Do you have a "slot" up at the carb or are both ends of the cable "fixed" to the levers?
(you need a slot so you can set some TP "pre-load" so light throttle shifts are where you want them)
DD
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| Need to work out better kick down ratio. https://www.slantsix.org/forum/viewtopic.php?t=54559 |
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| Author: | Sam Powell [ Sat Feb 08, 2014 5:39 am ] |
| Post subject: | Need to work out better kick down ratio. |
Have Lokar cable kick down installed using the GM throttle body, and it seems as if the throw on the TB is too far for proper functioning of the Mopar 904 kickdown. Shifts under light throttle are pretty soft, which would suggest not enough line pressure under light throttle. Having the lever pushed back more at light throttle might improve this. However, when adjusted so the kick down lever is all the way back at WOT, there is free play in the cable with the throttle closed. Under light throttle the trans kickdown lever is still fully forward. I can fix this by changing either the lever on the trans, or the lever on the TB. The TB lever is case hardened, so would be hard, (but not impossible) to drill. However, putting the hole closer to the TB shaft would reduce the throw and make it possible to adjust so the kick down lever gets pulled back some under light throttle, which it does not do now. I can also make a new cable connection plate for the TB shaft. There are two things that would make this easier to do: 1. Know how far the stock 904 kick down lever moves from closed throttle to WOT. Is this information available anywhere? 2. Have better math skills. I can measure the distance of the kick down fitting on the TB from the throttle shaft, and I can measure how far the cable is pulled currently from closed to WOT. I think if I knew how far the cable must move, and I knew what math formula to apply, I could figure out how far from the TB shaft the hole for the kickdown cable should be. I think it is a trig application using sine, or cosine or some such thing. Any match whizzes out there? This would keep the trial and error thing to a minimum. Perhaps this is a just a linear ratio kind of thing, but I suspect the arc it moves through complicates things somewhat. Thanks. Sam |
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| Author: | Rick Covalt [ Sat Feb 08, 2014 10:10 am ] |
| Post subject: | |
Sam, I may be totally wrong, but I would guess the movement would be linear. If the kick down lever moves 1 1/2" then I would guess that the throttle body need to move roughly the same amount. If someone does not know the answer I can go out and measure how far the factory 2 barrel moves the kickdown linkage for you. Just let me know. Rick |
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| Author: | Doctor Dodge [ Sat Feb 08, 2014 10:15 am ] |
| Post subject: | |
Do you have a "slot" up at the carb or are both ends of the cable "fixed" to the levers? (you need a slot so you can set some TP "pre-load" so light throttle shifts are where you want them) DD
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| Author: | DusterIdiot [ Sat Feb 08, 2014 10:16 am ] |
| Post subject: | Yep... |
Quote: If the kick down lever moves 1 1/2" then I would guess that the throttle body need to move roughly the same amount.
The last one of these I helped install in a mid-60's Dart, we had to bolt a slightly longer piece of metal to the Holley 350 cfm throttle arm to get the range of motion needed to make it all work out right...worked fine after that.-D.Idiot |
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| Author: | Sam Powell [ Sat Feb 08, 2014 4:32 pm ] |
| Post subject: | |
The end at the trans is fixed. The other end is not. There is an adjustable stop at the throttle end of the that can be removed and/or tightened anywhere along the end of the cable. This stop is pulled on by another stop attached to the throttle plate . I think I can put a coil spring over the cable between the cable end and the throttle plate stop which would allow me to tighten up the light throttle adjustment. The spring could then compress when the trans kick down lever reached the end of its travel and allow the throttle to open further still. Fine adjustment of the kick down is made with a pair of nuts on the cable shield like a bike hand brake. Thanks for the feedback. Sam |
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| Author: | Sam Powell [ Mon Feb 10, 2014 11:18 am ] |
| Post subject: | |
Rick, It might help to know how far the kick rod moves on your truck. Thanks. Sam |
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| Author: | Joshie225 [ Mon Feb 10, 2014 12:34 pm ] |
| Post subject: | |
If the throttle body lever is tough to modify for shorter cable travel why not lengthen the transmission lever? Or find a longer one. |
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| Author: | Rick Covalt [ Mon Feb 10, 2014 12:51 pm ] |
| Post subject: | |
Sam, I just checked my truck with a 2280 Carb and the Volare I got from Charles that has a factory super six. Both of them move the kickdown rod just about 1 5/8" This is measured from where the the throttle cable hooks to the carb at idle setting to where the same cable ends up at WOT. If you allow a little more distance if I was to back the idle screw clear out you may be at 1 11/16" or 1 3/4 at the most. Rick |
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| Author: | Sam Powell [ Sat Feb 22, 2014 4:45 am ] |
| Post subject: | |
I put a compression, coil spring between the cable stop at the far throttle body end, and the throttle lever. The TB lever pushes on the spring, and the spring pushes on the cable end. This takes the slack out of the system. It works much better now, but it is pretty clear that I need a longer lever on the trans. When I adjust it so the 1-2 shift is where I like it, the 3-4 shift is too high. I end up having to lift slightly on the gas pedal to get it to shift into 3rd. I guess that is alright, but I would feel better if it would shift under constant throttle pressure. A longer lever on the trans would match the movement of the GM TB. If I have to, I will do that. I have a spare one I can play with. So far I have not felt it go into lock up mode, but I guess that may be a good thing. I need to calibrate the electronic speedo before I can make further judgements about the timing of these events. In general it seems as if this project has been a success. Thanks for all the advice and help. Sam |
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| Author: | Rick Covalt [ Sat Feb 22, 2014 4:50 am ] |
| Post subject: | |
Quote: So far I have not felt it go into lock up mode
You should definitely be able to feel it go into lock up mode. At least see a RPM drop. Rick |
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| Author: | Sam Powell [ Sat Feb 22, 2014 5:05 am ] |
| Post subject: | |
I will look for that. Thanks. Sam |
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| Author: | Sam Powell [ Tue Feb 25, 2014 6:34 am ] |
| Post subject: | |
It does seem to go into lock up mode but does it too subtly to "feel". When it is in lock up, more throttle changes the intake pitch but not the rpm. Before lock up more throttle changes the intake pitch, and you see the tac needle move up a bit too. Sam |
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