MT75 to Lotus TC - Spacing of ring gear & starter

We are in the process of attaching a Spyder sourced MT75 five speed to my stock Twin Cam. Spyder supplied a revised fly wheel and ring gear, clutch assembly, along with a new starter motor. We bolted the whole affair together. Bell housing mated correctly to the TC, and all looked good to go.

Luckily my mechanic checked the starter motor pinion gear protrusion length with the ring gear position. Turns out the supplied starter is to short to engage the ring gear, appearing to be ~0.5" short. From inspection the fly wheel and ring gear assembly looks to me to be located as far forward as it can reasonably go without fouling the engine end plate bolts.

Have been communicating directly with Andy and Sean to sort out what is wrong, which has the usual time zone issues from NA to GB. Andy thought the starter motor is correct based on the dimensions and photo’s we supplied him last week. Sending off some more photo’s of the fly wheel and ring gear today, but it really appears correct to us, and the solution will be a different starter with a longer pinion gear nose on it.

Has anyone had experience with this bolt-up? Are starters with different pinion gear depths and the MT75 three bolt configuration available? Any help with a P/N certainly appreciated.

Quick edit for a second question. Where is the speedo cable take-off located on the MT75? I have the speedo drive listed in my shipping documents, but cannot find it as a separate piece in my parts bin. It may already be attached correctly to the transmission, and all is good. Unfortunately the transmission is at the mechanic’s shop, so I can’t check again today. Would like to let Sean know if I don’t have it available in one email if possible. During a quick look last Friday and I did not see it.

Stu,

sorry I can’t help.
My rebuild used a Zetec & Twin cam g/box; the complete opposite.
However I’d like to join your thread because the question of the speedo drive on the MT75 g/box remained for me unanswered at the time.
All of the MT75 g/boxes that were available to me appeared to have only a connection for an electronic speedo.
That plus the extra cost of a new concentric clutch cylinder caused me to make the decision to stick with the Elan g/box.
So whilst we’re at it maybe somebody can explain what is needed to connect the MT75 to the Elan speedo; perhaps with a picture or 2?

Thanks & cheers
John

Thanks John. I picked up from an archive search last night that you retained the Lotus four speed, hence your interest in the other gearbox options being discussed in other threads.

elan-f15/anyone-ever-fitted-scorpio-mt75-elan-before-t14170.html

Thread also contains an excellent post from GerryM regarding installing the MT75 in a Spyder chassis, but not sure if he was going to a Zetec or a TC; have a PM in to him to see if he can help as he appeared to have dimensions for the starter and cautions it will not work without the bell housing closing plate, which I currently do not have. With 85 views of this thread and only one reply I am starting to get the feeling the MT75 to TC deal might be a bit out there!

I have send a detailed question to Sean and Andy regarding the speedo drive. All I know so far is in my shipment list they provided Spyder P/N as follows:

1 X SPEEDO DRIVE GEAR ZTCSDG21 12.75 GBP

Buggered if I see this bit in my parts storage, so hoping it was attached to the gearbox for shipping. :slight_smile: I was so focused on the bell to engine issue I did not examine the transmission assembly very well for the speedo drive, so hoping it is “hiding in plain sight”.

Just trying to figure out how to get the digital photo’s we have taken so far down to the correct resolution to be accepted by the list and I will post a summary to this thread, including hopefully the speedo drive!

Also want to indicate Andy and Sean have been great on this issue, responding very quickly to emails and phone calls. We have a seven hour time difference to contend with, so pretty much an over night deal, and they are very busy. Full marks to Spyder on customer service though.

Cheers and thanks again to a fantastic list and resource. On a positive note, I just about have the Spyder chassis built up and will hopefully fuss the brake lines into place over the next couple of days. Body should be ready for paint in about three weeks. The engine is just waiting on a minor part to buttoned up the valve cover. Hoping to be circling the neighbourhood before the snow flies, but we shall see.

Frankly speaking, I would have thought that the guys at Spyder would have all of the facilities availabl to be able to determine exactly what is needed & the dimensions you require.
They must have slave g/boxes & engines lying around to enable them to give precise answers.
Yes Gerrry will have most of the answers, he has fitted the MT75 + Zetec.
Did you mention what type of chassis you have in/for the car?
There should be sufficient room in the stock Elan fold along the lines chassis.
The earlier non-Zetec Spyder chassis have round section diagonals in the front forks of the space frame.
The rearmost pair will have to be replaced with the oval tubing that Spyder use on the Zetec chassi’s (& their A Frames)
There is a partial “closing plate” at the front of the “box section” of the chassis which will also need to be opened out as req’d.
I’ve repeated this last bit from a posting I made not too long ago.
The reason being is that I do not know if Spyder have rationalised all of their new chassis, Twin Cam/ Elan g/box Zetec/MT75 or not to include the oval tubes & req’d clearance. (Hope that’s understandable :blush: )

Cheers
John

John, the frame is Spyder supplied about a year and a half ago. It looks identical to this one taken from the Spyder site under the “Spyder News Page” where they show the MT75 to TC lash-up, except that it is LHD configuration. I have attached the clearest photo of my frame from the site. Only other detail I can spot that is a bit different than my set-up is this one seems to use four bolt hubs rather than peg drive.

Hoping that as my frame and MT75 were all shipped together that they should be compatible. My frame does have provision for the double wishbone rear suspension (I am not using this set-up), and appears to have provision for the double fuel line set-up required with their Zetec install.

The MT75 “kit” was supplied with a new steel transmission mount, what appears to be an alloy spacer to hold the rear of the transmission, and a rubber transmission mount. With the Spyder supplied engine mounts and removable oil pan cross member I am hoping it will all fit in place pretty easily. Note my starter is on right hand side of the MT75 bell housing, as in this photo. Spyder supplied clutch uses a concentric hydraulic slave cylinder, with a bleed hose on the left hand side of the bell housing emerging from the inspection hole shown in the photo. The clutch hydraulic line emerges from another inspection hole on the right hand side of the bell housing, and uses a Spyder supplied SS braided line that is hopefully long enough to reach a LHD pedal box. :slight_smile: We put my early type Plus 2 tunnel cap on top of the frame, and it appears the Spyder supplied shift lever may be slightly further back than stock (maybe an inch or so); hoping this is OK as I would hate to have to do a hack job on my plastic tunnel cover or replace it with the later version upholstered ones. Further details on the fitment mystery when we lower it in, but Looks OK so far.

Note some of the other photo’s on the “Spyder News Page” are clearly a different car, as they show a Zetec engine with a different frame configuration. My frame does not utilize a removable brace on the top side of the frame as shown on the MT75 photo’s with the Zetec engine. Nor does it have tapped holes in the upper frame rail to accommodate this brace. Not sure if this is now removed from all Spyder frames or not, but mine does not appear to use it. As the page is pretty dated (2002 in the heading), they may have further rationalized the frames since, which is kind of the heart of your question. :slight_smile:

As in the attached photo, the rear diagonal on my frame is round. The front diagonal is an oval profile. It appears the closing plate, with the forward facing oval hole, is sized to prevent interference with the MT75, but I guess we will find out shortly. :slight_smile: Looking at the photo in more detail by zooming the view, I am thinking that is the speedo drive within the oval hole on the left hand side of the gearbox, so I will now check my transmission carefully in this area. Will have to run over to Malcolm’s shop to look.

Agree completely Andy and Sean should be able to sort out. Maybe we have made a simple assembly error :blush: or either the flywheel or starter is a simple part pull error, and all will be good. For the life of me I can’t spot what is wrong though. I have sent several more photo’s and various measurements of the flywheel and ring gear to Sean today, but pretty sure it will be a few days before he can get back as he needs to chack flywheel dimensions with their supplier directly.

Ah, now I can see what spyder have done.
They’ve actually deleted the rear diagonals.
From the vertical tube (with the mounting bosses for the scuttle) back they’ve gone over to sheet steel.
I assume that that part of the chassis would then represent the Lotus “Fold along the lines” chassis & provide the required clearance for the MT75.
I expect that this chassis generation eliminates the problems that I have previously mentioned
I don’t know why they’ve used oval tubing for the front diagonals but I suppose any gained space is a plus.
Maybe you should be pleased that your chassis doesn’t have any form of top brace; Gerry was recently pondering on how to remove it because the bolts are apparently inaccessible when the body’s on.

Many thanks for your lengthy & informative reply Stu.

Cheers
John

It would be nice to get a list from Spyder of all their chassis variations made over time for future reference and trouble shooting.

Do Spyder have one or is their record keeping on model changes maintained in that fine Lotus tradition.

Do we have enough knowledge on the site to recreate it if Spyder dont have it or will not produce it publically? Do we need a topic on photos of Spyder chassis variations?

cheers
Rohan

Thanks John, that clears up the confusion very well. I did see Gerry?s post on the top brace and was a bit mystified as I did not have one. Wonder if it is dropped from the Zetec frame now?

The oval front diagonal appears to provide more clearance for the bell housing on the MT75, potentially for the starter motor flange area? Gerry reported in his 2007 post that he had to dimple one of the frame members to get the MT75 in place, so perhaps this ?running change? takes care of the 10 pound hammer effect.

As the MT75 box and engine are still split, I will try to take a direct on photo of the MT75 bell housing with a tape measure prior to install so folks will have a more exact reference of the clearance in this critical area. Not sure if this is also one of the areas that potentially foul the T9 conversions under discussion in other threads, but I expect as they have a separate bell housing they are OK. However, I do not know the starter motor set-up the T9 uses.

I haven?t heard back from Spyder yet, but will be giving them a trunk call here shortly to see about the original starter motor issue, closing plate, and speedo drive.

I did examine the box yesterday, and I can see the provision for the speedo drive on the LHS of the box, right where the diagonal oval hole is in the above photo. It has a plastic blanking plate installed for shipment, and it appears I did not receive the speedo drive with my shipment. Lesson for the day is to check shipment against bill of lading when received for all components! :blush: I am sure Sean can ship me one shortly, so no big issue. Who knows, maybe the available drive gears will motivate me to change from a 3.77 to a 3.54 diff!

I think Rohan?s suggestion is a great one. Mine is chassis number SPY 2318, so I expect there are potentially several versions out there.

In addition to the parts in the post above, the kit came with a Lotus to MT75 prop shaft, which has a larger flange at the transmission end to mate to the MT75 output flange and a sliding sleave arrangement to take up any minor length issues. Looks like it will fit OK.

Managed to finish the chassis build yesterday, and will be tackling the brake lines this week. :sunglasses:

Cheers!

I expect that the “Lotus Tradition” will apply.
I think that some form of development history & derivative list could be very helpful but would be a challenge.
Like many Spyder chassis owners, my chassis is now clothed in an Elan body so a Photo would be difficult.
I’m presently looking at scanning the non-digital photos I took during the rebuild of my Elan, so when I get it right I could post a few.
There would be no harm in asking Spyder for records if they have them.
Perhaps someone on here with closer connections to them could take on that task?
I’m afraid I’ve been a bit critical in the past so don’t fancy my chances :blush:

Cheers
John

Just off the horn with Andy at Spyder. Seems it is the incorrect starter motor, and he will be shipping the correct one express right away. Full marks to Spyder for excellent follow-up in correcting a simple parts pull error.

Andy is going to send me a photo of the speedo drive arrangement, and will post for sure once I check if I have what I need, etc. From our phone conversation, the assembly uses the L-drive off of the Lotus four speed. This may be completely my error, as I did not open the blanking plate, and it sounds like the drive is internal to the box. Will try to install L-drive and see where we end up.

Looks like I can now attempt the drive train assembly this week as gaskets arrived today for the engine. I am hoping the starter can be put in next week with the transmission mounted in the frame.

Another very curious item from the chassis build. The ball joints attached to the steering arms threaded correctly on to the Plus 2 adapter rods (presumably UNF). However, the ball joint attachment stud to the steering arm turned out to be M10 x 1 metric thread, perhaps from a more modern model car? I purchased the steering rack and ball joints from Spyder in my giant parts order last year. Andy was mystified by this one, but as they fit the ball joint cone and I was able to get SS jamb nuts locally I feel I am good to go. Thinking the jamb nuts are easier for alignment anyway as getting a Nyloc threaded on to the unseated ball joint cone was somewhat difficult, even with the body off the car. I have no idea how this would go with the body in place! The new LHD rack fit the Spyder frame OK, but I had to relieve the housing in front of the steering wheel shaft with a Dremel a fair bit to prevent fouling on the steering rack platform on the frame. This only caused a problem when the rack was correctly positioned with an upward angle to the steering column spline shaft.

Cheers! :smiley: