RPM Change 727
#2690827
08/24/19 01:54 AM
08/24/19 01:54 AM
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Joined: Jan 2003
Posts: 3,831 N.E. Ohio
6bblFLASH
OP
master
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OP
master
Joined: Jan 2003
Posts: 3,831
N.E. Ohio
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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.
70` Cuda`,440 6BBL Jerico,Dana 4.56 Still on 93 Pump Gas 9.87 @ 136/1.31-60ft.`09 Mopar Nationals PASSON PERFORMANCE "Stick-Shift" Champ! 2013 StickShift Challenge Winner@ Mopar Nationals!
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Re: RPM Change 727
[Re: MR_P_BODY]
#2690877
08/24/19 10:14 AM
08/24/19 10:14 AM
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Joined: Jan 2003
Posts: 3,831 N.E. Ohio
6bblFLASH
OP
master
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OP
master
Joined: Jan 2003
Posts: 3,831
N.E. Ohio
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I would guess that the clutches are slipping some.. how is the adjustment on them.. check line pressure also 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...........
70` Cuda`,440 6BBL Jerico,Dana 4.56 Still on 93 Pump Gas 9.87 @ 136/1.31-60ft.`09 Mopar Nationals PASSON PERFORMANCE "Stick-Shift" Champ! 2013 StickShift Challenge Winner@ Mopar Nationals!
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Re: RPM Change 727
[Re: MR_P_BODY]
#2690934
08/24/19 02:28 PM
08/24/19 02:28 PM
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Joined: Dec 2005
Posts: 11,551 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,551
Fulton County, PA
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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.
Last edited by CMcAllister; 08/24/19 02:31 PM.
If the results don't match the theory, change the theory.
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Re: RPM Change 727
[Re: Hutch]
#2691086
08/25/19 12:45 AM
08/25/19 12:45 AM
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Joined: Jan 2003
Posts: 3,831 N.E. Ohio
6bblFLASH
OP
master
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OP
master
Joined: Jan 2003
Posts: 3,831
N.E. Ohio
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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
70` Cuda`,440 6BBL Jerico,Dana 4.56 Still on 93 Pump Gas 9.87 @ 136/1.31-60ft.`09 Mopar Nationals PASSON PERFORMANCE "Stick-Shift" Champ! 2013 StickShift Challenge Winner@ Mopar Nationals!
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Re: RPM Change 727
[Re: 6bblFLASH]
#2691095
08/25/19 01:56 AM
08/25/19 01:56 AM
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Joined: Aug 2003
Posts: 43,159 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,159
Bend,OR USA
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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
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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