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Old 05-14-2009, 01:46 PM
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TH350 Modulator problems, need savvy advise

Hey Guys,

I have this problem with two TH350's and one TH400, actually this happens with all automatics that use a vaccum modulator, here we are at 6.600 feet of altitude therefore the engine make very little vaccum at idle or at part throttle so the transmissions behaves like if the throttle was at WOT while shifting at part gas while cruising making the shift too hard and harsh, I have tried adjusting the kickdown cable but then the WOT downshift and the shift points get very upset.

I have seen adjustable modulators but even if they still are available it would be quite difficult for me to get them due to customs restrictions we have nowadays here.

is it possible to shim or grind or modify the modulator in some way to compensate for the low vaccum? how about a weaker spring? no problem cutting one open and modifying it's guts for me.

how about converting it to be cable operated like those that B&M used to sell for supercharged aplications?

Please take a moment and help me solve this uncomfortable situation.

thanks,

Augusto.

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Old 05-14-2009, 01:48 PM
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south america! wow!

actually, most are adjustable if you look inside the vacuum hose port on the valve it should have a flat blade screw in there to adjust when it makes the shift

if not then get one that does, most replacement ones have the screw. and are cheap.


good luck
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Old 05-14-2009, 08:48 PM
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indeed, I have this one which has a allen head screw inside, which way should I go? I guess ccw to ease the spring tension, am I rigth?

Augusto.
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Old 05-14-2009, 09:05 PM
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you can thread that screw completely out , no problem.
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Old 05-14-2009, 10:16 PM
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Ok, I'll try it out tomorrow

thanks a lot.


Crosley, I also have this BIG BLACK modulator that came in one TH350, what is it for? is this the one with the altitude compensating bellows? it only has one vaccum nipple, does not seem to vented to the atmosphere wich should be in order to sense altitude... if it's just a regular unit, why is it so big compared to the regular gold ones? please explain.


Augusto.
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Old 05-15-2009, 02:55 PM
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Modulators

Augusto, The aftermarket Large Black modulators are for engines with low manifold vacuum= large cams. > http://www.makcotransmissionparts.co...modulator.html

Last edited by SSedan64; 05-15-2009 at 07:24 PM. Reason: correction
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Old 05-15-2009, 06:42 PM
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the large OEM vacuum modulators were altitude compensating.

Some of these had adjustment screws on them.
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Old 05-15-2009, 06:43 PM
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Wow !!! seems like I had the solution to my problem abandoned on a shelf collecting dust... I'll check it, hope it's good.

thanks a lot guys I appreciate your help.

Augusto.
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Old 05-15-2009, 08:51 PM
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haha what happened to your post crosley, augusto's post is inside your post ? confused lol
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Old 05-15-2009, 09:26 PM
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I was wondering about the same...

or is it because you are moderator?

never seen it before.

Augusto
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Old 05-15-2009, 10:08 PM
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uh-oh Things are getting very smalllllllll...Put on yer tinfoil hats boys, and smoke em if ya got em...I'll bet we're going through a wormhole...


Later, (maybe), Mikey
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Old 05-15-2009, 10:45 PM
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ahahhaha all i have to say is.........



ribbit!


and i think crosley broke the internet ahahha
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Old 05-16-2009, 04:11 PM
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yes!! Crosley broke it , don't blame me...

Augusto.
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