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Old 03-07-2003, 02:29 PM
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don340-4 don340-4 is offline
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Default 904 shift problems.

Is there a transmission expert out there that can tell me why my 904 is shifting so quickly? it is a street strip w/shift kit & low 1st gear set behind a 340 w/3.23s in the rear, has about 3000 mi on it & no other problems. When the linkage is adjusted per the shop manual, under normal acceleration it will shift to 2nd at 5mph & 3rd at 10mph, if I lenghthen the throttle rod to the throttle lever about 2" then it will shift normal but the lever will hit its stop before the throttle plates are wide open, this 904 transmission replaced a 727 all else is original, is there an adjustment inside the tranny for the throttle lever or do i need a different set of linkage? This is in a 70 Challenger. Would appreciate any help on this, Thanks
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Old 03-07-2003, 04:27 PM
John Kunkel John Kunkel is offline
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Sounds like you might have a mismatch of components.
What type of carb?
If it's a Holley, is the correct Mopar throttle arm adapter installed?
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Old 03-07-2003, 05:03 PM
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don340-4 don340-4 is offline
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John, i have a Holley 670 w/the correct Mopar throttle adapter, the amount of movement of the kickdown lever & throttle lever are perfect along with the carb linkage when adjusted to factory specs, you know pin in the holes in the upper bellcrank & throttle lever all the way forward, but the shifts are way to quick. the shifts are solid & prolonged when i get on it hard.
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Old 03-07-2003, 07:59 PM
skankweirdall skankweirdall is offline
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OK, first, how much throttle travel is left after the K/D stops if you adjust it to where it shifts right? A little is OK, maybe a quarter inch or so. The linkage will bend that much.

Second there is an adjustment on the valve body that will change it but it will also shift out higher at wide open throttle.

Third, since you have a fair amount of aftermarket parts on it I would not expect the factory adjustment procedure to work, I've never liked it any way.

I usually set mine so the K/D lever is all the way rearward at WOT. Still might have to add a little more so the K/D linkage will actually bend a little at WOT. Keep in mind though that the early trannies shifted out at lower speeds. Usually in third by 30 MPH. What you have to be careful of is that there is no flair in between 2nd and 3rd at the lightest possible throttle pressure. That would indicate too little throttle pressure.
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Old 03-07-2003, 08:34 PM
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skankweirdall, i have about a 1/4" to the wide open throttle stop on the carb, the primary plates are about 80% open, at that setting it shifts into 3rd about 30mph which seems about perfect. i will try your way of adjusting the K/D lever & see how that works. what is the adjustment you mentioned that would also delay the upshift, not that i really want to go there? thanks for the help. i never get any flairup at all regardless of the adjustment, chirps the tires 2nd to 3rd most of the time at 1/2 to 3/4 throttle.
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Old 03-07-2003, 08:44 PM
skankweirdall skankweirdall is offline
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There are a couple of pressure adjustments on the valve body, the one you would want looks like a bolt sticking out of the drivers side of the valve body. It is the stop for the throttle pressure valve. With the pan off it doesn't look like it would do much of anything but keep the valve from falling out. However small adjustments here can make a big difference. If you do decide to adjust it do it in 1/4 turn increments. Button it back up and road test. Re adjust as nec. Messy and time consuming to say the least.
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Old 03-07-2003, 09:12 PM
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don340-4 don340-4 is offline
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skankweirdall, thank you for the help, i see the the adjusting screw on the valve body your talking about in the shop manual they call it the throttle lever stop screw, is that the one? it will be messy & time consuming for sure. i'm going out in the garage now & try your K/D lever adjustment, before i do any thing else. thanks.
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Old 03-07-2003, 09:32 PM
skankweirdall skankweirdall is offline
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Yep, that's the one. Good luck to you.
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Old 03-08-2003, 01:37 PM
skankweirdall skankweirdall is offline
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Well? How's it working?
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Old 03-08-2003, 10:14 PM
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don340-4 don340-4 is offline
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skankweirdall, sorry for not getting back sooner, your K/D adjustment works perfect , will not have to mess with throttle lever screw, thank God. at light throttle shifts are 1st to 2nd 18mph, 2nd to 3rd 32mph, if i get on it pretty hard 2nd to 3rd at 67mph, shifts are firm and solid & throttle plates full open. thank you for your help.
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Old 03-08-2003, 10:21 PM
skankweirdall skankweirdall is offline
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Cool deal, glad it worked out for you.
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