Vrv diagnostics - m1008 1986

[dom1986ck30]

Aloha All, I recently had a post, "th400 not Upshifting/Late Shifting". I was able to receive a lot of good input and advise. So... I am starting a new post/thread to "Diagnose" this predicament that I have more precisely. I have a VRV on order. Should be here today or tomorrow. I will follow the TM instructions as needed for adjustments. With a spacing of .646 on the throttle, 24"hg at Vac. Source, and 8"hg at Trans. Modulator from the VRV. Any pointers? Also, before I decided to order part, I previously thought the VRV to be good still. It had 24"hg but was very gradually losing pressure. I did this check upwards of 30 times. Making sure that all rubber was tight. I used new as well. If it is gradually, "The Needle", going down on gage, does this mean it was bad? How "Tight" or "On Point" does the VRV need to be? How "SENSITIVE" is the VRV, is probably the best way to put it. I hope new one works. I feel it was a minor loss of vacuum, but I could be wrong. Something so simple and cheap. Hmmm... and if that's not it... ouch.

 

[Barrman]

I actually have never tested one. I have three trucks on the road each day with that set up though. Sorry I can't comment about the slow seeping of the vacuum.

I can comment about the set up of the valve though. If you wish, go ahead and try to get exactly .646. You might or might not like where the shifting occurs. I live in a town with 35 mph speed limits. My M1009's wanted to shift at around 38-40 mph into 3rd gear. I carried a small socket around and adjusted the valve to get my shifts in at 33-35 instead. That might just be me being OCD. Your M1008 will be in 3rd gear probably before 30 mph anyway with the different axles.

I would suggest going ahead and following the procedure. Do your normal daily drive and see if it fits. If not, move the valve around to suit your drive and when you want the truck to shift.