BC847

Alrighty then:
- I've got a tachometer.
- Got the transmission overhauled/upgraded.

If I understand things correctly, the transmission's wide-open throttle (WOT) shift points should occur slightly before if not right at the engine's torque peak (definitely NOT after).

Is this correct?





- I know I can make small WOT shift-point changes (1st to 2nd, 2nd to 3rd) with the Throttle-Valve (TV) cable adjustment, and the TransGo kit allows changes in 200rpm (approx) increments if need be.
- I know I can adjust the WOT Overdrive (OD) shift-point (3rd to OD) by way of the Throttle Position Sensor (TPS).

I'm hoping to get a good dyno chart the 10th of November on a 248H (CAM). With that, I plan on adjusting accordingly.



What say Y'all?

JD730

I don't think it should work that way. WOT shifts should occur just before the the defuel point.

apwatson50

I agree to a point, you want to shift to the next gear so that your rpm drop into the next gear puts you at your peak torque rpm.

example(theoretical):

2nd to 3rd gear shift.

Shift from 2nd at 2500 into 3rd drops rpm's to 2000 with peak torque developing at 2000 rpms.

Make sense?

So that may not necessarily be at the de-fuel point. This is what I would do for getting down the track the fastest.

Now towing you may want to keep your rpms higher to keep things cooler.

BC847

You both make good points.

This is from the TransGo install instruction and appears to be more in line with that that apwatson50 suggests.



JD730 ~ Mike, wouldn't that you suggest be better suited to a gasser?


I think what's got me with the TransGo instruction is there term "Best Power". I think they're referring to the engine's torque peak. I think . . . ?

I believe that's where I need an accurate dyno sheet that shows the engine's rpm. That I currently have shows everything in terms of mph. DOH!



And then there's the slip associated with the torque converter. The additional engine rpm figure skews the tachometer a bit . . . . . I think.


Stupid math!

wannadiesel

You want your shift recovery points at peak torque for best acceleration. Don't worry about when it shifts, worry about what the RPM drops to on recovery. Set the hydraulic stuff so the 2-3 recovery happens at peak torque, and do the same with the TPS to get 3-4 recovery right.

This is theory, if setting it up this way makes you defuel before it shifts, then lower the shift points.

BC847

Dave, dinking around at the track tonight had me playing with the shift points. I think they were a bit too high when I got there.

The ET slips suggest I've taken .1sec off with lowering them some. Not real sure as I need to practice watching the tach when driving isn't more important.

At present, the tach pretty-much stays at 2400rpm till I'm well into OD (WOT). I really don't see substantial drops in rpm as the gears change.

wannadiesel

That's the converter. Since it's still kinda slushy, set it up so it hangs right around peak power for the whole pass. Kinda like the multi-stage clutches on top fuel cars.

Rampage1967

I'd set it to just let the engine start to pass converter stall speed & use a 3200 spring in the pump . . .
Should just pass 2500, then wham!! next gear . .that's what i plan to do to mine . . (not ideal for engine . . but seems best compromise on trans)

flashgordon

David, explain a little bit more about you shift kit.

Spring in 200 RPM increments? What spring and were does it go?

I under stand the TV cable helping with the shifts, but i have never been able to make the 1-2 shift the same as the 2-3 shift by a TV cable adj. with or with out a shift kit. I have always had to manually shift it to get it to shift at the same RPM. And is why i finally just ordered a CHEETAH manual shift valve body(No TV cables to adj
Of course theses experience are with a "Gas 727" and my diesel is a standard.

Flash

gomerpile

well wouldnt it help just to install a 3200 spring, i mean it changes your defuel so much, sure you wont be making as much power but if you dont get your shifts perfect unstead of messing up and loosing fuel before shift, your still gettin full fuel

BC847

Folks I've been running the 3200rpm injection pump governor spring for a while now.


Flash, I'm running the TransGo TFOD/518. It comes with three different springs that are used with your Throttle-Valve. As I understand it, one would use one of them when it's determined the TV adjustment isn't enough (in terms of raising the shift point(s).

It's interesting that you mention the 1st to 2nd shifts compared to the 2nd to 3rd. At one point the other night at the track, I noticed that 1st gear would wind on out, go to 2nd, and almost immediately go to 3rd.
To me. that kind of suggests the TV adjustment has more effect on the 1st to 2nd shift than the later. But then there's the governor on the tail-shaft.

I need to get the FSM back out and read up more on the standard operation of the valve-body.

flashgordon

Have you tried a different spring? Just curious if there would be a different(better) shifting spread.(1-2, 2-3 )
I now that the governor has a lot to do with it................Is this where the spring go?
I just re read your post (throttle valve)

I remember, at one time, i had a Different weighted governor......Piston? if you will,.....But I never put it in. Thats when I Went with the manual shift valve body instead.

The more i thing about it, the 1-2 and 2-3 are a Hydraulic shift. Meaning that if you had a Stiffer(?) spring in the 2-3 shift valve in the valve body, maybe it would hold on longer....... Just kinda thing out loud here.


Flash