The 700 in my 55 Olds has a vacuum lockout switch from TCI, but kicks in and out of 4th at around 55-60. It is hooked to the constant vacuum port on the front of a Holley 600. Am I getting to much vacuum or to little, what do you think?
the lockup torque converter isn't really related to the downshifting of the transmission. What ratio rearend gears are in the car?
I ran the vacuum switch in my converter circuit for a while, but didn't really like it. The purpose can be too fold. If it is on "ported vacuum" when you are all the way off the gas it will open and unlock the converter. Now that the convert isn't locked it can free wheel and your rpm's will drop some compared to road speed. If it is locked they your rpm will go up and down with road speed like with a standard. I think the OEM's do this to improve mileage a little during coasting periods. The other thing it can do is say you are pulling a moderate hill. The vacuum goes down and the convert unlocks and flashes 200-300 higher rpm than when it is locked. That might get you up into the torque curve enough that the transmission stays in fourth and does not down shift to 3rd. I didn't like either feature and by-p***ed it. On the tech pages on my site you can see how it is wired to do this, but if you have the TCI instructions you have all of that stuff. The other thing is that if it is hunting back and forth between 3 and 4th and is not the convert locking and unlocking that is somewhat normal on a lot of 700R4's from the factory. The HO Camaro ones and the vette ones have a valve in them that delays downshifts until 2/3 rds to 3/4's throttle. You can get it from Summit and others and install it in a 700R4. My 700 came from an HO and had it. I like it and would install one for sure if I ever had a 700 that didn't have one. The other thing it does is allows a WOT shift from 3rd to 4th at about 5000 rpm and it stays in 4th. The last thing is are you sure your TV cable is setup right and adjusted right (see the link)? This is the most important thing you can do for the shifting and to ensure your 700 will last a while. Don't do it and they will not last. c ya, Sum 700R4 Info
THERES A VALVE UPGRADE to cure part trottle crusin 60 mph shifts like that all so gives full throttle up shifts. u can get one from summit or any ****** supply co.
Get yourself a transgo "no yo-yo" kit - they sell them at a lot of rebuilders shops and if you're looking for an internet source northern auto parts seems to have good prices on them - get the full kit and not the "Jr" kit (the full kit has the shift point reprogramming stuff, the jr just the shift quality improvement parts. Less than $40 and it's almost a must for any rebuilder... Also if you've got an aftermarket lockup kit that uses the lockup vacuum switch - check to see if it's adjustable then hook up a vacuum gauge and at normal cruise note your vacuum, then set the switch to cut out around 2" lower than cruise.
I adjusted the TV just as the guy that built it said to and it shifts just fine in all other gears. I will look into one of the valve upgrade kits though. Thanks for the input fellas. Dusitn
I recently installed a kit from Bowtie Overdrives, in my fathers car. It was shifting bad and seemed to never get into OD, after the install, all is cured. Here is a link to the site, it explains alot about 700r transmissions. http://www.700r4.com/sitemap.shtml
I think what you are getting is the converter unlocking, not downshifting. You can just wire the lock-up to a manual switch, but remember to unlock it. The vacuum switch simply applies 12 v to the lock-up once the vacuum level is high enough.
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