3-4 shift adjustment through Cruse control cable adjustment?
09-15-2018, 09:34 PM
#1
Registered User
Thread Starter
3-4 shift adjustment through Cruse control cable adjustment?
Riddle me this
Why did adjusting the cruise control cable move the 3-4 shift point up or down~2.5mph per notch?
why did this adjustment allow ~ 50°f more Egt(more throttle) per notch, holding 4th gear below max shift point? Eg 4 notches= 50mph ,975°EGT. Vs 60mph ,800max throttle below shift point to stay in 4th. Hit 825 and hellow 3rd.
91.5 D250 auto.
When I moved the WOT/max shift point 4th gear engagement point from 60mph to 50mph thinking I was adjusting the TV cable (thinking this because I was successful in adjusting the shift point as low as 45mph, ) I was actually adjusting the cruise control cable. I adjust this cable several times at Bonneville with the same result increasing the speed at which I could maintain WOT and %of throttle without causing a down shift. IE above85(interstate) 80(salt). On run 4 I had this pulled tight enough to raise idle to ~1200 rpm. Made 90mph but triped into 3rd gear 1/8 before the trap. If I haddent triped the trans I may have been able to hit the 92.5 limmit @~85-90% throttle allass 87.14mph in the standing mile not bad for a 99% stock late 1st gen. With 350k
modds:
2000 degree ceramic paint and wraped extra thick headder wrap(.125 vs .062)head to downpipe +t3 Ti basalt turbo blanket .
= reduced EGT and increased boost , drastically reduced underhood temperatures can run hours and still touch the turbo hot side and alternator, before couldn't run down the road more than 15 minutes before the alternator was too hot to touch, it should live longer happier life. More power from the same mass of fuel, less throttle required for the same speed.
-Bd 16cm exhaust housing.
= done same time as wrap, improved spool from 250' down to 150' for 1psi. Still requires pre spool to make left turns in the big city
-custom aerodynamic canopy.
The truck has the same top speed(92.5mph) with or without the canopy when the 2500 gov limmits out.
Why did adjusting the cruise control cable move the 3-4 shift point up or down~2.5mph per notch?
why did this adjustment allow ~ 50°f more Egt(more throttle) per notch, holding 4th gear below max shift point? Eg 4 notches= 50mph ,975°EGT. Vs 60mph ,800max throttle below shift point to stay in 4th. Hit 825 and hellow 3rd.
91.5 D250 auto.
When I moved the WOT/max shift point 4th gear engagement point from 60mph to 50mph thinking I was adjusting the TV cable (thinking this because I was successful in adjusting the shift point as low as 45mph, ) I was actually adjusting the cruise control cable. I adjust this cable several times at Bonneville with the same result increasing the speed at which I could maintain WOT and %of throttle without causing a down shift. IE above85(interstate) 80(salt). On run 4 I had this pulled tight enough to raise idle to ~1200 rpm. Made 90mph but triped into 3rd gear 1/8 before the trap. If I haddent triped the trans I may have been able to hit the 92.5 limmit @~85-90% throttle allass 87.14mph in the standing mile not bad for a 99% stock late 1st gen. With 350k
modds:
2000 degree ceramic paint and wraped extra thick headder wrap(.125 vs .062)head to downpipe +t3 Ti basalt turbo blanket .
= reduced EGT and increased boost , drastically reduced underhood temperatures can run hours and still touch the turbo hot side and alternator, before couldn't run down the road more than 15 minutes before the alternator was too hot to touch, it should live longer happier life. More power from the same mass of fuel, less throttle required for the same speed.
-Bd 16cm exhaust housing.
= done same time as wrap, improved spool from 250' down to 150' for 1psi. Still requires pre spool to make left turns in the big city
-custom aerodynamic canopy.
The truck has the same top speed(92.5mph) with or without the canopy when the 2500 gov limmits out.
10-28-2019, 03:14 PM
#2
Registered User
Thread Starter
No known cause
Solved I instard a Allison 1000 6sp. That refuses 6-5 downshift above 86 miles an hour.
I kept the OEM TCM to control the toaster oven and cruise control and whatever other mysterious things it does.
I kept the OEM TCM to control the toaster oven and cruise control and whatever other mysterious things it does.
Thread
Thread Starter
Forum
Replies
Last Post
Fredbearstalksm
12 Valve Engine and Drivetrain
6
10-31-2005 11:15 AM