Good skills and nice work, Dave!

I don't recognise the wishbone brackets, but they look proprietary - Triumph?

Cheers, John

To get back onto topic, your mph per thousand rpm. Can we assume you have a standard 3.58 rear axle. If you tell us what size tyres you have fitted then a simple calculation will give the answer to the question.

Hi Peter,

Here you go, theoretical shift points and mph/rev'. Will compare against actuals
John, lower wishbone brackets are home made brackets

Cheers Dave

Guys,

Many years ago, I raced an MG Midget. I wrote this webpage to calculate speeds & Rpms etc


http://www.fisc-racing.com/misc/ratios.html

you may find it useful.

S.

good work and well presented. Steve

Jeeeeeeezzzzz.
You deserve a medal for that.
Even to be brave enough to attempt it.

Hello once agian,

Thought I'd give a bit of an update on how the 6 speed conversion panned out in real life terms. I'm glad to say everything has worked perfectly and no further modifications have been required to the ones already mentioned in the write up. The clutch bite point is about 2" off the floor and clutch pressure is perfect even for the wife. The theoretical shift points are almost spot on and cruise is 70mph at about 2700rpm. The gear lever throw is just right in standard form, I did think about modifying to a short shift lever but no need. Propshaft has been stable, no vibrations or knocking and the gap left between the propshaft splined slider going into the gearbox tail has proved sufficient to stop it bottoming out with the live axle travel. Starter motor has engaged/disengaged with no problem and spins the engine easily with plenty of oomph.

Couple of pictures showing the position of the gear lever which is about 120mm further aft, and the adapter plate/ bulkhead clearance.
The drivability has been a joy, first gear is short lived and I tend to miss it unless a hill start is required. The torque of the V8 allows most driving conditions to be catered for between 3rd and 5th. 6th is a pleasure and allows very relaxed cruising revs with no real need to change down in standard traffic. Also I now have six exhaust notes to play with so can get a good song out of the car when giving it some.

So the upshot is all good and the modification has worked with no teething problems
Cheers and thank you Dave

Excellent Dave, that is a great result, well done.

Regards.

Richard.

Excellent article Dave, thanks for posting.
Did you make a custom carpet for the gearbox tunnel or did the standard one adapt to fit?
Also would you be willing to share the CAD file of the mounting plate, I have a very good RX 8 gearbox already that was to be used on another project but after reading your article I’ll use it on the Dart instead.
How does the acceleration compare with the standard box when setting off in 2nd gear?
Look to hearing from you
Thanks
Peter

Hi Peter,

Yes the tunnel was bespoke only because I was in the process of fitting new carpets at the time, however I'm sure you could make the new hole the same size as the old and transfer the cutout into it.

More than willing to share the CAD file but can't post the .DXF file format here on the forum, so PM me your email and I'll sent it across.

You'll see in the write-up that on page two I mentioned I wasn't sure what the Mazda dowel pin diameter was, well its 15mm not the suggested 16mm diameter. (I'll updated my drawings to reflect this)

2nd gear is fine, not short lived at all

Cheers Dave