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A518 no shift problem

Transmission and Drivetrain

  1. chargerdon

    chargerdon Member

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    Just finished installing an A518 46RH transmission into my 74 Challenger with 360 LA engine. It is a 92 model with the locking torque converter and is hydraulic. Before installing took the time to "freshen" the transmission by putting in an overhaul kit for the seals and clutchpacks. All looked great inside. During the overhaul i left the governor untouched. I also put in a transgo shift improver kit and a new locking torque converter. This is my second overhaul as i successfully overhauled the old 904 torqueflite that was in the car. I plan on just using toggle switches to activate the locking torque converter and overdrive engagement. I was careful adjusting the throttle rod so that at wide open throttle, it would push the lever nearly to the end.

    After putting in 8 qts of tranny fluid, started the engine and checked for leaks... didnt see any, so put it in neutral to activate the pump and let it warm up. Checked dip stick and it wasn't showing anything so put in another qt and then it was showing, so added another and that got it pretty close to the "cold" mark on dipstick. Put it into reverse and it engaged, then into drive and it engaged.

    Great, so with it warmed up took for test drive, but no shifting at all, all the way up to 4,000 rpm and no shift ...stuck in first. Now, when i back off to let it low down, it goes into neutral, with no propulsion, tach goes to idle.. Then when car slows down to under 10 mph, it reengages 1st gear, and i was able to drive it home. Rechecked the fluid level in neutral now that it is fully hot, and added a little more...now has about 10+ qts in it. Did another drive and same thing... i start out in first and it never shifts. Doesnt matter if i pull the shift lever to D or 2 or 1...it acts the same.

    Any transmission guru's that can give me probable problems? I'm thinking most probable is to pull the valve body and go over it... This i can do while transmission is still in the car. Ive also heard that this can be from a "stuck" governor in the tail section, or that in reassembly from my overhaul that the "tubes" might have gotten bent. If that is the case, can i pull the tail section while it is still in the car...or... Suggestions please !!
     
  2. Adam

    Adam Well-Known Member

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    Do you have another valve body to swap in? I’m not sure about the 518, but the 904 & 727 valve bodies are interchangeable.
     
  3. chargerdon

    chargerdon Member

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    No... only the one in my 904...i dont think it would work.
     
  4. oldkimmer

    oldkimmer Well-Known Member

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    Vb won’t interchange. Sounds like a stuck governor. I have only done a few over drives, but n m ant 727s abb n d 904s Kim
     
  5. Jim Hurley

    Jim Hurley Member

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    Your best bet would be to take it to a transmission shop and have it diagnosed. There are so many variables as to what could be wrong. It could be servo, governor gasket under supp on the back of case, fluid level, valve body...and the list goes on and on. Without knowing what you did during overhaul it's going to be pretty hard to diagnose properly. Good luck!
     
  6. chargerdon

    chargerdon Member

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    I decided to make check the governor first by putting a pressure gauge on the governor port. Book says 0 psi at idle, and then 1 psi or each mile per hour. Ok, that a518 sits in the transmission tunnel very, very tight... So, to even get the pressure gauge into it had to drill a 1" hole in the floor pan opposite the governor pressure port. Did that and used a long hose thru the hole and got the fitting in and with wheels jacked up off the ground started her up.

    Yep 0-1 psi at idle, then while in gear brought the speed up to 35 with 4200 rpm and pressure read right around 35... 20 psi at 20 mph etc.

    So, glad to me that means the governor isn't stuck and the tubes are in the case correctly or i wouldn't get the pressure reading at the port !! Yippee...I think...so i'm going tomorrow in good daylight, recheck the throttle kick down linkage, but it seems to be good.
    If that truly is the case, and ill adjust it in each direction and recheck for shift, but, if still no shift then i'm thinking it has to be in the valve body. That i can remove, disassemble and reassemble while the transmission is still in the car. Sure, am glad i put a drain plug into the pan to make this easier.

    Thoughts???? Anybody disagree, or agree ? Any other tests i should do before doing this?
     
  7. Jim Hurley

    Jim Hurley Member

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    Before you tear out the vb, elevate the rear and see if it will shift under light throttle. Also make sure the spring that pulls the kick down lever is pulling it to the front of the vehicle not towards the back
     
  8. chargerdon

    chargerdon Member

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    Yes, i even readjusted kick down rod to give LESS mothion...spring where it should be, and wheels up off the ground, light throttle still no upshift. So took out the VB and draining everything...will tear it back down towmorrow, looking for anything obviously wrong.
     
  9. KMikk

    KMikk Well-Known Member

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    I hope you find your problem and it is a easy fix. So are you saying that you did not have to modify your original tunnel to install the 518 or just that it is a tight fit with the tunnel modified?
     
  10. chargerdon

    chargerdon Member

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    No sir, did not have to modify the tunnel....and yes it is a tight fit, but it does fit with no tunnel modifications. The Transmission support need to be reworked, as the 518 has a much fatter tail section. I made mine out of 12 Gauge steel...lot of work, and then used a gm style support with it. I do not know if on a 727 or 904 if the governor port could be accessed easily or not. In my case i was replacing a 904 with the a518 46rh so it was total of nearly 7 inches longer... also the 904 yoke didnt fit, so needed a new one of those, and a new torque converter. I think if your replacing a 727 then its a bit easier.

    Yesterday, redid the entire valve body, and i think i found where i had a spring in the 1-2 shift and governor valve in the wrong place. Cant put it back in till probably friday due to the cold snap here in NC... Garage isnt heated. will let everyone know..
     
  11. KMikk

    KMikk Well-Known Member

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  12. KMikk

    KMikk Well-Known Member

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    Thanks for the information, I have a 70 Challenger I would like to upgrade to a OD auto transmission. I always assumed the tunnel needed to be cut up, I didn't want to go that route.
     
  13. chargerdon

    chargerdon Member

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    yippee...its fixed !!

    Looks like i was right with a spring in the wrong place on the 1-2/governor valves .

    Just finished getting it back in the car and with wheels jacked up to start, it shifted into second and then into 3rd..

    Then took it for a test drive, and i got all three gears, shifting with mid throttle at about 25 into second, and then into third at around 45.. Light throttle earlier shifts. Also, i tested WOT and the kickdown to 2nd is working and so is the kickdown to first if i do it below 30. So i think i have the throttle rod hooked up about right.

    A little disappointed in that from dead start, wot is shifting into 2nd at only around 35 mph (4,000 rpm). But ill live with that..probably about right. Can always hold it in first with gearshift longer, but, have to be careful no to over rev as it revs quick and my console/floor shifter doesnt have the slap stick.

    I haven;t hooked up the wires for the locking torque converter or overdrive yet...(just going to use toggle switches for both) at least initially. Tomorrow for that... I'm tired.. no easy task in my opinion to put that valve body in, getting the parking brake rod hooked up and the clip in for it, then all of that linkage. Will keep you posted on the overdrive when i get it hooked up.

    Thanks for the help guys !!
     
  14. chargerdon

    chargerdon Member

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    Ok, more progress.

    With rear wheels jacked up, tried the wires to operate the OD and the Lock-up torque converter. The OD worked...i.e with wheels off ground, brought it up to 50 mph...was showing around 2400-2500 rpm.

    Tried the wire for the Lockup first, and nothing !! I could see a light spark as i gave it ground but no noticeable difference !! Darn..

    Then i tried the wire for the OD..again slight noticeable spark but nothing...for about 1-2 seconds, and then it engaged !! Speedo jumped from about 50 to right around 65! Turned it off and back down to 50.

    So, i then shut off engine and rechecked the ohms for the TC and it was right around 30-35 ohms which is what it is supposed to be.. So have to believe the electric solenoid is good...

    Next, i hooked up a toggle switch for the OD and took it for a test drive... at 50 mph in third and around 2400-2600 rpm, flipped the toggle switch and two seconds later i could feel it engage and rpms dropped to about 2,000.. Brought car up to 65 and rpm went to around 2500 yes yes... still bummed that the TC didnt seem to do anything, but, i didn't try it on the road.

    On E-bodies forum, one guy said hook up the TC with toggle switch and try it on the road. Jacked up it probably wasnt any slipping any with no load...so try it on the road. Will do that over the weekend.

    PS... my next project with this challenger is on the transmission shifter. All E-bodies are supposed to have the "slap stick" function. Mine doesn't... With console out to bring thru the wires for TC and OD seemed like a good time to examine then shifter. i took it out out and its missing the slap stick plate and spring...so someone swapped the shifter from another car probably an A body.

    Anybody have a spare slap stick shifter mechanism they can give/sell me? PS mine is the round ball type not the T-handle.

    Will keep you further posted when i try the TC on the road. !!
     
  15. chargerdon

    chargerdon Member

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    Yep...on the road, flip switch i hooked up for locking torque convertor and at 50mph it drops the rpms about another 250 rpm. More important it should keep the heat down !!

    Also, i sourced a reasonably priced slap stik shifter (t handle type) and will put it in after i get it hopefully in a few days !!
     
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