Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Flywheel/clutch size

I'm going to "roll my own" 3 wheeler using a Harley Milwaukee 8 engine and T-5 gearbox (used by many carmakers) and am trying to gather as much baseline info as I can.

Can someone tell me which MX-5 flywheel/clutch the M3W uses?

I've read on MX-5 forums that the 1.6L engine uses a 265mm flywheel and 215mm clutch and the 1.8L uses 290mm flywheel and 200mm clutch.

Also, since the inertia of the MX-5 flywheel and pressure plate is in addition to the engine's already massive crankshaft flywheels, I'm wondering if anyone thinks the engine response is at all sluggish.

The M3W clutch is not a MX5/Miata clutch but is made by a company called TTV Racing, if you contact them and mention M3W they will not bother replying even. If you contact www.clutch-specialists.co.uk they will help you with standard M3W clutch parts.

An illustration of the M3W clutch is below, as you can probably see it doesn't use any MX5 parts, even the release bearing is a Volvo /Land Rover part, not Mazda. The "flywheel" is more of a starter ring gear.

Ah, very interesting, thanks.

I don't know what MX5 parts look like, but I wonder if Morgan used an MX5 flywheel to keep the ring gear compatible with where the (presumably stock MX5) bell housing puts the starter, and lightened around the O.D. to reduce inertia.

Would you happen to know the M3W's clutch disc diameter?

As you are using a T-5 gearbox, I would look at custom 5" or 7" clutches, which should be readily available with the Ford type input shaft spline. Perhaps you already have this figured out, but the engine to gearbox mating housing and coupling would I think be the difficult part. This housing would have an impact on the flywheel diameter and stater options. r

Right, the engine-gearbox connection is the hard nut to crack; Morgan sure failed at it.

From what I've read Phil Bleasey seems to have the coupling part licked; maybe I can adapt it, though it's not clear that I can do that without first having a Centa housing, which may prove hard to get.

Also I'm looking for more suitable alternatives, either one of Centa's other torsional couplings or another supplier's.

It sounds like your T-5 knowledge exceeds what I learned from my recent googling; would you happen to know which is the smallest bell housing diameter that it used?

I'll be using a Tremec T-5 with Ford bolt pattern.

Whichever that is, I imagine there's room for a lot bigger than a 5" or 7" clutch, and I'd be concerned about slipping from those mighty torque pulses.

Not sure about smallest bellhousing, but I purchased one (to use with T-5 Ford) for my Lotus Elan project, and Elans have modest sized housings. You might check others at rwdmotorsports.com. There's a company or two out there that makes custom bell housings from spun steel. Sorry I don't remember names.

5" to 7" racing type clutches are typically multi disc and can handle hundreds of pounds feet of torque. And they can be adapted to most any size flywheel. The small diameter is about reducing rotational inertia, not limiting torque capacity. Keep in mind racing type clutches tend to have quick engagement characteristics, i.e. 'grabby'.
For smooth engagement, you need a street clutch disc, and to get the torque capacity you are likely looking at 7.5" or larger disc with an appropriately rated pressure plate.

For multi disc see for example:https://www.speedwaymotors.com/Ram-Clutches-9371S-Disc-Clutch-Chevy-Triple-Disc-10-Spline-1986-Up,49600.html

I would be looking at performance clutches for Formula Ford or BMC A series engines or similar. Small, ubiquitous, so not too exotic or expensive.

Thanks for the additional info.

I'm not keen on the possibility of a touchy clutch, and I understand multidisc clutches can be noisy with all of those parts rattling around.

Also, rotational inertia is a good thing as far as drivability, as it lowers the driveline torsional resonance frequency*.

But back to the original question, do you know the diameter of the M3W flywheel and/or clutch disc?

I figure if I use at least as big a single-plate clutch I should be fine, as the M8 has about 10% less displacement than the X-Wedge, and for the most part I'm easy on clutches.


* Interesting and educational articles here:

http://www.epi-eng.com/propeller_reduction_technology/torsional_vibration_issues.htm (this is about propeller reduction gearbox systems, but fully applicable to automotive power transmission)

http://www.epi-eng.com/mechanical_engineering_basics/transmissibility.htm

I did some calculations for the inertia of a normal size clutch and it's about 2/3 of the Harley's massive crank, so too high I think.

From the parts diagram it looks like they reduced inertia by thinning and drilling the periphery of the flywheel, so it looks like the way to go.

> If you contact www.clutch-specialists.co.uk they will help you with standard M3W clutch parts.

So to be clear, clutch-specialists.co.uk get the M3W clutch parts from TTV?

Couple of pix of my clutch with broken diaphragm plate
May help?

A couple more
This is VERY rough sketch of dimensions of bell housing with clutch release bearing and pivot
https://www.tm-img.com/image/xPVAS

https://www.tm-img.com/image/xPSup
https://www.tm-img.com/image/xPibH