Lotus Elan

Fitting a MT75 box to a std elan chassis

PostPost by: gerrym » Tue Jun 14, 2011 4:54 pm

Dan, did you mention your chassis type. If a Spyder, easiest way to mount rear of box is to use Spyders bracket which in turn uses the standard FoMoCo rubber mount same as Rocket box.

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PostPost by: desprit dan » Tue Jun 14, 2011 5:30 pm

Should have said, this is a std plus2 elan chassis, a bit of a pain, because I can't actually see the tail shaft from top or btm, and because the body is on, from the sides either!
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PostPost by: stugilmour » Wed Jun 15, 2011 6:28 am

Dan, to add to Gerry's reply above, I think you will need to fab up a custom bracket, or consider one from Spyder perhaps as a starting point to modify as required or at least provide a bit of a clue on how to make something up. The rubber mount is the stock one, but I believe the bolt into the transmission is metric thread.

Going a bit from memory here, but I believe the Spyder bracket for the MT75 mounts about 2" forward of the stock mount; the current version Spyder chassis has two extra mounting holes threaded into the chassis to accept both types of transmission mount brackets in different positions. In addition, the Spyder MT75 bracket does not bump up to hold the rubber saddle mount for the transmission. The Spyder bracket came with a ~3/8" Ali spacer to position below the rubber saddle. We opted to mod the Spyder MT75 bracket, which was essentially mounted flat across the bottom of the Spyder frame in stock form, to bump it up ~3/8" and remove the Ali spacer. This allowed slightly more room for the exhaust pipe.

Sorry, I can't recall what the stock frame looks like under this area, but HTH to approximate a bracket design, which in the simplest form could be a flat steel plate on the bottom of the frame and a suitably thick spacer. Captive nuts or riv-nuts on the rubber mount make assembly a lot easier.

Can you remove your rubber inspection cap on the tunnel to see the transmission output flange? Thinking you will want to position the transmission level by examining the output flange to get it 90 degrees to the floor and the measure for the spacer and/or bracket dimensions. On a previous thread it was pointed out the flanges on each end of the prop shaft should be parallel to one another for the universal joints work correctly. We planned to do final adjustment of the flange angle with spacer washers as req'd, but I think the bracket worked OK without spacers. Easier to see in there with the Spyder chassis for sure, but hopefully this helps you a bit with process suggestions.
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PostPost by: gerrym » Wed Jun 15, 2011 6:37 am

Dan, let me know if you need any photos of the rear mount hardware (for Spyder chassis) as it may give you some ideas. Certainly without the captive nuts in the rubber mount you will have a difficult/impossible assembly proposition.

There is one other assembly problem. Have you figured out how you will access the screw heads that fasten the prop shaft flange to the output flange from the MT75 gearbox. Ideally you should also measure the flange angles (gearbox output shaft and diff input shaft) and ensure they are both at the s`ame angle from vertical. Eg difference should be no more than say 1.5 degrees to minimise vibration. To change the angle of the gearbox flange you may need to have a spacer between the gearbox rear mounting bracket and the rubber mount. Obviously when you measure this, the engine needs to be in place to correctly hold the other end of the 'box.

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Gerry
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PostPost by: worzel » Fri Jun 17, 2011 10:21 am

Hi

Still batting on with this transplant and I've not forgotten my promise to take relevant pictures/retain dimensions of altered parts etc. A short update- worked out that in a std chassis using off the shelf linkage kits won't work because the lever will jam against the chassis in 2nd/4th/reverse. So have had a kit made to shift the lever forward without (hopefully) introducing any imprecision in shift quality. Was going to use the 3 lug output shaft (so the prop would fit into the centre spine but have followed the route of others and had the large circular 6 bolt flange machined down on two opposite sides to leave a 4 bolt fixing flange. Am now waiting for the new prop to be made and then pretty much ready to do the swap. Keep you posted!

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John
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PostPost by: gerrym » Fri Jun 17, 2011 10:58 am

John, I think the 4 bolt flange for the prop shaft (that has 6 matching threaded holes on the box output shaft) originally comes from a Transit?. Any idea of the Ford Number in case I ever need a replacement.

Still not sure how you and Dan will access the fastener heads to make up the propshaft flange to the gearbox. Although you could conceivably insert the gearbox and propshaft as one unit and then install the engine separately onto the gearbox????

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Gerry
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PostPost by: desprit dan » Fri Jun 17, 2011 11:46 am

Hi Gerry, I think putting the propshaft/gearbox/engine combination might be the only way other than to cut a hole through the side of the transmission tunnel for access; the problem might be be measuring the prop length in the first place!
I'm awaiting a std gearbox mount to see if that will fit, box is out again, and the shift linkage is cut apart (again)!
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PostPost by: worzel » Fri Jun 17, 2011 1:58 pm

Hi Gerry

Don't know the Ford number for the flange but I can certainly get it for you from an acquaintance. Re fitting the prop to the gearbox. I've looked at and measured more than a few times. This shouldn't be a problem- on the chassis I'm using (a Spyder Stressed Skin)- which is basically a copy of the std lotus frame, Lotus have very thoughtfully provided a large cut out in the side of the frame, the prop bolts can be accessed thru it- in fact the job looks easier than removing the prop from the diff end because there's more room to swing a spanner. The big issue will be the exhaust run, since the MCT box is deeper than the Type 9 a small run of exhaust will need to be routed up and along by the side of the box and then turn to meet the centre pipe. Should have the added advantage of raising the vulnerable part of the exhaust anyway. The options with the speedo cable are 2- either fit an adaptor to the box and use a right angle drive or- go thru the side of the transmission tunnel just ahead of the driver's seat and circlip it into place as per std Ford practice. The hole required would be only about 1 inch maximum and a plate could be made up to screw over the hole in the fibreglass. The cable would then be fixed to the floor of the footwell rear (there's no danger of feet making contact with it unless your shoes are around 2 foot long!). Either way some part of the body would need to have a hole with the cable passing thru the bulkhead there's another route for water entry so a hole in the side would at least be watertight!

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PostPost by: desprit dan » Fri Jun 17, 2011 5:11 pm

If you have a hole in your chassis adjacent to the propshaft flange, it must have been put there by spyder, unfortunately mine has no hole anywhere near, and is the original chassis for the car.
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PostPost by: c42 » Sun Jun 19, 2011 7:33 pm

Hi All
I am in the process of fitting an MT75 box and Zetec into my standard +2 chassis, does anyone have any photographs or details of the engine mounts and/or front of chassis modifications required; any details would be helpful.

Thanks in anticipation
John
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PostPost by: gerrym » Mon Jun 20, 2011 4:37 pm

Hi John, no I don't need a prop shaft flange (for the MT75) but I was hoping to document all the part numbers of the various bits that have been used (Plus interchangeability).

Did you know that the UJs used in the propshaft (MT75 end) are the same as that used in the Classic Range Rover. (Rover part number TVC100010, GKN U110). Dimensions 27mm od x 10mm x 75mm , all nominal of course.

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PostPost by: desprit dan » Tue Aug 16, 2011 7:19 pm

The first problem was working out which mt75 gearbox into an elan thread to use, as there appears to be 3 in the mods section alone!

The second, bought a clutch plate for a granada scorpio 2 litre and it doesn't fit; it's a 9.5" plate and it needs to be a 8.5", there doesn't seem to be much room inside the bell housing for a larger flywheel than the twincam one (although mine is sans ring gear at the moment) so have I been supplied with the wrong plate, or have I got the right plate for the box but not the flywheel, and does anyone know what one I need? It started out looking quite easy..........
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PostPost by: worzel » Wed Aug 24, 2011 12:21 pm

Hi

Another short update re a "slight" technical issue!. The MCT box I have has thrown up a hitch- I don't know if it is standard Ford practice when they made these boxes but the input shaft has splines starting further back from the nose than either the 4 speed box or the (apparently identically dimensioned apart from spline numbers and diameter) Type 9 as fiitted to 1.6/2.0 litre Fords. Not only do the splines start further back but immediately before them (nose end) there is a "step" before the nose.

Apparently there were 3 types of input shafts (correct me on this one if you have n more info)- boxes fitted to 2.0 litre Granadas etc had splines starting back from the nose as per the Type 9 BUT-the input shaft on those boxes was shorter than that fitted to bigger engined cars. I've seen pictures of boxes fitted to Spyder conversions where the splines start in the usual place so I'm guessing these were 2.0 litre boxes. To get round this problem I've had to source an input shaft from the Ford LDV plus a matching 1st gear cluster. This is being machined down to suit (it's a lot longer than input shafts on other MT75 boxes. Fortunately this will produce an input shaft with splines that are only 0.25 inches shorter than those of a Type 9 but it could have been a big problem otherwise- worth keeping in mind if anybody else is contemplating doing what I'm doing. I'm not sure how this will affect the gearing since this new shaft has 26 as opposed to 25 teeth on the box as I bought it. I'm guessing this will up 1st to 3.61 from the current 3.89 since Ford
appear to have only offered two 1st gear ratios anyway. I know 3.89 is pretty low but that's not much of a concern to me- I originally had a 2.5 1st in this car and that was, shall we say, a pain in the ****- at least moving off from standstill won't mean should be clutch slip free!.

John
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PostPost by: Bob » Thu Aug 25, 2011 7:37 pm

Hi,
I have not tried to do this yet, but I have a +2 that is being converted or has mostly been converted to a Zetec, when I spoke to Andy at Spyder he recomended a MT75 Gearbox from a 2.3 Scorpio, two reasons, 1 gives a hydraulic clutch, and 2 put the starter motor on the correct side. If this helps and you need one, I might be able to find someone who knows where there are a couple or there were a couple.
Bob
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PostPost by: desprit dan » Sun Sep 11, 2011 2:58 pm

Ok, clutch plate issue is over, not sure what plate it is I now have, but it's 8.5" and 23 spline, so that's all that matters!

Next problem; mentioned elsewhere, is the need for a maxi/ europa starter, does anyone know why the scorpio one can't be used? and what ring gear would you use, the pre-engage type is slightly different is it not?
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