904 transmission shifting adjustments

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70dart65coronet

mopar or nocar
Joined
Jan 2, 2013
Messages
92
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Location
Spokane
Hello to all at FABO, its been a while.

I had my 904 transmission rebuilt at the local transmission shop and im having some problems with shifting. The same problems i had before it was rebuild, i was hoping the rebuild was going to fix this. it needed rebuild reguardless because the clutch materials were heavy in the oil pan, so i assumed that was the problem. When you are on it, shifting from 1 to 2, and then 2 to 3, its a long shift engagement almost like its slipping, you have to get off the throttle and then get back on it. When you drive it nice and easy it shifts fine.

How do i get that solid shift when im shifting at wot.

This has a B and M after market cable shifter, where you simple push the shifter forward when your ready for the next shift. I looked at the adjustment when i had the oil pan off, and its sitting in the right detents.

It doesnt have a kick down lever any more, if i remember right, the guy i bought it from, zip tied that lever in the applied position...does that make any since? now that im thinking about it, i need to check what position it is in currently.

I wish i would have done my own rebuild on this one. Im not sure how it was built and rebuilt. Valve body options like manual reverse valve body.. whats the point of forward or reverse shift patterns?

Also I put a 3" dual exhaust kit on from summit, i have hooker headers, and the thing is still really load. I used summits turbo mufflers #633230, is there another performance muffler out there that will hold up to the horsepower, i need to dyno this thing but i think im putting out around 300-400 horsepower.

Also was thinking about changing to hood scoop, any ideas?

Thanks

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You need the throttle linkage for the transmission. It controls the pressure. You will burn the clutches as you said you felt a long shift (that's slipping). Hope it's not to late. Don't drive until you have it installed and adjusted properly. You can install a full manual valve body that has full line pressure all the time and you will not need the throttle linkage, this set up is not street friendly more for strip.
 
I see a few problem areas. Yes, the car needs to have actual functioning throttle pressure (Kickdown) linkage. It controls when it upshifts and downshifts as well as how hard it shifts.
There is a fat spring in between the valve body and trans case. This "accumulator spring" softens the line pressure between shifts. Toss it out. Finally, you can raise the line pressure to firm up shifts. It is an allen hex screw above the valve body on the drivers side. You can google search for Torqueflite shift improvement tips and see pictures on what I mentioned. FREE adjustments like this are great. You can thank Rick Ehrenberg from Mopar Action magazine for that one.
Also, the traction bars.....Not needed nor helpful with a Mopar. The design of the Mopar leaf springs is not like a Chevy or Ford. Our cars have stiffer front sections of the springs and the traction bars are just dead weight.
 
In my own little world of opinion a cable for the throttle pressure is the easiest way to solve a missing linkage problem.
Also agree with why it acts like it does when shifting AND probably what killed the trans the first time.
 
hello moparlvr166, im pretty sure i must have a manual valve body because when i put it in 3rd, it acts like its in 3rd, it doesn't move forward without throttle, as soon as i drop it down to 1st it starts moving forward, so that would take care of not having a throttle linkage for the transmission (kick down lever) but what position do i want that lever to be in even though its unhooked.

Kern Dog, so if the accumulator spring is in there, simply remove it and that will make firmer shifts? is there any linkages i have to change or worry about? Would a manual valve body have an line pressure adjustment? I guess i can try adjusting, how many turns in or out should i go? The traction bars, yeah...some chevy guy gave those to me, i threw them on because when i got on it my mufflers would hit the ground, i have really low ground clearance, and it seemed to help, but now i have very little suspension travel back there. LOL, i mounted a swivel castor to my k member to keep the oil pan from dragging on my drive way approach.

67 gt, yeah it was a little trickey getting the car up that high, it took about 6 different lifts and increasing blocking, i also have a HD rolling cart i can put the floor jack on. But boy was it worth it! made it nice for doing that exhaust work.

Famous bob, your right about the seats, they suck, but they are so cheap, and luckily i fit in them...someday i will pony up and put some good ones in there, lol

TrailBeast, a cable for the throttle pressure is the easiest way to solve a missing linkage problem, if i do need this linkage you suggesting using a push pull cable? thats a good idea.

I think i figured out the forward/reverse pattern valve body option, that just refers to which way you push or pull the shifter? Since i push my shifter foward i have a forward pattern?

I'll get some pictures tonight, if i remember right the guy i bought it from had a zip tie holding the linkage lever in a certain position...but even when i had bought the car it had the same shifting feel, uggghh, this is driving me nuts... i have had this car for 13 years now and i have had it at the drag strip once the year i bought it, and i just drove it around the block yesterday and still fighting the same problem.

Thanks for your input guys!
 
so even with a manual valve body you need a kick down linkage because the transmission needs to know the position of the throttle?
 
U more than likely have a TF-3 manual shift kit put in ur valve body. So yes u would been a cable or linkage on it or tie the lever all the way to the rear. Kim
 
I thought that the manual valve body eliminated the need for the kickdown linkage.
I personally don't see the advantage of a manual valve body in a mild street car. It eliminates the convenience of an automatic transmission.
 
im not sure what i should do with this kick down lever, here are some more pictures. looks like right now its tied all the way forward, im pretty sure that is how it was when i bought the car. see pictures of the linkage zip tied, also have a couple extra linkage mounts that came with the car.

I have about 4" ground clearance to the oil pan and header flanges. i bolt the caster on when i need to get in and out of my drive way, but i have to take it off when working on the car that k member is the best place to lift with floor jack.

Its got a much bigger trans cooler mounted to the face of the radiator, i would like to go to a bigger oil pan too but i think that might reduce my ground clearance more.

Im thinking about using this all steel motor mounts instead of the solid home made ones that are in there.

Im thinking about building my own aluminum hood scoop, i just figured out that the engine doesnt sit center of the car, so the air cleaner is a couple inches of center. i was going to bring the air filter up through the hood instead of the hood scoop but that wont look good being off center.

Let me know what you guys think about that kick down lever

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U meet to tie it to the rear. Kim

Absolutely, unless something weird is going on with that thing tied forward is going to fry that thing if it hasn't already.
The reason I say unless something weird is going on is because it's possible it's manual body and they just plugged the linkage hole with the linkage and it isn't actually doing anything.

Tying it all the way rearward should produce some really late and hard shifts if it's NOT a manual VB.

Then if it is determined that is NOT a manual VB, then the cable solution would take care of that easy enough.

Thanks oldkimmer for letting me piggy back this on your comment.
 
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I see a few areas that need work. The "hose" used for the forward ATF cooler line really should be solid steel tubing like stock. If you cannot find any, the hose needs to be Heavy Duty hose designed for the heat and pressure that they would see for this kind of use.
Seeing the linkage arm held forward with plastic zip ties tells me that your transmission guy took some short cuts. I don't mean to offend but someone does not know what they are doing. If this is a manual valve body setup, why not just remove the arm? Still, why use what looks like light duty fuel line hose to handle transmission oil that can get to 180 degrees or more?

Also, you wrote......" i need to dyno this thing but i think im putting out around 300-400 horsepower."
That is a pretty wide range to estimate...25%. I didn't see if this was a 318 or 360, the cam or the compression. No matter what, that transmission could get fried to bits pretty quick if you don't get the kickdown sorted out quickly. No engine with more than 180 HP ever was installed with a 904 transmission behind it. Every 340 had a 727 if it was an automatic and they were rated at 290 HP for the 1970 340 six pack, 275 for the 340 4 barrel from 68-71 and 240 HP from 72-73. A stock rebuild on a 904 cannot take the abuse that a 727 can. Even if you are on the low end of the HP estimate, a stock 904 is not designed to take it. Is this a stock rebuild? Does it have a billet drum? Kevlar clutches? Drilled valve body to increase flow? Anti-balloon plate in the converter? What size and stall of the converter?
 
Did the trans guy just put new clutches and seals in trans or did he install the manual v/b kit, you need to get more info from him. It looks like you can do various things on your car you mite want to spend less then 100.00 an buy some tools and read some information on transmissions, they are very simple
I have used 2 manual v/b in the past t/f forward pattern and rev pattern both had full line pressure, there are ways to make it manual v/b and keep the throttle pressure stock (needing linkage from carb). It sounds like test time like kern dog said the linkage arm needs to be all the way back and will give full line pressure, take for a road test and report back.
 
ok guys, i tied the lever to the rear and it works way better now. it feels like its shifting way better now. too bad the roads were wet so i couldn't get a good feel for it. but yeah its way better....so simple. so when you pull it to the rear you can feel the spring tension. i had to use a long piece of tie wire to go to the transmission cross member.

Kern Dog yea the previous owner and my transmission shop have some issues for sure. I need to get those hoses upgraded, i think steel lines are out of the picture due to the cooler being mounted on the front of the radiator, is there a good flexible hose out there that i can use?

This is a 340 bored 30 over (345 cubic inches) 2.02" intake valves 1.6" exhaust valves, with erson high flow cam (420421), holly 4150 750 cfm carb, 360 heads and 273 adjustable rocker arms, im not sure what has been done to the transmission, not sure of the size and stall of the converter either. looking through old invoices looks like GER thunderbolt 10 plus f/c transbrake 904 340 1972 ext 4:56 3100 lbs, part number g-19732 10 plus transbrake nitrous w/wtgs trade in,. 8.85:1 compression ratio, MSD ignition system with m6 box. will be taking it to a dyno very soon so we can see what horse power its realy putting out. both the transmission shop and original owners were flakes and i no longer talk to them. so im sort of starting from scratch.

The trans guy just put new clutches, steels, bands, seals. i am guessing the manual vb kit was already there from the previous owner.


Hopefully these roads dry up and can do some more testing, boooyahhh baby
 
Any other thoughts on this stuff guys?

Im using dayco transmssion cooler line, DAYCO® Transmission Oil Cooler/Power Steering Return Line Hose think this stuff will hold up, or do i need to use some copper, aluminum or braided lines?

Another questions i have is how do adjust my valves, i have 587 heads (are those considered 360 heads?) with the 273 adjustable rockers, how do i adjust those or check adjustment? When i first blue printed the engine, i found some excessive wear on the rocker shafts and rock arms on one side, i polished them up to smooth them out, im thinking some of the oil passages were plugged? anyway now i need to check and adjust them. Valve cover gaskets are leaking, so i can address this at the same time, any ideas on the gasket and what is the best installation method.

Any one here updated the rear axles to get a bigger bolt pattern for bigger tires?

I got the hood scoop done, check it out, i bought it off craigslist for 65 bucks. Im getting a k and n x stream airflow top plate so that air will be pushed right in the top of the air cleaner.

What are your guys guess on the horse power? I should be going to the dyno soon, if the winter stays away.

Any ideas on some mufflers that will make it quiet but hold up to the horsepower without taking away horsepower? i was thinking of adding a H pipe too. i have the summit mufflers in it right now, 3", 633230, still to loud

Kern Dog any more ideas, think i should take that accumulator spring out or do you think its probably already gone? Also should i try adjusting line pressure? The shifts are way better now that lever is in the right spot, but i think i have room for improvement.

Thanks for the input

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The rocker shafts have a specific orientation. look on the ends. there is a little notch there. The notch always goes to the left and down. On the passenger side left is up by the firewall. On the drivers side, left is up by the rad.
This is done this way to align the oil supply from the rocker pedestals with the oil access holes in the rockershafts.
For street use I leave some accumulator spring in there.Is this car gonna spend time on the street? It's a personal thing. Without any spring in there at all, I find the 1-2 shift rather violent. Especially with the KD tied back like that. BTW, that lever should be tied to the tranny itself and not to the chassis.

3" pipes are loud, no matter what. I am very happy with my Dynomax 3pass mufflers.
What brand of headers are those?
What are the cam specs? I googled and came up with nothing
8.85 compression ratio? Is that thing set up for supercharging? As far as 340s go, that's pretty low.
What stall speed and rear gears are you running
 
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Two thoughts from me:
  1. 904's don't need a lot of work to take a pounding. Many run them behind high hp motors, and I'm talking drag cars.
  2. "traction bars don't work" is pure bologna. There are systems that work better, but I can tell you, when you back end raises up 2 inches when you floor it, it's because something is giving it the torque to raise it up. It's called Pressure. I've seen them make one leggers spin both tires. They work, may not be the best, but they work. I've used pinion snubbers, slapper bars that replace the shock mounts, but traction bars help also.
 
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