Will it shorten the life of an intermediate band if it is adjusted less than the factory spec of 1 1/2 turns? I still get the rev up shift from 2nd to 3rd. with the factory specs. I realize the trans probably needs a rebuild, but I would prefer not to rebuild until the fall when I am not depending upon it as a daily driver.
It depends on a number of variables. If you tighten the bands to 10 foot pounds and don't back them out as mush as the factory recommends then yes, it will affect the life of the band. Think about how much friction there is on that band as the drum it rides on is turning. That friction builds heat and wears the band lining. Now if the drum is drilled for oil to cool the band and there is an aux. cooler then it may not affect it as much. If the shifts are quick and at lower speeds it will affect it less. What has been done to the transmission that is causing the 2-3 flare?
The 2 to 3 flare has been there in some form ever since I owned the car, about 12 years. At the time I had it to a trans shop to change the fluid and filter. He may have ajusted the band beacause it seemed to shift smoother. I haven't driven the car much in the last several years, but the flare seems to have returned if the engine is shifting under light load or If I deliberatley creep along. Under moderate load it shifts fine. I saw your recommedation on another post and set the adjustment to 1 turn out. It seems to shift better with only and increase in about 200 RPM with as opposed to about 500 RPM or more with the adjustment at 1 1/2 turns. I am thinking that less slippage should be better and maybe I should move the adjustment another 1/8 of a turn or so. I can't see it being easy to drill holes for heat dissipation without dissassembling the trans. I don't drive the car hard so I hope this adjustment will not wear out the band in the 5000 miles or so I drive during the summer. It has a rebuilt 289 with stock 2bbl. The car is originally from North Carolina with 110,000 miles on it and I think the trans was never rebuilt. It probably is time and was thinking of taking the trans out over the winter and either getting it proffesionally rebuilt or trying it myself. I have a haynes transmission manual which details the steps, but it looks a little intimidating. Is this a project that is doable if a person takes his time and is carefull each step? Also do you think the band will last another 5000 to 10000 miles with the tighter adjustment? thanks.
I only sggest that the band be loosened 1 turn when you began by just sngging the adjusment screw and not torquing it. There is a delicate balance between tight enough to operate normally and too tight which will cause a burnt band and fluid degradation. If you started by torquing the screw to the 10 Ft Lbs that the factory recommends then the bend is too tight. It is causing friction that will destroy the band and the drun it rides on, The fluid will also burn before long. As for how long it will last that is anyones guess. If you can build an engibe you can probably rebuild a C4. You would want to get a manual and keep records of how things looked before you diassemble the C4. I do believe that most anyoneCan build one.
Re: C4 band adjust Thaks for the info Paul. I guess the sensible thing would be to adjust to the previous or factory setting and live with the 2 to 3 shift flare for the summer driving season. I do have a torque wrench (120 inch pounds) but found it difficult to manipulate around the factory shift linkage. Does the linkage normally require disconnecting for this adjustment? Previously I had used a six inch wrench on the adjustment and slowly tightened it up until I felt it "snug". Would replacing or resealing the servo help with the shifting problem? I do have another core transmission (attached to 255 V8). Would it do any good to swap servos around? Also do you have a prefereded manufacturer for the rebuild kit? I would like to order and purchase the kit in advance. Did you ever find the fluid diagrams for the AOD you were looking for?
The flare is caused by the servo diengaging completely before the direct clutch engages. Using a servo with a larger release side is about all you can do. If you are using an "H", "A", or "C" servo you are using a servo with the largest release area available. If you are using a "R" then you can try switching to one of the other three I mentioned.
