742? 741?

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irelandmoss

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I always hear about 742 rearends. Mine has the stamp
number 741. What is the difference? Is the 741 smaller?
Is the 742 a heavier housing? I would like to put 3.55 to
3.90 gears in mine. But I don't want it blowing up.
Thanks for any help.
Bill
 
pinion gear in 741 is 1 3/8 inches
pinion gear in 742 is 1 3/4 inches

the 742 is stronger but unless you are drag racing a heavy car with a big motor the 741 will be fine especially if you are just driving on the street.
 
Plan on putting a built up 383 in a 67 barracuda.
Will the 741 take it? also is the 741 an 8 3/4?
Also, will the 1 3/4 fit in a 741 case?
Thanks
 
irelandmoss said:
Plan on putting a built up 383 in a 67 barracuda.
Will the 741 take it? also is the 741 an 8 3/4?
Also, will the 1 3/4 fit in a 741 case?
Thanks
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stock 383 or ?

yes...741 is the 3rd member...center section..pumkin...for a 8 3/4 rear.
 
741, 742, 489 are all 8 3/4" center sections. Interchangeable as complete units. Sure grips can be swapped between them. Not much available in aftermarket ratios for the 741. The 741 will probably work okay for you, might be a problem if you start really hooking up with slicks or something. I'm sure others will report their experiences.
 
Plan on putting some fire into a 383. Or it may be possible
a 440. Want to put some power to the ground.
Bill
 
Planning on putting the body back to, or close to, showroom
condition and dump everything into the drivetrain.
 
There are enough 742 and 489 cases out there, I would seek one of those out if you have the option. The 741 case will work just fine, but if you have a choice, choose a 742 or 489. The 489 case has a tapered pinion bearing that requires setting the depth (the distance between the ring gear and the pinion gear) with a crush sleeve, making it a one time setting unless you have the newer style hard spacer and shims. The 742 pinion depth is set by shims alone, so dialing in the wear pattern on the gearset is a little easier. The difference in the pinion shaft diameter is only 1/8" between those two cases, which makes my personal favorite the 742 case. Try to find a clutch style suregrip unit if you can, but don't scoff at the cone style, as it is considered a superior design. Just make sure that the cone housing has not been scored at the bottom, as it will render it unrebuildable. Good luck with your search, Geof
 
Yes there is, as stated above, it's easier to set the pinion depth. I think they sell for around 30-40 bones, but I haven't looked as of late to be sure on the price.
 
For a hot big block I'd look for a 489 or 742. The 741 is plenty good for a moderate 360 or smaller cube engine but when you get big cubes you have big torque and torque is what kills rearends.
 
fishy68 said:
For a hot big block I'd look for a 489 or 742. The 741 is plenty good for a moderate 360 or smaller cube engine but when you get big cubes you have big torque and torque is what kills rearends.
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I'm not sure it really maters on which one you use. The 741's, 742's and 489's all use the same diameter yoke and thats the smallest diameter on the pinion so you would think that, that is where it would break. The only failures that I have ever seen is with the ring gear and they are all the same size across the board. Has anyone on the site ever experenced a pinion shaft failure?
 
I don't even think you can buy any parts or gears for the 741 case.
 
............My 11.001 drag car has a 1.34 60 ft....on 12.2x31.25 slicks....4 over 20 years.......with the 741..........kim.........
 
In advertisements I've seen third members for 742's and 489's.
My car started life with a 273, auto and 2.76 gears.
I want to change all that.
Bill
 
mcodecuda said:
I'm not sure it really maters on which one you use. The 741's, 742's and 489's all use the same diameter yoke and thats the smallest diameter on the pinion so you would think that, that is where it would break. The only failures that I have ever seen is with the ring gear and they are all the same size across the board. Has anyone on the site ever experenced a pinion shaft failure?
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I know where your coming from and that does make sense but I have seen a 741 pinion broken right behind the rear bearing. Coincidence? Dunno?

Blownfish said:
Maybe it's the 742 case you can't get anything for, I know one of them are impossible to get parts for.
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It used to be hard to get parts for one of the cases (741 if I remember right) but now everybody carries a wide variety of parts for all cases. I've rebuilt every case style in the last few yrs. and never had trouble getting parts for anything.
 
If I'm not mistaken, the 1 3/8" pinion shaft in the 741 case is the same diameter as in the "famed" 9" Ford rearends, no??? Geof
 
most i,ve seen broke was due to broken housing bearing retainers, i think this can be stopped with billet caps and a backbrace .The Ford 9 inch has a front and rear pinion bearing to prevent pinion deflection. big difference.
 
daredevil said:
most i,ve seen broke was due to broken housing bearing retainers, i think this can be stopped with billet caps and a backbrace .The Ford 9 inch has a front and rear pinion bearing to prevent pinion deflection. big difference.
Click to expand...

Actually the 9" uses 3 bearings on the pinion. It also has a caged roller bearing on the nose or very end of it. It has to, the front and rear bearing are so close together that it had to use the third bearing to stabelize the pinion.
 
The 741 case has limited ring gear sizes especially in the higher numbers. I`ve found very little selection over 3.73:1. The 742 case takes a larger pinion shaft and is the same thickness front to back. There`s a large selection of parts and even some pro gear sets available for the 742 case. The 489 case has a larger pinion shaft at the gear but tapers from back to front. Many 489 cases will be found with a cone-style sure-grip unit that was non-rebuildable, the earlier clutch-style sure-grip is favored by most. The popular unit for heavier cars with a lot of hp is the 742 case as the shaft size is the largest without tapering and it retains an ample bearing.
 
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