want to hold 4th gear until converter locks

[LWATSON]

Ive got a loose converter and when I'm accelerating with mid to moderate throttle the trans will go through the gears and ride 5th out to 80 mph without the converter locked. Light throttle it does great and wot it does great its just mid throttle. My trans tune downshifts from 6th to 5th with very little throttle input so I can pass without blacking out the road, I have an S475 charger. My thoughts were if I was to make the same changes on the 5-4 downshift it would hold 4th gear under mid throttle situations until the converter locks at 52 mph and I wouldnt have that blowing through the convrter feeling. Im pretty sure this wold work if I use the tap shift function and set it on 4 and manually upshift at around 55 the truck pulls harder with way less throttle input and the converter will lock under moderate to heavy throttle input in 4th. From what I understand there were adjustments made by my tuner on the 6-5 that reduced the % of throttle required to make the downshift. He would adjust the tune more for me but I have a feeling this is something thats going to take some trial and error to fine tune. So I you guys could give me a brief description on how to make the changes needed I would appreciate it. I already know how to pull up my trans tune and find the table for the 5-4 part throttle downshift just dont know how to make the changes. I've never tuned before, calibrating my speedo is the extent of my expertice LOL! Thanks!

[LWATSON]

Also I know shiftpoints can be raised to eliminate this problem but I want the trans to go ahead and shift under light throttle situations.

[Wheelz]

One solution is to copy the 3>4 shift speeds to the 4th gear converter lockup table and then increase them by 2 mph. That will command a converter lockup 2 mph after the shift at every throttle input for 4th gear. Also do the same for downshifts (4>3 to 4th release and add 2 mph) if you do this for 3rd thru 6th you will have very consistent behavior between shifts.

Now in my logging of my dads dmax, his light throttle shifting occurred under 25% throttle position. So you can raise the shift points above that throttle position and it won't effect your light driving.

[LWATSON]

Although the first suggestion would defnately work, I think adjusting the % of throttle when the shift occurs under would be better for daily driving. I've got a tune with the shiftpoints raised and it shifts at about 2000 rpms but it gets annoying driving around town and my neighbors dont like it much at 5:00 in the morning LOL.

[LWATSON]

I remember a little about the changes my tuner made on my 6-5 downshift but he did it pretty fast and I really wasn't paying attention. The best I can remember he dropped the % of throttle required to downshift from 6 to 5 to about 15%. It downshifts and as I'm passing and in the throttle it will upshift at about 65 mph. I would think the % for the 5-4 would need to be set around 35% throttle since the blowing through the converter issue is only a problem at 40% and up throttle.

[Wheelz]

This is the tune I've been working on for my dad. Look at each of the part throttle shift tables (D5000 - D5009). I've not gotten to drive it yet, but he likes it. I know it will shift easy (under 1600 rpms) lightly driving it, but you can see how the shift points raise quickly above 30 something percent. That way its not lugging and will hold each gear longer if you give much fuel. (I've not touched the tow/haul mode yet, just still tweaking things) Thats what I was trying to say in the end of my original post. Then modify the TCC lockup/release tables as I mentioned earlier.

He is running 33" tires, so be sure to scale the shift curves so that the shift point at 100% throttle matches your desired WOT shift speed.

15076

[Wheelz]

I remember a little about the changes my tuner made on my 6-5 downshift but he did it pretty fast and I really wasn't paying attention. The best I can remember he dropped the % of throttle required to downshift from 6 to 5 to about 15%. It downshifts and as I'm passing and in the throttle it will upshift at about 65 mph. I would think the % for the 5-4 would need to be set around 35% throttle since the blowing through the converter issue is only a problem at 40% and up throttle.

If you have your stock tune, do the following...

1. Open the tune your running (I'll refer to this tune as Tune A later)
2. File->Load Alternate Calibration for Comparison. Select the tune to compare too. (For right now, the stock tune)
3. File->Display Calibration Difference Summary

Then you will be able to see a list of all tables your tuner modified from a stock tune. double click each one and it will take you to each table. (ctl+4 will show you tune A. ctl+5 will show you the stock tune). There are buttons on the toolbar to jump back and forth as well. Look for the ones labeled "Cal" and "Alt"

[LWATSON]

I do have my stock and modified tunes, also I'm going to check out the tune your working on for your dad. Thanks for the pointers!

[LWATSON]

I made some changes, raised shiftpoints a little and now command the tcc to lockup mid way through 4th gear. So far I like the way it drives. Now if I could just get it to hold 4th longer when I'm on the trottle it would be great. Trans shifts 4th accelerates tcc locks, accelerates about 5 more mph then shifts to 5th at 52 mph regardless of throttle position. It would work great if it would rev 5th out more when I'm in the throttle a bit. At wot it does fine, my wot shiftpoints are at around 3700-3800 rpms. As mentioned before 6th gear has been adjusted so it downshifts with very little accelerator input. This also helps it rev 5th gear out more, up to about 65-70 mph when I'm at moderate throttle, about 20%.

[Wheelz]

I made some changes, raised shiftpoints a little and now command the tcc to lockup mid way through 4th gear. So far I like the way it drives. Now if I could just get it to hold 4th longer when I'm on the trottle it would be great. Trans shifts 4th accelerates tcc locks, accelerates about 5 more mph then shifts to 5th at 52 mph regardless of throttle position. It would work great if it would rev 5th out more when I'm in the throttle a bit. At wot it does fine, my wot shiftpoints are at around 3700-3800 rpms. As mentioned before 6th gear has been adjusted so it downshifts with very little accelerator input. This also helps it rev 5th gear out more, up to about 65-70 mph when I'm at moderate throttle, about 20%.

*should* be one of the following

A) your 4->5 upshift isn't commanding the shift to occur any higher than 52 mph. You would want to raise the shift speeds for higher throttle positions. In my experiences, 68% throttle and above should be your WOT shift speed for the truck to not short shift. But with as much work as you've done that could vary

B) your shift speed is set correctly to what the truck speedo is showing for your WOT speed, but your tranny speedometer is not matched to the ECM speedometer, causing all your shift points to not match up perfectly with what your commanding.

I'd say that it shifts ok at WOT because both the RPM and speed conditions must be met before it will shift, so technically it will only shift at the higher of the 2.

[LWATSON]

Yes, you are correct. I've done allot to the truck that makes it need to hold a gear longer. When I had my stock charger the stock trans tune was perfect, but with this S475 it likes RPM's and shifting at stock shiftpoints wont let me get on top of the charger when I'm at moderate acceleration. Light acceleration is fine and WOT is fine but it just short shifts and lags and smokes at the beginning of 5th gear if Im on the throttle moderately.

[Wheelz]

I just redid my dads allison tune this week. It was a 6 speed as well. It doesn't grab 4th till 52 mph at WOT.

If you'd post up the tune I'd take a look at it and try to help you out. The only other things I would need is the tire size your running

[LWATSON]

I'm having trouble attaching the tune here, if you dont mind I'd like to email it to you?

[Wheelz]

Pm'd you my email

[LWATSON]

Thanks buddy!

[Wheelz]

I hadn't seen it come in yet.

[Wheelz]

You have mail :thumbsup: