Arrant

Hello... I have a 2004 roush stage 2 manual with a vortech v-1 332 rwhp

I can feel and just barely hear a little slop in rear end when getting on and off throttle quickly. Is that normal?

Also would like to know how much power the stock axels and rear end with street tires and 355-373 gears would safely take? thinking about upping HP and a gear change.

Thanks for any info....

boduke0220

its the driveshaft. mine did the same thing. as far as the rear holding power though, i dropped the clutch at 5500 on slicks with the stock rear and 4.10s and it held lol

Arrant

I had it in the air and the u-joints seemed ok. if I held the drive shaft and spun the rear wheel it had some play and made a slight noise when play got taken up.

Thanks for reply.....

cliffyk

Power transmission devices like transmissions and gear boxes are rated by torque, not horsepower. The 8.8" 28-spline axle rear end is rated for 1250 lb-ft continuous output torque, and 4600 lb-ft maximum output torque. 31-spline axles ar rated for 1360 lb-ft continuous output and 5100 lb-ft maximum--or about 10 % higher.

Calculating how much horsepower can be supported requires a number of assumptions, predominately final drive ratio, engine speed at maximum torque to the ground, and a guesstimate as to how much that maximum torque might be. As most people start to get glassy-eyed when the math part come up, and just want a simple answer (even if it is an incomplete and incorrect answer), here it is:

Around 400 HP actually passing through the 28-spline axles is a reasonable and practical limit. The "actually passing through the axles" part is important. You could have a 1500 HP engine, but if the tires could not hook up for crap the rear-end may never even see 200 HP passing through it.

Here are driveline analysis, diagnostic and testing procedures from the Shop Manual...

rygi23

cliffy always has a magical way to give you an accurate answer, lol. With street tires add as much power as your heart desires. If you plan on doing any kind of launching with sticky tires, a steeper gear ratio helps take alot of the stress off of the entire drivetrain. I had around your power level with my Mach. I had ALOT of 5k-6k launches on Mickey Thompsons with 4.10s in an otherwise stock rear. Never had a single issue.

lizzyfan

Bud of mine had about 290 rwhp on stock axle's and M/T DR's. Launched at 3500 and broke stock axle. If you do any rear end work might as well upgrade to 31 spline axle's, added insurance

rygi23

Was your friend on stock gears when the axles went?

lizzyfan

No, 4.10's but that really doesn't matter

speedkills

Cliff always has the best answer to these types of questions lol.

Mustang_NTriangle

I had 470 rwhp on my 5 speed mustang with Nitto Drag radials with no problems and 3.55gears on stock tranny and rear end. No need to build rear end if you still have stock motor these 8.8 rear ends can take alot of abuse.