Cascade Crew

Twilightoptics · Posted: Tue Aug 11, 2009 9:57 pm Post subject:

Think there is something inside the tranny you gotta add and change around. The vacuum switch is specific to engine vacuum... IE... 0-100kpa.

83Z28BlackBetty · Posted: Tue Aug 11, 2009 10:00 pm Post subject:

from what i gather, the TCI switch is adjustable for engine vacuum so you can control when TCC locks.

~JAKE

Alphius · Posted: Wed Aug 12, 2009 6:26 am Post subject:

Jake, you could find a brake switch from any cruise-equipped thirdgen. It's the exact same Normally Closed switch as was used for GM cruise.

Isn't most of the expense of the TCI kit the adjustable vacuum switch? If you could find a cheaper vac switch that still works, you could definitely wire this up for cheaper I would think.

I need to do the same thing eventually for the Trans Am I gave my brother. Watching this thread closely... Squint

83Z28BlackBetty · Posted: Wed Aug 12, 2009 8:36 am Post subject:

So i found a company called DesignFlex that makes an adjustable vacuum switch that i can get for super cheap/ maybe even free!

But i need to know what range switch i should get.

.2 - .5 inches Hg
.6 - 6 inches Hg
6 - 24 inches Hg

Does anyone know what the range is for the TCI switch?

~JAKE

Alphius · Posted: Wed Aug 12, 2009 12:25 pm Post subject:

Jake, you would probably want the one that's adjustable from 6-24 in. Hg.

I'll explain the reason as best I can. Wink

The time that you want your TCC locked is when you're cruising in 4th gear on the highway. This is one of the two times your engine is producing the most vacuum, the other being deceleration. The vacuum switch works in conjunction with the 4th gear pressure switch to ensure you only get TCC lockup in 4th while cruising or decelerating. So, when cruising, let's say you have to speed up to pass someone. When you depress the accelerator, (and engine load increases), your vacuum signal decreases. At WOT, there is effectively 0 vacuum relative to outside air pressure. What the vacuum switch does is make the TCC unlock when vacuum signal goes under a certain setpoint so your RPMs come up against the stall converter, and you make more power for passing. When your load decreases enough (vacuum gets high enough), the TCC locks again and gives you better mileage and prolongs the life of your tranny. The best way to set this is to drive around with a vacuum gauge and determine the best vacuum at which to disengage the TCC under acceleration.

Normal vacuum ranges for a standard street SBC are somewhat near these:

Idle: 13-17 in. Hg for a better-than-stock-but-not-huge cam (depends on cam overlap - big cam=less vacuum)
Accel: Has a wide range, depends on engine load. Higher numbers=less load. Lower numbers=more load. 0 in. Hg=WOT
Cruise:Generally a bit above idle numbers. So from 15-21 in. Hg or so.
Decel: Highest of all, generally up to 25 in. Hg or so.

Most load=WOT=0 in. Hg
Least load=Decel=~25? in. Hg

So, if your cruise vacuum was 20 in. Hg, and you wanted the TCC to unlock with a bit of throttle, you would set it at 17 in. Hg or so. That would make it so when the load increased, your TCC would unlock, and when the vacuum returned to over 17 in. Hg the TCC would lock again and give you good mileage.

----------------------------------------------------------------------------------

Short version: Get the 6-24 in. Hg adjustable because it is in the correct range to adjust your cruise TCC lockup. Check and adjust your settings on it with a vacuum gauge while driving.

Sorry for the long read. Even if you already know this information, it may help someone else. Very Happy

Alphius · Posted: Wed Aug 12, 2009 1:20 pm Post subject:

You also need a 4th gear pressure switch like your diagram shows. That's one of the parts that also comes with the TCI kit. It's not in the tranny already, you need to add it, like Paul said earlier.

83Z28BlackBetty · Posted: Wed Aug 12, 2009 2:06 pm Post subject:

Thanks for the info Gabe!

So it looks like all i need to make this work is the switch from DesignFlex (<$20 possibly free if i schmooze the sales guy), a 4th gear pressure switch ($5 from GM), brake switch (i already have), and some wire.

just a reference for anyone else in the future, here are a few very helpful sites.
http://www.purplesagetradingpost.com/sumner/techinfo/700R4p1.html
http://www.rowand.net/Shop/Tech/LockupTCCWiring.htm
http://www.designflexswitches.com/switches/psf109s.php
http://www.scribd.com/doc/487923/700R4-Diagnosis-Fundamentals

83Z28BlackBetty · Posted: Tue Aug 18, 2009 9:49 am Post subject:

Ok so my tranny is done! I am picking it up tomorrow! WOO HOO

So my question now is how much fluid am i going to need and is there any brand recommendations?

I'm picking up a trans cooler, and poly trans mount tonight.

*update on lockup stuff*
I scored a free adjustable vacuum switch from design flex as a promo! It won't be here for a while so i think i may just wire up lockup with a toggle for now then stick the vacuum switch in when i get it.

chevymad · Posted: Tue Aug 18, 2009 4:45 pm Post subject:

I'd grab a case of fluid. I think they usually hold about 11qts, but add about 5 then start checking. Any dexron III should be fine. I like to add a bottle of the lubegard protectant as well. It will keep the fluid from burning/turning color. If you have a thick wallet you could try some dex VI. It's synthetic and supposed to be backward compatible, but of course costs $$.

redlava · Posted: Tue Aug 18, 2009 7:50 pm Post subject:

Nice thing about the dex 3/4 is that they will basically give it to you because its only for older vehicles.

iansane · Posted: Tue Aug 18, 2009 8:22 pm Post subject:

83Z28BlackBetty · Posted: Thu Aug 20, 2009 8:01 am Post subject:

well i picked up a case of Dex/merc, big Hayden 404 trans cooler, poly trans mount bushing, AND THE NEW TRANNY!

I got it stabbed last night but my trans bushing is thicker than the previous one and the torque arm mount is hitting the tunnel Confused

I'm thinking of spacing the cross member down with a few washers to help this problem. Hopefully i should have this thing running soon!!! Burnout

83Z28BlackBetty · Posted: Mon Aug 24, 2009 7:02 am Post subject:

DONE!!!

Oh man this thing feels like a totally different car! With the higher stall TCC, and the shiftkit it has more power on acceleration, shifts very quick and firm, and responds very well to my right foot Very Happy

plus i can do burnouts WAY EASIER lol

~JAKE

aaron_sK · Posted: Mon Aug 24, 2009 8:03 am Post subject:

Converter swap makes a hell of a difference doesn't it? Very Happy

What stall did you end up going with, Jake?

83Z28BlackBetty · Posted: Mon Aug 24, 2009 8:39 am Post subject:

its only a 2200 Stall, but that kicks the butt of my old stock 1800 stall. maybe someday i'll go higher, but for my stock motor it works great Very Happy

~JAKE

83Z28BlackBetty · Posted: Tue Aug 25, 2009 7:56 am Post subject:

If anyone ever cares to do this themselves, I thought i'd continue to post updates.

I just got the Adjustable Vacuum Switch from Design Flex Switches in the mail. It looks like it should work perfectly! I'll try and hook it up this week and let you all know how it goes.

So Eff TCI and their $70 lockup kit. I've basically built the same thing for under $20. The switch i got for free as a promo Very Happy

But the sales guy Lary at Design Flex was super helpful and helped me figure out what was the best switch for my application. I highly recommend them for future use.

~JAKE

Alphius · Posted: Tue Aug 25, 2009 9:07 am Post subject:

Awesome Jake! Please continue with the lockup story. I need to do the same thing with my brother's T/A when we get the drivetrain back in it. So I for one am very interested.