'90 F150 AOD "clunk"
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'90 F150 AOD "clunk"
My '90 pickup with a 5.0 and AOD automatic shifts into and out of OD slugishly and with an audible clank. Short of replacing the tranny, is there any fix? Will an adjustable vacuume modulator help? Is there a wire somewhere that I can put a switch into, to only enable the OD at highway speeds? (I shift it manually with the lever now, but sometimes mis-shift if I don't pay attention.)
Thanks for any help.
Mack
Thanks for any help.
Mack
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Joined: Feb 2000
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From: Connecticut
'90 F150 AOD "clunk"
Is your vehicle a 4x4? If it is, it may be backlash in the drivetrain. The Borg Warner 1356 and 1756 transfer cases seem to have enough backlash designed into them to create some clunking in the driveline when shifting gears and going from coast to drive/drive to coast. The rear axle and the driveshaft spline can contribute to this backlash as well if they are excessive. The AOD shifts into OD while the torque converter is locked worsening the impact/clunking you feel.
The AOD does not have a vacuum modulator, it has a throttle valve and cable that may need to be adjusted, it controls the line pressure in the transmission like a vacuum modulator, which in turn controls the "shift feel." Loosening the cable allows softer shifting, however, it will wear out the friction elements faster if adjusted too loose. No switches can be installed as the AOD is mechanical in design, not controlled by the drivetrain electronics.
Mark
The AOD does not have a vacuum modulator, it has a throttle valve and cable that may need to be adjusted, it controls the line pressure in the transmission like a vacuum modulator, which in turn controls the "shift feel." Loosening the cable allows softer shifting, however, it will wear out the friction elements faster if adjusted too loose. No switches can be installed as the AOD is mechanical in design, not controlled by the drivetrain electronics.
Mark
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Joined: Mar 2001
Posts: 177
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'90 F150 AOD "clunk"
Check for play in your drive shaft. My truck had that clank, and it got considerable worse. I needed to get my diff rebuilt...not too expensive. 500 bucks canadian. Does your speedo kind move around when your on the highway??
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