Moparts Main Index | READ - Info & Help Page | Moparts Sponsors | Tech Archive

Forums Calendar Active Threads Search Forum Help
Previous Thread
Next Thread
Print Thread
Page 2 of 3 1 2 3
Re: Broke 727 Tailshaft... Why? [Re: Jimi_Vignogna] #359409
06/28/09 08:07 PM 06/28/09 08:07 PM
Joined: Jan 2003
Posts: 4,288
Danville, NH
M
Mopar_Mike Offline OP
master
Mopar_Mike  Offline OP
master
M

Joined: Jan 2003
Posts: 4,288
Danville, NH
Quote:

it is the poly rear mount that caused it you cannot do that with solid engine mounts you need a solid rear trans mount.



I have heard this before too..

Does anyone know where to get a solid transmission mount for a 727?

RS23L7 4-Speed



Re: Broke 727 Tailshaft... Why? [Re: Mopar_Mike] #359410
06/28/09 08:35 PM 06/28/09 08:35 PM
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
Dodgem Offline
master
Dodgem  Offline
master

Joined: Mar 2008
Posts: 5,746
Ontario, Canada
I've heard the opposite the solid trans mount will brake tail shafts. I've run solid motor mounts for years with a factory trans mount or better MP but only broke a tail shaft when my drive shaft was too short after I put different rear shackles on which moved rear end back. New drive shaft and never another problem
Re: Broke 727 Tailshaft... Why? [Re: Jimi_Vignogna] #359411
06/28/09 08:35 PM 06/28/09 08:35 PM
Joined: Jan 2003
Posts: 16,932
NC
440Jim Offline
I Live Here
440Jim  Offline
I Live Here

Joined: Jan 2003
Posts: 16,932
NC
Quote:

it is the poly rear mount that caused it you cannot do that with solid engine mounts you need a solid rear trans mount.

I don't know his problem, but that isn't it, IMO. I have been running a front motor plate, with a fore-aft "limiter" (no movement) with a stock (new) rubber trans mount. 7-8 years, ladder bar rear suspension and minimal pinion angle (correct for ladder bars). And this car launches hard...

1993 Daytona, 5.50 at 130mph (1/8) 1.19 sixty ft (PG). Link to 572 B1 - Part 1
Re: Broke 727 Tailshaft... Why? [Re: 440Jim] #359412
06/28/09 08:38 PM 06/28/09 08:38 PM
Joined: Nov 2003
Posts: 7,348
Mt.Vernon ,Ohio
VernMotor Offline
master
VernMotor  Offline
master

Joined: Nov 2003
Posts: 7,348
Mt.Vernon ,Ohio
Do not run a solid trans mount with solid engine mounts !!! It will break parts ! Car flexs something has to give...
Re: Broke 727 Tailshaft... Why? [Re: VernMotor] #359413
06/28/09 11:23 PM 06/28/09 11:23 PM
Joined: Jan 2003
Posts: 1,090
Saskatchewan, Canada
B
barracudabob Offline
super stock
barracudabob  Offline
super stock
B

Joined: Jan 2003
Posts: 1,090
Saskatchewan, Canada
Are there different strength tail shafts? I was told somewhere, maybe here, that the ones with the opening for the circlip on the side were stronger than the bottom opening ones? Apparently they're a truck application. Any truth to this? Thanks, Bob
Re: Broke 727 Tailshaft... Why? [Re: VernMotor] #359414
06/29/09 06:39 AM 06/29/09 06:39 AM
Joined: Jan 2003
Posts: 4,288
Danville, NH
M
Mopar_Mike Offline OP
master
Mopar_Mike  Offline OP
master
M

Joined: Jan 2003
Posts: 4,288
Danville, NH
Quote:

Do not run a solid trans mount with solid engine mounts !!! It will break parts ! Car flexs something has to give...



Thanks Guys.. I appreciate the help with this.

RS23L7 4-Speed



Re: Broke 727 Tailshaft... Why? [Re: barracudabob] #359415
06/29/09 07:44 AM 06/29/09 07:44 AM
Joined: Mar 2006
Posts: 9,882
MI, usa
dvw Offline
master
dvw  Offline
master

Joined: Mar 2006
Posts: 9,882
MI, usa
Any tail housing will work when properly set-up. Look at a 727 compared to other transmisions. The tail is very long. There's not any support way out at the end. When the drive shaft fits correctly,the pinion angle doesn't pull over center at launch, and the shaft is balanced with tight u-joints there won't be a problem. The only other cause is chassis flex. The stock crossmember and mount don't seem to be an issue. Unless the car has no frame connectors or cage and it is in the power range that it should have them. Tube chassis could be a different issue as I have no experiance with them. If I had a car with a tube chassis and it flexed more than a stocker I'd be worried about more than trans cracking.
Doug
Re: Broke 727 Tailshaft... Why? [Re: Mopar_Mike] #359416
06/29/09 07:57 AM 06/29/09 07:57 AM
Joined: Jan 2003
Posts: 13,402
Marion, South Carolina [><]
an8sec70cuda Offline
I Live Here
an8sec70cuda  Offline
I Live Here

Joined: Jan 2003
Posts: 13,402
Marion, South Carolina [><]
The poly trans mount is not the problem. I've been running a motorplate w/ a poly mount and haven't had a problem breaking tailshaft housings.

In the past I broke two tailshaft housings, both times it was due to a twisted driveshaft. Had them checked at my local driveshaft shop and they were twisted. I twisted one stock driveshaft, broke the housing...replaced it with another stock shaft thinking it was a fluke. 3 passes later it twisted that shaft and broke another housing. I then had a custom 3" thickwall shaft built and never had another problem. This was with stock motor mounts (with a torque strap) and a poly trans mount. I later switched to the motorplate and installed a motor that makes 250 hp more and haven't had any problems. CHIP

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
Re: Broke 727 Tailshaft... Why? [Re: an8sec70cuda] #359417
06/29/09 08:41 AM 06/29/09 08:41 AM
Joined: Jan 2003
Posts: 4,288
Danville, NH
M
Mopar_Mike Offline OP
master
Mopar_Mike  Offline OP
master
M

Joined: Jan 2003
Posts: 4,288
Danville, NH
Thanks, this is looking more and more like it is a driveshaft problem. I do have frame ties and as mentioned the rear housing is stock with stock perches so it should be stock pinion angle.. right?

I know it is a custom shaft (was this way when I bought the car) and is xtra thick, 3"+

As mentioned above I did replace the differential yoke so length might be the issue there.

The trans is a 71 so it has only the rear yoke.

RS23L7 4-Speed



Re: Broke 727 Tailshaft... Why? [Re: Mopar_Mike] #359418
06/29/09 10:05 AM 06/29/09 10:05 AM
Joined: Jan 2003
Posts: 75,094
A Banana Republic near you.
JohnRR Offline
I Win
JohnRR  Offline
I Win

Joined: Jan 2003
Posts: 75,094
A Banana Republic near you.
Quote:

Thanks, this is looking more and more like it is a driveshaft problem. I do have frame ties and as mentioned the rear housing is stock with stock perches so it should be stock pinion angle.. right?

I know it is a custom shaft (was this way when I bought the car) and is xtra thick, 3"+

As mentioned above I did replace the differential yoke so length might be the issue there.

The trans is a 71 so it has only the rear yoke.



Mike what rear springs are you using ?

I'd ditch the poly mount for now and run a rubber mount .
Re: Broke 727 Tailshaft... Why? [Re: JohnRR] #359419
06/29/09 10:14 AM 06/29/09 10:14 AM
Joined: Jan 2003
Posts: 19,384
Las Vegas
Al_Alguire Offline
I Live Here
Al_Alguire  Offline
I Live Here

Joined: Jan 2003
Posts: 19,384
Las Vegas
While these are all great suggestions my suggestion is have the driveshaft checked. EVERY broken tailshaft I have ever dealt with was caused by an out of balance driveshaft. Find a good shop that can check it that you can trust. Just my

"I am not ashamed to confess I am ignorant of what I do not know."

"It's never wrong to do the right thing"
Re: Broke 727 Tailshaft... Why? [Re: JohnRR] #359420
06/29/09 02:32 PM 06/29/09 02:32 PM
Joined: Jan 2003
Posts: 4,288
Danville, NH
M
Mopar_Mike Offline OP
master
Mopar_Mike  Offline OP
master
M

Joined: Jan 2003
Posts: 4,288
Danville, NH
John,
I am using new (less than a year) cal-tracs 1" over ride height mono springs with the bars and rancho shocks.

RS23L7 4-Speed



Re: Broke 727 Tailshaft... Why? [Re: Al_Alguire] #359421
06/29/09 02:33 PM 06/29/09 02:33 PM
Joined: Jan 2003
Posts: 4,288
Danville, NH
M
Mopar_Mike Offline OP
master
Mopar_Mike  Offline OP
master
M

Joined: Jan 2003
Posts: 4,288
Danville, NH
Quote:

While these are all great suggestions my suggestion is have the driveshaft checked. EVERY broken tailshaft I have ever dealt with was caused by an out of balance driveshaft. Find a good shop that can check it that you can trust. Just my



Since I have never done anything with the shaft, I think I should get it checked too. Thanks for your help.

RS23L7 4-Speed



Re: Broke 727 Tailshaft... Why? [Re: Mopar_Mike] #359422
06/29/09 03:16 PM 06/29/09 03:16 PM
Joined: Jan 2003
Posts: 75,094
A Banana Republic near you.
JohnRR Offline
I Win
JohnRR  Offline
I Win

Joined: Jan 2003
Posts: 75,094
A Banana Republic near you.
Quote:

John,
I am using new (less than a year) cal-tracs 1" over ride height mono springs with the bars and rancho shocks.



Then you need to look at your pinion angle also as the spring can have an effect on it. The stock housing is ok with STOCK springs and their just good enough factory tolerance .
Re: Broke 727 Tailshaft... Why? [Re: JohnRR] #359423
06/30/09 09:41 AM 06/30/09 09:41 AM
Joined: Jan 2003
Posts: 4,288
Danville, NH
M
Mopar_Mike Offline OP
master
Mopar_Mike  Offline OP
master
M

Joined: Jan 2003
Posts: 4,288
Danville, NH
Quote:

Quote:

John,
I am using new (less than a year) cal-tracs 1" over ride height mono springs with the bars and rancho shocks.



Then you need to look at your pinion angle also as the spring can have an effect on it. The stock housing is ok with STOCK springs and their just good enough factory tolerance .



Whats the best way to measure pinion angle? I have been reading up on it, so I understand what it is and the need for a negative angle, but I am not understanding the best way to measure it.

If I need more of a negative angle what do you guys think of using wedges on the perches?

Last edited by Mopar_Mike; 06/30/09 09:42 AM.
RS23L7 4-Speed



Re: Broke 727 Tailshaft... Why? [Re: Mopar_Mike] #359424
06/30/09 09:49 AM 06/30/09 09:49 AM
Joined: May 2003
Posts: 13,202
aZLiViN
J
J_BODY Offline
I Live Here
J_BODY  Offline
I Live Here
J

Joined: May 2003
Posts: 13,202
aZLiViN
Things I changed back when I was "using" tailshafts.

Added bars from the cage to the front.
Added engine fore/aft limiter
Stock mount to poly mount

Pinion angle was ok, the drive shaft had been checked prior the dana install and was "ok". Had the shaft shortened when the dana was installed. Was still breaking tails. Ordered an aluminum drive shaft.....been trouble free since.
Re: Broke 727 Tailshaft... Why? [Re: 440Jim] #359425
06/30/09 09:53 AM 06/30/09 09:53 AM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Quote:

Quote:

it is the poly rear mount that caused it you cannot do that with solid engine mounts you need a solid rear trans mount.

I don't know his problem, but that isn't it, IMO. I have been running a front motor plate, with a fore-aft "limiter" (no movement) with a stock (new) rubber trans mount. 7-8 years, ladder bar rear suspension and minimal pinion angle (correct for ladder bars). And this car launches hard...



I'm with Jim..... I would NEVER run a solid trans
mount... if the chassis twists it will break the
tail shaft
For you pinion angle Caltracs calls for a 2*-4* angle
(less than stock type springs due to less wind up)
Re: Broke 727 Tailshaft... Why? [Re: Mopar_Mike] #359426
06/30/09 09:55 AM 06/30/09 09:55 AM
Joined: Jan 2005
Posts: 716
Indiana
6
65dragnet Offline
super stock
65dragnet  Offline
super stock
6

Joined: Jan 2005
Posts: 716
Indiana
Wedges will work fine if you only need to move a few degrees. I agree with some of the others Mike have your driveshaft checked for balance first.As far as the trans mount I would keep it rubber if your using a motor plate or elephant ears , and yes use a fore and aft limiter on the motor. Hope this helps !

E. Williams 65 Coronet 500 3400lbs w/d, 446, Indy EZ'S, A&A transbrake,Comp 650 lift cam, 6.50 @ 105 mph 1/8th 10.25 @ 130mph 1/4
Re: Broke 727 Tailshaft... Why? [Re: 65dragnet] #359427
06/30/09 09:58 AM 06/30/09 09:58 AM
Joined: Jan 2003
Posts: 4,288
Danville, NH
M
Mopar_Mike Offline OP
master
Mopar_Mike  Offline OP
master
M

Joined: Jan 2003
Posts: 4,288
Danville, NH
Quote:

Wedges will work fine if you only need to move a few degrees. I agree with some of the others Mike have your driveshaft checked for balance first.As far as the trans mount I would keep it rubber if your using a motor plate or elephant ears , and yes use a fore and aft limiter on the motor. Hope this helps !



Thanks Guys, I am just trying to get all the info I can on this fix. What are "for and aft limiter on the motor" ??

RS23L7 4-Speed



Re: Broke 727 Tailshaft... Why? [Re: Mopar_Mike] #359428
06/30/09 10:07 AM 06/30/09 10:07 AM
Joined: Jan 2005
Posts: 716
Indiana
6
65dragnet Offline
super stock
65dragnet  Offline
super stock
6

Joined: Jan 2005
Posts: 716
Indiana
It's a fabricated means of keeping the engine from moving back and forth in the chassis from the torque of launching when the engine is mounted on a motor plate or elephant ears. Wow that the best way I know how to describe it !LOL I think they are all pretty much home made ,I put mine from the trans ear on the pass. side of trans to the trans crossmember. It's adjustable like a turnbuckle , alot of them I've seen are mounted from engine to frame on the front

E. Williams 65 Coronet 500 3400lbs w/d, 446, Indy EZ'S, A&A transbrake,Comp 650 lift cam, 6.50 @ 105 mph 1/8th 10.25 @ 130mph 1/4
Page 2 of 3 1 2 3

Moderated by  Al_Alguire, Hotwheelsjr, moparts, not_a_charger, RangerDan440, tboomer 
Privacy Policy · Forum Rules · Mark All Read Contact Us · Moparts




Moparts Main Index | READ - Info & Help Page | Moparts Sponsors | Tech Archive


Powered by UBB.threads™ PHP Forum Software 7.7.1