904 trans shifting issue

[DartVadar]

I was just going through a few threads on here and kinda made me think that I may have a problem with my trans. Its a 904 and I installed a tf2 shift kit in it (followed instructions closely). When shifting into 2nd it is nice and firm like it should be, but the 2-3 shift isn't firm, its smooth, the rpms just drop down. The kickdown is adjusted properly and the fluid is full (checked while warm in neutral). The fluid also looks and doesn't smell burnt or anything.

What would shift overlap feel like? and another thing I noticed is it likes to shift pretty early all the time, I can usually go everywhere including 65mph on the highway without going past 2k rpm, but I still haven't changed out the 2.76 gears so that could be a reason. It only lets the rpms get up with more throttle, probably at least half, is this normal? It kicksdown good though.

Giving it good throttle it chirps the tires on the 1-2 shift and when it shifts into 3rd it almost feels like it bogs down a bit and the rpms drop. This may be completely normal, but just want to make sure.

 

[fishy68]

Shift overlap is when it's in a gear and a shift valve calls for the next gear but the previous gear is slow to release so for a split second its in 2 gears. Not good as you can imagine.

You say it's smooth going from 2 to 3. That doesn't really sound like overlap because overlap is generally a "jerky" sort of feel. Maybe I'm reading it wrong but to me your last sentence kinda contradicts how you described the 2-3 shifter earlier. If it is truly bogging down when it shifts and there's nothing wrong with the engine it may be experiencing overlap. Or it could be that with the tall hwy gears it's bogging down because the engine doesn't have enough guts to pull through the 3rd gear shift?? Shooting in the dark here

 

[FredS]

did you also follow the tf2 instructions to the minimum hole sizes, or did you go bigger? Did you adjust the pressures at all?
Was the trans fresh, or does it have some miles on it?
Did you block the Accumulator when you did the shift kit?

Stock converter?

Any other factors you can share?

 

[oldkimmer]

............Sounds like u have a problem..................give us more details............kim.......

 

[DartVadar]

Shift overlap is when it's in a gear and a shift valve calls for the next gear but the previous gear is slow to release so for a split second its in 2 gears. Not good as you can imagine.

You say it's smooth going from 2 to 3. That doesn't really sound like overlap because overlap is generally a "jerky" sort of feel. Maybe I'm reading it wrong but to me your last sentence kinda contradicts how you described the 2-3 shifter earlier. If it is truly bogging down when it shifts and there's nothing wrong with the engine it may be experiencing overlap. Or it could be that with the tall hwy gears it's bogging down because the engine doesn't have enough guts to pull through the 3rd gear shift?? Shooting in the dark here

It isnt jerky at all. I know the gears really hurt the car, I have read that I need at least 3.55s for the car to really perform properly. The motor is fine as far as I can tell, and usually when I notice this it shifts into third and the rpms drop to about 1800, the car really starts to get going past 2500 ish. Maybe I did contradict myself, but the shift feels almost like shifting a manual trans 2 gears instead of one (2-4 or something), and it stays like that until the car speeds up and starts to get into stride again, so maybe its just bogging nothing else. I also have a 27 inch rear tire, so that mixed with the 2.76 gears gets the rpms pretty low.

did you also follow the tf2 instructions to the minimum hole sizes, or did you go bigger? Did you adjust the pressures at all?
Was the trans fresh, or does it have some miles on it?
Did you block the Accumulator when you did the shift kit?

Stock converter?

Any other factors you can share?

I am using the stock converter, and when I installed the shift kit I went a bit on the larger side for the holes, no too big though. I didn't adjust anything, just what the instructions said to do. The trans mileage is actually unknown, but I think its fairly low mileage, I just used it because it is actually a 999 with a low gear set, I have a 727 on the shelf that I will use if this one turns out to be no good or doesn't hold up. And what was the accumulator? is that the orifice plug?

The car used to have a 318, I pulled that out and put in a fresh 360, I just installed the shift kit and put the trans back in (the converter was brand new, and the trans looked really nice inside, I got the trans with that converter). Also before the engine swap the trans shifted nicely as far as I can remember, I never drove it much so I cant fully remember what the 2-3 shift was like.


Other details, engine is a 400hp ish 360, 2.76 rear gears, stock lockup converter, low gear set, running a 27 inch rear tire, don't think there is much else.

 

[fishy68]

It isnt jerky at all. I know the gears really hurt the car, I have read that I need at least 3.55s for the car to really perform properly. The motor is fine as far as I can tell, and usually when I notice this it shifts into third and the rpms drop to about 1800, the car really starts to get going past 2500 ish. Maybe I did contradict myself, but the shift feels almost like shifting a manual trans 2 gears instead of one (2-4 or something), and it stays like that until the car speeds up and starts to get into stride again, so maybe its just bogging nothing else. I also have a 27 inch rear tire, so that mixed with the 2.76 gears gets the rpms pretty low.

I bet it's the gears boggin it down if it truly is a 400'ish hp 360. They like to rev.

I am using the stock converter, and when I installed the shift kit I went a bit on the larger side for the holes, no too big though. I didn't adjust anything, just what the instructions said to do. The trans mileage is actually unknown, but I think its fairly low mileage, I just used it because it is actually a 999 with a low gear set, I have a 727 on the shelf that I will use if this one turns out to be no good or doesn't hold up. And what was the accumulator? is that the orifice plug?

The accumulator is the round aluminum piston with a short thick spring that falls out when you take down the valve body. A trick to firm up the 1-2 shift is to block the accumulator.

The car used to have a 318, I pulled that out and put in a fresh 360, I just installed the shift kit and put the trans back in (the converter was brand new, and the trans looked really nice inside, I got the trans with that converter). Also before the engine swap the trans shifted nicely as far as I can remember, I never drove it much so I cant fully remember what the 2-3 shift was like.


Other details, engine is a 400hp ish 360, 2.76 rear gears, stock lockup converter, low gear set, running a 27 inch rear tire, don't think there is much else.

....

 

[DartVadar]

Yea it loves to rev alot, once the RPMs get up I start to loose traction no matter how fast im going lol.

And I didn't block it I don't think, I just did what the transgo kit said in the instructions, I'm really happy with how it shifts and drives besides the bogging issue, or even if its an issue associated to me messing with the trans.

If I get the car out any more before winter I will maybe take a video of the tach.

 

[tekslk]

Not sure but you might need some 391 gears with that set up that will take the high gear bog out of it. Good luck.

 

[DartVadar]

I am planning on 3.91s when I put in my 8 3/4, I can imagine they will make the car feel like it has alot more go.

 

[fishy68]

3.91's will make a world of a difference