8 3/4 rear end 450-500 HP

[velrob]

71 charger superbee

would I be able to use the stock 8 3/4 rear end with 450-500 hp  or would i need to swap out the entire axle or beef it up ?

[Troy]

What transmission and rear gears? Do you plan on drag racing with sticky tires?

Troy

[c00nhunterjoe]

Bfgoodrich radial ta's- 500 hp/727 will be no problem.

Mickey thompson drag radials/ 400hp/ 4 speed- broken all the time

[XH29N0G]

I have a naïve question that I think is relevant to this thread.   Can you tell me what happens when an you break an 8 3/4 and whether it is easy to diagnose?  My guess is that it just stops working/makes a lot of noise etc..., but not having done this I don't know what to expect.

I am assuming this occurs really only when the clutch is dropped at relatively high (3500) or higher rpm. 

The reason I ask is I am thinking about going to the track next year with a manual and think I am close to the power range for breaking - I am running drag radials and a manual with 4:30 gears. 

[c00nhunterjoe]

I have a naïve question that I think is relevant to this thread.   Can you tell me what happens when an you break an 8 3/4 and whether it is easy to diagnose?  My guess is that it just stops working/makes a lot of noise etc..., but not having done this I don't know what to expect.

I am assuming this occurs really only when the clutch is dropped at relatively high (3500) or higher rpm.  

The reason I ask is I am thinking about going to the track next year with a manual and think I am close to the power range for breaking - I am running drag radials and a manual with 4:30 gears.  

The good news it wont dead hook on drag radials and a 4 speed. The bad news, it will hook enough to snap axles. I have a pile of them. Stick cars are historically harder on parts, but the autos are not a whole lot better. Broke several axles in my auto equipped belvedere as well. I never made enough torque (or never put it to the ground) to break more then shafts. The belvedere was a 741 case with a minispool and after putting hardened axles in, it lived. The charger got a dana with 35 spline shafts.... no more worries.... ever....

2600 rpm, side step... boom.... funny part is, i set a .007 light there, and snapped the axle, before my buddy took off... lmao
https://youtu.be/cH1rhB8FIkU

This is what happens, and axle wrap is terrible. I tried clamping leafs, adding old school slapper bars, nothing worked. Mangles bars and snaps the clamps. If you have traction, you need to invest in a set of caltracs.

[XH29N0G]

Thanks.  I'm a little worried, but will see what happens when I try at the track.

[velrob]

I wont be drag racing just street car.

Mostly cruising car with some blasts here and there. 

It has stock 727 Tranny.

[c00nhunterjoe]

Thanks.  I'm a little worried, but will see what happens when I try at the track.

Please take video. Either way, it will be fun to watch.

[c00nhunterjoe]

I wont be drag racing just street car.

Mostly cruising car with some blasts here and there. 

It has stock 727 Tranny.

Stock 727 and 500hp wont go together very well either. If you put a hard street tire on it, it will live for a while.

[Challenger340]

When a "performance rebuild" is performed, and it is rebuilt properly by someone familiar with the 727, including a shift kit, cooler, etc., in my experience the 727"s are an extremely reliable and tough unit behind a 500 hp Engine.

[firefighter3931]

With an auto trans and street tires it will never dead hook. You're fine 



Ron

[ChargerST]

I guess a soft-lok clutch or a cluchtamer (read about it on forabodiesonly --> cluchtamer.com) would help with breakage up to a certain point.

[BSB67]

.......in my experience the 727"s are an extremely reliable and tough unit behind a 500 hp Engine.

Mine too 

[c00nhunterjoe]

.......in my experience the 727"s are an extremely reliable and tough unit behind a 500 hp Engine.

Mine too 

But like he said, a performance rebuild, the op has a "bone stock" unit. In my opinion, even on street tires, 500 hp will wear it out.

[BSB67]

.......in my experience the 727"s are an extremely reliable and tough unit behind a 500 hp Engine.

Mine too 

But like he said, a performance rebuild, the op has a "bone stock" unit. In my opinion, even on street tires, 500 hp will wear it out.

The first time you used the word "live", not "will wear it out".  Sure, some parts are consumable. 

[RECHRGD]

Are we talking 450 to 500 at the wheels or the crank?

[c00nhunterjoe]

.......in my experience the 727"s are an extremely reliable and tough unit behind a 500 hp Engine.

Mine too 

But like he said, a performance rebuild, the op has a "bone stock" unit. In my opinion, even on street tires, 500 hp will wear it out.

The first time you used the word "live", not "will wear it out".  Sure, some parts are consumable. 

Ok, let me be more specific- will it explode and send peices through the case with 500 flywheel horsepower on bfg radial t/a's? No, it will not. But a bone stock 727 behind a 500 flywheel hp engine on any tire will not last, live, or wear very well in my opinion. The shifts will suck. They will be soft at first and degrade to mush and then a flair. Band adjustments will be twice as often as they should be, fluid will darken quicker and burn. It will not hold up.

[polywideblock]

  how'd we git to 727 autos       wasn't the thread about 8 3/4 diff strength,  or lack there of     

[c00nhunterjoe]

Because the op also stated that he has a bone stock 727 behind the engine.

[velrob]

ROFL i guess you answered another question of mine.

I guess I need to upgrade the 727 as well.

Someone told me to grab a Dana 60 from scrap yard and upgrade the tranny?
I dont want anything living a short time I want it to last awhile

[c00nhunterjoe]

If it were me, i would do the trans 1st.

[morepower]

well i am gonna find out how my 600hp stroker, and drag radials do within the next year and ill let you know

[6spd68]

If it were me, i would do the trans 1st.

I agree, I bought the Dana mainly because the opportunity came up, and I'm going with a t56.

[c00nhunterjoe]

Broke many a tremec behind my 302 fox body mustang.... cant imagine it with another 1000 pounds behind it. Will make a cool cruiser though.

[fy469rtse]

Yep as above , your week link is the stock trans,
I've got a little bit more than that  well Ok a lot
Ron warned me ,
and I've only broken two so far , Dana's next 

[6spd68]

Broke many a tremec behind my 302 fox body mustang.... cant imagine it with another 1000 pounds behind it. Will make a cool cruiser though.

3rd gear forever

[Highbanked Hauler]

 Since I don't race I ask,  what RPM  do you LEAVE at ? 

[c00nhunterjoe]

Broke many a tremec behind my 302 fox body mustang.... cant imagine it with another 1000 pounds behind it. Will make a cool cruiser though.

3rd gear forever

2nd and 3rd both, many many times. Broke the shifter off the top of one once, and split a case in one.

[c00nhunterjoe]

Since I don't race I ask,  what RPM  do you LEAVE at ? 

The mustang got side stepped at 6500 on a 12" wide bias slick. The charger has been everywhere from 3000-6000 depending on whether it had drag radials or slicks on it.