740 GLE 1985 Auto Transmission problem
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Nick
740 GLE 1985 Auto Transmission problem
It's acting like it's in almost continuous kick-down mode. As long as I'm accelerating lightly, it'll run up thru the gears (to 3rd, won't go into Drive), but as soon as I lift my foot or start to go downhill and the 'thrust' goes, it downshifts into second. No slippage in the gears; just replaced the trannie fluid and filter and the problem stayed. No warning lights. No rise in water temp. Any thoughts that save me a new trannie will be gratefully received!!
The kickdown cable adjustment on this transmission is very sensitive. It sounds like the cable is adjusted too tight, just back off the adjustment a few turns and give it a try. It may take a couple of adjustm,ents to get it right.
Volvord 784VC
http://www.telusplanet.net/public/gilesij/Volvord/
Volvord 784VC
http://www.telusplanet.net/public/gilesij/Volvord/
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Jarhead JAG
Mine does the same thing, but only in coming to a stop. It shifts down into 1st, right before I'm completely stopped. What's up? Could this be a speed sensor thing? If it is the kickdown cable, how do I know?
The problem you describe Jarhead JAG is much more difficult to diagnose over the internet... It sounds like a clutch pack or selector valve in the trany may be hanging up causing an abrupt and delayed downshift. It would probably be worth taking your car into a reputable trany shop for a "tune-up" which includes a flush, fill , and adjustment.
Volvord 784VC
http://www.telusplanet.net/public/gilesij/Volvord/
Volvord 784VC
http://www.telusplanet.net/public/gilesij/Volvord/
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Nick
Well, I think I'm stuffed. Drove in and back, 35 miles each way, max speed 35 mph, and I can't get it into 3rd or Drive. That's after loosening the kickdown fairly severely. It worked fine, at least 3rd did, for the first few miles while it was warming up. Then, nada.
What's the cable linkage that's driven by some form of vacuum bellows right beside the kickdown, that has a linkage disappearing towards the transmission and has a cable runing over the throttle spool as well...? Any mileage in tweaking that?
Cheers, and a curse or two, Nick
What's the cable linkage that's driven by some form of vacuum bellows right beside the kickdown, that has a linkage disappearing towards the transmission and has a cable runing over the throttle spool as well...? Any mileage in tweaking that?
Cheers, and a curse or two, Nick
The vacuum bellows you describe is the cruise control. When activated a vacuum signal is sent to the bellows which pulls the throttle to maintain the set speed.
Now for the kick down, rather than trying to explain here is a fairly good article on the adjustment. When adjusted a very short drive should identify if the problem is solved. (source: http://www.brickboard.com/FAQ/700-900/T ... Adjustment
"Kick-Down Cable Adjustment.
Function of Kickdown Cable. [Discussion from Abe Crombie] The kickdown cable is used to regulate a pressure in the transmission valve body. This is called throttle pressure. The throttle pressure is effectively a pressure that "tells" shift valves in transmission how hard you are pushing the throttle and these shift valves now have a contest to see if governor pressure or throttle pressure is going to win. This pressure is also used to apply the clutches/brakes that engage a gear and the higher pressure goes along with higher engine power at higher throttle. Firmer shifts are a result of higher throttle pressure. If throttle pressure wins the contest the trans remains in lower gear, if governor pressure wins the trans upshifts. Governor pressure is directly related to driveshaft, and thus road speed. If you tighten cable you increase throttle pressure and the whole shift point/road speed "map" goes higher. If you loosen cable the shift point map moves lower. The trans throttle cable (kickdown cable) also depresses a valve if you (or the throttle spool) pull the cable all the way out past that hard spot which is a detent to make you aware of the actual kickdown feature. The kickdown valve increases the throttle pressure drastically above the linear rate that you get from the rest of the throttle pedal travel range and makes the gearbox goes to lowest possible gear allowed at the road speed you are at when you activate it.
Adjustment of Cable. The kickdown cable has no adjustment at the transmission end, it's fixed. All the adjustment is under the hood, at the throttle spindle. To adjust, loosen the cable housing jam nuts until there's plenty of slack in the cable. Pull on the cable, then let it snap back in. Listen carefully, and you'll hear the cam that the cable is attached to in the automatic transmission click up against its stop. Try this a few times, so you'll know the sound. Now adjust slack out of the cable, keep testing by pulling and letting go of the cable, always listening for the click inside the transmission. As you take more and more slack out, there will be a point where you've tightened the cable just enough so the cam inside the transmission can no longer click up against the stop, because the tightened cable won't let the cam go back far enough. When you reach this point where you just stop hearing the cam click against its stop, the cable is adjusted properly. [Don Foster] Loosen the cable to soften the shifts, and shorten (or tighten) the cable to cause the tranny to shift harder and at higher RPMs. Be sure to keep notes of which way you adjust the cable and by how much so you can restore it to original position if you're unhappy with the results. "Loosening" the cable means to adjust the cable housing (outer sheath) so the inner core is looser around the throttle spool. This means adjusting the housing (outer sheath) TOWARD the throttle spool. This has the effect of providing a bit more "slop" in the core, which is wrapped on the spool. Thus, it becomes looser. If you want to tighten the cable, adjust the cable housing so it backs away from the throttle spool, effectively pulling the core tighter. Normally you adjust in turns or "flats." A flat is one flat on the hex head where you fit the wrench, six per full turn."
Good luck
Volvord 784VC
http://www.telusplanet.net/public/gilesij/Volvord/
Now for the kick down, rather than trying to explain here is a fairly good article on the adjustment. When adjusted a very short drive should identify if the problem is solved. (source: http://www.brickboard.com/FAQ/700-900/T ... Adjustment
"Kick-Down Cable Adjustment.
Function of Kickdown Cable. [Discussion from Abe Crombie] The kickdown cable is used to regulate a pressure in the transmission valve body. This is called throttle pressure. The throttle pressure is effectively a pressure that "tells" shift valves in transmission how hard you are pushing the throttle and these shift valves now have a contest to see if governor pressure or throttle pressure is going to win. This pressure is also used to apply the clutches/brakes that engage a gear and the higher pressure goes along with higher engine power at higher throttle. Firmer shifts are a result of higher throttle pressure. If throttle pressure wins the contest the trans remains in lower gear, if governor pressure wins the trans upshifts. Governor pressure is directly related to driveshaft, and thus road speed. If you tighten cable you increase throttle pressure and the whole shift point/road speed "map" goes higher. If you loosen cable the shift point map moves lower. The trans throttle cable (kickdown cable) also depresses a valve if you (or the throttle spool) pull the cable all the way out past that hard spot which is a detent to make you aware of the actual kickdown feature. The kickdown valve increases the throttle pressure drastically above the linear rate that you get from the rest of the throttle pedal travel range and makes the gearbox goes to lowest possible gear allowed at the road speed you are at when you activate it.
Adjustment of Cable. The kickdown cable has no adjustment at the transmission end, it's fixed. All the adjustment is under the hood, at the throttle spindle. To adjust, loosen the cable housing jam nuts until there's plenty of slack in the cable. Pull on the cable, then let it snap back in. Listen carefully, and you'll hear the cam that the cable is attached to in the automatic transmission click up against its stop. Try this a few times, so you'll know the sound. Now adjust slack out of the cable, keep testing by pulling and letting go of the cable, always listening for the click inside the transmission. As you take more and more slack out, there will be a point where you've tightened the cable just enough so the cam inside the transmission can no longer click up against the stop, because the tightened cable won't let the cam go back far enough. When you reach this point where you just stop hearing the cam click against its stop, the cable is adjusted properly. [Don Foster] Loosen the cable to soften the shifts, and shorten (or tighten) the cable to cause the tranny to shift harder and at higher RPMs. Be sure to keep notes of which way you adjust the cable and by how much so you can restore it to original position if you're unhappy with the results. "Loosening" the cable means to adjust the cable housing (outer sheath) so the inner core is looser around the throttle spool. This means adjusting the housing (outer sheath) TOWARD the throttle spool. This has the effect of providing a bit more "slop" in the core, which is wrapped on the spool. Thus, it becomes looser. If you want to tighten the cable, adjust the cable housing so it backs away from the throttle spool, effectively pulling the core tighter. Normally you adjust in turns or "flats." A flat is one flat on the hex head where you fit the wrench, six per full turn."
Good luck
Volvord 784VC
http://www.telusplanet.net/public/gilesij/Volvord/
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