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TH700-R4 Holds first gear until 6000 rpm
Hi everyone - its been awhile since i visted last but i've run into a bit of a snag.
I've got a 3/4 ton chevy truck (1989) with a 700-R4 in it. The truck was a farm truck and was rarely out of first gear. Its only got 52,780 miles on it. Everything looks great, no rust etc but the transmission no longer shifts properly. I learned to drive on this truck and then it worked great, but in the last year it hasnt been shifting. I found two stuck valves and ran some crockus paper over them and it worked good for a month or so and now its doing the same thing again. So far i've run emery cloth over any valves that felt like they had any possibility of sticking, (except the ones that have the tapered roll pin retaining them like the line bias valve, but they all move freely when i poke them with a scribe), installed a B&M shift improver kit for heavy duty/towing, new filter, new gaskets, new valve body spacer plate, new filter, and 75,000 mile plus fluid. I don't suppose the fluid really matters; it said it was good for reconditioning old seals and i figured, even though it only has 52,000 miles, it had old seals! Nothing has helped so far. I just realized that this time, after installing the kit, i did not adjust the TV cable so maybe that is the cause of the problem. Second gear does not shift well into third either, it holds until about 4500 or 5000 rpm. Any advice or help is appreciated! <edit> just for the sake of argument say the TV cable wasn't the problem... then what should i do? Last edited by Fasttrack137; 08-07-2007 at 09:54 PM. |
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I've not seen many farm trucks that would rev till 6k RPM... congrats.
The TV cable is very important to the life of a 700-4L60 trans. Is it possible the larger check ball was retained in the v-body? This is a fail safe check ball IF the TV cable is not adjusted correctly or broken. IF the fail safe check ball seats the trans will go into fail safe and all shifts are late like the throttle is wide open.
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At the Bonneville Salt Flats, first gear is known as 130 mph. |
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Interesting ... isn't that the copper flashed ball thats slightly larger than the others? I'll have to check that. The govenor looked good the first time i took it apart and the friction material looked "like new" according to a mechanic so the transmission should be in good shape if i can get it to shift correctly.
I just installed a tachometer as well - i wanted to see where it was shifting at. I almost crapped my pants when i saw the needle hit 5500 rpm...
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Quote:
It is a larger check ball and some were copper coated . If the v-body bore is worn out where the inner throttle valve moves , it can flood the TV system with oil and cause a "false" fail safe mode.
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At the Bonneville Salt Flats, first gear is known as 130 mph. |
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I've adjusted the TV cable - which was a rather big ordeal because the plastic clip broke in the process and the ratcheting mechanism didn't want to work worth a darn. I had to do it by hand. I basically just slid the cable a little bit forward (like one "click") then checked to see if the throttle would go to the stop and kept doing that until i got it there. I'm going to go look at it again and make sure its ok.
I took it out for a drive and it seems to sorta work. When i'm doing 25 i run at about 2000 rpm and i feel engine braking going from [d] to d but there is no engine braking from d to 2. From 2 to 1 there is noticeable engine braking. Somethings not right ... it doesn't really feel like its taking off in first most of the time and it doesn't shift up even at 45mph with an rpm of about 3500 or 4000. What should i do? |
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700r4
In your first post you stated you found two stuck valves that you tended to, what was making them stick?
In other words, was there some stuff in the pan that shouldn't have been there? Wrong gear starts are not common with a 700R4. Very late upshifts because, of a myriad of reasons, some of which Crosley pointed out, definitely are. If the governor were sticking, it would have wrong gear starts but, again if this is the case and you've had sticking valves, well, maybe the trans has bigger problems. If this vehicle were in a shop, the TV cable would be checked, then there would be a gauge put on it. This would tell you if the TV valve was sticking. It would register about 100 psi in park, if TV was a problem. If the pressure was ok and you did in fact have wrong gear starts, pulling the governor and checking it would be a good idea. See if this trans is not happy and it starts flaking out [ or pieces start flaking off, like clutch material ] it will keep on sticking valves. If there was trash in the pan when you pulled it, then stop chasing your tail. |
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