Just curious if anyone has toyed with replacing the cable system with an electronic system.

Only have them on my work ride as a backup to mech linkage Jim. Things are moving on though.

Grant

Do you have any photos?

I could be wrong Jim but I think Bobley on here had a fly by wire setup at one time.

I could be wrong tho

Yeah, it was a hacked Racelogic box running a chopped down BMW V12 throttle body. The throttle pedal sensor was off a Transit and I bolted it under the cab floor and used a pushrod off the standard pedal.


The throttle motor was mounted on the block and ran the Jenveys using a std CSP bellcrank linkage but with the throttle motor pretending to be the centre pillar.


I ran it for a year with alsorts of plans to introduce cruise control and integrate it with the DTA and use it to give me a controlled fast idle on cold start (if you do fast idle leaving a cracked throttle and then retard spark to slow it down then you waste fuel).

Anyway, I started to find niggly problems pretty quickly. The throttle ECU couldn't compensate for the amount the block and heads expand as the engine heats up. So when it was cold it would bring the throttles down to sit on the idle stops but as the engine grew the ECU found that it could no longer pull the throttle back to where it thought fully closed should be and then it locked out on error. It was very difficult to set up and you had to have a laptop with you at all times to sort it out. Eventually one of the tracks on the position sensor in the motor packed up so it just locked out, when I was miles from home and it cost a packet to get the AA t tow the whole lot home.

I've still got some of the bits and my pal's working on his own bespoke system so we can get better access to the strategy but its still messy if you want to run 2 throttles on opposite sides of the engine bay off 1 motor. I did find an Audi twin bosch E-gas throttle body at work but it was 2 x 54mm IIRC. Perhaps you could modify a jenvey type body with a motor, alternatively use a BMW E46 M3 throttle motor to drive a CSP linkage but that brings you back to the thermal growth problem again.

What would you like to achieve with such a system Jim?

when i see things like this i just think why bother you might as well go and buy a modern van, i thought the idea of keeping things simple and fixable at the side of the road a good thing

Simply because you can. You could say the same thing about disk brakes, IRS, big engines. I thought my total stocker crewie was great to drive and easy to fix. As soon as you mod anything you're out on your own.

I did buy a modern van too though

Like Bob said, because it's possible and great to have the best of both worlds. I think most twin carb linkages are average at best. So if that can be improved on and gain the functions the ECU offers like cruise control then even better.

IMO the only time you really need this is if the engine is far too powerful and cannot be driven smoothly.

This would allow you to map the throttle position against pedal demand dependant on engine speed (ie at 3000rpm my engine is making no more power at 100% as it is at 50% pedal) so that for small pedal inputs the actual throttle positio.n is very small and the pedal is filtered to smooth the engine out.

If this is the case though you can always use a cam operated linkage to achieve the same like this

http://www.g2ergo.com/g2-throttle-cam-system-80.html

The E46 m3 has a nice standalone throttle actuator - though it is rather large. I have one I bought on eBay (together with a BMW e pedal) with the intention of looking at putting together an h bridge circuit and some software to drive it. Haven't got to it yet...

A sheathed cable throttle wheel linkage would solve the thermal expansion issue...

Simon

shambly wrote:A sheathed cable throttle wheel linkage would solve the thermal expansion issue...

How's that work? Sounds interesting?

I've just been out with my electronic meddling colleague. He reckons his latest box would work fine because it has a strategy to learn the endstops. Do you want me to ask if he's got one ready to sell?

i think its great you guys have the know how and dare to do things a little different, it makes interesting reading even if its not for me

bobley wrote:

shambly wrote:A sheathed cable throttle wheel linkage would solve the thermal expansion issue...

How's that work? Sounds interesting?

A sheathed cable takes up any expansion as the sheath length between the two throttle bodies remains constant (as sheath is slightly longer than the actual distance and doesn't suffer from thermal expansion to the extent that the engine case does)

A master wheel operates a second cable to a slave wheel on the second throttle body.

Its like the Jenvey operating wheel linkage for a V engine but with a sheath over the cable interlinking the two throttle bodies.

Here is a mock up of a master (operating wheel is a 3d printed prototype) wheel on set of Jenvey TFs (also with my air filter trumpets)



Simon

Not mine but a good clean install



and a wright up on it

http://www.shoptalkforums.com/viewtopic ... 9&start=45

ooooh, now that I like