Re: Broken 727 Tail Housing Causes?
[Re: Moparrob68]
#3060747
07/19/22 11:44 PM
07/19/22 11:44 PM
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Joined: Jan 2003
Posts: 9,986 Frostbitefalls MN (Rocky&Bullw...
gregsdart
master
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master
Joined: Jan 2003
Posts: 9,986
Frostbitefalls MN (Rocky&Bullw...
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The problem is you have too solid of a support (rear trans mount) and have enough flex in your chassis to break the tail housing. Maybe it was barelyholding up, and the engine failurepushed it over the limits. I run a mount that "floats" between rubber bisquits from bayonet end shocks. That gives it support, but i am carefull there is still a bit of give incase of severe stress. Running that deal since 1997, maybe i should check to see if i need new biscuits. 8.70s, no problems ever.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Broken 727 Tail Housing Causes?
[Re: gregsdart]
#3060799
07/20/22 06:48 AM
07/20/22 06:48 AM
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Joined: Jan 2003
Posts: 8,021 Tulsa OK
Bad340fish
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master
Joined: Jan 2003
Posts: 8,021
Tulsa OK
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Those poly trans mounts are really stiff, I'd put something much softer in there.
68 Barracuda Formula S 340
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Re: Broken 727 Tail Housing Causes?
[Re: dvw]
#3060812
07/20/22 07:59 AM
07/20/22 07:59 AM
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Joined: Jan 2003
Posts: 13,357 Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
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Marion, South Carolina [><]
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I've broken two tailshaft housings w/ my cuda years ago. Both were due to twisted driveshafts. This was back when I had stock motor mounts w/ a torque strap and a poly trans mount. Car ran 10.40s then.
CHIP '70 hemicuda, 575" Hemi, 727, Dana 60 '69 road runner, 440-6, 18 spline 4 speed, Dana 60 '71 Demon, 340, low gear 904, 8.75 '73 Chrysler New Yorker, 440, 727, 8.75 '90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt '06 GMC 2500HD LBZ Duramax
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Re: Broken 727 Tail Housing Causes?
[Re: Moparrob68]
#3060930
07/20/22 12:43 PM
07/20/22 12:43 PM
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Joined: Feb 2005
Posts: 20,159 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,159
PA.
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Cracked the tail housing on the first pass of the year. Looking for probable causes. 1968 Cuda tube chassis car 440/727 1/4" front motor plate, 0.090 mid plate, bolt through urethane trans mount New 3.5" CM driveshaft, 1350 solid joints, 1" freeplay, same length as old 3" shaft Ladder bars with coil overs, 1degree pinion angle, so there shouldn't be much movement in the front yoke 4200 two step chip on the trans brake.
Have been running this setup 4 years, last year it broke 2 rods in a violent explosion at the 1/4 mile finish line so I suppose the shock from that could have cracks it. Just trying to avoid cracking another one as it wasn't a fun ride when the fluid got on the slicks at 135mph One degree or minus one degree. Nose up or nose down.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: Broken 727 Tail Housing Causes?
[Re: pittsburghracer]
#3060932
07/20/22 12:46 PM
07/20/22 12:46 PM
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Joined: Jan 2003
Posts: 19,361 Las Vegas
Al_Alguire
I Live Here
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I Live Here
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Posts: 19,361
Las Vegas
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I would look very closely at our driveshaft....Every broken tailshaft housing I have ever worked on or seen was due to a bad driveshaft.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: Broken 727 Tail Housing Causes?
[Re: dvw]
#3061122
07/20/22 10:04 PM
07/20/22 10:04 PM
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Joined: May 2019
Posts: 712 Lake Villa Il
INTMD8
super stock
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super stock
Joined: May 2019
Posts: 712
Lake Villa Il
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What's the front u-joint angle? Also what front slip yoke? (I've seen many sloppy billet ones which can vibrate like hell)
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Broken 727 Tail Housing Causes?
[Re: dvw]
#3061140
07/20/22 10:42 PM
07/20/22 10:42 PM
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Joined: Apr 2016
Posts: 108 WNY
Moparrob68
OP
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WNY
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Re: Broken 727 Tail Housing Causes?
[Re: Moparrob68]
#3061145
07/20/22 11:27 PM
07/20/22 11:27 PM
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Joined: Mar 2006
Posts: 9,825 MI, usa
dvw
master
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master
Joined: Mar 2006
Posts: 9,825
MI, usa
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That would be my smoking gun. Unless the mid plate has some tubing across its length tied to the cage. That would leave all the fore/aft movement taken up by the trans mount. That transfers all the load to the tail shaft housing. Doug
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Re: Broken 727 Tail Housing Causes?
[Re: dvw]
#3061147
07/20/22 11:46 PM
07/20/22 11:46 PM
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Joined: May 2019
Posts: 712 Lake Villa Il
INTMD8
super stock
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super stock
Joined: May 2019
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Lake Villa Il
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Wouldn't hurt to also check that the u-joints on the driveshaft line up. New doesn't always mean good and that's a newly introduced variable.
My experience is the same as Al_Alguire. Broken tailshaft almost always due to the driveshaft. (specifically approaching critical speed or imbalance)
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Broken 727 Tail Housing Causes?
[Re: INTMD8]
#3061177
07/21/22 04:59 AM
07/21/22 04:59 AM
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Joined: Dec 2013
Posts: 4,669 Wichita
GY3
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master
Joined: Dec 2013
Posts: 4,669
Wichita
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We had a u-joint retaining clip come out and a u-joint cap come out.
The driveshaft had been shortened, rebuilt and had been in the car for thousands of miles.
It happened on a backroad at the top of second gear. Sliding around in transmisison fluid at close to 100 mph.
It didn't come fully apart but just the one missing cap caused the tailshaft housing to break and the tailshaft to bend.
I use another driveshaft shop now...
'63 Dodge 330 11.19 @ 121 mph Pump gas, n/a, through the mufflers on street tires with 3.54's. 3,600 lbs. 10.01 @ 133mph with a 250 shot of nitrous an a splash of race gas. 1.36 60 ft. 3,700 lbs.
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Re: Broken 727 Tail Housing Causes?
[Re: SLO-KID]
#3061337
07/21/22 01:25 PM
07/21/22 01:25 PM
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Joined: Jan 2003
Posts: 19,361 Las Vegas
Al_Alguire
I Live Here
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I Live Here
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Posts: 19,361
Las Vegas
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(Artist formerly known as J-body)
You could have just changed your username ya know, rather than "starting over"
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: Broken 727 Tail Housing Causes?
[Re: Al_Alguire]
#3061522
07/21/22 09:58 PM
07/21/22 09:58 PM
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Joined: Jul 2022
Posts: 11 AZLIVN
SLO-KID
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member
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Posts: 11
AZLIVN
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(Artist formerly known as J-body)
You could have just changed your username ya know, rather than "starting over" Not sure what happenedâŚ.. one day I just couldnât log in. Been lurking a couple weeks or better. âŚ..and I still have 3 727 tailshafts from âthe good ole daysâ đ
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