Big power & 727… input or output shaft the weak link?
#3125412
02/28/23 07:06 PM
02/28/23 07:06 PM
|
Joined: Jan 2003
Posts: 2,697 Renton Wa
topfueldart
OP
master
|
OP
master
Joined: Jan 2003
Posts: 2,697
Renton Wa
|
I’ve got a 727 with all the normal heavy duty must haves, billet front drum, super sprag, steel front planet, billet servos and heavy struts and pump gears. I’ve got the trans out for a converter check and refresh, and just considering my remaining options for making it even stronger. Who has had a failure with an input shaft/hub, or an output shaft? Both look to be approaching $1000, so trying to decide if one or the other is more of a weak link. Also considering a rear roller kit.
Car is 3600 lbs with driver, leaving off a transbrake, running low 10’s, 60’s high 1.3x, and hopefully a little faster in the future.
Thanks all!
Last edited by topfueldart; 02/28/23 07:27 PM.
11.48 @ 120 with a 1.80 60' 318, stock 1.88 heads, stock 904, Pump Gas, 13 lbs of boost.
9.94 @ 134, 318 on pump gas, 14 lbs w/ Eddies, transbrake 727, 3600 lbs, 3.54 gear and 28's.
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: J_BODY]
#3125444
02/28/23 09:53 PM
02/28/23 09:53 PM
|
Joined: Mar 2006
Posts: 9,834 MI, usa
dvw
master
|
master
Joined: Mar 2006
Posts: 9,834
MI, usa
|
My input and output shafts have 850+ passes. Though all are footbrake. I've broken 3 Dana pinion gears. Dizusters turbo car also ran stock shafts. Its broken rear axle pinion shafts, aftermarket steel drive shafts. But never either trans shaft, Both were over 850 hp. His weighed 3750, mine 3350. Both are 65 push button. Both have stripped stock front planet carriers. Both run stock pump gears. Doug
Last edited by dvw; 02/28/23 09:54 PM.
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: J_BODY]
#3125468
02/28/23 10:44 PM
02/28/23 10:44 PM
|
Joined: Jan 2003
Posts: 2,697 Renton Wa
topfueldart
OP
master
|
OP
master
Joined: Jan 2003
Posts: 2,697
Renton Wa
|
I’d run em! Personally I’ll think you’ll be fine. At its current power level, I think it’s ok, but being it’s turbo’d, it’s really easy to pickup another 100 horse. I did already break a set of stock pump gears, and I plan to do a drag and drive this year, so considering all upgrade options since it’s already out. I think my combo is potentially pretty hard on hard parts leaving on a bunch of boost with the transbrake, and stiff/short radials.
11.48 @ 120 with a 1.80 60' 318, stock 1.88 heads, stock 904, Pump Gas, 13 lbs of boost.
9.94 @ 134, 318 on pump gas, 14 lbs w/ Eddies, transbrake 727, 3600 lbs, 3.54 gear and 28's.
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: topfueldart]
#3125470
02/28/23 10:54 PM
02/28/23 10:54 PM
|
Joined: Dec 2005
Posts: 11,551 Fulton County, PA
CMcAllister
Mr. Helpful
|
Mr. Helpful
Joined: Dec 2005
Posts: 11,551
Fulton County, PA
|
Rollerized rear support is a no brainer.
If the results don't match the theory, change the theory.
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: topfueldart]
#3125474
02/28/23 11:00 PM
02/28/23 11:00 PM
|
Joined: Mar 2006
Posts: 9,834 MI, usa
dvw
master
|
master
Joined: Mar 2006
Posts: 9,834
MI, usa
|
I’d run em! Personally I’ll think you’ll be fine. At its current power level, I think it’s ok, but being it’s turbo’d, it’s really easy to pickup another 100 horse. I did already break a set of stock pump gears, and I plan to do a drag and drive this year, so considering all upgrade options since it’s already out. I think my combo is potentially pretty hard on hard parts leaving on a bunch of boost with the transbrake, and stiff/short radials. Dizusters ran 22lbs boost, trans brake, radials. 1.38/9.55@142 3750lbs full exhaust with the same M/T radials it ran on tthe street. Doug
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: topfueldart]
#3125523
03/01/23 04:47 AM
03/01/23 04:47 AM
|
Joined: Jan 2005
Posts: 2,540 Milwaukee WI
TRENDZ
master
|
master
Joined: Jan 2005
Posts: 2,540
Milwaukee WI
|
if you have it apart, look at the oil holes in both the input and output. when they’re getting ready to let loose, the oil holes will be oval instead of round. also check the input splines. if they aren’t straight, you’re at the limits of stock shafts.
"use it 'till it breaks, replace as needed"
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: topfueldart]
#3125527
03/01/23 07:14 AM
03/01/23 07:14 AM
|
Joined: Jan 2003
Posts: 2,915 A shed in England
Tig
master
|
master
Joined: Jan 2003
Posts: 2,915
A shed in England
|
Broke an O/P shaft, 9.60 / 9.70 1/4, mid 1.30's 60, car w/d was 3900lb, motor around 880hp at the time, footbrake only. We upgraded the I/P and O/P shaft while it was apart. We have a 655 waiting for parts, to go in. We will run it behind that but before we fit N20 we are going to a TH400 derived box.
Last edited by Tig; 03/01/23 07:21 AM.
'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
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: topfueldart]
#3125558
03/01/23 09:29 AM
03/01/23 09:29 AM
|
Joined: Oct 2007
Posts: 4,206 New York
polyspheric
master
|
master
Joined: Oct 2007
Posts: 4,206
New York
|
What does this remind me of? "When should I stop "improving" my 8-3/4 and get a 9"?"
Rossler T400
Boffin Emeritus
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: A727Tflite]
#3125577
03/01/23 10:07 AM
03/01/23 10:07 AM
|
Joined: May 2003
Posts: 13,187 aZLiViN
J_BODY
I Live Here
|
I Live Here
Joined: May 2003
Posts: 13,187
aZLiViN
|
Interesting on the pump gears….. I lost a set in my old dump truck trans. What kind of power were you making? Mid 9 sec small block. 3k weight. Leave 4500-5k off the brake. I’m now at low 9’s with an incredibly stock component 904…… but I used simple mopar math for that swap 904>727. 86 passes and ok so far. Good thing I don’t race much I guess.
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: topfueldart]
#3125658
03/01/23 02:02 PM
03/01/23 02:02 PM
|
Joined: Jan 2003
Posts: 25,783 Rio Linda, CA
John_Kunkel
Too Many Posts
|
Too Many Posts
Joined: Jan 2003
Posts: 25,783
Rio Linda, CA
|
As most probably know, there is a factory HP input shaft identified by a radial groove and (sometimes) a yellow paint daub, it's made of a better alloy steel. I believe the majority of input failures aren't the shaft itself but the hub at the rear clutch piston retainer.
The INTERNET, the MISinformation superhighway
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: 440Jim]
#3125699
03/01/23 04:38 PM
03/01/23 04:38 PM
|
Joined: Mar 2009
Posts: 2,461 Sydney,Australia
tex013
top fuel
|
top fuel
Joined: Mar 2009
Posts: 2,461
Sydney,Australia
|
[ [/quote] I broke the "ears" off one set of stock 727 pump gears also. It happened during the Mopar weekend about 2008, during time trials. With the help of a couple racers, we pulled the trans, took it apart, found some new pump gears at a vendor; and I made the first round of eliminations. [/quote] I sheared the pump lugs/ears driving up the freeway , trans shop asked if I had any backfires . None , I think after 15 yrs use it was bad luck . But it filled the trans and cooler with metal . So I bought billet gears and a super sprag as upgrades . Footbrake low mid 10s . I do have a Griner vb . Tex
New best ET 10.259@129.65 . New best MPH 130.32 Finally fitted a solid cam, stepped it up a bit more 3690lbs through the mufflers New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm Power by Tex's Automotive
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: 71Demon528]
#3125704
03/01/23 04:56 PM
03/01/23 04:56 PM
|
Joined: Jan 2003
Posts: 75,003 U.S.S.A.
JohnRR
I Win
|
I Win
Joined: Jan 2003
Posts: 75,003
U.S.S.A.
|
Dang Jim! That’s crazy.
I know mine has hardened input and output shaft and steel input hub. But for what he’s doing I wonder if it will be ok running 10s.
I know Rick Allison gives a general recommendation of 800hp and above 3,000lbs, he recommends the aftermarket shafts. A friend of mine was doing the burnout contest at carlisle one year and broke the output shaft at the end of the front planet splines. Car was stationary , 383 - 2bbl in a 69 Satellite wagon. What happened was the spiders in his single track 3.23 gear rear end seized on it's shaft shaft and in the split second it took for the spiders to break into pieces it shocked the driveline enough to break the output shaft. He was lucky because the rear sprag in the trans was also rolled, I don't know when that happened though as he didn't really beat on the car outside of that one burnout contest.
running up my post count some more .
|
|
|
Re: Big power & 727… input or output shaft the weak link?
[Re: John_Kunkel]
#3125705
03/01/23 04:58 PM
03/01/23 04:58 PM
|
Joined: Jan 2003
Posts: 75,003 U.S.S.A.
JohnRR
I Win
|
I Win
Joined: Jan 2003
Posts: 75,003
U.S.S.A.
|
As most probably know, there is a factory HP input shaft identified by a radial groove and (sometimes) a yellow paint daub, it's made of a better alloy steel. I believe the majority of input failures aren't the shaft itself but the hub at the front clutch piston retainer. The Diesel trucks usually split the hub instead of breaking the shaft out of the hub.
running up my post count some more .
|
|
|
|
|