So, maybe it's a matter of getting older, but highway driving at 70+ mph with the engine buzzing at 4000+ and lots of wind noise is less appealing today than 30 years ago. I had a Hyundai Elantra recently and 5th gear at 75 mph, 4500 rpm, was dead quiet - no engine noise, no wind noise, and if you didn't look at the tach, it could have been 1500 rpm. But, I'm not about to add tons of sound deadener to the Elan to achieve this. But, I think with the proper gearing, I can get close.
I've owned my Elan Sprint for 43 years now and still love driving it, long distances too. There's been plenty of buzz on the Elan forums, for the last ten years or so, on how to make long distance highway driving less… youth-like and more relaxed, i.e., adult like.
Lots of talk on the Elan forums about changing the diff ratio to something 'higher' but it's a compromise. Better cruising rpms but loss of snappy acceleration. The talk then really steered toward a 5-speed. Discussions abounded then about which 5-speed. Many graphs and charts were generated which triggered debates about graphs and charts, boiling down to rpms to road speed and what gearbox fits and what frame modifications are required.
I decided, at first, on the Lotus 5-speed. Derived from the Austin Maxi, Lotus used the Austin internals, but cast their own case and tailshaft. I purchased mine from Dave Bean but it didn't have a bellhousing. Just so happens Frank Filicicchia had a bellhousing, a 4-speed one with an adapter plate for said gearbox, meant for a mid-70s Elite. Just the ticket… sort of. So, I had yet another adapter plate made, more measurements taken, cut this, jostle that, etc., and voila! I now have a 5 speed, but with ratios meant for a heavier car, a shifter with a lousy feel and a speedometer drive that's nearly impossible to access. Yet another compromise.
I'm not giving up on this 5-speed thing yet. The Tremec T5 has been on my radar for some time. It's got tremendous aftermarket support. (they were fitted in a million Mustangs, Camaros and Firebirds, among others, from the early 80s through the mid-90s). A variety of ratios to choose from, slick shifting, and with no frame modifications, it fits! There's a caveat with the frame mod thing but I'll get to that later. The 'Z' spec’d T5, which is the one most everyone uses now on rebuilds, has all the fancy internal stuff, like carbon fiber this and that, synchro'd reverse, etc. The ratios that I like are exactly, give or take a tooth, in line with the semi-close 4-speed, the one all Elan owners love. A great shifting box, as we know.
A major piece of this puzzle is how to mate the gear-box to the engine. I chose the bellhousing specially made for this purpose from RWD Motorsports. It's the right depth, with provisions for the starter on both sides. I modified a 4-speed block plate and fitted it to the engine for testing. Because it moves the starter down slightly, it runs into the oil pan. A little 'relief' (read ball peen hammer) and presto, the starter fits. An added bonus is easy access to the top bolt, which any Elan owner knows is the bane of fitment.
And what about the clutch? I really wanted to stick to the external slave and fork arrangement for the obvious, i.e., easy to remove the slave for servicing, and the ability to adjust the free play. But, a fair number of mods were needed to the bellhousing to make this work, and there is no guarantee that this arrangement will give the feel I want. So, I went with the hydraulic throw-out bearing. Months of research brought me to the Tilton one I'm using now.
What's interesting is it's a flat-faced bearing and I'm using a diaphragm pressure plate with no platen. I've got some 'splaining to do. The platen is a big flat disc that's attached to the fingers of the pressure plate. A throw-out bearing with a flat face is used because it’s now 'flat to flat’ and it works. It's always been the recommendation, in our Elan world, that a pressure plate without the platen needs a throw-out bearing with a curved face. Anyway, Tilton recommends a certain type for the 8 1/2” pressure plate with bent fingers (same one I used with the 4 speed) and it all works just fine. What about the disc, you ask? A Ford SVO 2.3 Turbo is the disc to use. 10 splines by 1 1/16” because the input shaft is a Ford. A little tough to find but I now realize there's a clutch rebuilding place near me and I could’ve had one made. Duh!
Now, back to the T5Z gearbox. I used an empty T5 case from a Chevy S10 pickup, which has the ‘proper' placement of the shifter in its tailshaft, for mock up purposes. Modern Driveline, a T5 distributor, has the entire package needed. A T5Z - with their own tail-shaft casting (placing the shifter far forward), and utilizing a different shift rod (placing the shifter even farther forward). So, you have to use their own shifter (not cheap!). But, it's exactly the package I'm looking for. It's a 2.95 first gear and a choice of .68 or .73 5th gear. I went with the .73 gear. Even though the gear-box is mostly Ford, the .73 gear is GM. They made it work with the Ford stuff.
It's still not totally 'plug and play'. The input shaft is too long for this application. It's easily removed and I had to have 1/4 inch taken off the tip, then a 1/4” removed from the splines. A good machinist can easily do this.
I now have to think about how to drive my speedometer. If I wanted it to be driven from the speedo drive location in the tailshaft, either mechanically or electronically, a hole would have to be drilled in the frame, and maybe the body for the cable, or wires, because the opening is very close to the frame. Easy solution for me is a GPS driven speedometer. No drive is needed from the tailshaft so I simply put a plug in the hole. The GPS unit is about the size of a voltage regulator. In keeping with wanting an oem look, the only (so far) location I can put this unit, is in the glove box. Again, keeping with the oem look, I didn't want to ruin my original glove box so I found a glove box roughly the same dimension as the door opening, but the box was rather shallow, so I bought two. I cut out the back of one and 'piggybacked' the other to it to get some depth. The glove boxes are for a 90s Jeep, if I recall, and only $10 each from Summit Racing. The GPS unit has a cable end and a wiring end. Cable comes out of the glove box, travels behind the dash and makes a 90 degree turn into the speedometer. The little GPS signal picker upper thingy sits under the right-hand side fender. Can't do that on a metal car. It's all hidden, and accurate. No leaky speedometer angle drives. The drive shaft is a custom unit. I took the stock one to a driveshaft making shop and told them to replicate exactly, except for the sliding spline yoke. It needs to be 28 spline, the usual Ford stuff.
How am I going to support the tailshaft? The tailshaft mounting holes are up against the tunnel and really can't be accessed directly, so I made a plate that mounts to the tailshaft and essentially 'cantilevered' it forward so some sort of frame mount could be utilized. Turns out the oem frame mount, turned backwards, will mate up to it just nicely. I used rubber discs between the frame mount and cantilevered mount and played with the amount needed to get the tailshaft up high enough to equal the stock tilt of the engine. The shifter is nearly up against the frame flange and the tilt is 2 degrees more than stock. I'm calling it good.
What's it like to drive, you ask? Good enough that I don't want to go back to the 4-speed. Shifting is a bit stiff and notchy but I'm calling it 95% as good as the 4-speed. But the real benefit is this: 3100 rpm in 5th gear at 70 mph. It's a stroker motor so the engine has the grunt to keep it there without lugging. No real need to downshift for a little extra mph. With the 4-speed, the engine was turning 4100 rpm.
Price? Yes, pricey, that's all I'll say, but worth it. I'm totally chuffed with this project.
