IS THERE A TH400 KICK DOWN LINKAGE?

[RudyC]

Is there a kick down linkage on the TH400 of my 79 Wagoneer? If yes, were is it? I dont see one. It won't down shift on uphills.

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1979 WAGONEER, 360, TH400, Q- TRAC. 3" ADD A LEAFS, 31" MUD T/A'S (PEP BOYS CLONES).
" Go farther, it only breaks on the street"

[Veepster]

there is no kickdown linkage..as I understand it uses a vacuum modulator, it is on the passenger side of the tranny, if you clumb under you will see a vacuum line going to a round thing......how it works? I don't know and I hope someone explains it weel cause I would like to know also!

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Peace.............BartG

the Green Flash!
78 Cherokee
360 2v, TH400 QT with low
4" skyjacker Rancho 9000's
33x12.50 BFG KO's 8" American Racing Baja Rims
Thorley headers, 3" exhaust, Dyno Max
Infiniti power leather seats
50%LuxuryCar,50%Tractor

[Shane]

I believe the TH400 uses a vacume modulator valve. It controls the upshifts and kickdown of the trany by modulating the fluid pressure according to the engine vaccume. It is located on the side of the trany just above the oil pan.

If it doesn't have vaccume it will delay the shifts untill high RPM, but if the valve in the valve body is sticking it may prevent down shifts.

Hope this helps.
Shane

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1982 J10 Model 25 Pioneer
My Daily driver since 1988
D44,258(.030" over),T5,NP208,AMC20

[Dean]

I think that there is a switch above the accel pedle. Worth looking under the dash.
Dean.

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'78 Wagoneer Limited
401/Q-trac W/low range
Mods so far, carter 4 bbl., rancho 3" lift, rancho RS5000 & RS9000, stage one of the GB ign upgrade.

Donor rigs, '84 GW, '78 J20.

[oddfire]

The th400 kickdown lever is a plastic sliding switch that engages the gas pedal linkage rod by the gas pedal. Check continuity through switch to see if it works

[Veepster]

hey oddfire...how does that slide work?

------------------
Peace.............BartG

the Green Flash!
78 Cherokee
360 2v, TH400 QT with low
4" skyjacker Rancho 9000's
33x12.50 BFG KO's 8" American Racing Baja Rims
Thorley headers, 3" exhaust, Dyno Max
Infiniti power leather seats
50%LuxuryCar,50%Tractor

[RudyC]

Were does it plug into the tranny? I see only one wire into the side of the tranny. I thought that was the reverse light switch.

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1979 WAGONEER, 360, TH400, Q- TRAC. 3" ADD A LEAFS, 31" MUD T/A'S (PEP BOYS CLONES).
" Go farther, it only breaks on the street"

[Shane]

Unless the TH400 used by Jeep is different from the GM products, the transmision throtle presure used to determine shift points in the transmision is governed by a vaccume modulator valve. As vacume decreases throtle pressure increases (in the valve body) to delay shifts or if it equals line pressure with the assist of a spring it will cause a down shift.

Shane

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1982 J10 Model 25 Pioneer
My Daily driver since 1988
D44,258(.030" over),T5,NP208,AMC20

[oddfire]

Both my 76 cherokee WT 360/t400/qt and
my 78 waggie 401/t400/qt, use the electic
kickdown switch thats located just above the gas pedal. As you press down the pedal, the
linkage engages a switch that signals the tranny to downshift, You can check if the switch is working by removing it {one screw}
and checking the continuity across the terminals while moving the switch lever.
I slipped a small piece of fuel line {1/2 inch] on the bar
that engages the linkage to give me more rapid downshifts. Ive replaced 2 of them, about 15 bucks from any tranny shop. Hope this helps.

[Dean]

The reverse switch is on top of the steering column under the dash, part of the nuetral safety switch. So the wire going to the trans should be the kickdown from the pedal switch.

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'78 Wagoneer Limited
401/Q-trac W/low range
Mods so far, carter 4 bbl., rancho 3" lift, rancho RS5000 & RS9000, stage one of the GB ign upgrade.

Donor rigs, '84 GW, '78 J20.

[scotty]

an electric doenshift switch on the gas pedal? now THAT is funky...



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scott
85 grand wagoneer
258 with motorcraft 2bbl/904/twin stick dana 300/dana 44/welded amc 20
38x15.5 gumbo mudders
snorkel/dual batteries/onboard air/"custom" convertable
3 inch body lift/mostly stock suspension/"modified" fender openings
custom front/rear bumpers and brushgaurd

T18/dana 20 swap very soon
searching for dana 18 to replace the 20...

[jonmurr]

Yes, the turbo 400 was a orphan in this respect, the modulator vacuum controls line pressure over a narrow range (about 5 mph shift point difference at W.O.T.) The 2-3 kickdown is controlled by the one wire to the driver side of tranny. Other GM trannes only use the modulator(turbo 350) or a throttle valve linkage (A727,A904,TH200-4R,TH700-R4.)for kickdown

[Dean]

<BLOCKQUOTE>quote:</font><HR>Originally posted by scotty:
an electric doenshift switch on the gas pedal? now THAT is funky...
<HR></BLOCKQUOTE>

Scotty, a person could take advantage of the design by adding a second switch to allow the driver to downshift at less then WOT.....Hmmm, gear oil leaking from ears again.


------------------
'78 Wagoneer Limited
401/Q-trac W/low range
Mods so far, carter 4 bbl., rancho 3" lift, rancho RS5000 & RS9000, stage one of the GB ign upgrade.

Donor rigs, '84 GW, '78 J20.