auto into 5 speed truck

L

lews930

NOT A DIESEL PRO
Joined
Sep 25, 2008
Messages
751
Ive read dozens of threads and even saved a few but one question I cant seem to find an answer.

On the tc lock up switch, how easy is it to forget its on? I do a LOT of thinking when driving, probably shouldnt but thats when it gets done. That being said, when coming to a stop and the truck starts to buck with tc locked, will the switch unlock the tc instantly? if the truck stalls, will the switch unlock the tc so thaat the engine can be started?

will those"hobbs" switches unlock the tc or am I switch dependent forever?


Have I missed anyting?

i
 
47rh and re won't lock in first so it will unlock on 2-1 down shift and re-lock on 1-2 up shift.
 
Thats true, but the transmission doesnt downshift locked. It will stay locked in 4th, or if O/D is off, stay locked in 3rd. The switch unlocks it instantly and should shudder long enough that you remember to flip the switch.
 
47rh and re won't lock in first so it will unlock on 2-1 down shift and re-lock on 1-2 up shift.
Click to expand...

yes, but no.


you'll know when the truck starts bucking @ 25mph or so. I have a switch with indicator light in my truck... it gets annoying at night when im on & off the throttle because it lights up accordingly
 
so do I have to switch the tc on and off every time? and the o/d on and offf every time?
 
if you install the TPS or the pot mod, you do not have to switch on/off OD manually.

You can buy pressure switches that attach to the ports on the side of the trans to control OD and TC lock as well
 
Measure pressure vs mph at the govenor port of the trans. Install hobbs or nason switches at whatever speeds you want o/d and lockup to engauge. You can also wire in a override switch to cancell out the signals for more control in some instances.
 
good deal. any part numbers for these hobbs switches and a wiring diagram. If you havent sensed it yet I'm a little electrically challenged
 
Hmm, I have an old 94 with a luckup switch and it will shift down to 1st with the switch locked and then relock when it hits 2nd. My 98 does the shudder deal though, any idea why the 94 will downshift while in manual lockup?
 
kscummins said:
Hmm, I have an old 94 with a luckup switch and it will shift down to 1st with the switch locked and then relock when it hits 2nd. My 98 does the shudder deal though, any idea why the 94 will downshift while in manual lockup?
Click to expand...

My guess is that the 94 is a 47rh "mechanical governor" transmission and the 98 is a 47re "electronic governor" transmission.
 
I know that much, just didn't realize that the RH would downshift in manual lockup and the RE wouldn't. Thanks for the info Big Blue.
 
You must log in or register to reply here.
Back
Top