of the lever would cause the selector rod to rotate. This would only apply to a single rail gearbox since sideways movement on the 4 speed 3 rail box simply lines up a different selector rod. I'll have to look at this one again I think!

I'm going back on the pink pills!

John
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PostPost by: gav » Wed May 11, 2011 8:26 pm

For what its worth, I am running a diesel MT75 mated to the twincam with ford hyd. clutch release in my sprint. I do have a modified chassis so discount the installation point but.. 5th gear is great - first is too close to second and hardly worth the effort.

Worth cheking the ratios as well.

Good luck
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PostPost by: worzel » Fri May 13, 2011 9:02 am

Hi all- again

Can anybody help with info- Ford dealers don't seem to have the answer to this one! The box pictured in the ad posted by Chris shows a MT75 with the gearlever attached. I'm trying to get hold of the part that actually attaches to the selector rod- it's comprised of 3 parts I understand- a metal "box" filled with rubber (for insulation?), a case hardened pin that passes thru the hole in the selector rod and a special spring that holds things in place. I thought it might be Ford Transit rather than Sierra/Granada/Scorpio simply because they use a remote linkage system (I believe) whereas in the Transit the gearbox is situated much closer to the driver.

All info treated in confidence!

Regards and thanks

John
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PostPost by: stugilmour » Sat May 14, 2011 5:22 pm

Hi John. Disaster struck on my Spyder MT75 to TC install last week, and the engine and transmission are presently split and on the bench. The pilot bearing dramatically failed, completely fracturing and jamming the clutch action, and making splitting the engine and transmission difficult. I can therefore send you better detail pic's of the shift rod to lever connection on the Spyder supplied MT75 next week if it would help. The clutch cover plate, friction plate, and axial slave cylinder/throwout bearing assembly all appear to be OK; do you need photo's of this part of the assembly as well? Can add photo's of the prop shaft and output flange if required.

I guess a thing to check from my unfortunate experience is the size of the pilot bearing being used in your Twin Cam engine and size of MT75 shaft to make sure everything as correct. I have a replacement pilot on order from Dave Bean, and their catalog lists four different pilot sizes for the TC, and they caution it is easy to get the wrong part. Not sure what was in the car originally as it is totally fractured, but my stock four speed has a 15 mm shaft as does the replacement MT75, so perhaps the bearing was correctly sized and just failed. Hopefully I have ordered the correct replacement, and it arrives early next week. Can take photos when I take the new parts over to the shop where the work is being done.
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PostPost by: worzel » Sun May 15, 2011 10:20 am

Hi Stu

Sorry about your mishap- the trouble is the changes that might have been made by previous owners over the years and then the last owner has to deal with them- sometimes originality is useful as a reference point (and I speak as someone who has made a few "slight" alterations to my car over the years).

Yes the pictures would be very helpful- once you've stopped crying that is!.

Regards and thanks

John
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PostPost by: stugilmour » Tue May 17, 2011 4:36 am

John

Here are a few more pics. I can see now how it works and why it was so confusing. There is an additional link connecting the selector rod to the bush at the base of the shift lever in the box shaped fork. This link or 'collar' allows the base of the lever to move side to side, and also converts this side to side movement to a rotational motion of the selector rod. I can't tell how the collar piece is assembled or installed. i expect Chris has the same deal on his box, but you can't see it as he has a bellows covering it up?

Good news! My pilot bearing arrived today, and will start re-assembly tomorrow. Hoping some additional gaskets get here tomorrow, and we have things buttoned for Thursday in time to drive to a show I have entered.

Mentioned the box seemed to shift a bit notchy when cold. Thinking this might have been caused by the failing pilot; will find out shorty I guess.

Cheers!
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MT75 Axial Slave Cylinder and Throw out Bearing Assbly .jpg and
This is I believe the stock throw out and slave cylinder setup from the source car, which I understand is a Scorpio; we did not get these cars in Canada so don't know details. It is one assembly and very expensive, but works very well.
MT75 Output Flange to Prop Shaft.jpg and
Shows the output flange that connects to the prop shaft. IIRC these were a special metric bolt with a socket head; I recall it was unusual but can't remember details. You can also see the bush and cross bolt that connects the box at the base of the shift lever and the link to the collar attached to the selector rod.
MT75 Linkage Top.jpg and
Shows top of shift linkage with mounting for top rose joint and shift lever stub. Shift lever stub is internally threaded to accept a shift lever extension directly into the car interior. Shift lever is in centered neutral position.
MT75 linkage showing Collar over to fifth.jpg and
Sorry for pic quality. The shift lever is in neutral over to the far right between fifth and reverse. The link that goes inside the collar is moved to the side by the box on the base of the lever.
MT75 Linkage Centered showing Collar .jpg and
This shows the extra collar and the cross pin that attach the base of the shift lever to the slector rod. You can also see the stub of the shift lever, which threads into a shift lever extension. Thinking it over, I could probably attach the stock 'anti-sizzle' lever to this stub in a forward position and the shift lever would come to a stock position on the car interior.
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PostPost by: worzel » Tue May 17, 2011 11:15 am

Hi Stu

Many thanks for the info/pictures. The penny has now dropped! I'm going to use a MCT 75 box which is basically a std MT75 but without the integral bellhousing. In my case the front casing of the box has been drilled and tapped to accept either a Rocket to BDA bellhousing or one from a Ford RS2000. I'm going with the Rocket item for simplicity- by using this I can retain the std flywheel/starter motor/clutch cover/external clutch hydraulics- the only item that alters is the friction plate which is one from a race spec MGB/GT. Although the bellhousing is pretty expensive new it does make for a simpler conversion. The only problem is the cost of a MCT box- they're not particularly common apparently and even secondhand cost around £500 or so. I was lucky to get hold of a brand new one at a price that makes the conversion an economic viability. I also bought a second brand new one but don't need it so if any other owner reads this and fancies a similar conversion it's available for £500 against the new price as listed of just under £1300- the only snag (if it is a snag) is that 1st is low at 3.8 but 5th is .76. I suppose 1st could be swapped for the 3.61 std at a reasonable price- I've recently seen a brand new input shaft of 3.61 on ebay for £20 but you'd need to have the corresponding gear removed and replaced with the correct match to the 3.61.

Good luck with your repair and again thanks for the info.

Regards

John
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PostPost by: stugilmour » Tue May 17, 2011 2:55 pm

Sounds like a plan John. Take lots of pic's with your progress.

The 3.8 will be pretty low. I believe mine is the 3.61 first from various GPS speed readings & tach readings I took in conjunction with David's excellent spreadsheet. Is your 2nd gear the 2.08? The issue with the 3.61 to 2.08 is the gap between the gears, as mentioned several times in some of David's posts. I am actually quite happy with the first gear, as I always found the Lotus stock first gear a bit tall with the Rotaflex's and 3.77 diff installed, particularly when trying to creep around in traffic. With CV's, 3.55 diff, and the MT75 3.61 first all is good, although there is a pretty hefty gap first to second.

As for fifth, I can pull 100 mph but it takes a while to get there. The 0.76 and 3.55 diff should be a nice combo, but there will probably be no oumph for passing without dropping to fourth, which is very cool anyway. I saw a web page on changing the 0.82 fifth for the 0.76 gearing, and it looked doable if somewhat involved. The required p/n's were on the page; might have been a Morgan site I can't remember.

Curious with your MCT75 box regarding the tail piece/linkage. Will you be able to use something similar to mine, or will it be like the Transit one's I have seen on eBay where the shifter comes out the top of the tail piece?

Very interesting if you can use stock ring gear & starter. I experienced fair bit of difficulty getting the starter to fit, even with additional clearance in the Spyder frame. IIRC the fit was difficult because of the integral solenoid on the starter bulging out; I think the stock starter would prevent a lot of that hassle, but I guess you will find out.

Also curious; is the body off the frame? Sure was easier doing the fettling with the body out of the way.

As an aside, when I was trying to road test with the GPS, I had a heck of a time adjusting the tach to read correctly. Running the car for about half an hour changed the tach readings somewhat, so if calibrating make sure it is stable. Last step for me (next winter) will be to calibrate the speedo, as it is presently ~15% high or fast to reality. Might want to give some thought to the speedo gear in the box prior to install, as it is a pig to get to on the car.

As mentioned before, my reverse switch is pouched. If same as mine, will be impossible to access with the stock frame, and even with Spyder frame required adding an inspection hatch in the body. Check this item out before install. I did a work around by adding a micro-switch to the shift lever area inside the cabin. Not a idle consideration here as reverse lights were required for my road inspection and it became a bit of an issue.

Quick added note. We think we found the failure mode for the pilot bearing, and might be something to check. Appears the new 15 mm needle/roller bearing we just got from Spyder was standing proud of the seal housing, causing interference with the input shaft splines. Can see wear on the very end of the splines. Solution is a machined pilot bush to prevent interference with splines. A lot more comfortable with this setup. Check your shaft length and bell length carefully. Bean seems to recommend the bush rather than the bearing approach.

Good luck with the project and continue to post.
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PostPost by: worzel » Tue May 17, 2011 7:20 pm

Hi Stu

My only reason for going the MCT route was simplicity- I've already converted my own car to a Type 9 setup and this uses the Rocket bellhousing, the std flywheel/ring gear and starter plus the external clutch cylinder. Using the MCT box means the only change is the box and as dimensionally it will fit the std Lotus frame (or the Spyder Stressed Skin version in my case) it makes life a bit easier. The only real snag is the size of the box output shaft- I'm going to use the 3 lug Ford Transit output shaft since this should fit into the centre tunnel of the chassis (just).

The MCT box is exactly the same as yours but no bellhousing so the linkage system you're using will also fit mine. Speedo drive might be problematic- I'll have to fit an adaptor to the box to enable a right angle drive to be used. As for the reversing lights I think the MCT uses the screw in switch from the Type 9 box. The body is on the frame so space is compromised so I think I'll have to alter slightly the design of the linkage in order that it can be assembled with the box in place. It probably means having it made out of more components that bolt together so it can be put in piece by piece. The only alterations I have to make to the MCT box is to have the guide sleeve for the release bearing machined down slightly to suit the std release bearing and unless I'm mistaken the input shaft diameter is the same as the Type 9 and std elan 4 speed boxes- but I'll check anyway in view of your experience.

I'll let you know how it goes.

Regards and thanks

John
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PostPost by: desprit dan » Tue Jun 14, 2011 12:03 pm

Just started fitting my mt75 gearbox and engine block to the car, basically looking for snags and problems, wasn't long till I got both! I need to set the height of the gear box, and was wondering if anyone knew which g/b mounting was the easiest to fit; car is an S/130-5 and the cross member is present but the original mounting ( and box) isn't.
As practical as a fur lined toilet.
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