tranny
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tranny
so im pretty new to this and i was reading a post that said he had 3.55 gears i have noticed after about 40 mph my truck dosent seem to change gears am i to assume i only have 3 and a half forward gears also my tack floats like my fuel gauge sometimes im going 45mph and my tack will say im doin 900rpm then ill be doing 65 mph the tack will be at like 3500 rpm then ill get to 70 mph and be down to 2500 rpm oh yeah this is a 1987 6.9
Fleet Mechanic
Joined: Jan 2011
Posts: 1,709
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From: 8600 ft in Colo
Gee, I'm trying to remember when Ford went to the E4OD...
Do you have an OD button on the shifter?
If so, than you have an E4OD (Electronic 4-speed Over-Drive) trans, and that can act funny if it's getting bad signals. It gets input from the VSS on the rear diff, the Tach sender next to the oil filler, the MLPS on the side of the trans, the TPS on the IP. and a barometric pressure sensor.
Your flaky tach is probably the tach sender. It's the big hex head with two wires coming out of it, next to the oil filler. The wire inslation tends to break down exposing the wires. If you don't find anything obvious like that, it probably needs to be replaced.
Do you have an OD button on the shifter?
If so, than you have an E4OD (Electronic 4-speed Over-Drive) trans, and that can act funny if it's getting bad signals. It gets input from the VSS on the rear diff, the Tach sender next to the oil filler, the MLPS on the side of the trans, the TPS on the IP. and a barometric pressure sensor.
Your flaky tach is probably the tach sender. It's the big hex head with two wires coming out of it, next to the oil filler. The wire inslation tends to break down exposing the wires. If you don't find anything obvious like that, it probably needs to be replaced.
Fleet Owner
Joined: Jul 2006
Posts: 20,377
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From: Mi'kma'ki
it wasn't until '89 i think when the E40D came out.
so for sure in '87 if its an auto,its the old 3 spd C6 trans.
if you drive the truck a lot,you can find a donor truck with the E40D and swap its brain/wiring/trans in to your truck.if you don't drive much,or don't plan on owning the truck much longer,it'll just be cheaper to try and keep her 45-50 mph.
of course there are other ways to get a more modern over drive trans,such as a gear vender unit or zf5 manual swap as well.
so for sure in '87 if its an auto,its the old 3 spd C6 trans.
if you drive the truck a lot,you can find a donor truck with the E40D and swap its brain/wiring/trans in to your truck.if you don't drive much,or don't plan on owning the truck much longer,it'll just be cheaper to try and keep her 45-50 mph.
of course there are other ways to get a more modern over drive trans,such as a gear vender unit or zf5 manual swap as well.
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