Diesel Governor Recommendations

[AugustDiesel]

So, it seems to be a success. Prior to the diesel governor, it wouldn't shift from 1-2 until 26mph, 2-3 at 35mph, and 3-4 at 40mph. Now that the diesel governor is installed, it actually seems to shift earlier (doesn't seem to be a bad thing): 1-2 is at 10mph, 2-3 is at 20mph, but then 3-4 isn't until 45mph, and it seems to hold 4th really well vs before it wouldn't. Trans temp stayed right at 200 degrees, which is warm, but maybe not considering it's 95 degrees here in north Florida. No leaks anywhere, and it moves through the gears pretty well and fasts too.

[AugustDiesel]

So it seems, after a few test drives, I may not be out of the woods yet. While the shift points seem to be okay, the trans does not seem to want to down shift when getting on the throttle. Particularly in highway speeds, if I'm already in 4th, I can play with the pedal a bit to get it to downshift to 3rd, but even then, once I slam the pedal (for either passing other vehicles or climbing uphill) it just pops right back into 4th gear and bogs down. Any ideas on the cause of this?

[convert2diesel]

Tis the nature of the beast. Without the control afforded to electronic transmissions, the older mechanical trans, needed that governor to keep the engine speed below the governed RPM (3,200 to 3,500 RPMs). The intent is to keep the RPMs as close to 2,000 as possible.

Takes a bit of getting used to as far as driving is concerned but the neither the 6.2 nor the 6.5 were ever envisioned as hot rods. Keep it calm and it will live a long and reliable life.

Bill

[JohnC]

Sounds like you need to adjust the TV cable.

[DmaxMaverick]

Shift points can be affected by more than just the governor. More often, it's the fuel filter (really), or a TV (Throttle Valve) cable out of adjustment. The fuel filter is as easy as a change. The TV cable needs to be adjusted properly or it won't shift properly, and can damage the tranny. First, be sure the skinny pedal is actually allowing for full throttle travel. Mash it to the floor and check for limit of travel at the throttle on the IP. Next, calibrate the TV cable. Make a note of the length of bare cable exposed. Press/squeeze the button at the TV cable bracket nearest the IP. This should allow the cable to retract. If it doesn't, it could indicate a failure of the TV inside the tranny, or a damaged cable. Once it's retracted, mash the skinny pedal to full throttle travel. Measure the exposed cable again, and compare it to your previous measurement. As little as 1-2mm can make a significant difference.

[convert2diesel]

Shift points can be affected by more than just the governor. More often, it's the fuel filter (really), or a TV (Throttle Valve) cable out of adjustment. The fuel filter is as easy as a change. The TV cable needs to be adjusted properly or it won't shift properly, and can damage the tranny. First, be sure the skinny pedal is actually allowing for full throttle travel. Mash it to the floor and check for limit of travel at the throttle on the IP. Next, calibrate the TV cable. Make a note of the length of bare cable exposed. Press/squeeze the button at the TV cable bracket nearest the IP. This should allow the cable to retract. If it doesn't, it could indicate a failure of the TV inside the tranny, or a damaged cable. Once it's retracted, mash the skinny pedal to full throttle travel. Measure the exposed cable again, and compare it to your previous measurement. As little as 1-2mm can make a significant difference.

All very valid but when I did the Buick conversion, I went through the same issues as August is going through after swapping out the governor. Got thoroughly frustrated trying to correct the TV cable and finally did it using a line pressure gauge, only to find I had adjusted it correctly.

Turns out the previous owner had also installed the infamous "Corvette Servo" and combined with the new governor, the result was the 4/3 shift would only happen at 3/4 throttle and a 3/2 shift would only happen with the skinny pedal mashed to the floor. Suited me fine as with the gears I had, anything over 50 MPH and 2nd gear would take it up to the engine governed RPM and stay there until I backed off the throttle.

All was made more tractable when I finally replaced the torque convertor with the required 1,200 stall version. The combination lasted over 100K miles with no trans issues.

Bill

[AugustDiesel]

All very valid but when I did the Buick conversion, I went through the same issues as August is going through after swapping out the governor. Got thoroughly frustrated trying to correct the TV cable and finally did it using a line pressure gauge, only to find I had adjusted it correctly.

Turns out the previous owner had also installed the infamous "Corvette Servo" and combined with the new governor, the result was the 4/3 shift would only happen at 3/4 throttle and a 3/2 shift would only happen with the skinny pedal mashed to the floor. Suited me fine as with the gears I had, anything over 50 MPH and 2nd gear would take it up to the engine governed RPM and stay there until I backed off the throttle.

All was made more tractable when I finally replaced the torque convertor with the required 1,200 stall version. The combination lasted over 100K miles with no trans issues.

Bill

So here is what I discovered during my tv cable adjustments: During the above-mentioned shifting patterns, the tv cable was pulled all the way out, resulting in the 1-2 shift at 10mph. So, I push it all the way in, which results in a 1-2 shift at 26mph. Way too high. So, I set the tv cable halfway, and it gives perfect shift patterns: 1-2 at 15, 2-3 at 25, and 3-4 at 50. Not only that, but during an uphill climb on a long STEEP bridge (Jacksonville, FL), with the pedal all the way to the floor, it down shifted to 3rd gear and not only maintained speed, but gained speed during the uphill climb.

Me thinks this is a good sign, except once I get over the bridge and exit the highway, come to a complete stop, now the shift patterns have changed to 1-2 at 27, 2-3 at 45, and 3-4 at 65mph!! I pull over, check the tv cable, STILL in the same position I set it in before the test drive. Just took it on a short drive around the block after letting it cool off, no change, 1-2 is still at 27mph. What's the deal?

I should mention that shortly after the transmission install, one of the cooler lines failed, blowing out all my transmission fluid while driving down the highway (which led to me rebuilding all my lines). My transmission builder is recommending I drop the pan and see if there was any damage. I certainly will if it comes to that, but I have not seen or smelled any burned fluid or black stuff in the fluid when pulling samples from the drain hole in the bottom of the pan.

Thoughts?

I'll also add that my 700r4 also has the corvette servo. In fact, here's the build list:

5 pinion front and rear planetary gears - factory GM parts
Beast Sun shell - thick billet steel
Corvette servo
New band clutches bushes seals washers gaskets
10 vein pump rotor
Drilled out plate
New sprag
K case

The tv cable is the original not a new cable

Thanks in advance for all the feedback. It's been very helpful!

Andy

PS- I'll also add that during that uphill climb when shifts were perfect, the trans temp was surprisingly cool, no higher than 160, and on the way back over the bridge with the messed up way high shifts points, temp stayed at 180. Whereas the same uphill climb yesterday with the early shifts resulted in 200-217 temps.

[DmaxMaverick]

Mashing the pedal on the uphill climb reset the TV cable to where it MUST be. Independent and regardless of everything else, if it is not adjusted properly, you will cook the tranny in a hurry. If the cable moves freely, it's in good shape. If it slacks while releasing the throttle, it may need cleaning (don't use WD40), or replacing.