Re: Transmission planetary pinion ?
[Re: racerx]
#2855640
12/05/20 11:55 AM
12/05/20 11:55 AM
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Joined: Jan 2003
Posts: 2,915
A shed in England
Tig
master
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master
Joined: Jan 2003
Posts: 2,915
A shed in England
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https://www.bing.com/videos/search?q=how+to+detremine+the+gear+ratio+in+a+727+transmission&&view=detail&mid=68DF957DF16E85999B6068DF957DF16E85999B60&&FORM=VRDGAR&ru=%2Fvideos%2Fsearch%3Fq%3Dhow%2Bto%2Bdetremine%2Bthe%2Bgear%2Bratio%2Bin%2Ba%2B727%2Btransmission%26%26FORM%3DVDVVXX Hope this link works........found a youtube link that pretty much explains the way the gear ratio is calculated. Years ago i replace an 3 pinion for a 4 pinion planetary set that i found in a spare transmission (my thought for the change was strength) but now looking back and understanding that the planetary can be modified with a steel(for strength)so with replacing the 3 pinion for the 4 pinion with nothing else change would the gear ratio remain the same? If that makes sense.......Thanks for that response  No trans guru here but not neccessarily, if the pinion gears are the same size just spaced differently in the carrier (which is what I think they do with them) then there will be no change. Going from a 4 pinion aluminium to a 5 pinion steel never made any difference to the gear ratios and was not advertised as such. We smashed a stock O/P shaft after breaking a R and P on the Dana and upgraded both at the same time. We've had a 950ft/lb motor in front of it one time with no issues @ 3950lb. ![[Linked Image]](http://i.imgur.com/HwNJX5n.jpg) ![[Linked Image]](http://i.imgur.com/5O2t4Ss.jpg)
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Transmission planetary pinion ?
[Re: racerx]
#2855681
12/05/20 01:03 PM
12/05/20 01:03 PM
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Joined: Jan 2003
Posts: 25,750
Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,750
Rio Linda, CA
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The pics below show how the power flows through the various components in each gear.
The INTERNET, the MISinformation superhighway
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Re: Transmission planetary pinion ?
[Re: racerx]
#2855911
12/06/20 07:47 AM
12/06/20 07:47 AM
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Joined: Jan 2003
Posts: 2,915
A shed in England
Tig
master
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master
Joined: Jan 2003
Posts: 2,915
A shed in England
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That's a lot of ft/lb on a stock shaft but ,breaking a r/p doesn't help also how was that out put shaft was in that case? We broke the R and P when it had the 580 in it. Stock I/P and O/P at the time, and I'm guessing since the rear jammed, the "shock" broke the O/P shaft at the weakest place. The R and P failed as it was a hardened "street" set of gears. If you look closely you can see virtually all the teeth are cracked, they were just waiting to break. Since we were soon to be fitting a 655 motor in it, we upgraded both I/P and O/P shafts for insurance. We had previously changed the front drum gear carrier after stripping the splines out of the stock aluminium one.It's a pretty strong box and has all of the usual upgrades but if we keep increasing the power we will likely end up with a TH400 (or Rossler) Nearly everyone I know has picked up some et when doing that swap. HTH's
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Transmission planetary pinion ?
[Re: Tig]
#2855928
12/06/20 10:05 AM
12/06/20 10:05 AM
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Joined: Aug 2008
Posts: 4,066
Mo.
racerx
OP
master
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OP
master
Joined: Aug 2008
Posts: 4,066
Mo.
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That's a lot of ft/lb on a stock shaft but ,breaking a r/p doesn't help also how was that out put shaft was in that case? We broke the R and P when it had the 580 in it. Stock I/P and O/P at the time, and I'm guessing since the rear jammed, the "shock" broke the O/P shaft at the weakest place. The R and P failed as it was a hardened "street" set of gears. If you look closely you can see virtually all the teeth are cracked, they were just waiting to break. Since we were soon to be fitting a 655 motor in it, we upgraded both I/P and O/P shafts for insurance. We had previously changed the front drum gear carrier after stripping the splines out of the stock aluminium one.It's a pretty strong box and has all of the usual upgrades but if we keep increasing the power we will likely end up with a TH400 (or Rossler) Nearly everyone I know has picked up some et when doing that swap. HTH's Thanks those big cube motors are brutal........ 
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