Will my rear axle snap?

2377 Views 20 Replies 4 Participants Last post by kscoyote, Jan 20, 2006

Dustang99

Discussion Starter · Jan 16, 2006

Alright so I'm fixing up my 1999 V6... I haven't done much to it, I've only got dual exhaust and it's a stick. I'm planning on putting an x-pipe on and adding an intake real soon. I'm planning on doing much, much more to it, but my question is, do I need to get a GT axle to support the extra hp? I've heard of people's V6 axles snapping with very minor mods. And if so, what all comes on a GT axle? I'm supposing the t-lock will already be on there? And what else would I need to get to complete the change-over. If you could give me a price on it, that'd be great too. Thanks.

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kscoyote

· #2 · Jan 16, 2006

Dustang99 said:
Alright so I'm fixing up my 1999 V6... I haven't done much to it, I've only got dual exhaust and it's a stick. I'm planning on putting an x-pipe on and adding an intake real soon. I'm planning on doing much, much more to it, but my question is, do I need to get a GT axle to support the extra hp? I've heard of people's V6 axles snapping with very minor mods. And if so, what all comes on a GT axle? I'm supposing the t-lock will already be on there? And what else would I need to get to complete the change-over. If you could give me a price on it, that'd be great too. Thanks.

The GT may or may not have a T-Lok, and even if it does, chances are the clutches would have to be replaced anyway.

-in 2001, the axles are 28 spline, the same ad the GT.

You need to be putting out a LOT of power before the rear end will give up. (Around 300+ for pre-01s, 375+ or 400+ with a girdle).

You can pick up a kit from stangparts.com, or just get the entire axle assembly from a salvage yard (axle, housing, shocks (including quads) hubs and discs. You may want to use new fasteners.

Dustang99

Discussion Starter · #3 · Jan 16, 2006

Huh... so it should be fine if I don't put over 300 horses into it? Something tells me I'm not going to get to that point... maybe 260 max, unless it takes next to nothing to get there. I guess I'll just have to buy a t-lock and have it installed. Any idea on what that'll cost me for the t-lock and install? Also, I just got qouted $350 for install on a new clutch... sound about right to you? (the clutch is XTD Stage 3)

kscoyote

· #4 · Jan 16, 2006

Dustang99 said:
Huh... so it should be fine if I don't put over 300 horses into it? Something tells me I'm not going to get to that point... maybe 260 max, unless it takes next to nothing to get there. I guess I'll just have to buy a t-lock and have it installed. Any idea on what that'll cost me for the t-lock and install? Also, I just got qouted $350 for install on a new clutch... sound about right to you? (the clutch is XTD Stage 3)

When it's all said and done, count on 500-800 on the t-lok (But you should really go with the detroit locker). Installation is usually around $300-400 + tax, the differential is usually between 173-250 + shipping.

350 is a good price for a clutch installation. While you're in there, if you can afford it, go for a lightweight flywheel. It'll really wake up your car.

Dustang99

Discussion Starter · #5 · Jan 16, 2006

Cool... would they have the pulleys there? or would I need to order them? thanks dude for all your help I appreciate it

kscoyote

· #6 · Jan 16, 2006

Dustang99 said:
Cool... would they have the pulleys there? or would I need to order them? thanks dude for all your help I appreciate it

you'd need to order them.

Re: the rear end, if you are planning to build up to big power numbers, you can get a support girdle, that will allow you to go 350-400 hp.

Pete Campbell still runs his 7.5" and he's running in the 11's with a powerdyne SC unit.

That said, you shouldn't need to abuse it, an 8.8" will shred if you do 4-6000 RPM clutch drops.

But the six makes enough torque, you don't need to engage in that behavior anyway.

Pinto

· #7 · Jan 17, 2006

I think you will be more than fine with the 7.5 in there. I have 300+ rwhp and still run a 7.5 with drag radials. I'm not real comfortable anymore with it but it hasn't broken. A detroit locker is what I'll be putting in, that is a lot better than the GT rear IMO

speedytang

· #8 · Jan 17, 2006

I think you guys are not getting the point with the 8.8 compared to the 7.5. The axles are the same it is the weak casting thickness of the 7.5 gears and carrier bearing caps. You can put a support to control the cap walking but you will still have the problem of the carrier cracking unless a expensive upgrade which if you spending that kind of money you can get a 8.8 assy used with a good choice of gears for $400 and spend a couple of hours installing it. You will have more money in the gear install then getting the complete stronger rearend.

kscoyote

· #9 · Jan 17, 2006

speedytang said:
I think you guys are not getting the point with the 8.8 compared to the 7.5. The axles are the same it is the weak casting thickness of the 7.5 gears and carrier bearing caps. You can put a support to control the cap walking but you will still have the problem of the carrier cracking unless a expensive upgrade which if you spending that kind of money you can get a 8.8 assy used with a good choice of gears for $400 and spend a couple of hours installing it. You will have more money in the gear install then getting the complete stronger rearend.

You can get a girdle with a lot less hassle, and plenty of folks are running 400+ hp with the 7.5. (It has been upgraded a bit over the years).

The v6 makes a lot less torque than the 5.0L, so the driveline shock isn't as great . ..

Dustang99

Discussion Starter · #10 · Jan 18, 2006

so do you reccommend any brand of lightweight flywheels?

speedytang

· #11 · Jan 18, 2006

Are you guys sure about a lite weight flywheel with such low torque engine. Usually you use weight of the flywheel to increase torque to the wheels. I have driven 400hp 5.0 engines that just did not have the snap after a aluminum flywheel was installed without keeping the rpms way up over 4k rpm. If you road race I could see it because you would keep the rpms up because it will rev faster out of a turn but daily driving and if you drag race I can't see that flywheel helping but hurting to move the mass of the car. I still think that as cheap as a V8 rearend is and as hard as it is to find 7.5 gears and they cost more that the V8 rearend is a better choice.

kscoyote

· #12 · Jan 18, 2006

speedytang said:
Are you guys sure about a lite weight flywheel with such low torque engine. Usually you use weight of the flywheel to increase torque to the wheels. I have driven 400hp 5.0 engines that just did not have the snap after a aluminum flywheel was installed without keeping the rpms way up over 4k rpm. If you road race I could see it because you would keep the rpms up because it will rev faster out of a turn but daily driving and if you drag race I can't see that flywheel helping but hurting to move the mass of the car. I still think that as cheap as a V8 rearend is and as hard as it is to find 7.5 gears and they cost more that the V8 rearend is a better choice.

yeah, check out the archives. Reducing the rotational mass (especially on the six which uses a flywheel designed for the 5.0L) increases the efficiency of the system, and greatly reduces 1/4 mile times.

Honda proved the concept, and Hot Rod did a number of tests a couple of years ago, which also proved the concept.

the SVT Focus and Cobra both use lightweight flywheels with heavy duty clutches.

******************************************************************

an 8.8 rear is "relatively" inexpensive, but the installation isn't. It also adds more weight and even more rotational mass.

A lot of people feel safer running them, but a lot of people don't.

kscoyote

· #13 · Jan 18, 2006

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Dustang99

Discussion Starter · #14 · Jan 19, 2006

Thanks coyote... I suppose it'll save a lot on install if I put it in with the clutch? Seeing as how they have to take the flywheel out anyways?

Dustang99

Discussion Starter · #15 · Jan 19, 2006 (Edited)

Alright, I've got it all layed out... my clutch will have to wait til around feb. 9th... by then I would have gotten one paycheck to pay for the flywheel, and the next paycheck on that day will go towards install of those two. I will soon get an offroad x-pipe and a short shifter, maybe the next paycheck... then my tax return is going towards rims... whenever that comes in... and then comes lowering springs, and tower strut braces, then a t-lock. Sometime in the middle of all of that, hopefully I can get that little dent fixed ($350! sucks horribly) and little things here and there such as side stripes, new floor mats(mine are terrible), and windsheild banner. That'll be about all I'm lookin at doing to my car for a LONG time. Again thanks for your help! Any other recommendations are welcome, just nothing too expensive, cause we know all this is making me go broke!

kscoyote

· #16 · Jan 19, 2006

Dustang99 said:
Alright, I've got it all layed out... my clutch will have to wait til around feb. 9th... by then I would have gotten one paycheck to pay for the flywheel, and the next paycheck on that day will go towards install of those two. I will soon get an offroad x-pipe and a short shifter, maybe the next paycheck... then my tax return is going towards rims... whenever that comes in... and then comes lowering springs, and tower strut braces, then a t-lock. Sometime in the middle of all of that, hopefully I can get that little dent fixed ($350! sucks horribly) and little things here and there such as side stripes, new floor mats(mine are terrible), and windsheild banner. That'll be about all I'm lookin at doing to my car for a LONG time. Again thanks for your help! Any other recommendations are welcome, just nothing too expensive, cause we know all this is making me go broke!

you can wait a while on the x-pipe and the short shifter, they don't really add much. Chassis support, and the rest are so much more important.

Dustang99

Discussion Starter · #17 · Jan 20, 2006

Alright, alright. Next to last question... if I get a t-lock put on, will that make me lose any horsepower? (or 0-60 time) Because I'm looking at this 2 ways. One is that the drivetrain is now having to turn 2 wheels... therefor losing power because it's now turning more. Two, is that the drivetrain is now turning two wheels, but it's still only moving the car, and by turning both wheels it makes it easier to move the car... therefor not losing any power, if anything, gaining some. I see it both ways I just don't know which one is right. The only thing I do know, is I know it deffinately helps on traction. But any dumbass could tell you that, so it's not saying much for me. And now the LAST question, what size rims would be best for a V6? 17x8's or 17x9's? My guess would be 17x8's because the V6 really wouldn't need more, but I love the way my ex's 18x9's look on her car... I just wouldn't want to put 18's on mine. Stick with 17's.

kscoyote

· #18 · Jan 20, 2006

Dustang99 said:
Alright, alright. Next to last question... if I get a t-lock put on, will that make me lose any horsepower? (or 0-60 time) Because I'm looking at this 2 ways. One is that the drivetrain is now having to turn 2 wheels... therefor losing power because it's now turning more. Two, is that the drivetrain is now turning two wheels, but it's still only moving the car, and by turning both wheels it makes it easier to move the car... therefor not losing any power, if anything, gaining some. I see it both ways I just don't know which one is right. The only thing I do know, is I know it deffinately helps on traction. But any dumbass could tell you that, so it's not saying much for me. And now the LAST question, what size rims would be best for a V6? 17x8's or 17x9's? My guess would be 17x8's because the V6 really wouldn't need more, but I love the way my ex's 18x9's look on her car... I just wouldn't want to put 18's on mine. Stick with 17's.

yes, you "may" lose rear wheel hp, -but! the big loss occurs when 1 wheel is already spinning!

so, your 0-60 time should be faster, as a result.

you can fit a fairly wide tire on 16x8 or 8.5, or 9, and your rotational mass wouldn't be as bad as an 18x9.

17x8s really suck the torque out of the car . .. w/ 18x9's you may as well put a sandbag or 2 in the trunk and rear seat.

Dustang99

Discussion Starter · #19 · Jan 20, 2006

Okay so I found this site that has drag wheels on it...

http://www.prolightstar.com/dragwheels/dragwheel_dr11_18x75.htm
They say they're "lightweight", I'll look more into that later, but how trustworthy do you think they are? Would they be fine for everyday driving? If so then I'd deffinately want to get these... a nice alternative to bullitt rims, and much lighter. One thing I'm confused about that I've found out through searching, is that my year Mustang has a lugnut pattern of 5x4.5 right? Well the choices here are 5x100 and 5x114.3... which one is it? and would the offset being +45mm be any problem? Thank you again for all your help.

Dustang99

Discussion Starter · #20 · Jan 20, 2006

Ha! nevermind i got it... thanks to

http://www.convert-me.com/en/convert/length

it's 114.3... but I am still wondering about the +45mm offset and how reliable the rims would be in everyday driving

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