USER REVIEW WRITTEN BY DICK TAYLOR

The HVDA, of course, stands for Herman van den Akker, who designed the parts necessary to bolt the five speed Toyota transmission up to the Triumph engine. I've had mine installed and running for about six months. In between, I had the engine and tranny out for work on the engine, and readying the engine compartment for (slow) painting.
Why would anyone want to replace a Triumph transmission, one could reasonably ask? The answer here has to fit the needs of the owner. In my case, this was the original transmission that came with the car in 1973. It was the NON-overdrive unit. Perfectly suited for the 55 mph National speed limit, in effect for about, er... to long! Now that one could legally cruise at loftier speeds, and the fact that my TR transmission was well worn, (over 300,000 miles) it seemed like a good time to consider a transmission with a "tall" fifth gear. So here we go...
Herman van den Akker distributes a very fine instruction manual, for those interested in making this conversion. 1-661-242-1253 (or) handhvan@msn.com. It is competent in removing the Triumph transmission (as in replacing the clutch and t/o bearing) can probably do this conversion, by following the step-by-step instructions.
I chose the conversion that included the "hydraulic throwout bearing." Now that I was reasonably confident that the gremlins surrounding the Triumph clutch disengagement parts were conquered, I then chucked the whole apparatus for a setup that had NONE of these parts! (Of course I saved all parts and the tranny, should my heirs want to return to stock.)
No slave cylinder. No sc pushrod. No clutch-operating shaft. No clutch fork or pins. A moment of silence, here...
What's left is a throw out bearing that moves forward on the hydraulic pressure coming from a braided steel line down from the (standard) Master cylinder. This releases the clutch and feels somewhat easier to operate than before. Probably because there is less friction losses by eliminating some of the parts.
The clutch releases and engages in a smooth fashion, and much easier than with the original setup. That is, the disengagement point is when the clutch pedal is about two inches from the floor. A welcome relief from those who may be used to having to use the full stroke of the pedal. There are instructions included to keep the pedal from going farther than necessary, so as to not overthrow the release point. I found this short throw very easy to adapt to, as was the gearshift, described later on.
I won't attempt to re-write Herman's instructions here. They work just fin, as-is. Rather, I will only add a few of my own findings. Some of them were discussed with Herman, and whether he incorporates them in his newer conversion kits is, of course, up to him. "Kits" such as this must be kept reasonable in cost in order to appeal to more owners. I respect this, so adding more parts and time to designing may not always be in the works.
I.e. I found more chamfer was desired on the (new) pilot bushing, to aid in mating the input shaft into the flywheel.
Drilling a hole thru the floor plan to mount a clutch pedal stop-bolt was re-thought. Using existing studs in the pedal box mount, a metal strap was fashioned that included a bushing for the stop-bolt. Same purpose, that being to adjust the length of the bolt that controls how far the clutch pedal can be depressed.
Because I prefer the 205x70x15 rear tire size, the speedometer and odometer readings were off (short) by about 7% with the new gearbox. I had the speedo unit recalibrated by a local instrument repair so. ($60). The short story here is... the Smiths speedo unit I have was the one with the "1120" printed down near the face bottom. This, I found, means that the speedo drive cable turns 1, 120 revs when driven one mile. With the new transmission drive gear and cable, it was only turning 1,040. On instructions from West Valley Instruments, I was told to mark off 52 feet, 9.5 inches on the pavement, and count the turns of the speedo drive cable, which happened to be 10.4 cable turns when covering this distance. I didn't really drive one mile! Those wanting to spare themselves the recalibration expense just need to know of the difference, and adjust their driving accordingly. (Others who converted claim they found no error). Know that the use of smaller diameter rear tires will put the speed and distance much closer to actual, such as using 195x65x15 tires.
The Toyota Transmission chosen was the one with the tallest fifth gear. I would've settled for one not so tall, as they're all pretty close. It came from a 1983 Celica. My cost was $250. 1982---'85 are the years we want. This one had the 0.783:1 top gear, giving approx. a 21% drop in engine peed when in fifth gear. I use it anytime I'm on the freeway (when I remember!) As an example, cruising at 3,000 rpm now shows an actual corrected 78 mph.
The placement of the gearshift seems identical to what I was used to for the thirty prior years. The shifting pattern is close, with somewhat shorter throws. Fifth is forward and to the right, with all the other gear positions the same. First thru fourth are close to the same ratio as the TR box. Some difference is noticed when up-shifting to second, second gear being taller than before. This means less of an engine speed drop when going into third, which was welcomed.