The transmission in my COE is a 700R4. It was rebuilt a few years ago, but sat un-driven in the garage. On the drive from St Louis to KC, I noticed it did not stay in 2nd gear very long (1 or 2 seconds max) before it shifted into third gear. Other than that the trans works and shifts fine. I stopped by the trans sho that built it and they had two ideas... 1. the electric switches screwed into the valve body are bad and it is actually locking up in 2nd. Solution - REPLACE the switches 2. The valve body is messed up. Solution - REPLACE with a used valve body from a junk yard. Does anyone who knows these transmissions have any thoughts on this...?
Sounds like a governor problem to me.The TV cable can have a very minimal affect on shift points and if not set up properly with the correct geometry relative to throttle position will cause early failure of the transmission. Make sure that is set up properly and then consider the governor . Light throttle shifts (depending on what you would call light throttle) should be roughly 15-20 for the 1-2, 25-30 for the 2-3, and 35-45 for the 3-4shift. As far as mph for WOT shifts, that will vary depending on engine and rear end gearing, which at that point you will be looking for WOT shifts to happen at or near redline of the engine.When it comes to governor calibration, the springs will affect light throttle shifts (the lighter the springs, the later the shifts), and the weights on the governor will control the WOT shifts. (less centrifugal weights will allow higher rpm shifts.)
The 1-2 shift is at 15-20mph, but then it quickly jumps into 3rd gear (in 1-2 seconds) and stays there until time for the 3-4 shift around 35-40mph. Wouldn't the governor effect each of the shifts? Could it be a bad spring in the valve body? I also think I rewired the trans in the typical hotrod fashion, to eliminate all but the 4th gear lockup so I can't see how bad switches could effect the shift.
IIRC, this transmission uses a band for 2 and 4 ranges. Could the band be slipping or misadjusted? Might want to check that.
Many 700R4 have stacked shifts, adjusting the throttle cable would be the first step, attached is a procedure put together by TCI. If you can not get the shifts to come inline by adjusting the throttle cable the next thing to try would be increase the spring tension on the 2-3 shift valve to move that shift later this can be measured by a gram scale and a calipers (many shift kits will address this and may be the way to go). the size of the throttle boost valve also has a great effect on the personality of the shifts they are available in 6 diameters <TABLE style="BORDER-COLLAPSE: collapse; WIDTH: 282pt" cellSpacing=0 cellPadding=0 width=375 border=0 x:str><COLGROUP><COL style="WIDTH: 48pt" width=64><COL style="WIDTH: 101pt; mso-width-source: userset; mso-width-alt: 4778" width=134><COL style="WIDTH: 133pt; mso-width-source: userset; mso-width-alt: 6286" width=177><TBODY><TR style="HEIGHT: 13.2pt" height=18><TD style="BORDER-TOP: #f0f0f0; HEIGHT: 13.2pt; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; WIDTH: 48pt; BACKGROUND-COLOR: transparent" height=18 width=64 x:str="Diameter ">Diameter </TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; WIDTH: 101pt; BACKGROUND-COLOR: transparent" width=134>Engine size</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; WIDTH: 133pt; BACKGROUND-COLOR: transparent" width=177>Average full throttle Pressure</TD></TR><TR style="HEIGHT: 13.2pt" height=18><TD style="BORDER-TOP: #f0f0f0; HEIGHT: 13.2pt; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent" height=18>0.371"</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent">4 cyl</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent">110 PSI</TD></TR><TR style="HEIGHT: 13.2pt" height=18><TD style="BORDER-TOP: #f0f0f0; HEIGHT: 13.2pt; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent" height=18>0.391"</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent">6 cyl</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent">120 PSI</TD></TR><TR style="HEIGHT: 13.2pt" height=18><TD style="BORDER-TOP: #f0f0f0; HEIGHT: 13.2pt; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent" height=18>0.421"</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent">8 cyl</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent">130 PSI</TD></TR><TR style="HEIGHT: 13.2pt" height=18><TD style="BORDER-TOP: #f0f0f0; HEIGHT: 13.2pt; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent" height=18>0.451"</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent">HD gas and diesel</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent">145 PSI</TD></TR><TR style="HEIGHT: 13.2pt" height=18><TD style="BORDER-TOP: #f0f0f0; HEIGHT: 13.2pt; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent" height=18>0.471"</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent">HI perf & diesel</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent">155 PSI</TD></TR><TR style="HEIGHT: 13.2pt" height=18><TD style="BORDER-TOP: #f0f0f0; HEIGHT: 13.2pt; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent" height=18>0.500"</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent">After Market</TD><TD style="BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0; BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent"></TD></TR></TBODY></TABLE>Do you know what your transmission came out of ? do you know what your line pressure is? measuring your line pressure at full throttle will indicate the size of the boost valve you have in your truck as shown in the chart above. The use of a special tool to install the pressure regulator ***embly makes this much easier.
I messed with the TV cable adjustment quite a bit, first doing the full open throttle to pull the housing out of the factory bracket which made the shifts quite hard, so I followed up with tiny changes to move the housing further out until it felt right (still firm, but not earth pounding). I think is was 2-3 clicks from the WOT position. I was lucky and have the stock brackets and all the matching parts from a carb motor with the 700R4...so no modifications were needed. The trans came to me from a buddy who collected all kinds of stuff to build a stout transmission, basically as a pile of parts. It was then gone through and ***embled by a reputable trans builder. The mixed bag of parts makes me wonder if the valve body was messed with in the past How would a different (wrong?) throttle boost valve spring effect the 2-3 shift? I was originally thinking it is the 2-3 spring in the valve body. How do I increase the pressure on it? Do I just replace it?
Sorry in not getting back to you sooner; been busy the last couple of days getting ready for winter. If you look at the 700 valve body.gif illustration 316 is your 2-3 shift valve, illustration 315 is your 2-3 throttle valve and 314 would be your 2-3 throttle valve spring. So as you can see there is a valve stem on that valve that centers the spring and also provides a stop for that valve to stroke. If you were to hold that spring and valve against a scale and apply pressure until the stop hit the scale that would be your spring pressure if that spring pressure was 4 pounds and your shift was at 25 mph and you wanted to make it shift at 30 mph you would try to get a spring that bottomed out at 4.8 pounds. Governor pressure is applied to the back of valve 316 and is about 1 psi per mph; at about 60 mph 60 PSI the governor does not produce any more pressure (Governor Pressure would compress Spring 314) . Remember that valve 315 is your 2-3 throttle valve so TV pressure is applied to that valve MTV pressure up and MTV pressure down, depending on what the transmission came out of may dictate what the diameter of the valve land is. In an attempt to make firmer shifts many times larger TV boost valves are installed so this could influence this valve and you could get stacked shifts. The other issue that I potentially see is that the 2-3 shift valve provides oil to the 3/4 ac***ulator many times Teflon seals were used on them and they leak by ( I think some trans shop don't replace them) there are other Viton V shaped rings that work better IMOP. If you replace the spring you will want a chrome silicon spring so it resist's temperature and holds its tension (IE another valve body spring or shift kit spring). I could not get my scanner to work properly or I would have scanned the oil circuit schematics I hope this makes sense to you?
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