Adjusting Shift Points?

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farmerpete
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Adjusting Shift Points?

Post by farmerpete » 09 May 2017, 20:17

Is there a simple way to adjust the shift points on an FMX? My '70 shifts at very low RPMs - I'm in third gear by 30 MPH, even if I stay on the throttle. I'd like to have the RPMs come up a bit before the trans up-shifts. Any suggestions?
'70 Cougar vert 351W
'83 CJ5
'69 Caddy DeVille vert

allenman85
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Re: Adjusting Shift Points?

Post by allenman85 » 09 May 2017, 22:02

At low speed the vacuum modulator controls the input to the valve body to shift. Early shift is typically caused by a modulator adjustment screw that is out too far. You can pull the vacuum hose off of it and slip a small screwdriver into the hole and try turning in the screw about 2 turns.
Otherwise it's a governor problem and it'll require a bit more teardown to get access to.
1970 Cougar. 351C/FMX/AC/PS/PB/Comp Green w/White Top, 3:00 open
Now: 622 HP, 351W w/AFR, solid roller, 418ci, C6, 3.50:1 posi, 3" Magnaflow SS exhaust

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JETEXAS
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Re: Adjusting Shift Points?

Post by JETEXAS » 09 Oct 2017, 11:57

My C4 has the opposite issue. It seems to be maxing RPMs before finally upshifting, even at very low throttle. Would be great for drag racing, but it's not so great driving through the neighborhood at 25 mph still in first gear. Does the C4 adjust the same way?
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wish
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Re: Adjusting Shift Points?

Post by wish » 09 Oct 2017, 12:13

Have you checked the kick-down linkage to be sure that is adjusted properly ? If it is bound up or disconnected it may think you're pulling no or full throttle depending on which issue you have.

Third gear by 30mph under light throttle would not be surprising depending on gears and terrain ...
Just my $.02
wish
69 Cougar, That 70s Truck, 84 Cherokee Chief 2dr, 88 Grand Wagoneer, 95 Grand Cherokee,96 Mustang

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JETEXAS
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Re: Adjusting Shift Points?

Post by JETEXAS » 09 Oct 2017, 12:23

It's connected to the throttle on the carburetor, but I haven't attempted ajusting it in any way. I'll look at it tonight.
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