lower rev limit min gear

A forum for discussing applications and implementations of the MegaShift transmission controller code for the GPIO from B&G. This can control up to 8-speeds and 6 shift solenoids (plus a 16x9 table for controlling a PWM line pressure valve). It has manual and fully automatic modes (16x9 load x speed table), with under and over rev-limit protection, and full data logging of all inputs and outputs (among many other abilities). A TransStim to test your completed board is also available.
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gurov
Posts: 164
Joined: Mon Jun 01, 2009 1:01 pm

lower rev limit min gear

Post by gurov »

not sure how this one could be worked around, but say im rolling 30 mph, in 3rd gear, and downshift to 2nd. there's a one way clutch on 2nd gear, and engine braking is not engaged in this gear. so as i JUST downshfited to 2nd. engine speed falls down to idle, more or less, it doesn't matter what the input shaft rpm is, one way clutch will juts let the engine go. this causes the code to downshfit via lower RPM limit to 1st within about a second of shifting out of 3rd.

now, 1st also has this one way clutch, so the car is rolling at 30 mph, but in 1st, and to get any forward speed, it would have to upshift to 2nd instead of just staying in 2nd while there is speed registering.

again, i'm not sure what can be done about this. i will either disable this feature or set it below 1000, it's nice to have the code downshfit all the way down for me when i'm stopped, even in manual mode, although this might interfere with starting out in 2nd gear.
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: lower rev limit min gear

Post by Bernard Fife »

gurov,

Yeah, I'll have to think about this one - it's tough because of the conflicting operating requirements...

Incidentally, this is exactly why the auto shift table is based on vehicle speed rather than engine rpm.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
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