Slippery 1-2 shift on JAGUICK. Freshened trans over winter but same deal. Trans guy said the pump spring was weak. 2-3 shift is fine. Conveter slippage maybe? Trans clutches were not burnt...... Maybe vac modulator not retracting quick enough in time for the 1-2?
I'm having the same problem, but I would call mine more of a "lazy" shift. It's a valve body problem, a good place to start would be the springs used in the accumulator valve (according to my trans-go shift kit instructions). I haven't tried to fix mine yet either, so can't report results.
Pressure sounds ok if the 2-3 if firm enough. Assuming all is ok with the 34 element sprag (not starting to roll over), the issue is likely with the setup of the 1-2 accumulator valve in the valve body and the spring type used under the accumulator piston under the low/reverse servo piston. There are 2 types of accum. valve setups depending on the VB used. In either case, all the springs from the assembly should be removed and the valves held fully open by using a piece of copper tubing. Start with a little over 1" in length and install it in the VB first. Then put in the valves without the springs and test fit. Shorten the tubing (a bench grinder works) until the roll pin can fit snugly in. This locks the accum. valves full open to maximum firmness. Obviously, clean all burrs or shavings off the tubing before using it. The spring under the servo can be one of three types and vary in firmness by color. Weakest is blue, next is black and strongest is yellow. Not sure what, if any, is provided in the Trans-Go kit. You can usually get away with the blue one if the VB has the two piece accum. valve. Single valve setups need either the black or yellow to not have mushy 1-2 shifts. The two piece valves tend to deliver more pressure to the accumulator piston to firm up the shift than the single valves. The 1-2 check ball should also be left out as it can restrict flow to the clutch. Again, not sure what Trans-Go advises on this. Only two check balls are needed on the TH400 for good results. The low/reverse one and the one for modulator oil. Hope this helps, Scott
Hey Bruce, how about we just race for pinks (bracket style of course)? And then if I win I'll figure it out and let you know! :laugh:
Scott, I have the double valve that trans-go conveniently doesn't tell you how to adjust (but they carefully point out what to do with the single valve!). If I am understanding you right, the stiffer the spring below the inner valve (or a tube as you suggested) is the answer for this. I am thinking of putting the TransGo "blue spring" for the firm single valve shift inside of the stock inner spring of my double valve. And I drilled the holes up to "drag car or show-off" size on the triple-plate. Your thoughts?
Adam, Most late model trans' would have the single valve, so I can understand why the detail was left out. The 2 piece valves we pretty much phased out by 1973, though some units still had them. Am fairly certain, all 74's had the one piece valves but am not 100% sure. Not sure what the Trans-Go instructions refer to, but the stronger the spring under the 1st valve, the firmer the shift will be. This is the first spring that goes into the VB under the "cupped" valve. Do not use any spring in the aluminum sleeve under the aluminum plug as this will in effect reduce the strength of the first spring. Stage 1 VB's did not use this spring, so it is ok to leave it out. The firmest setup would be to just use the tubing to lock the valves open, but you should be ok if that blue spring is decently firm. Using the yellow spring under the servo would increase it even more. But you may not want to go that far. Good Luck, Scott
Thanks Scott. This is a 70 GS455 valve body. It didn't have an outer spring at least when I got it. I think the blue spring plus the stock spring should sharpen it pretty good compared to just the stock spring. I'm tool-limited right now,so it's the easy thing to do. The shift kit came with a servo spring, I don't remember the color or how the tension compared with the original. I should have used the spring from the trans the valve-body came from I guess(broken case).
