RPM Change 727

Have an odd problem ,maybe someone has seen before.
Had issues with RPM flare/slip 2/3 shift on my streetcar.
1st trans was a stock type rebuild with a Turbo Action RMVB thrown in it. Worked fine it I turned the blower faster. 2/3 didn`t like it.
2nd trans spare race trans for the bracket car. Did`nt take long till 2/3 issue again.
Went thru it and installed 5 Koleno frictions and thin plates.
Shifts really well and firm,very happy with it. Have abused it a LOT on the street.Works very well.
So 1st pass at the track with it tonight,lost 300-RPM at the stripe at the same MPH. Went 118.89 @ 4,700 RPM.
Used to go 119@ 5,000 RPM.
I don`t believe the trans was slipping enough to add RPM, probably made 50 passes with it flaring on 2/3 and it did`nt RPM or MPH any different before or after problem started.
Seems like the converter is much tighter now 10" Turbo Action 3,200 stall.
Lost 60ft [1/10th] too but made a cam change so that could to blame for that.

I would guess that the clutches are slipping some.. how is the adjustment on them.. check line
pressure also

The 2/3 shift on a torqueflite has one issue that's hard to get around. You have to release the band and apply the high clutch to get the shift, because of that no matter what you do for a little space of time you have a clutch and a band partially applied. Band lever ratio, and adjustment as well as clutch pack clearance, number and kind of clutches all have to be juggled to get a good no flare 2/3 shift. I always look at the condition of the band and clutches to see which area I need to juggle to get it just right. If the band is dark, I tighten the band adjustment, or try a different lever ratio for example.

But the rest of your post describes what sounds like a converter issue.

Thanks Mike
That might be be true if it GAINED RPM.

It lost RPM for a given MPH. About 300rpm....
Would`nt be a problem,even a benefit on most cars,but I`m under geared already 3.33 ratio. 118mph@4,700??? 3,600lbs.
Don`t make enough torq. to drag it in high gear.
Obvious answer: more gear.
But it drives so nice hate to ruin that.
I know can`t have it both ways...........

I think your band is staying on too long which will try to lock it up and drop RPM

Do you pay attention to the air? Good air vs bad air will make a difference in power/stall speed/MPH, etc.

Overlap would have to be excessive to affect MPH, depending on how close to the stripe the shift point is.

Flare vs overlap is hard to track without data. Even a Go-Pro that you can listen to will help. A clean shift at RPM will show a fair amount of overlap when running through the gears on jackstands. I didn't want to fiddle with parts used or adjustments. I preferred to adjust the spring load in the servo to adjust the timing. There are different was to do that.

The fast, high end, performance based applications I've paid attention to often have a barely perceptible flare on the shift, I presume by design to stay away from a momentum slowing overlap.

Sure you can. Just add boost.

Kevin

What is the combination in the trans?
Servo type?
Rocker ratio?
Rear clutch clearance?
Number of return spring and length of springs?
Stator support sealing ring type?


This is a start to try and figure out why the trans is flaring and slowing the car down.


Hutch

The trans DOES NOT flair, it did before I put the 5-clutch pack n. Shifts quick and firm,very happy with it.
Question is why is it going same MPH at less RPM now.
Shift into 3rd before the 1/8th mile.
As far as weather conditions. same MPH with less RPM?
Just asking if anyone had seen this and why?
Can`t understand how converter gets tighter. Probably the cam changed the torq. curve.. I have seen that before

More power affects the converter differently , my old race motor would shift into high gear at 7000 RPM and drop back to between 4600 and 4800 depending on the trans temp, outside air temp and density altitude using the Biondo 400 box to record the runs.
My new motor shifted at 7000 RPM drops the converter back to 5200 to 5500 RPM and that made the car run 5MPH faster in the 1/8 mile, 115. versus 120 MPH now.
New motor runs around .8 faster in the 60 ft. times also, it flashes around 800 RPM higher in low gear also
IHTHs