Sure grip reasonable price

Cranky said:

How many pinions have you seen broken on the other less stronger units? Keep in mind that they are all the same size where the yoke fits. In all the years I've been into Mopars (50+), what I see broken on the 8 3/4 are broken teeth and it involved ALL of the different cases including the 89. Personally, I won't run the 89 unit even on the street unless that damned crush sleeve is replaced with a solid spacer. Once that's done, I'm happy with it.

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I don't even consider smaller...lol....Are you saying the 489 is NOT stronger? physics prove otherwise....

I agree on eliminating the crush sleeve

moparnation74 said:

I don't even consider smaller...lol....Are you saying the 489 is NOT stronger? physics prove otherwise....

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What generally breaks on the 8 3/4 are teeth. Larger pinion...according to physics is stronger but why aren't the other smaller pinion rear ends not breaking the pinion? According to the physics, that tells me the pinion is strong enough in the others to keep from breaking. So, physics tell me the gears are the weak link in the 41, the 42 AND 89 and not the pinion. The same mindset has been going on since the 89 came out and some hot rod rag (Car Crap did a story first iirc and Shot Rod recently did the story again) came out with an article about how big the pinion was in the 89....so according to them, it must be the end all cure all. But what did it cure when there wasn't any problem with pinion breakage to begin with?? For over 35 years I capitalized on that theory and kept all the old cheap junk (41 and 42 cases and some were free!) for me to beat on and sold the new and better expensive junk for a premium price because everyone wanted the new and better 89 rear end.

Back in the early 80's a buddy and I ran a 69 roadrunner with a 440 and 4 speed and our goal was to get into the 10's with it which at the time wasn't exactly slow for a couple of yahoos on a budget and using a stick. As the car got into the low 11's, we started shaving the ring gear and we did it with the 89 and a 42 but never broke the pinion gear head or the front portion where the yoke connects on any of them. And we did that many times before finally throwing in a Dana 60. From there, we went on to running 10.70's with a bone stock 60 until the track tech inspector finally decided to take a harder look at us. And like I asked, how many 8 3/4 rears have you seen with a broken pinion? Over all the years I've been asking that question, only a couple of people have stepped up and said they did break one or has seen one broken and one of those was from an 89 case. Personally, I haven't seen one....

Try Tonys parts, then you can pick it up at Carlisle

Chrysler did use the 741 successfully behind their max wedge motors. Probably a higher chance of breaking the u joint or, like cranky said, the teeth before the pinion on any of them.

68chargerpilot said:

In reference to a 489 casting, dont they use the cone type unit and the 742 use the clutch unit? I have been looking for a 742 casting with one in it or a clutch unit by itself. That's why I mentioned the one for 125.00. It wasn't in the casting.

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Like mentioned they are sure grip style. I've got a 742 sure grip in my car right now and have had 2 489's all with sure grips. I've yet to try a cone style but like the fact that the sure grips are easily maintained by just putting new clutches in them... come to think of it I've yet to tear one down that even needed clutches.

Cranky said:

How many pinions have you seen broken on the other less stronger units? Keep in mind that they are all the same size where the yoke fits. In all the years I've been into Mopars (50+), what I see broken on the 8 3/4 are broken teeth and it involved ALL of the different cases including the 89. Personally, I won't run the 89 unit even on the street unless that damned crush sleeve is replaced with a solid spacer. Once that's done, I'm happy with it.

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Good info, I'm a bit of a newbie to Mopars lacking the years of experience but that makes perfect sense. It's kinda like putting H beam rods and forged pistons on a cast crank and saying it's stronger now.

threewood said:

Chrysler did use the 741 successfully behind their max wedge motors. Probably a higher chance of breaking the u joint or, like cranky said, the teeth before the pinion on any of them.

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Not sure why ChryCo went with the tapered pinion but maybe it was an effort to reduce the ring gear shaving due to pinion deflection? If so, it didn't work lol. Some years back, you could get the 'Pro' gears which are softer and not as brittle as street gears but by then, the 60 and the 9 was pretty much the rear of choice for drag racers and the Pro gears set wasn't selling very well and that was the end of it.

747mopar said:

Good info, I'm a bit of a newbie to Mopars lacking the years of experience but that makes perfect sense. It's kinda like putting H beam rods and forged pistons on a cast crank and saying it's stronger now.

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Well, mom's cast cranks are really not a bad piece although the forged unit are much better. Anytime you install lighter pistons and rods, you're helping the crank to live longer. Also, the cast crank is lighter than a forged crank and will spool up quicker.....but doubt I would spin one 7500

Cranky said:

Well, mom's cast cranks are really not a bad piece although the forged unit are much better. Anytime you install lighter pistons and rods, you're helping the crank to live longer. Also, the cast crank is lighter than a forged crank and will spool up quicker.....but doubt I would spin one 7500

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Let me ask this. What about the fact that an original sure grip unit was American made? Isn't most of the new stuff today made in China? Should that be considered when deciding new vs original used?

Aren't the side bearings different ID? Spring sure grip a little larger, OD is the same.

68chargerpilot said:

Let me ask this. What about the fact that an original sure grip unit was American made? Isn't most of the new stuff today made in China? Should that be considered when deciding new vs original used?

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Anything made in China makes me think twice about it but I haven't bought anything new for rear ends in a long time.

Fran Blacker said:

Aren't the side bearings different ID? Spring sure grip a little larger, OD is the same.

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The bearing fits on the carrier is different on the early units iirc but the race fit is the same on all of the cases...41,42 and 89. Not sure on the very early cases though. Not many of the early early ones show up these days.

Hey charger,
I will pm you the number for Lindsay
McClure. He is in dacusville and is the best on the rear ends. Worked for Richmond 30 yrs. Did the on-site set ups for NHRA . He was the field man. Now retired and has a shop at home.

Cranky said:

Well, mom's cast cranks are really not a bad piece although the forged unit are much better. Anytime you install lighter pistons and rods, you're helping the crank to live longer. Also, the cast crank is lighter than a forged crank and will spool up quicker.....but doubt I would spin one 7500

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O.K. maybe the analogy would have been better if I said forged crank and pistons with factory rods lol.