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Rear axle choices Ford 9" or 8.8" or other? (2008-2022 bump)

qwkswede said:
I don't know where you guys have been. But here is the rule straight from the nhra rulebook.

http://www.geocities.com/boosted_eine/nhrarulebook.html

2.3 REAREND

After market axles and axle-retention device mandatory on any car running 10.99 (*6.99) or quicker and any car with locked differential. Cars running 10.99 (*6.99) or quicker that weigh more than 2,000 pounds (907 kg) with independent rear suspension must have swing axle differential replaced with conventional differential housing assembly.
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Odd, I do know of more than a few sub 11 sec cars on factory IRS
 
Captain Bondo said:
edit: BBQ beat me...
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Is that a request? I don't normally do kinky stuff, but as you're a mate...............
kinky.gif







getmecoat.gif
 
i would go with the 9 in just because you can get parts for them anywere and if you ever plan on going faster you wont have to worry about replacing the axle.
 
The IRS rule was meant for Jaguar type IRS's that used the axle shaft as a means of holding the wheels attached to the car. If an axle snapped the wheel could go flying. The rule does NOT apply to an irs where the axle shaft is only used to transfer torque to the wheels.
 
thelostartof said:
Odd, I do know of more than a few sub 11 sec cars on factory IRS
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even guys with 03 cobras that have the stock 8.8" IRS setup tend to swap out for the solid rears if they are big on drag racing because the IRS loves to wheel hop.

buddy had his 11.8 sec cobra break a half axle at the track the last time he went..
 
Captain Bondo said:
Forg, What are you referencing that suggests a 31 spline 8.8 is no good for 11's in a 3200lb car? You think he will "waste" and 8.8? How come?
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Because I don't really know what I'm talking about, Ford fitted 9" diffs to cars that had 260hp from the factory (when the 200hp versions had 8.8" ones) ... and fitting the 8.8" smells a bit like a shortcut & every shortcut I've taken in Big Red Car has cost me 2x as much as just doing it properly in the first place. :-(

narancs said:
noob Q:
whats wrong with the IRS? Why it isn't good for dragging?
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Because the over-shoulder straps get all tangled-up in the extra links.
Well actually, it's because there's more room for movement & angles that can allow things to bend & break. You could definitely set something up to work, but the regulations are to stop the cheapskates from killing themselves.
 
Alex Buchka said:
The IRS rule was meant for Jaguar type IRS's that used the axle shaft as a means of holding the wheels attached to the car. If an axle snapped the wheel could go flying. The rule does NOT apply to an irs where the axle shaft is only used to transfer torque to the wheels.
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Which also includes Corvettes, and some of the other designs as well. Many use the halfshaft as a suspension member.
 
Forg said:
Because I don't really know what I'm talking about...
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I LOL'd :lol:
Because the over-shoulder straps get all tangled-up in the extra links.
Well actually, it's because there's more room for movement & angles that can allow things to bend & break. You could definitely set something up to work, but the regulations are to stop the cheapskates from killing themselves.
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thanks.. I know dragging and cornering are 2 different world, but i thought IRS is better.. bc it is more efficient or something :wtf:
mehh I stick with cornering.. ohh wait... I have teh FWD, i have teh fail.. lol :)

edit: and doesn't even have IRS
 
Forg said:
Because I don't really know what I'm talking about, Ford fitted 9" diffs to cars that had 260hp from the factory (when the 200hp versions had 8.8" ones) ... and fitting the 8.8" smells a bit like a shortcut...
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This is also the same company that fitted 7 litre engines when 3 litre ones would've done. American vehicles have historically been massively over- engineered. How do you think they produced these axles in the first place?:-P
 
Some of the corvette folks are going with longer swing arms which essentially reproduce the drag traction a good 4link solid axle has without the issue of torque lifting the right rear wheel slightly. It is however a much more complicated system than a simple 4link on a solid axle. 8.8 with upgraded axles would be my suggestion - when you start braking that we can then all kneel to your vast hp ;-)

my .02

Renny
 
Forg said:
Because I don't really know what I'm talking about, Ford fitted 9" diffs to cars that had 260hp from the factory (when the 200hp versions had 8.8" ones) ... and fitting the 8.8" smells a bit like a shortcut & every shortcut I've taken in Big Red Car has cost me 2x as much as just doing it properly in the first place. :-(


Because the over-shoulder straps get all tangled-up in the extra links.
Well actually, it's because there's more room for movement & angles that can allow things to bend & break. You could definitely set something up to work, but the regulations are to stop the cheapskates from killing themselves.
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Hehe. I like that over-shoulder straps comment.
 
BB-Q said:
This is also the same company that fitted 7 litre engines when 3 litre ones would've done. American vehicles have historically been massively over- engineered. How do you think they produced these axles in the first place?:-P
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S'not quite the same though; the 7L engine had a lot of marketing-clout, whereas barely a poofteenth of a percentage of the buying populace would've known anything about differentials.
Ford Australia weren't exactly "over engineerers" either, they did things like putting 250ci 6cyl Falcon engines into Mk3-Mk5 Cortinas such that the front ends would bend while the cars were still in warranty if you went for the optional factory aircon system ... :)
 
Forg said:
S'not quite the same though; the 7L engine had a lot of marketing-clout, whereas barely a poofteenth of a percentage of the buying populace would've known anything about differentials.
Ford Australia weren't exactly "over engineerers" either, they did things like putting 250ci 6cyl Falcon engines into Mk3-Mk5 Cortinas such that the front ends would bend while the cars were still in warranty if you went for the optional factory aircon system ... :)
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Ford America is a totally different animal to Ford ROW. How else can I explain it?

Ok then, let's put it this way: The Ford 8.8" axle is proven to be able to take the ultimate punishment of drag launches from big, heavy 9 second doorslammers.

What else would you like? There's hardly an excess of nine second Volvos here, is there (and I'm sure you could find some in the eights if you researched it)? The 9" actually takes a hell of a lot of modifications before it's capable of handling big horsepower without killing the gears on a regular basis. Also, as has just been revealed on here, the 9" robs hp- something we hardly have an excess off here on TB!
 
Hehe. The powerplant selection is underway. I have a couple years to get the chassis and body ready before I need a completed engine. Its top secret for now. All that I want to say is that is that the car will be way under 3000lbs. And the engine will make more power than the 488whp that my current 16v makes. And there could be a transbrake transmission involved if it really becomes a pure drag car. Probably not in the first iteration though. Or at least had hard launching stickshift. Thats rough on axles too.

Forg said:
I don't think he's using a Volvo engine of any sort if he's aiming in the 10's with a 240 ... not on the cheap, anyhoo. :)
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