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Any way to re-program the shift points on an older auto trans?

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Old school

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Discussion starter · #1 ·
My car has the potential to be a decent highway cruiser, but the shift points are maddeningly misplaced.
In city driving it doggedly hangs on to first gear until exactly 50km/h, but since the speed limits in my neighborhood are 40km/h it runs at really high rpms despite the fact that with 295lb-ft of torque it is eminently capable of burbling along at low revs.
Same thing goes for the highway. It refuses to shift to third below 100km/h so in 90 zones it threatens to overheat from running at such high rpms.
Is there anyway to "reset" the shift points?
 
#3 ·
Re: Any way to re-program the shift points on an older auto trans? (Old school)

That's odd that a domestic big engine automatic would be running at such high RPM's. In my experience, they loaf the engine whenever possible, granted most of that was with GM automatic overdrive transmissions.
 
#5 ·
There's a throttle position cable off the carb or throttle body that has been miss-adjusted. When you hit the gas it pulls on the cable, giving the transmission an indication of whether you are flooring it or loafing it.
If you are just putting around town at less than 2k, it should shift to second gear at less than 10mi an hour.....
Is your car a 1988 Fifth Ave?
 
#7 ·
I will second the opinion that it sounds like the load-sensing mechanism for the transmission is not doing what it's supposed to. (Wrongly adjusted; broken/disconnected, etc.)
Fix what's broken and it should be OK.
 
#8 ·
Re: (OneLap)

Quote, originally posted by OneLap »
There's a throttle position cable off the carb or throttle body that has been miss-adjusted. When you hit the gas it pulls on the cable, giving the transmission an indication of whether you are flooring it or loafing it.
If you are just putting around town at less than 2k, it should shift to second gear at less than 10mi an hour.....
Is your car a 1988 Fifth Ave?

Yep. It's called a TV cable. It's either that or a vacuum hose on old autos (not sure what chrysler uses). If the vacuum hose is leaking it can cause the same problems.
 
#9 ·
Re: (anarchyx34)

Heh... I didn't even think of diagnosing the issue. Upon further (actually first) consideration, I'd say that you guys are on the right track.
A reprogramming kit like I suggested would probably make the situation worse.
As for an excuse for completely overlooking the obvious problem here, my dog ate it. I know it doesn't make much sense, but it's all I've got.
 
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#10 ·
Re: Any way to re-program the shift points on an older auto trans? (Old school)

Here, this is the throttle pressure adjustment procedure for the Chrysler TorqueFlite 727. Your Fifth Avenue should have a TF904, which is similar:
http://books.google.com/books?...64,M1
Your transmission is hydromechanical, not electronic, so you can't "reprogram" the shift points on it. The valve body is completely hydraulic - there's no electronic solenoids to shift the flow of transmission fluid around.
So the point of the throttle pressure cable is to tell the valve body how far you have the throttle open. When puttering around town, the throttle cable should be adjusted so that it drops into second around 8-12 mph. But when you're holding the throttle down, it should be adjusted so that the transmission will hold gears almost up until redline.
 
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