7 1/4 Can handle how much

[Slantsix64]

i have a slant six with a 4 speed 9 to 1 with a mild camshaft 473 lift 255 duration super six carb 2.5 exhaust after breaking in the new camshaft less than a week BANG busted one gear off the ring gear. I had 3.55 in that rear my question is do I just need to upgrade to a 8 3/4 or was I just unlucky this time? I doubt I have more than 150 hp and the wheel. What do you guys think I had a 4 speed with a v8 and a 7 1/4 never had any problems dumped the clutch all day.

 

[BigBlockMopar]

Pull another plugwire or 2 and it will probably live...

Excessive, worn/loose carrier-play won't help these puny axles either.
And I've never read about anyone doing 'preventive maintenance' on a 7-1/4" axle.

 

[65 Dartman]

I’ve heard that the 7.25 tends to last longer if equipped with a Sure Grip. Don’t know how true that is as I’ve always gone straight to the 8.75. Personally, I’d Upgrade to at least the 8.25

 

[chryslerfat]

They dont like 4 speeds. Dad went through a few with a 273 4 speed back when they were only a few years old. One was a ring gear, one broke the ring gear bolts and another was spider gears.

 

[pishta]

7.25 SG is twice as strong as the peg leggers...Im told. I blew a 3.55 7.25 SG but it took a 340 and a neutral drop with 10" tires to do it. I think you got unlucky. Mine chomped the ring gear.

 

[Mopar to ya]

It will take more than 150hp, guaranteed. You were unlucky. Was it an old, probably already worn rear end or did you put in the 3.55 gears?

 

[Slantsix64]

It will take more than 150hp, guaranteed. You were unlucky. Was it an old, probably already worn rear end or did you put in the 3.55 gears?

It was a new gear set I had put in about a year ago I'm just debating on slapping in another ratio or just upgrade

 

[Slantsix64]

7.25 SG is twice as strong as the peg leggers...Im told. I blew a 3.55 7.25 SG but it took a 340 and a neutral drop with 10" tires to do it. I think you got unlucky. Mine chomped the ring gear.

I had two sure grips and sold them like an idiot, biggest regret ever

 

[AJ/FormS]

ripping a tooth off is a shock load. It usually takes off parts of one on either side of it too. The pattern may have just been too low. You were probably just unlucky.
I ran a 340 auto with a 7.25 NON-SG for about a year and a half, back in the seventies. The 1965 A904 gave up first.
Skinny tires saved the hiway gears I guess.

 

[sireland67]

ripping a tooth off is a shock load. It usually takes off parts of one on either side of it too. The pattern may have just been too low. You were probably just unlucky.
I ran a 340 auto with a 7.25 NON-SG for about a year and a half, back in the seventies. The 1965 A904 gave up first.
Skinny tires saved the hiway gears I guess.

X2 I beat the crap out of a 7.25 in my first duster, I knew the rear was weak, so I had a spare it never came out.
It had alot of clutch drops, abuse from me, but being a peg leg it slipped, not hooked.

I broke a 8.75 behind my first car, with a slant.
I am not easy on parts......

 

[Charrlie_S]

A 7 1/4 with a SG, is stronger then most realize, but they don't like the "shock" loads a stick puts on them. I ran 7 1/4 rears for many years, in "A" bodies with turbos and nitroused slants using slicks, (running low 13's in the 1/4) and didn't break it. Just wore out SG clutches once in a while. The main problem, now, with 7 1/4's is getting parts. Personally, I would do an upgrade to something that is stronger, and has parts available.

PS: I'm in the process of building a large bolt pattern 3.91 SG 7 1/4 rear, with all brand new parts, except spider cross shafts (could not find any). It has taken me about a year to find all the NOS parts, and close to $500. For less money, you can upgrade.

 

[rumblefish360]

Inexpensive & tuff = 8-1/4

Expensive & strong = 8-3/4

Expensive & strong like Hercules = DANA

 

[Mike69barracuda]

I’ve heard that the 7.25 tends to last longer if equipped with a Sure Grip. Don’t know how true that is as I’ve always gone straight to the 8.75. Personally, I’d Upgrade to at least the 8.25

How do I tell if I have a 7.25 sure grip. i have a 69 barracuda with the slant 6 225 engine automatic tranny. THX I'm getting a whine back there. Carrier bearings need replaced??? Any ideas.

 

[AJ/FormS]

From the factory, that car would have had a 7.25, and probably not a SG unless special ordered.
However, all these many years later, who knows. You will have to jack at least one side up and check/look.

 

[67Dart273]

How do I tell if I have a 7.25 sure grip. i have a 69 barracuda with the slant 6 225 engine automatic tranny. THX I'm getting a whine back there. Carrier bearings need replaced??? Any ideas.

Easy jack up one wheel, put the trans in neutral and see if you can turn the tire. If so, "open." If not some type of limited slip

Spiders are always the weak link, and doing burnouts, or "doing stuff" that results in sudden shock, suck as spinning one wheel in loose gravel "on the right" and suddenly "hooking up" with pavement is a guarantee for a junk rear axle.

In my day "weld a lock" was sometimes used, AKA 57 chev. I drove a whole winter with one, that will indeed "teach you to drive" LOL

 

[74Dusted]

This actually has a Chrysler 7.25” Front Differential in it, based off of the 7.25” Rear you find in A Bodies.

Knock on wood, I’ve been beating on it for a few years with a Turbo Diesel engine and 32x10.5-15” Tires and Fulltime AWD. Prior to the diesel it had a 5.2 Magnum and 30x9-15” Tires.

I know my luck, now that I’ve opened my mouth it’ll probably puke the ring & Pinion through the cover.

 

[deathdust73]

I have an a body 8.75 with a truetrac, green bearings, 3.23s hooked up to a slant lol upgrade n use dr diff