MoTeC Global Forum

What's the best way to implement a shift cut for flat foot shifting with an H patter dog box ?

Simple clutch switch or other ?

Driver isnt happy shifting without the clutch so literal flat shifting isnt an option. Looking to retain boost as currently after a shift it does take about 0.3-0.5sec to achieve max boost again.

Strain gauge on the gear stick to a Motorsport Systems strain gauge amplifier / threshold detector. Output from the SGT2 in to the M?00 to trigger the cut. This sort of thing was common on V8 supercar when they still ran the h pattern.

There is likely more modern technology around now these days, though this is still a good system in my opinion.

Ive heard of strain gauges, but never used or seen one.

Where exactly on the gearstick to they go ? Any pics or info ?

basically, you can send your gear lever to people (that guys is one solution) who can glue a strain gauge onto the stick.

the stick is wired to an amplifier, motec sell a Strain Gauge Amplifier for this purpose, I use that method in my car.

this is wired into the M800, and used to set cut forces.


it can then be used for flat changing up, but cant do blipping on downchanges..

-Jamie

Here is a photo of a Holinger gear lever out of an older supercar. Under the black heatshrink the strain gauge is glued to the stick. Wire goes to your strain gauge amplifier, I didn't know Motec did one

to complicate matters. It's for a 6 speed Subaru which has a "lift" collar for selecting reverse on the shaft.

How long is the strain gauge ? ie how much shaft does it require ? There really wouldnt be much accessible because of the reverse mech.

If the driver wants to use the clutch, and its hydraulic, a pressure sensor into an AT works. Most clutches are 1000+ PSIg so you need at least a 1500 PSIg sensor.

You can adjust the switch point to just before the clutch releases/grabs and do a simple cut strategy.

In that pic of the gear stick the heatshrunk bit is 70mm long. Since the strain gauge relies on deflection or bend in the stick, a short gearstick with the strain gauge fitted high may not bend enough for the system to work accurately.

Scott, with a simple clutch switch, can you make it cut only on upshifts?

Sean wrote:Scott, with a simple clutch switch, can you make it cut only on upshifts?

With your 'minimum throttle position' set up on the high side I would imagine it would only cut when you're upshifting at or near WOT. Would still allow a manual throttle blip to occur for downshifting if you don't exceed min TPS settings.

The gear shift strain gauge people would have to tell you what sort of lever is suitable or not.

you can get gear knobs with the strain gauge built into that, I think hollinger does that.

Yes, you can use a clutch switch instead, but in a race car, to be able to flat shift, without using the clutch is probabaly a better option.

Here is a video of my car using the flat shift option, with a strain gauge in a H pattern gearbox:

http://www.youtube.com/watch?v=Y-UyM-_j ... ature=plcp

Downshift throttle blipping on a h pattern gearbox is quite challenging, and probably not worthwhile..

works great on a sequential gearbox though.

-Jamie