Quick question about the canned 87 tow
 

Quick question for you guys. I've been running my canned 87 tow tune a lot lately.....I've really been liking the characteristics of the tune over anything else I've run.

I've started to notice that my 1st to 2nd upshift is very "firm" if I let it ease into gear....vs. if I'm accelerating moderately and/or towing...the shift is easier at higher RPMs. My question is.....is that a problem?...or could it cause any abnormal wear and tear on my tranny/engine? Overall, the periodic firm shift doesn't bother me....I just want to be sure I'm not hurting anything.

Thanks in advance.:cheesy smile:

It sounds like maybe the Torque Converter (TC) is locking, maybe just prior to the shift and then, since it's locked when the shift completes, you get a "jerk", since there's no fluid clutch to smooth things out. You could perhaps confirm this by monitoring the "Gear" PID on the Gryphon screen. (It's called "Comm Gear" in the monochrome Gryphon).

If that's the case, there's nothing to worry about at all. I've had it work that way during 2-3 upshifts when towing up a hill. It's a VERY "Hard" shift.

- Jack

I checked it out and I'm not seeing any locking going on b/w 1st and 2nd. The only time I'm seeing it lock is after I drop into OD and I'm on the gas. Seems to be pretty random....in most cases, the shift feels fine. It's really a sweet spot where I'm at just the right speed and RPMs and it only happens when I'm VERY slowly accelerating.....e.g. bumper to bumper traffic where I'm having to creep forward 50 ft and then slow back down again...and there's not much room to really accelerate.

Is it normal to see the comm gear advance prior to dropping into the corresponding gear? If I'm accelerating moderately, the interface shows 4th gear at 32 mph.....I don't actually drop into OD until about 40mph, which is when the TC locking occurs.

Are you sure it's not shifting at 32? If the TC is unlocked, there will be a "gentler" RPM change than if it is locked. It really sounds to me like the shift is happening at 32 and the the TC locks at 40.

But, I don't know that anything is amiss in your truck. I think you are possibly more "sensitive" to its shifting than I am, and I'm pretty "sensitive" too.

- Jack

I don't know....unless I'm missing something. I've always thought my tranny drops into OD (or 4th gear) around 40 mph when accelerating moderately. That is when you physically feel AND hear the truck change gear, as well as you'll see the RPMs drop to about 1000; however, of course that changes if I'm on the gas, which in that case, it drops to OD at a higher speed and RPM. When I was running my custom performance tune....the moderate acceleration shift to OD happened closer to 50 mph.

What I experienced today monitoring the comm gear is that it would change to 4th while in mid-acceleration and know noticeable changes in gear. Once I "heard and felt" the tranny drop into OD at 40 mph....the TC would lock. Is it possible that I'm too INsensitive and my truck is changing gears without me feeling it?

Heck, anything's possible in these subjective kinds of observations. :) I don't really have a good reply for you. I would expect though, that the the TC would lock AFTER the shift up had completed in normal shifting, which would reduce strain on the transmission. Likewise, it should unlock BEFORE any downshift.

- Jack

I know an easy way for you to check if you have the monochrome Gryphon.

Get a datalog of mph (MPH), rpm (RPM), engine load (LOAD) comm gear (COMM GEAR), and pedal position (APP). While you are sitting still start the logging. Once it starts recording SLOWLY accelerate. One MPH per second is a good rate of acceleration. If you keep an even rate of acceleration you'll get a graph like this...
http://forum.gopowerhungry.com/membe...k-examples.jpg

If you dont know how, read the little article I wrote that is included in my sig. vvvvv

I might very well try that. Seems simple enough. I'm questioning the programmer now though, b/c I remember Jack recommending I monitor comm gear back in the day for a different issue I was having, and I don't remember this happening. Then...the gear would change with the truck. ?????

Maybe I'll try to plot a graph and follow up to this. Much appreciated.

Guys....I did a bunch of driving around town today and noticed something new. I AM feeling a light shift around 32 mph...and then again at 40mph when the TC locks up. I can only feel the shift at 32 if I'm under very light throttle....otherwise, you almost don't feel it. I can usually pick up on it regardless if I'm paying attention.

This threw me for a loop.....does this mean I have a 5 spd tranny? I'm feeling the shifts from 1 to 2, 2 to 3, NOW 3 to 4? if I'm paying attention, but then at about 40....it drops into OD and the TC locks up. Time to bust out the owner's manual I guess.

Guys.....I've figured it out. Shows how knowledgeable I am abot this stuff :matt-roloff: I've been misinterpreting dropping into OD at 40 mph as my shift into 4th gear. Completely different. I think I always believed this to be the case, b/c again, my 3rd to 4th upshift is definitely hard to notice sometimes. Learn something new every day :cheesy smile:

This brings me back to my original issue of the hard 1 to 2 upshift. It's not the TC locking up. I've had someone tell me that it may be a clutch pack issue b/c they had the same issue with the same year/make/model of truck. With that said...I'm good with it unless something starts to noticeably go wrong.

As always.....thanks very much for the help and support.