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84 Mutt
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284 Posts
Discussion Starter #1
Hey all. I just got a new set of gears(3.73) and an eaton posi unit (26-spline). How much hp can the stock axles take w/this rear set up? Currently running a 406sb pushing about 400 hp. Have a set of 255/60/15 tires to go with it. I am debating on getting a set of new axles for a decent price ,but if these (bone yard) axles will hold then I wont bother ,but then again I'm not to sure.
:rolleyes: Some input would be great...:p Thank you.
 

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current hot rod: CTS-V
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1,821 Posts
I would not trust them, 406's torque/horsepower will probably do them in more sooner than later. Get a pair of new Mosers or something of equal quality. Better safe than sorry.
 

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84 Mutt
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284 Posts
Discussion Starter #3
Thanks Ghetto Jet. I was thinking the same. Spend $550 on gears and carrier , might as well spend another $200-250 on axles (not to mention paying the shop for the labor. Good thing I know him, he built my engine).. What is the standard axle length on a 10 bolt 7.5.? I think its 30 1/2" but just want to double check...Thanks again.:thumbup:
 

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Premium Member
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2,233 Posts
Worry about the axles not holding, then worry about the carrier bearing caps breaking under hard load.

You could replace the spider gears and axleshafts with the 28 spline pieces for a slight upgrade.

You could drill and tap the drivers side cap and housing hole to accomodate 1/2 inch bolts, which will help the longevity of the housing a little.

You are still asking more than this axle was designed for every time you start that 406 and move the car.

Your best bet will be saving up for an 8.5 GM, 8.8 or 9 inch ford housing to replace the 7.5.
 

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84 Mutt
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284 Posts
Discussion Starter #8
Thanks [email protected] , but I already have a brand new eaton carrier , install kit , and new 3.73 gears all for 7.5---(also LPW t56 end cover with bearing cap nuts) So i'm pretty much stuck with the realm of the 7.5.....I would love to bump up to a 8.5 (gn rear) but like I said, these all came to me at decent prices. I think I have to go with new axles too...:embarrass
 

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M&M CUSTOM said:


You could replace the spider gears and axleshafts with the 28 spline pieces for a slight upgrade.

You could drill and tap the drivers side cap and housing hole to accomodate 1/2 inch bolts, which will help the longevity of the housing a little.

Installing the cast aluminum cover with bearing preload studs you have described will also help, BUT I would only go with half the stud torque rating the manufacturer states in the instruction that come with it.

YES the pre-load WILL help, but if you torque the stud to the specs in the instructions you are putting stress on the carrier bearing caps and in effect distorting them, causing a whole new possibility of a potential for failure. Try reducing the proload torque to 50% of what the manufacturer recommends if using used bearings or races, and 75% in new.

NOT running slicks will also help.

These are the only mods I have seen others use that gives them more time with their 7.5 axles until they upgrade the whole thing later.

Before you install those new axleshafts, paint a straight line the whole length of them, and periodically check this for twisting of the shaft. A fellow member on another board I belong to did this and was surprised at how much it twisted before it broke. It was a name branded aftermarket shaft.
 

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84 Mutt
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284 Posts
Discussion Starter #10
Wow... Thanks [email protected] think the torque specs. is 15 to 20 ft.lbs
So I would be safer in the 7-8 range. There are all new bearings too..Good idea w/ the painted line..I would have to pull them out time to time, or is there an easier way to check for twisting.? By all means ,its not a pro-stock but its got some balls(a lot) More torque if anything.More torque, more twisting.:embarrass Guess I gotta watch how I leave the line.
Thanks again...:thumbup:
 

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hey i have 85 camaro with 550hp and i am going to try to use the 7.5 rear jegs and summit told me to use a mini spool to stengthen it so all i will brake is the axles ? it should only bend them my friends have put 750hp and only bent them.
 

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I had a stock 10-bolt GM rear in my '95 Firehawk until I passed the 400hp mark and put slicks on. That was it for the rear. If you run slicks those axles will snap pretty quick.
 

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84 Mutt
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284 Posts
Discussion Starter #13
Well I think with aftermarket shafts, LPW cast alum.cover w/cap preloads, all new internals(eaton carrier and timkin bearings and 3.73 richmonds) it should do...Not gonna run slicks(although once or twice in the beginning would'nt hurt:drool: )Just want something to play with.It hooks pretty good now after installing trick springs in front and back along with adjustable shocks. Just want a decent aftermarket shaft to prolong some life into it.Any good ones out there??
 
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