Heres the scooby with my trans. At one time it had a full manual valve body with associated parts and pieces. It now has a normal valve body with a shift kit. It also still has the high pressure valves and springs in the pump. I do not have any part throttle down shift. I have full throttle down shift only. Where do I need to start looking? Funny things like this start to show up after having a life at the drag strip and not on the street. TIA Rick
how are the part throttle upshifts? Next what did the valve-body come from? There was a long discussion about having the wrong VB a while back with pictures and everything from one of our BB trans gurus. Can somebody post a link?
I am assuming the car is in "drive" when you have this issue, and you have the accelerator pedal electric switch hooked up, and it is working to the connector on the side of the transmission...
If I did it right, here is the link. SP The issue with the part throttle down shift is the type of VB you are using and an interesting thing that was found about using high line pressure. When Joe (nailheadina67) rebuilt his SP with a later VB, he used a high pressure pump spring. This caused very firm shifts and he decided to go back to the stock blue one. He noted that the part throttle down shift worked better with the lower line pressure. Again, the calibration of both the VB and the governor will affect this. Somehow, you need to identify what VB you have, if it has a 3-2 valve and how your governor is setup. Mark P.S. I will be doing a manual to automatic VB conversion on saturday. Will look at what was done to this particular trans and see if there are any changes that relate to your situation.
Rick......yes, that spring has to go. I had my adjustable modulator cranked all the way out, and still couldn't soften the part throttle shifts. Part throttle downshifts weren't hardly happening. When I put the stock pump spring back in, presto! I have softer part throttle shifts and my full throttle 1-2 shifts chirp the tires. I now have part throttle downshifts too, and if I crank the modulator back in too far, the part throttle downshifts actually happen too often. :Brow:
When you say you cranked the modulator in further, are you talking about the vaccum modulator that mounts to the side of the tranny )passenger side)? I thought this piece spun freely in there basically; in other words, just pressed in with an o-ring or something. o No:
My part throttle upshifts happen very soon it doesn't matter how much throttle is applied. I am not concerned about harsh or firmness of the shifts, actually the firmer the better. The full manual kit was a B&M kit I think I still have the paper work on it. Wide open shifts are at about 3700 rpm at this point. I will try and find the paper work and see what was done to the pressure valve. I have some extra tranny parts here so maybe I can replace the spring and valve. TIA Rick
Aftermarket modulators usually have a set screw on the end for adjustment....factory ones do not. :bglasses:
Actually, the big factory modulators could be adjusted. I don't think they were meant to be though. There was a screw on the end, but it was sealed with silicone. After you adjusted it, you had to reseal it or it would leak vacuum from around the threads.
Rick, If the part throttle upshifts are also early, it is probably just the modulator. You should be able to adjust it to where you want by screwing the modulator screw in. Also, some of the shift kits have you put a spring behind the modulator valve in the valve body. You can tell by pulling the modulator and pushing the valve with a finger or screwdriver. If it springs back you can use a magnet to pull out the valve and then the spring (should be about 1/2" long spring), then put the valve back in without the spring. Hope that isn't too garbled....
Adam I had this valve body built by someone else so I am not sure whats what there. I will have to do some digging this weekend and find all my paper work. Thanks Again Rick
