904 shifting problems 2nd to 3rd

[airwoofer]

So I finally got the trusty old 340 out of my fish and put in the 416 stroker. I rigged the kickdown linkage for the 904 so when the carb is strating to turn on the secondaries (manual) the kickdown was starting to get "tension" or feel like it was doing something. Full throttle coincides with full kickdown travel.

At the track for the first time and the footbraks launch was good (converter only about 2000-2200) and the 1st to 2nd shift went OK (I am shifting the car). When it came time to hit 3rd I thought I had overrun into neutral as the engine raced up to the 7000 limiter. I let up, down shifted and coasted across the line. The car did the same thing the next pass and on the third pass I noticed that if I let up as the engine raced as the tranny shifted to 3rd then stomped on the gas again the thing would shift faster but still has the issue.

Is my kickdown not adjusted properly? Should I "loosen" it up some?

Is the added power of the stroker causing havoc with the valve body or whatever inside the tranny?

The car was shifting fine (not in Drive but me shifting) with the 340.

 

[oldkimmer]

............sounds like the kd isnt set right............adj so the carb and kd are at the max at wot......block the gas pedal inside or have some1 help u, maybe its not going wot........kim.................

 

[TrailBeast]

Too tight of a kickdown linkage wouldn't neutral out, it would just shift really late.
It's not burning the fluid is it?

So I finally got the trusty old 340 out of my fish and put in the 416 stroker. I rigged the kickdown linkage for the 904 so when the carb is strating to turn on the secondaries (manual) the kickdown was starting to get "tension" or feel like it was doing something. Full throttle coincides with full kickdown travel.

At the track for the first time and the footbraks launch was good (converter only about 2000-2200) and the 1st to 2nd shift went OK (I am shifting the car). When it came time to hit 3rd I thought I had overrun into neutral as the engine raced up to the 7000 limiter. I let up, down shifted and coasted across the line. The car did the same thing the next pass and on the third pass I noticed that if I let up as the engine raced as the tranny shifted to 3rd then stomped on the gas again the thing would shift faster but still has the issue.

Is my kickdown not adjusted properly? Should I "loosen" it up some?

Is the added power of the stroker causing havoc with the valve body or whatever inside the tranny?

The car was shifting fine (not in Drive but me shifting) with the 340.

 

[airwoofer]

KD and carb both max out together. I'll smell the fluid but doubt it is burned. 1st to 2nd shifts OK. I am manually shifting, not in DRIVE.

 

[cudamark]

So it will go into 3rd but not at WOT? I'm assuming this is still a full automatic and not converted to manual only? Standard shift pattern....not reverse? Sounds like the front clutch isn't applying like it should. You may want to pull the pan and valve body to do a pressure test. I'd look at the 2-3 shift and shuttle valve while I was at it.

 

[dodge freak]

Man your putting a fresh stroker engine up to an old trans--its going to slip !!

If you don't mind shirting yourself you might want to look in to a manual valve body for the trans and ditch the kickdown linkage--the tranny might last longer..that engine is going to be putting out good power at part throtlle--a cable vs the rod would be best if you don't want a manual valve body

 

[fishy68]

If the KD is for sure wide open when the carb is and it's flaring up going into 3rd it sounds like the front clutch pack is slipping. That can happen if you put a fresh engine (especially a torquey stroker) in front of an old trans. If it isn't real high mileage trans. a good shift improver kit or manual VB may help but if it has very many miles on it it probably needs rebuilt and a shift improver kit or manual valve body added. 904's are decent transmissions but they have their limit, especially when their stock. My personal feeling is a stock rebuilt 904 is good for about 325-400 hp depending on how many clutch plates in the clutch packs. Add a Trans-go shift kit or manual VB and it's good for 450'ish hp. They can be easily upgraded to handle more.

 

[airwoofer]

Well the stroker dyno'd at 500 HP so maybe the little 904 is overwhelmed. It has led a hard life being flogged on the track for the last bunch of years. Guess when I take all this apart for paint it will be tranny time. This is the reason I put the engine in - to get the bugs worked out before I get pretty paint put on.

I want to keep the VB so the car can be driven as normal and not have to shift manually all the time. Just like shifting manually at the track.

 

[fishy68]

That's what it is then. Put a Trans-go TF-2 kit in it when you rebuild it and you can manually shift it when you want yet it'll still shift on it's own. When you rebuild it make sure and use top quality friction plates and kolene coated steels and make sure there's at least 4 frictions in the front drum and convert it to a multi return spring drum.

BTW: how in the heck did you get the weight so low on your 68 FB? I have the same car except a 727 trans. and it weighs 3460 with a half tank of gas and without me in it. I've never seen a fastback 3050# unless it was stripped for racing. I have a stereo system and dynomat under that carpet so that may add an extra 50# to mine but that's it.

 

[airwoofer]

This thing is stripped pretty bad. Aluminum panels instead of sides, no rear seat, no heater, no wipers. I have stock doors on it now with the glass but the ones that were on only had a piece of plastic stuck where the windows would be (not the wing vent though). I estimate the stock doors added 20+ pounds each. The car also had mufflers plus I weigh 240 so the car itself was probably 2800 or less. I am trying to get mufflers put on before this Sundays track day and will see if they will weigh it again. It is too fast now and needs to gain weight which it will cause I will be putting the interior back to stock with headre4st bucket seats and console from the 67 parts car. The car has a 5 gallon race tank in the spare tire well and it was probably 1 gallon down when I weighed it.

Hopefully I can find someone locally here to do the tranny work. I knew the stroker would find the next weak link. Gonna try putting it in DRIVE and letting it shift itself next time. Didn't work with the 340 though.

 

[fishy68]

Ahh... No wonder it's so light. You might contact strokerscamp and see if he knows someone that might be able to help. He's in Georgia so he's only a state away.

 

[airwoofer]

Well, before taking the rod to the track last weekend I had it running in my shop and actually took the time to measure how much fluid was in it. Looked low so I added a quart of ehat I had around, B&M trick shift which was blue instead of the red stuff the PO had inside. Phunny cause I got the case of B&M with the other stuff he had with the car from his widow. The added quart didn't look like enough so I added another. Now it was too full. Took it down the street, jumped on it a couple times. Had some leaks on the shop floor after that. loaded it up on the trailer and took it to the track.

No miss on 2-3 shirt this time. Basically the same ET (tad quicker but it was 2 degreees cooler that day) with exact same MPH and 60' and 330'. Guess the tranny is OK, just operator error. Probably still need a looser converter for the launch.