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Old 08-11-2018, 03:02 PM   #26
Sharptrans
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

Ok, but make sure the connection at the manifold is not carboned up and Good Luck with your repairs.
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Old 08-11-2018, 03:28 PM   #27
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

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thanks I tested the line and the modulator's response to vacuum and even replaced the modulator for a brand new one already
Is it an adjustable modulator ?
An adjustable modulator can control amount of vacuum going into the modulator diaphragm.

Quote from another forum:
The modulator valve controls upshift via the engine vacuum so WOT = no vacuum = shift at max RPM. I learned this when I had no line going to the modulator valve it would not upshift till near redline!! even with no throttle.

So closing the valve with the screw will increase the shift rpm, open is the reverse. Not sure which direction you need to go, but that's the operation theory of the valve itself.
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Old 08-11-2018, 04:00 PM   #28
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

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Originally Posted by Getter-Done View Post
Is it an adjustable modulator ?
An adjustable modulator can control amount of vacuum going into the modulator diaphragm.

Quote from another forum:
The modulator valve controls upshift via the engine vacuum so WOT = no vacuum = shift at max RPM. I learned this when I had no line going to the modulator valve it would not upshift till near redline!! even with no throttle.

So closing the valve with the screw will increase the shift rpm, open is the reverse. Not sure which direction you need to go, but that's the operation theory of the valve itself.
thanks, I played with that screw already, my understanding is that it just makes the shifts more pronounced, so bigger bumps rather than smoother
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Old 08-11-2018, 11:36 PM   #29
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

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thanks, I played with that screw already, my understanding is that it just makes the shifts more pronounced, so bigger bumps rather than smoother
Yes. That is a fine tune adjustment.
You are taking the right path with the governor adjustment kit. That will take care of your issue.
I have installed a lot of B&M Shift Improver Kits back (__ years ago) you have a choice to make them shift hard or shift strong. If my memory serves me good it was RV/Towing and Race. It tells you to throw either 2 ball bearing away or throw 4 of them out/ You drill 2 holes out (Bigger) the trick is you need to (DeBurr) these holes that you drill out.
After you get your governor tune in you may want to put the rv shift kit in.
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Old 08-12-2018, 04:36 AM   #30
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

Anytime you get a chance to read any of Clinebarger's posts or comments you should take them to heart! He was directly involved in the development of the Turbo-Hydramatic transmissions when these trucks were still rolling off the lines. Just thought I'd throw that in since you posted that old thread. You have to be careful who you listen to on these forums. He taught me via this forum, how to rebuild a Turbo-350 so I'll pass along a bit of that knowledge...Your on the right track with the Superior Solutions shift kit. I was about to point you in their direction, compare the price, bet you paid more?https://www.ebay.com/itm/TH350-TH400...item3f0ef6bb1e The fact that your trans. quit shifting after you installed the lighter springs indicates more of a problem than just the lighter spring change. Did you back out that adjusting screw in the modulator? Remember that the modulator works in conjunction with the governor by holding off shift points by raising line pressure. I'm suspecting that the present screw adjustment in the modulator has rendered the governor useless with the light springs installed. Back that screw out and try it again...1/4 turns make all the difference in those red stripe modulators...Let us know what you find. I have some notes out there in the shop (somewhere) on tuning governor for a 69 L34 396 BBC as I dialed one in to make both shift points occur at 5900 rpm @ WOT in the truck shown in my avatar. (72 C/10 SS COPO) "Modulated pressure & Governor pressure work against each other on the shift valves....Adjusting the Modulator allows Modulated pressure to overcome Governor pressure at a higher manifold vacuum & hold-off upshifts...
If you lower Governor pressure via springs...It WILL do the same thing, But without the side effects of higher Modulated pressure." Gospel!
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Old 08-12-2018, 10:09 AM   #31
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

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Your on the right track with the Superior Solutions shift kit. I was about to point you in their direction, compare the price, bet you paid more?https://www.ebay.com/itm/TH350-TH400...item3f0ef6bb1e
I paid $42.50 on eBay for mine with free shipping.
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Old 08-12-2018, 10:13 AM   #32
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

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The fact that your trans. quit shifting after you installed the lighter springs indicates more of a problem than just the lighter spring change. Did you back out that adjusting screw in the modulator? Remember that the modulator works in conjunction with the governor by holding off shift points by raising line pressure. I'm suspecting that the present screw adjustment in the modulator has rendered the governor useless with the light springs installed. Back that screw out and try it again...1/4 turns make all the difference in those red stripe modulators...Let us know what you find.
Thank you for the heads up on this. I did not make any adjustments on the modulator as I am a firm believer in change one thing at a time, however I will do so now.

To be honest with you all, one thing that may have thrown a Monkey Wrench into this whole experiment is all that automatic transmission fluid that dumped out when I removed the governor, I have since added more fluid (yes before the first test drive, ha ha) however I need to check the level and make sure we have the proper amount. Just thought I throw that in there.
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Old 08-12-2018, 10:21 AM   #33
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

Well here's a Fun Fact off of the SHIFT Technology Products Shift Point Package instructions that came with the spring and weight kit.

Although it's for the 700-R4 transmission governors for what seems to be the closest thing to our trucks C.K. 5.7L V8 they recommend the Brown and Pink springs with the C weight.

Go ahead and find those Brown and Pink springs in the pics I provided above, I'll hold, LOL.... for some other applications they also recommend a White spring, again see if you can find it in the pics above.

Good Times... Not!
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Old 08-12-2018, 10:51 AM   #34
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

I used to build a lot of 350 turbos. I always put a shift kit in them. I would use Mr. Shift kits from my parts supplier. I think they were $13 at that time.
The governor is mainly going to affect shift timing. Same for the modulator.
The cable is for downshift only on a 350. It will upshift the same with the cable unhooked.

Last edited by Hoosier Rick; 08-12-2018 at 10:54 AM. Reason: added comment
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Old 08-12-2018, 11:15 AM   #35
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

I just installed a B&M trans pack kit in my El Camino. I went with street/strip version. It didn't change my shift points but the shifts are nice and crisp!
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Old 08-12-2018, 12:04 PM   #36
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

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Originally Posted by Ironangel View Post
Did you back out that adjusting screw in the modulator? Remember that the modulator works in conjunction with the governor by holding off shift points by raising line pressure. I'm suspecting that the present screw adjustment in the modulator has rendered the governor useless with the light springs installed. Back that screw out and try it again...1/4 turns make all the difference in those red stripe modulators...Let us know what you find.
OK, backed out the modulator screw a 1/4 turn and no difference, transmission still won't shift at all.
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Old 08-12-2018, 12:08 PM   #37
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

OK, Eureka I figured out the problem, after changing the springs I installed the internal weights wrong, I installed them below the plunger top instead of above it, not allowing the weights to press down on the plunger properly.

It is easy for me to say this now, but I swear the weights did not feel right to me when I did that, there was a bit less travel in them, but I just thought that was do to the lighter spring change or something.

so first pic (with my hand in it) is the wrong way to do it, the second pic is how they should go in, if you look above a few posts you will see it's a good thing I took some initial pics, I highly recommend you all doing the same
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Last edited by Gregski; 08-12-2018 at 12:16 PM.
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Old 08-12-2018, 12:12 PM   #38
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

so... I put the modulator screw back in a 1/4 turn, I checked the transmission fluid level, and...

First Test Drive muligan (for you golfers out there)

... and ~ R E S U L T ~

Wow, mission accomplished, I am so pleased, there is now a nice big gap between the 1-2 and the 2-3 gear change, just what I was looking for. We can now enjoy each of the gears ha ha, so happy

the 1-2 gear change at part throttle seems to happen consistently around 2700 RPM and then the 2-3 change happens at around 3400 RPM but that's not what matters what matters is there is a space between the 2nd to 3rd gear shift now, YES!

thank you all for chiming in, I hope together we have learned something
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Old 08-12-2018, 01:52 PM   #39
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

Well good deal Greg. Now you can let those horses run.
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Old 08-12-2018, 02:15 PM   #40
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

Quote:
Originally Posted by Gregski View Post
...they recommend the Brown and Pink springs with the C weight.

Go ahead and find those Brown and Pink springs in the pics I provided above, I'll hold, LOL.... for some other applications they also recommend a White spring, again see if you can find it in the pics above.

Good Times... Not!
That was a very helpful post Gregski, I really got a kick out of how you worded this part!

Glad you're happy with your results!
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Old 08-12-2018, 03:06 PM   #41
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Re: Turbo 350 Transmission Don't Feel Shift 2 to 3

I'm glad you got it figured out. Now you can have good times!!
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