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| Point of throttle opening when kick down takes place Q https://slantsix.org/forum/viewtopic.php?t=41803 |
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| Author: | wjajr [ Tue Sep 07, 2010 1:23 pm ] |
| Post subject: | Point of throttle opening when kick down takes place Q |
Until a few days ago my transmission would only kick down if the throttle was mashed with great force to the carpet at which point it would happily kick down as long as rpm was below 2800 or so rpm. Recently the transmission has been shifting earler than normal under WOT from first to second, and reluctant to down shift back into first while moving over 2000 rpm. I decided to adjust the tension in the throttle position cable (Kick-down cable) so the down shift point came with a little less throttle opening and not flat out on the carpet as before. Also I wanted to get the transmission to stay longer in first gear by regulating shift point by throttle position. I have a Holley 390 #8007 with a Chrysler throttle cam adapter with cable kick-down stud. My question is: At what throttle position should the transmission down shift a gear? Would it be flat on the floor, 3/4th WOT, or whatever I like? What would be the normal factory setting? Another question; is it me, or is that transmission dipstick hard to read. I can never tell if the fluid is at the correct level, as there is no clean demarcation between fluid on the stick, and no fluid on the stick. It is all kind of vague and streaky. Bill |
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| Author: | wagonmaster [ Tue Sep 07, 2010 3:03 pm ] |
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Hi,do you happen to know what year the valve body is in your transmission? it sounds like you need to adjust your throttle pressure linkage,rule of thumb is when the carb is full open the throttle pressure lever on the trans should be as far back to the rear as it will go,if you have the part throttle kickdown feature in your valve body you can adjust the linkage a little tighter for less pedal effort,to downshift. another rule of thumb,the longer the rod,or cable the longer the shift,if that makes sense. |
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| Author: | wjajr [ Tue Sep 07, 2010 4:58 pm ] |
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Thanks Wagonmaster, I'm still getting a handle on automatic transmissions. The learning curve on those things has been a bit steeper for me than the other car stuff. It is a TCI valve body (model escapes my at the moment) with about 6000 miles on it; automatic/manual shift, with shift kit, and the transmission is a 1976-77 A-904. I have a Bouchillon Performance Engineering Kick Down cable kit installed, which is very similar to a stock Mopar set-up. There is no part throttle kick down feature in this valve body. I’ll recheck that cable adjustment. I may have slowly come out of adjustment, or when I had the transmission out last month, it may have gotten slightly out of adjustment somehow. I know this pressure adjustment on this transmission is quite picky, and hard to get it dialed in just right. Bill |
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| Author: | wagonmaster [ Tue Sep 07, 2010 5:26 pm ] |
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ok,well at least you know what you have,the part throttle kickdown really helps with the driving response espesially at lower speeds,I just built one for the wife`s 65 cuda,I used the low gearset along with the front drum from an A-999 with 5 clutches,I kept the lock up convertor for mileage, stock valve body,but I set the throttle pressure kinda tight,and when it kicks down at 45 mph it really moves,this is my first slant,we`ve always had V-8`s. I put a small erson cam in it, she idles very smooth,but runs great,I`m impressed,I think Iwill build another one just for fun. |
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| Author: | wjajr [ Wed Sep 08, 2010 5:20 am ] |
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Wagonmaster, I have not had the pan off since installing the TCI valve body to replace a manual reverse valve body that drove me to drink. At the time of install, the excitement was so great, that I forgot to check the factory set measurement of “Line Pressure†& “Throttle Pressure†adjustment. I have often wondered if the factory settings were correct. The instructions stated that the valve body had been tested & calibrated. [quote]ok,well at least you know what you have,the part throttle kickdown really helps with the driving response espesially at lower speeds,I just built one for the wife`s 65 cuda,[/quote] Than a part throttle kick down valve can be fitted to my valve body, correct? That would be nice for around town driving where WOT is a bit much, but a quick down shift would help getting things moving, eliminating that manual gear change. [quote]I set the throttle pressure kinda tight,[/quote] When you set the throttle pressure, you are referring to an adjustment at the valve body of the throttle lever stop screw? Or, the way you adjusted kick-down linkage or cable? Another modification I have thought would benefit performance would to rise the governor’s shift point close to 5000 rpm. This car has an uppity race cam, and the engine doesn’t start to pull hard until past 3000 rpm. That stock 4000 rpm shift point comes up real fast, and there is still 1300 rpm left of the power band when it shifts, so a manual down shift is needed to get that last thousand or so of rpm out of it. Controlling this shift point with the right foot would be much easer, than watching the tachometer, shifting, and navigating down the road. |
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| Author: | wagonmaster [ Wed Sep 08, 2010 7:46 am ] |
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To answer the question of if your valve body can be up graded to the PTK feature depends on if you have a small passage in your valve body by and normally covered by a steel plate on the shift valve bores of your valve body that will enable the feature if you install a 3-2 downshift limit valve where the steel plate was,not all valve bodies had this orfice. To set the throttle pressure,there is an internal adjustment that can be made,if you find that you cannot acheive the results from the external lever adjustment,from your cable. Now on to the upshift rpm of your torqueflite,as long as we have retained the full automatic feature of the valve body,you can turn your attention to the governor area in the rear of the trans,located on the mainshaft,the output housing has to come off,if you are like me and like to fiddle,and have lots of patience,you can remove the governor weights and modify them yourself,easy,but will require lots of trial and error,if you want quicker results,contact A&A transmission,or go to their website,they have a kit for about a hundred bux that will allow you to dial your upshift speeds of both 1-2 and 2-3 shifts, since they are both on different circuits they will have different shift points,although the governor uses centrifugal motion to overcome the spring tension. I think that is what you asked,I`ve got to go set up a rear end,so I will be away from the computer most of the day. |
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