8 3/4 question

[nutz]

i see a lot of either questons 489 or 741 dif is one better then other
whats the differance ...do they both bolt in the housing ,are there even more #s
the one i got for my dart is a 489 that i want to change the gear ratio and put a clutch type sure lock
i think my 67 pu is a 741 ? when i was getting bearings think i had to know if early or late
not sure what the 65 pu has
thanks

 

[AJ/FormS]

For the Dart, on the street, with stock wheel houses, my opinion is that with any Normally Aspirated engine; what the number on the carrier is, hardly matters and all Mopar Sure-Grips will fit into it, with the appropriate bearings.
Your 489, if it matters, is the strongest.
And, whether you use the Cone-type or the Clutch-type, again, on the street it hardly matters, and I prefer the cone-type for it's smooth and consistent action, and; Contrary to common understanding, the cone-type is rebuildable and adjustable.
I speak from my experience with a 367 cubic inch engine pushing 430 hp, in a 68 Barracuda, with a manual trans, that has the factory tubs, and running up to 325/50-15s.. At one time or another, since 1999, that combo has seen every carrier and clutch combo, and nearly every gear from 2.76 to 4.88, most of them spinning 295s. I have never broke a pinion.

 

[Oldmanmopar]

There are three different carriers.
741 small diameter pinion pre 69,
742 Large diameter pinion pre 69.
and 489 tapered pinion 69 -72.

All three carriers the sure grips and trac-locks are interchangeable. 489's are desired for performance car restoration for 69-72. 741 usually found in trucks and passenger cars pre 69. 742's are found in big block or performance cars pre 69

I use a 742 in my race car with a spool. 741 and 742 came with clutch style trac-locks. 489's all came with the cone style sure grips. I would always replace the sure grip with the trac-lock in my cars with the 489 in my big block cars, less slip with big tires.

I would Just keep the races with the bearings they are on unless replacing the bearings. 741 and 742 are easier to change the gears they use shims on the pinion where as the 489 uses a crush sleeve which should always be replace with a gear change.

I prefer the 742 with slicks at the track. 741 works great with street tires on a street car. although if you get a good 489 set up correctly would be the strongest. I just like the 742 for the convenience of easy repairs.

741's get a bad rap for snapping the pinion threads . But this is usually caused by the housing wrapping up with weak springs on a hard launch which usually rips the yoke off due to the smaller threads holding it on. All the early Max Wedge and Hemis came with 742' if not a Dana car.

The most important add on you can install is a housing brace which prevents housing flex that causes the axle pressure to crack the carrier caps. Hope this info off the top of my head from experience I remembered helps.

 

[Syleng1]

IMHO: they all work well as anything will fail regardless of case of number if you beat the snot out of it.
If you have a large hp / tq engine the 489 or 742 is more desirable. If you run a stock or street modified engine and drive like normal. All 3 will last as long as they can. All parts eventually wear out. Most of these pumpkins are 50 years old now.
I’d take a 741 case any day over say a 7-1/4 rear behind my 340.

 

[nutz]

Have a 489 with cone type and 410
Want either 323 or 355
For my stock 340 4spd build
The spider gears are shot so think I'll look for a clutch type ....or if a good cone comes up

 

[Scody21]

Tire size and cam selection should help dictate what gear ratio you pick..

 

[nutz]

Stock cam
245 60 15
So nothing big
Thinking 355 is my dream gear
If i can find them

 

[Oldmanmopar]

I am in Danielsville Pa. I have rears depending on what you are looking to spend. I believe there is a 323 here with a clutch style. Make me an offer. I use to travel to the Can on 31 everyday for work. Most of my rears were pulled in the early 80's so they are in good condition.

 

[Newbomb Turk]

The tapered pinion 489 case is not as strong as the straight pinion 742 case.

That’s the fact.

If you have even a remote question about your rear axle being strong enough, sell the 8.75 and build a Dana 60.

You’ll be money ahead in the long run.

 

[Newbomb Turk]

For the Dart, on the street, with stock wheel houses, my opinion is that with any Normally Aspirated engine; what the number on the carrier is, hardly matters and all Mopar Sure-Grips will fit into it, with the appropriate bearings.
Your 489, if it matters, is the strongest.
And, whether you use the Cone-type or the Clutch-type, again, on the street it hardly matters, and I prefer the cone-type for it's smooth and consistent action, and; Contrary to common understanding, the cone-type is rebuildable and adjustable.
I speak from my experience with a 367 cubic inch engine pushing 430 hp, in a 68 Barracuda, with a manual trans, that has the factory tubs, and running up to 325/50-15s.. At one time or another, since 1999, that combo has seen every carrier and clutch combo, and nearly every gear from 2.76 to 4.88, most of them spinning 295s. I have never broke a pinion.

 

[nutz]

I am in Danielsville Pa. I have rears depending on what you are looking to spend. I believe there is a 323 here with a clutch style. Make me an offer. I use to travel to the Can on 31 everyday for work. Most of my rears were pulled in the early 80's so they are in good condition.

Sound good i saved your #
I do want to come visit

 

[nutz]

The tapered pinion 489 case is not as strong as the straight pinion 742 case.

That’s the fact.

If you have even a remote question about your rear axle being strong enough, sell the 8.75 and build a Dana 60.

You’ll be money ahead in the long run.

Not questioning strong enough
More what the difference was

 

[Newbomb Turk]

Not questioning strong enough
More what the difference was

Got it. Like I said, the tapered pinion isn’t as strong as the straight pinion.

 

[Vaanth]

i see a lot of either questons 489 or 741 dif is one better then other
whats the differance ...do they both bolt in the housing ,are there even more #s
the one i got for my dart is a 489 that i want to change the gear ratio and put a clutch type sure lock
i think my 67 pu is a 741 ? when i was getting bearings think i had to know if early or late
not sure what the 65 pu has
thanks

Some notes from my 8-3/4" Axle Guide. FYI...

8-3/4" Axle Center Section Types
The 8-3/4" axle was available in three basic types. The axle types are differentiated by the following pinion stem diameters:

• 1-3/8"
• 1-3/4"
• 1-7/8"

The choice of the axle pinion assembly was determined based on the application, vehicle weight, and power level.

1-3/8" small stem pinion... (aka. '741')
Carrier casting numbers: 1820657 (1957-1964), 2070741 (1964-1972).

This assembly was typically used in low weight/low horsepower applications through low weight/medium horsepower and high weight/low horsepower applications. Pinion depth and bearing preload is set with shims. Differential bearing setting, or backlash, is set with threaded adjusters.

1-3/4" large stem pinion... (aka. '742')
Carrier casting numbers: 1634985 (1957-1964), 2070742 (~1961-1969).

This assembly was replaced by a phase-in of the 1-7/8" pinion starting in the 1969 model year. 1970 Plymouth and Dodge mid-size models were the last models to use the 1-3/4" pinion which was built in a 2881489 case. This assembly was typically used in high weight/medium horsepower applications through high weight/high horsepower applications. Pinion depth and bearing preload is set with shims. Differential
bearing setting, or backlash, is set with threaded adjusters.

1-7/8" tapered stem pinion... (aka. '489')
Carrier casting numbers: 2881488, 2881489 (1969-1974).

This assembly was introduced in 1969 and was phased-in to replace the 1-3/4" unit through 1970. NOTE: the 1-3/4" pinion also appeared in some '489' carriers during this period. By 1973, the '489' was the only unit available in passenger car applications. This assembly was typically used in high weight/medium horsepower
applications through high weight/high horsepower applications. Pinion depth is set with shims, preload is set with a crush sleeve although aftermarket solid spacers are available. Differential bearing setting, or backlash, is set with threaded adjusters.


General and Interchange
The 8-3/4" axle assembly was used in Chrysler product car lines, light duty trucks, and vans from 1957 through 1974.

8-3/4" carrier assemblies can be identified externally by the casting numbers. Additionally, the '741' commonly has a large X cast on the left side, the '742' may have a large 2 cast on the left side, and the
'489' has a large 9 cast on the left side. Through 1965, the factory ratio was stamped on the identification boss, followed by an 'S' if Sure Grip equipped. After 1965, a tag was affixed under one of the carrier mounting nuts to identify the ratio. If Sure Grip equipped, an additional Sure Grip lube tag was sometimes affixed and later years sometimes had the filler plug painted orange.

Any 8-3/4" center section can be interchanged for another as an entire assembly. Sure Grip types can be interchanged between the carriers if the matching differential axle bearings are retained. The outside diameter of the cups are the same between the '741'/'742' and the '489' but the inner cone differs. Note that prior to 1964, a difference in thrust blocks affect center section interchange, as well as axle interchange. The axle shaft thrust spacer, or thrust block, for open differentials was a little thicker than units made after 1964.

Strength Considerations

Pinions
The 1-3/8" '741' pinion is considered the weakest of the three pinion sizes. It is still a capable unit in most moderate power, moderate traction street applications. For high torque applications with high traction tires, the 1-3/4" or 1-7/8" should be considered.

The 1-7/8" '489' pinion is supposedly the strongest. Although the stem tapers down along it's length, it appears inherently stronger from a pinion stem perspective and the inherent strength of the fine splines of OEM gears.

The 1-3/4" '742' pinion has a larger rear pinion bearing yielding greater strength in this area. The preload shim method of this unit is stronger then the '489' crush sleeve. The '742' is likely the stronger of the two overall. The 1-3/4" shares yoke mount diameter and mounting nut with the 1-3/8".

For perspective, the 7-1/4" axle has a 1-3/8" pinion, the 8-1/4 axle has a 1-5/8" pinion, the 9-1/4" Chrysler axle has a 1-7/8" pinion.

Sure Grips
Of the two OEM Sure Grip units, the Dana Power-Lok (1958-1969, # 2881487) is inherently stronger and provides better, equal torque transmission to both axles. It's locking capability is also proportionate to the applied torque. The Borg Warner Spin Resistant unit (1969-1974 # 2881343)is weaker, but is a more versatile unit for practical street applications in inclement traction periods. The Dana unit is better for racing applications and has clutch rebuild kits available. The Borg Warner unit was not intended to be rebuildable, but there are re-machining/rebuild methods available.

 

[abdywgn]

I believe you are missing one housing, #657. It was used in a 61 only Canadian 383 car if memory serves me correctly. the large bearing in a 742 is the smallest bearing in this unit.
If somebody has an old BCA catalog, please verify this. if not, ignore the ramblings over here...

 

[Vaanth]

I believe you are missing one housing, #657. It was used in a 61 only Canadian 383 car if memory serves me correctly. the large bearing in a 742 is the smallest bearing in this unit.
If somebody has an old BCA catalog, please verify this. if not, ignore the ramblings over here...

Carrier casting number 1820657 is listed under "1-3/8" small stem pinion... (aka. '741')". I didn't list it with the casting number identification though, but this is an abbreviated set of notes.

1820657 was the predecessor to the 2070741 from 1957-1964. The '741' replaced it for 1964-1972.

Similarly, carrier casting number 1634985 was the predecessor to the 2070742 from 1957-1964. The '742' production crossed over with it, then replaced it ~1961-1969.

Carriers 1820657 and 2070741 Timken/BCA/Bower bearing numbers (Cup/Cone) are as follows:

• Differential, side 25590/25520
• Pinion, front M88048/M88010
• Pinion, rear HM89446/HM89410

The '742' and '985' front pinion bearing (cone) is the same as the '741' and '657' rear pinion bearing, but the cups (races) are different.

 

[crackedback]

To give you an idea of how much BS and red herring nonsense there is about 8.75 carriers... Read this.

Pinion Comparison - Quality Body Shop Drivetrain

All Chrysler 8 3/4″ rearends are good all-around designs, with none having a significant design advantage over the others. The 741 case 8 3/4″ has unjustly earned the reputation as a “weak” rearend, which these pictures will dispell. 8 3/4″ pinion shaft designs: Notice, all pinion shafts neck...

www.doctordiff.com

All 8.75 use the same ring gear for the respective ratio. Caps and ring gear deflection are the big deals with these rears.
Only the pinion bearing stuff is different and it is NOT the issue in any of the cases.

489's many times fail because of the crush sleeve. Nothing to do with the bearing size. Any of them are usually good for our cars.
If you can break a 741, you are likely to break the others.

 

[Newbomb Turk]

To give you an idea of how much BS and red herring nonsense there is about 8.75 carriers... Read this.

http://[URL]https://www.doctordiff.com/blog/tech-info/rearend-pinion-comparison/

[/URL]

All 8.75 use the same ring gear for the respective ratio. Caps and ring gear deflection are the big deals with these rears.
Only the pinion bearing stuff is different and it is NOT the issue in any of the cases.

489's many times fail because of the crush sleeve. Nothing to do with the bearing size. Any of them are usually good for our cars.
If you can break a 741, you are likely to break the others.

I failed a tapered pinion in the car I have now. It fractured at the small end of the taper.

It was a high 12 second stick car with 3.23 gears.

It got a 742 case with 4.56’s and a locker. It went mid 12’s.

It would have went faster and probably quicker with a 3.90 gear or for sure it would have been happy with more cam than a .474 purple cam.

 

[oldkimmer]

I raced a 741 for years and never broke it. After all the max wedges and hemi’s used the 741s. Kim

 

[AJ/FormS]

View attachment 1716374282

i see a lot of either questons 489 or 741 dif is one better then other
whats the differance ...do they both bolt in the housing ,are there even more #s
the one i got for my dart is a 489 that i want to change the gear ratio and put a clutch type sure lock
i think my 67 pu is a 741 ? when i was getting bearings think i had to know if early or late
not sure what the 65 pu has
thanks

How is it that MY OPINION rates such a big fat X?
You can't big red X an opinion. A little one maybe, but what's the point. I bet you Turk, Red-Xs all the Christians too, just for having a different opinion.
I've been driving A-bodies since 1970, most of them with stock 340s or 360s, 4-speeds, and maybe headers.
In street-stock class, they are low to mid 14 second cars. Good luck killing any 8.75 on the street, in a Stock Dart.

OP said;
stock 340/4-speed, with 245/60-15s, looking for 3.55s
Who the heck cares about anyone's racing experience.

You guys are so busy swinging dicks, you can't even agree on a simple answer.
I'll say it again, for this OP, it hardly matters.

 

[nutz]

its all good info
i was just wondering what was the difference ,and now have more info then i ever needed to know
all good ,its funny but my helper want to build i burn-out truck ..told him he could have my 65 dodge parts truck ,i would think it has a 741
think i pay him too much

 

[Newbomb Turk]

How is it that MY OPINION rates such a big fat X?
You can't big red X an opinion. A little one maybe, but what's the point. I bet you Turk, Red-Xs all the Christians too, just for having a different opinion.
I've been driving A-bodies since 1970, most of them with stock 340s or 360s, 4-speeds, and maybe headers.
In street-stock class, they are low to mid 14 second cars. Good luck killing any 8.75 on the street, in a Stock Dart.

OP said;
stock 340/4-speed, with 245/60-15s, looking for 3.55s
Who the heck cares about anyone's racing experience.

View attachment 1716374977

You guys are so busy swinging dicks, you can't even agree on a simple answer.
I'll say it again, for this OP, it hardly matters.

Can you read? It broke in a 12 second street car. Not some race car. If you think 12 seconds is a race car (and don’t try and tell me about some 273 2 barrel in Stock Eliminator being a race car because that don’t wash) then that explains a lot.

Second, you are so triggered by anyone you think views everything through a “racing” perspective that’s it just stupid.

Just because you can’t drive something on the street or you can’t run higher than orthodox compression ratios on pump gas doesn’t mean it shouldn’t be done.

The benefits are incredible but you are too old and too pig headed to realize that you didn’t keep up with how things can be done. And your goal is to drag people down into your antiquated thinking.

Let’s see…things like you can run more compression with aluminum (or as you call them as you wrongly “alloy” but I suppose you think it makes you sound cool or something but in reality there are many alloys that are not aluminum and most metals are an alloy) heads but the fact is you are dead wrong. I’ve explained it and you’ve never posted an SAE paper or any peer reviewed article that proves it. You are wrong about that too, unless you think the junk test that frybooger and dullchek did on engine masters was legit. It wasn’t. It was set up to make the iron heads look bad. You should know better.

To that end, one reason you can’t do compression like I can is you refuse to accept that cold engines make more power. By a long way.

Of course, you will refer to engineering text books and SAE papers saying hot engines make more power but the reality is they don’t. I can prove it on the dyno. Oh wait, that’s race car stuff but the OEM’s dyno test everything. They must be stupid to waste all that time and money on street car stuff. That’s why coolant AND oil temps are critical to accurate test numbers. A few degrees one way or the other changes power output. But it reduces emissions. I try and increase carbon footprint. It’s more environmentally friendly.

Then you will say but what about asscar. The asscar guys are dealing with weight and aerodynamics. To get a cooling system capable of handling 160 degree temperatures for a race of that duration would require a massive (aerodynamically a disaster) radiator that would weigh so much and would throw off the balance of the car so bad that if the temperature was held at 160 it would be a slug. Not because it made less power but the 30-40 hp you gain was ate up by the huge weight increase and the aerodynamic hit that would be equal to hanging a giant sail on it. Plus the weight balance would be so bad it wouldn’t go around a corner on rails.

So why the giant red X. Because I don’t have a smaller one and because you deserved it.

The claim that the tapered pinion is stronger is just wrong. There are very few times where a taper is stronger. This is not the case.

So who cares if is a 22 second street car or a 10 second daily driver? If the option is a straight or tapered pinion you take the straight pinion every time? Why risk it?

Along those same lines, it is absolutely idiotic if you don’t have a rear axle and you chose to build the 8.75 rather than a Dana. That’s dumb.

The small weight gain is nothing compared to the cost and in the end the strength of not only the gear set but the housing itself. I’d suggest a 9 inch but they cost far too much for zero benefit.

I know you think that nothing from racing translates to street or street/strip stuff but it does. If you ever learn that you’ll be miles ahead.

Why you would claim I gave you a red X because you are a “Christian” defies common sense and logic.

I don’t care if you are a Christian, Jew, Orthodox, unorthodox, Muslim, Hindu, atheist or even a cross dresser. It has nothing to do with my response to you.

That’s just ignorant on your part. I don’t care what you are, you were wrong and for that you got the red X.

A grown man would never post what you did over a colored letter. Just damn silly.

Edit: I can and did red X your opinion. You can have your own opinions but you are still wrong. I’m not sure where the FABO rule is that you can’t red X an opinion. I’m sure if I was breaking a rule @toolmanmike would be on me like stink on poo. This is supposed to be grown men here, acting like grown men.

You see, the red X makes it so I can disagree with your backwards opinions and not have to respond like this. I disagreed with your wrong opinion. Why explain that? Seems self explanatory to me.

 

[nutz]

in the immortal words of rodney king cant we all get along.........
racing is how you find what parts break ....when do i get my X

 

[Newbomb Turk]

in the immortal words of rodney king cant we all get along.........
racing is how you find what parts break ....when do i get my X

I agree. But AJ has a bunch of pent up butt hurt and the dreaded red X sent him over the edge and back in the village again.

That is a reference to an Iron Maiden song which is based on a 1967 TV show.

 

[Scody21]

Can you read? It broke in a 12 second street car. Not some race car. If you think 12 seconds is a race car (and don’t try and tell me about some 273 2 barrel in Stock Eliminator being a race car because that don’t wash) then that explains a lot.

Second, you are so triggered by anyone you think views everything through a “racing” perspective that’s it just stupid.

Just because you can’t drive something on the street or you can’t run higher than orthodox compression ratios on pump gas doesn’t mean it shouldn’t be done.

The benefits are incredible but you are too old and too pig headed to realize that you didn’t keep up with how things can be done. And your goal is to drag people down into your antiquated thinking.

Let’s see…things like you can run more compression with aluminum (or as you call them as you wrongly “alloy” but I suppose you think it makes you sound cool or something but in reality there are many alloys that are not aluminum and most metals are an alloy) heads but the fact is you are dead wrong. I’ve explained it and you’ve never posted an SAE paper or any peer reviewed article that proves it. You are wrong about that too, unless you think the junk test that frybooger and dullchek did on engine masters was legit. It wasn’t. It was set up to make the iron heads look bad. You should know better.

To that end, one reason you can’t do compression like I can is you refuse to accept that cold engines make more power. By a long way.

Of course, you will refer to engineering text books and SAE papers saying hot engines make more power but the reality is they don’t. I can prove it on the dyno. Oh wait, that’s race car stuff but the OEM’s dyno test everything. They must be stupid to waste all that time and money on street car stuff. That’s why coolant AND oil temps are critical to accurate test numbers. A few degrees one way or the other changes power output. But it reduces emissions. I try and increase carbon footprint. It’s more environmentally friendly.

Then you will say but what about asscar. The asscar guys are dealing with weight and aerodynamics. To get a cooling system capable of handling 160 degree temperatures for a race of that duration would require a massive (aerodynamically a disaster) radiator that would weigh so much and would throw off the balance of the car so bad that if the temperature was held at 160 it would be a slug. Not because it made less power but the 30-40 hp you gain was ate up by the huge weight increase and the aerodynamic hit that would be equal to hanging a giant sail on it. Plus the weight balance would be so bad it wouldn’t go around a corner on rails.

So why the giant red X. Because I don’t have a smaller one and because you deserved it.

The claim that the tapered pinion is stronger is just wrong. There are very few times where a taper is stronger. This is not the case.

So who cares if is a 22 second street car or a 10 second daily driver? If the option is a straight or tapered pinion you take the straight pinion every time? Why risk it?

Along those same lines, it is absolutely idiotic if you don’t have a rear axle and you chose to build the 8.75 rather than a Dana. That’s dumb.

The small weight gain is nothing compared to the cost and in the end the strength of not only the gear set but the housing itself. I’d suggest a 9 inch but they cost far too much for zero benefit.

I know you think that nothing from racing translates to street or street/strip stuff but it does. If you ever learn that you’ll be miles ahead.

Why you would claim I gave you a red X because you are a “Christian” defies common sense and logic.

I don’t care if you are a Christian, Jew, Orthodox, unorthodox, Muslim, Hindu, atheist or even a cross dresser. It has nothing to do with my response to you.

That’s just ignorant on your part. I don’t care what you are, you were wrong and for that you got the red X.

A grown man would never post what you did over a colored letter. Just damn silly.

Edit: I can and did red X your opinion. You can have your own opinions but you are still wrong. I’m not sure where the FABO rule is that you can’t red X an opinion. I’m sure if I was breaking a rule @toolmanmike would be on me like stink on poo. This is supposed to be grown men here, acting like grown men.

You see, the red X makes it so I can disagree with your backwards opinions and not have to respond like this. I disagreed with your wrong opinion. Why explain that? Seems self explanatory to me.

FYI, Your like 5,000 words short in your reply…