741 housing strength

Thread Tools
 
Search this Thread
 
Old Sep 2, 2018 | 05:59 PM
  #1  
lemontwist's Avatar
Thread Starter
New Member
 
Joined: Jun 2018
Posts: 11
Likes: 0
741 housing strength

I recently obtained a 741 chunk for my 8.75. When talking about an 741 lots of people say, "it won't hold up" however, I don't hear any actual stories or details of 741s being destroyed. If you have a personal experience with a 741 failure I'd like to hear it along with the details. I'd rather not read a bunch of arm chair theory and specs. If you've broken one, I'd like to hear about it.
Reply
Old Sep 3, 2018 | 04:34 AM
  #2  
Coronet 500's Avatar
Mopar Lover
 
Joined: May 2011
Posts: 2,732
Likes: 361
From: Ontario Canada
If you search Forbbobiesonly or Forabodiesonly this same question many will trash it then you'll find others who have drag raced this with 400-500hp doing 12,11 and10 seconds with no failure. I have not broken one but would not race one with 500hp good slicks and definitely no with a trans brake, on the street no problem.
Reply
Old Sep 3, 2018 | 09:03 AM
  #3  
Iowan's Avatar
Super Moderator
 
Joined: Mar 2015
Posts: 5,482
Likes: 553
They came in Abodys and pickups, I have a friend running the same gears in his 340 69 4 speed Dart for over 30 years and no failure. I would hate to guess how many times the car has been down the track in that time, it runs mid 12s.

The old Mopar Chassis Book doesn't recommend using the 1-3/8 stem units for high performance applications.......
I would think it's like Dan says how much power and how much traction and the fact you can take you transmission out with the the rear end would make me pass on it. But it depends on the power level and intended use.
Reply
Old Sep 3, 2018 | 09:40 AM
  #4  
RacerHog's Avatar
Mopar Lover
 
Joined: Jun 2013
Posts: 11,096
Likes: 955
From: Monrovia SO-CAL (USA)
I broke 2 of them... Both snapped the drive pinion. Both broken in my 1972 Duster 4/Speed Car.
Reply
Old Sep 3, 2018 | 08:29 PM
  #5  
lemontwist's Avatar
Thread Starter
New Member
 
Joined: Jun 2018
Posts: 11
Likes: 0
Originally Posted by RacerHog
I broke 2 of them... Both snapped the drive pinion. Both broken in my 1972 Duster 4/Speed Car.
What engine / horse power did you have? What exactly were you doing with the car at the time they broke? Were you running slicks? Are these the only pinions you've ever snapped?
Reply
Old Sep 4, 2018 | 09:13 AM
  #6  
Iowan's Avatar
Super Moderator
 
Joined: Mar 2015
Posts: 5,482
Likes: 553
Curiosity got The best of me last night and I called my buddy was the 69 dart, hes got the 742 case, it was in the car when I bought it. He said he had a 741 center in his 62 Plymouth for one weekend and broke it out on the black top.
Reply
Old Sep 6, 2018 | 05:46 AM
  #7  
RacerHog's Avatar
Mopar Lover
 
Joined: Jun 2013
Posts: 11,096
Likes: 955
From: Monrovia SO-CAL (USA)
Originally Posted by lemontwist
What engine / horse power did you have? What exactly were you doing with the car at the time they broke? Were you running slicks? Are these the only pinions you've ever snapped?
Not sure what this has to do with "The Price of Milk">>>>> 1- I broke trying to doing a burnout..lol >>>>>>>> The other one was broke, Drag Racing, I think it was about the 3rd pass...
It's a small step pinion. I guess I just "Side stepped" the clutch and it didnt like it. Moved on to bigger and stronger..
But just to answer the question... Yes I have broken the Small Step Pinion Diffs...
Reply
Old Sep 6, 2018 | 05:50 AM
  #8  
RacerHog's Avatar
Mopar Lover
 
Joined: Jun 2013
Posts: 11,096
Likes: 955
From: Monrovia SO-CAL (USA)
Originally Posted by Iowan
Curiosity got The best of me last night and I called my buddy was the 69 dart, hes got the 742 case, it was in the car when I bought it. He said he had a 741 center in his 62 Plymouth for one weekend and broke it out on the black top.
I had good luck with my 742 case in my Challenger with the 440... We did out grow it on the performance side, But I never pushed the limit to try and find out what the breaking point was....lol
Reply
Old Sep 6, 2018 | 12:20 PM
  #9  
Iowan's Avatar
Super Moderator
 
Joined: Mar 2015
Posts: 5,482
Likes: 553
742 weakness is the casting itself behind the caps, you can put billit bearing caps on the center and the casting blows apart. I've only broken ring gears and that was before going to synthetic gearlube.
I don't use a trans brake, 1.40 60' foot brake 3400 lbs race weight

Last edited by Iowan; Sep 6, 2018 at 12:26 PM.
Reply
Old Sep 7, 2018 | 08:57 PM
  #10  
RacerHog's Avatar
Mopar Lover
 
Joined: Jun 2013
Posts: 11,096
Likes: 955
From: Monrovia SO-CAL (USA)
I had some problems with "ProGear" but that was for defects from them.... Also I use to run Torco gear lube back in the day, Or my good stuff from Texas Refinery.. I didn't have really and load issues.. Mostly it would be a part failure....lol
Reply
Old Sep 14, 2018 | 08:10 PM
  #11  
TVLynn's Avatar
Mopar Lover
 
Joined: Apr 2011
Posts: 4,282
Likes: 388
You might find gears will be hard to find MORE options for the 742 & 489 case
Reply
Old Sep 15, 2018 | 08:26 AM
  #12  
lemontwist's Avatar
Thread Starter
New Member
 
Joined: Jun 2018
Posts: 11
Likes: 0
Yeah, you're right about limited gear choices for the 741. Fortunately for me I wanted a 3.73 and that was one of the sets readily available. Thanks for the input.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
1968newport
Transmissions, Transfer Cases and Rear Ends
16
Jul 19, 2015 04:47 PM
baccaruda
Transmissions, Transfer Cases and Rear Ends
3
Feb 19, 2012 12:14 PM
67gtxclone
General Discussion
9
Apr 7, 2010 01:56 PM
v6spitfire
General Technical Questions
7
Feb 18, 2009 10:54 PM
thedusterridesagain
A-Body
11
Dec 21, 2008 06:36 PM




All times are GMT -7. The time now is 09:22 PM.