how much can the stock rear end take?

mean2001gt

New Member
Jan 27, 2004
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danville, ca
my car is a daily driver and it's n/a. i just got the engine rebuilt and it's .020 over with high compression pistons and p&p heads with xe270 cams. i'm hoping for the 310 rwhp range. i've seen as high as 320 with the exact same setup (with a little less compression).

well my question is how much can the stock rear end take? i have 3.73 and i go to the track once a month or so, and i do not plan on getting slicks, but i'm thinking about drag radials. i do have upper and lower control arms. will the stock rear end handle about 310 rwhp on a full weight gt with 15 inch drag radials? i'm not worried about 17 inch drag radials, the rear end should be able to handle that no problem.

also how big of a difference is there between 17 inch drag radials and 15 inch drag radials?

thanks
--chris
 
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mean2001gt said:
will the stock rear end handle about 310 rwhp on a full weight gt with 15 inch drag radials? i'm not worried about 17 inch drag radials, the rear end should be able to handle that no problem.

also how big of a difference is there between 17 inch drag radials and 15 inch drag radials?

thanks
--chris
well with my mods (including 17 inch drag radials) i already have damaged my rear axle.. actually at 7000 miles there was signs of wear and it looked as if i had about 60,000miles on it.. Depends on how you drive, a daily driver for me is tearing out and getting about 3500rpms probly 2 times a week max but when you launch 315x35x17 nitto 555r DR's from 5000 and dumping the clutch and they still barely even skip....not gonna last forever :bang: but who cares, im gonna have to upgrade it eventually anyways right! :nice:
 
If your concerned and you have the $1K, just upgrade now and be done with it. I hear of alot of Mach1's breaking rears on DR's. Moser/Superior 31 spline axles and diff of your choice (Eaton). If it's your daily driver take the extra insurance and just do it.
 
Just blew mine

I got a 99 Gt with some mods.....410 drag shocks and struts shifter...the usual bolt ons, and ran nitto DR's last summer. I ran slicks once at the track and ran them on the street just for fun. I pulled it out after winter got on it and it broke on street tires. The 410 has been in for 2 years, but I know why it broke cuz I drive the car like its stolen. DR's will take some life off of the rear end, especially if u run 15" DR's they have a taller sidewall which helps the car hook a lot better than the low profile sidewall of the 17" nittos. I'm replacing my whole rearend and the upper and lower control arms, hopefully it makes a difference. Just remember if u do put a new rearend in ull be able to launch at high rpm's with no issues or worries!
 
common spline patterns are 28, 31, and 33 spline in axles. that's the number of individual bumps (splines) on an axle. a 31 spline axles has 3 extra splines than a stock 28 spline axle. more splines means a bigger axle in diameter. when you upgrade axles size from 28 to 31 spline, you must also get a new carrier (differential) with the same spline pattern so they will fit together. most people go with 31 spline unless you run insane HP numbers. moser 31 spline axles should hold 500+ HP with slicks. if you run a stock GT with drag radials or slicks, you will eventually snap (or shear) the splines off your current axles. the stock axles are fine unless you do heavy duty driving.
 
oh... btw. you'd want to get a new differential for better traction. the stock one won't give very even power distribution to each drive wheel. a new and better aftermarket differential will help split the power 50/50 to each wheel, which is optimum.
 
99StanGT said:
Just remember if u do put a new rearend in ull be able to launch at high rpm's with no issues or worries!
Everyone seems to be forgetting the mustangs main weakness...just because your rear end can take a 6k launch does NOT mean that your tranny is gonna...no worries is not something you can say when it comes to stangs!
 
The number of splines on an axle is dependent on the diameter of the axle. The larger the diameter the more the splines the stronger the axle. The spline is actually a gear that is cut into the end of the axle. Usually its machined, but the better and stronger axles have them cold rolled for better strength. A stock 8.8 rear end comes with 28 spline axles. The prefered aftermarket application is a 31 spline with a 33 spline being the prefered all out race choice.
 
How much would it cost to replace a rear end? My gears are loose and I think it is from major wear from the previous owner. I think it would do me good to just replace the axles, either with stock or 31 spline as well as and most importantly replace the diff so there is no more looseness (sp?)
 
87whitevert said:
How much would it cost to replace a rear end? My gears are loose and I think it is from major wear from the previous owner. I think it would do me good to just replace the axles, either with stock or 31 spline as well as and most importantly replace the diff so there is no more looseness (sp?)

Axles, ABS Rings and Studs - $300
Eaton Posi - $380
Rear End Girdle - $180
Gears - $170

Approximate Prices!