742 gears in a 741 case

[Dana67Dart]

I have seen info that with the correct bearings a set of 742 gears can be put in to a 741 case.

Anyone have first hand knowledge of this and perhaps bearing part numbers.

(yes i could get a 742 case)

 

[pishta]

pinion stem diameter was only design change. I think putting a larger pinion stem in a small case would be the wrong way to do it. Maybe the other way around? No first hand knowledge.

 

[Jadaharabi]

Think about it.
The 741 has a small inner pinion bearing that is 1 3/8 ID, then a solid spacer sleeve.
The 742 pinion is a 1 3/4 ID bearing and is solid all the way.

 

[Dana67Dart]

Is the pinion inner bearing cup the same OD 742 to 741?
Is the pinion outer bearing cup the same OD 742 to 741?

I understand that the ID of the race on the Inner will be different 742 = 1-3/4, 741= 1-3/8
Is the outer race ID different as well?

 

[john-9]

741 case takes pinion bearing HM89446 cone , HM89410 race -- O.D. 3.000 ,,, I.D. 1.375
742 case takes pinion bearing HM803149 cone , HM 803110 race -- O.D 3.500 ,,, I.D. 1.750
don't waste your time with this ,,, get the correct gear for the correct case

 

[Dana67Dart]

OK I give up!

I found a 741 case (correct date code / PN for what I'm trying to do) with Power-lock and the gearing I wanted that looks to be in usable shape or at least rebuildable for a great price. If the gears are trashed I want to be able to get a replacement set in the same gear. But the gear selection for 741 seems limited to 3.55 and 3.73. Rockauto says they have in stock, "US Standard Gear" in the ratio I want, for a 741 case, but I don't want to gamble that they will be available by the time I can get the rear in the car and tryout the OE gears for noise etc.

Guess I'll keep looking

Thanks All

 

[4spdragtop]

I was wondering same thing. Both cuda have 323 gears. One is 741 case and one is 489 case. I was hoping to be able to buy a 355 pumpkin and be able to use it for both the 741 and 489.
I saw those gears at RA as well.
Thanks all

 

[mderoy340]

OK I give up!

I found a 741 case (correct date code / PN for what I'm trying to do) with Power-lock and the gearing I wanted that looks to be in usable shape or at least rebuildable for a great price. If the gears are trashed I want to be able to get a replacement set in the same gear. But the gear selection for 741 seems limited to 3.55 and 3.73. Rockauto says they have in stock, "US Standard Gear" in the ratio I want, for a 741 case, but I don't want to gamble that they will be available by the time I can get the rear in the car and tryout the OE gears for noise etc.

Guess I'll keep looking

Thanks All

What gear ratio do you want to run?

 

[brian6pac]

The power lok fits all 3 cases, the 742 case has the biggest pinion bearing, bigger than the 489, but the 489 has the bigger carrier bearings, so to me the 742 is the stronger case

 

[Dana67Dart]

I saw those gears at RA as well.

Unfortunately RO has mis listed the gears for 741 case. look carefully at the last 2 numbers of the part numbers. 42,41,89 so again for 741 = 3.55 and 3.73 are only option
Curse you RO getting my hopes up that you had old stock in stock

 

[Dana67Dart]

What gear ratio do you want to run?

3.23... lots of used gears available

 

[Dana67Dart]

Both cuda have 323 gears. One is 741 case and one is 489 case. I was hoping to be able to buy a 355 pumpkin and be able to use it for both the 741 and 489.

from everything I know any fully assembled case 741 , 742, 489 will fit your any 8 3/4 housing and axles. (watch center axle spacer if you have / dont have green bearings.)

 

[Dana67Dart]

so to me the 742 is the stronger case

I wasn't looking for strength I was looking for period correctness and ratio.
Do these gear teeth look functional? from what I have seen the setup doesn't seem to have any chips or major damage to it. there might be some rust pitting on some teeth. never used used gears before, any advice,

Its just such a good deal even if it needs rebuilding if the gears are usable (IE not noisey)
If it needs new gears than its about the same price as piecing it together with new power lock, used case and new gears

 

[Dana67Dart]

Why did It have to be a 67 dart. My life would be so much easier if it was a 68-69,

 

[mderoy340]

3.23... lots of used gears available

If you are running 450HP or less don't get hung up on the case #.

I ran an old 741/OEM 3:91 in my Dart 250 passes. 2 ring gear teeth finally cracked at the base. I ran 8 passes that day and the car never slowed down. When I capped the headers I heard the gear noise. Drove it home 50 miles. The ring and pinion gear are the weak link IMO, not the pinion diameter.

 

[Dana67Dart]

If you are running 450HP or less don't get hung up on the case #

my only hang up on the case number is I would prefer a 741 for period correctness. I'm not making any HP and don't plan to.

But thanks for the input.

 

[brian6pac]

I wasn't looking for strength I was looking for period correctness and ratio.
Do these gear teeth look functional? from what I have seen the setup doesn't seem to have any chips or major damage to it. there might be some rust pitting on some teeth. never used used gears before, any advice,

Its just such a good deal even if it needs rebuilding if the gears are usable (IE not noisey)
If it needs new gears than its about the same price as piecing it together with new power lock, used case and new gears

View attachment 1715202868View attachment 1715202874

I wouldn't worry about it if your not putting a lot of power to it, i have used the same looking gears, just polish the rust off with a wire wheel on a drill and run them, they wont make noise unless you have rusty bearings, I would change them.

 

[brian6pac]

If you are running 450HP or less don't get hung up on the case #. View attachment 1715202894 I ran an old 741/OEM 3:91 in my Dart 250 passes. 2 ring gear teeth finally cracked at the base. I ran 8 passes that day and the car never slowed down. When I capped the headers I heard the gear noise. Drove it home 50 miles. The ring and pinion gear are the weak link IMO, not the pinion diameter.

Was it a Richmond gear set ??

 

[mderoy340]

Was it a Richmond gear set ??

No, 50 year old OEM gear set. I'm running an old set of Richmonds now in a 489 case.

 

[brian6pac]

About 5 years ago my friend broke 2 sets of Richmond gears, switched to Motive gear and hasn't broke it yet.

 

[4spdragtop]

I had heard same thing. Completely assembled can be swapped between the 3 different cases.
Thanks.

from everything I know any fully assembled case 741 , 742, 489 will fit your any 8 3/4 housing and axles. (watch center axle spacer if you have / dont have green bearings.)