GT6 needing an automatic

A gent emailed me today.

He owns a GT6, but recently had an operation on his left leg and no longer can drive a stick shift.

He has asked me if I have any info on automatic transmission conversion options...

Any suggestions please.

Tks.

A.

There was a Triumph model that had a six and offered an Auto option. I wish I could give you more info, but I just cant remember where I read it...I belive that it may have been in "Britsh Car" magazine...

Leo

Hand clutch. Put the lever on the shifter.

Being a hydraulic clutch, a hand clutch is theoretically possible... at the same time, think about the leverages and forces required...

The Triumph 2000/2500 saloons use the same engine. Most of those came with auto gearboxes. Could that work?

Luke wrote: The Triumph 2000/2500 saloons use the same engine. Most of those came with auto gearboxes. Could that work?

Probably a BW35 box - about half of Europe used it around that time.

Hand clutch sounds like a better idea to me. The other one - if he can still move his leg and just doesn't have the strength - might be some sort of hydraulic booster for the clutch.

I've been wrestling with a similar issue for years. The forces are fairly significant - clutch spring pressure on my mg is around 325 # - pedal ratio is like 6:1 so a 25# pedal pressure translates to 150# of force at the master cylinder - on to the slave - perhaps some force multiplication there and there's usually some mechanical leverage from the slave to the fork - like 2:1. What I came up with is using a pneumatic air cylinder - 2" bore and 1" stroke - with a position feedback feature (using a wilwood mc with a 1.1" stroke - air cylinder just needs to match). An onboard air compressor feeds an accumulator tank with pressure switch and maintains a steady 100psi at the ready. I found a high speed, proportional air valve (2ms reaction time) and controller board from some salvage medical equipment. To operate the valve I have the trigger from a video game controller that feeds 0-10vdc.

The short version - video game trigger on gear shift lever is a potentiometer - feeds proportional voltage to open the air valve - how far you pull the trigger is proportional to how far the air cylinder moves - and proportional to how far the clutch master gets pushed. Similar to an F2 car with the 2 pedal AP Brake system (except theirs is $11,000 with a minimum order of 20 units) .

People think you feel the clutch with your foot. The feedback actually comes mostly through your inner ear - it's not the issue people think. To simplify you could use a single acting air cylinder and direct control to a high speed valve.

I'm still working out optimizing a bellcrank arrangement to put the mc side by side with the air cylinder - but it all lives in the trunk with the compressor mounted outside under the car. So far it works on the bench. Compressor is a bit loud - needs some rubber mounts - with filtering you could use an old york ac compressor.

To calculate air cylinder - air pressure x cylinder bore pi r squared = force exerted. For mine - 2" bore at 100 psi = 314lbs of force to the mc - more than enough margin.

Sorry to ramble. Send me a pm if you want more info. Tom

BoxheadTim wrote: Probably a BW35 box - about half of Europe used it around that time.

In that case: run away!!! Unfortunately, I have experience with the BW35 in a Volvo 1800ES... we converted it to a manual.

oldtin's servo-actuated clutch idea sounds like it has potential.

That's a well thought-out hand clutch idea. Fabricating the system and getting it to work reliably are still hurdles, but I love the concept.

I'd love to hear more about it, oldtin.

Is there not a Ford type-9 5-speed conversion? Is there a comparible (C3 or C4) automatic that could be substituted? cheers Ron

Here's pretty much all the bits except the gearshift knob (or I could go flappy paddle on the steering column). An air valve that would allow direct proportional control would eliminate the controller board (and a bunch of complexity and cost if that controller board wasn't a cast off). It packages up in a box 13" x 6" x 6" (other than the compressor and accumulator tank). It adds about 17 lbs for the compressor and box - could probably shave 5lbs of that. I'm hoping with just a couple more tweaks this is a plug n play for about any car with a hydraulic clutch.

I knew a guy who took a TR6 and made it auto with a 2500 box, wonder if the 2000 box would mate easily to the GT6 engine.

rconlon wrote: Is there not a Ford type-9 5-speed conversion? Is there a comparible (C3 or C4) automatic that could be substituted? cheers Ron

Unlikely.

The T-9 conversions use an adapter to fit the transmission to the original Triumph bell-housing. Plus, it still uses the original flywheel as well. The tricky part for an automatic is that the bell-housing is usually part of the transmission and instead of a flywheel there is a flex-plate that the torque convertor bolts to.

Next, there is a matter of space. In the Volvo 1800, there is a difference in the transmission tunnels between the earlier and '69 thru '73 cars in order to fit the newly optional BW35, which wouldn't fit into the earlier M41-sized tunnel. I have had a BW35 in my grubby hands... I've also had a couple of Triumph transmissions and did an o/d conversion in a Spitfire (basically the same as a GT6). There is no way a BW35 will fit in a GT6 frame without some serious messaging. The BW35 is smaller than the C4.

A quick look on wikipedia suggests that the Triumph 2000/2500 were indeed fitted with BW35s.

Wasn't there a thread here (or on the GRM side) where some enthusiasts converted a sporting car of some type to a hand operated clutch setup for one of their own?

I can't remember details, else I'd provide them. That said, oldtin's setup sounds really cool.

Rig up a Vacuum unit on the clutch master, move it to where ever if needed. Like the Booster for the brakes on a TR6. Rig a push to hold switch right below shift knob, actives the booster to operate by solenoid, and rig in a adjustable manual vac release valve for slow vac release. A lot less money. Or, hand clutch on the shifter, actuating a motorcyle hydraulic unit mounted on the tunnel, with areoquip from shift to hydraulic unit.. Could rig in a one way system to keep the org clutch hydraulics. Turn a knob for either foot or hand shift. In reply to André Rousseau:

That actually may work since the slave is right under the tunnel or the right side.

If the boost was powerful enough we could maybe remove the clutch master.

An X1/9 Fiat was converted. Check at FLU forum for details.

Cheers Ron

At the shop I drive for they just did a conversion for a guy with a similar disability on his Spitfire. He shipped us the motor and trans and they shipped it back when it was finished. I know it's onky a 4 banger but most likely it should be similar..

Currently I'm on vacation in the caribbbean and don't have any access to the particulars other than I know they fabbed up an adapter plate and used some air cooled borg warner box.

I could find out more when I get home in a week or so if you would like it.

Or you could PM me and I can send you the phone number to the shop and you can give them a call.

In reply to André Rousseau:

BW65 as fitted to the later 2000/2500 is a lot narrower and will fit. I've seen a conversion using a BW65 on a Spitfire and a couple on a Vitesse and will be doing the same on my Vitesse convertible as my left leg is now wrecked. It's a pretty straight forward conversion.

The BW65 is a better box than the BW35 - the latest move with the Stag boys is to use the ZF4HP22 box, a bit more involved, but is a really good box with a lock up and easy to source. Guy I know has done that conversion on his Vitesse… sweet conversion with little power loss and still a hot car.

Andy