12 Bolt what E.T. do they start to break?
06-26-2009, 07:11 AM
#1
12 Bolt what E.T. do they start to break? I am looking to go mid 9s, by next year, but have heard that the 12 bolt might not be strong enough, possibly should go 9” or s60 (tank rearend, haha)…just wanted to hear some opinions, or what you have gone with a 12 bolt?
Setup will be h/c/I and 150 shot…
Was think of a strange 12 bolt with 4.10 gears, shortened 2”, 33 or 35 splines, aluminum spool, support cover…
thanks
Setup will be h/c/I and 150 shot…
Was think of a strange 12 bolt with 4.10 gears, shortened 2”, 33 or 35 splines, aluminum spool, support cover…
thanks
06-26-2009, 08:00 AM
#3
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I broke the posi on my 12-bolt twice, and taken out 1 set of 4.11's and 2 sets of 4.56's
If I had to do it again, I would go with a S60
Automatic cars will clearly be more gentile on the 12-bolt, but for 6spd cars... it seems to suck lol
People have gone 7's on a Fabbed 12-bolt [Paul Major]
If I had to do it again, I would go with a S60
Automatic cars will clearly be more gentile on the 12-bolt, but for 6spd cars... it seems to suck lol
People have gone 7's on a Fabbed 12-bolt [Paul Major]
06-26-2009, 02:06 PM
#6
another quick question 35 splines is when you can get the axles gun drilled correct??? is this worth it for the weight saving or will it make them alot weaker...i want a light read but for it to be strong also, hense the aluminum spool...thanks
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06-26-2009, 10:36 PM
#10
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06-28-2009, 08:59 AM
#14
I don't have any A4 results, but A3 results 
No problems at all, I took it apart last year figuring it was time after 3 years of being in the car and probably 200 track passes since it was installed... nothing wrong at all, and that was with a regular HD eaton posi.
Spool and a gear change went in (wish I had left the gearing alone since the change didn't help anything at all other then dropping the rpm's, car ran the same) and it's been taking mid 9 second passes for a year with no issues.
Regular 33 spline moser axles, 5/8 studs, regular steel spool.
The studs are the one thing you should think about, I'd go with 5/8 unless you absolutely have to have the ability to run a street wheel.
Now, if I could do it over again, I would probably spend the $ on a fab 9 and an alum center section, please let me explain why. 2 reasons: #1 gear choices, there's alot more choices and you can fine tune the gearing alot better, something that if you are going to stay on a limited power level (say under 550 at the tires) could help your cause. The 2nd reason, is if you are willing to spend the $ you can go lightweight and save alot of weight.
Gundrilling at your point, not really needed, but would help with limited power and if you can float it I would do it. If the car is 100% race, and you are going to buy rims, I would get the rims you want to run, then have it built to the width you need for where you want the tires to sit. Dish the rims so they're a centered wheel (15x10 with a 5 inch backspace, 15x12 with a 6 inch backspace) and then put the tire/rim in the car how you want it to sit, and build the rear to that. If you have the $, and can float it I would go fab 9, do an alum center section, 35 or 40 spline gun drilled star flanged axles, lw steel spool (alum ones don't last forever, but at a limited power level it may not be a concern at all).
When I redo the back of my car, that's on the list to do.... and if I can't float it, at least narow up the rear I have.
No problems at all, I took it apart last year figuring it was time after 3 years of being in the car and probably 200 track passes since it was installed... nothing wrong at all, and that was with a regular HD eaton posi.Spool and a gear change went in (wish I had left the gearing alone since the change didn't help anything at all other then dropping the rpm's, car ran the same) and it's been taking mid 9 second passes for a year with no issues.
Regular 33 spline moser axles, 5/8 studs, regular steel spool.
The studs are the one thing you should think about, I'd go with 5/8 unless you absolutely have to have the ability to run a street wheel.
Now, if I could do it over again, I would probably spend the $ on a fab 9 and an alum center section, please let me explain why. 2 reasons: #1 gear choices, there's alot more choices and you can fine tune the gearing alot better, something that if you are going to stay on a limited power level (say under 550 at the tires) could help your cause. The 2nd reason, is if you are willing to spend the $ you can go lightweight and save alot of weight.
Gundrilling at your point, not really needed, but would help with limited power and if you can float it I would do it. If the car is 100% race, and you are going to buy rims, I would get the rims you want to run, then have it built to the width you need for where you want the tires to sit. Dish the rims so they're a centered wheel (15x10 with a 5 inch backspace, 15x12 with a 6 inch backspace) and then put the tire/rim in the car how you want it to sit, and build the rear to that. If you have the $, and can float it I would go fab 9, do an alum center section, 35 or 40 spline gun drilled star flanged axles, lw steel spool (alum ones don't last forever, but at a limited power level it may not be a concern at all).
When I redo the back of my car, that's on the list to do.... and if I can't float it, at least narow up the rear I have.
06-28-2009, 10:55 AM
#16
my convos no are the correct backspacing 6.5" on a 9.25" (measured) rim...
06-28-2009, 10:58 AM
#17
Thanks for the post it was very informative....now i am thinking about the ( but i know they are usually heavier, and have more drivetrain loss than a 12 bolt...that is why i wanted a lightened 12 bolt...i do like the idea of centering the rim, is there any science behind that or just looks...
Time to go rim shopping too
Time to go rim shopping too
I don't have any A4 results, but A3 results No problems at all, I took it apart last year figuring it was time after 3 years of being in the car and probably 200 track passes since it was installed... nothing wrong at all, and that was with a regular HD eaton posi.
Spool and a gear change went in (wish I had left the gearing alone since the change didn't help anything at all other then dropping the rpm's, car ran the same) and it's been taking mid 9 second passes for a year with no issues.
Regular 33 spline moser axles, 5/8 studs, regular steel spool.
The studs are the one thing you should think about, I'd go with 5/8 unless you absolutely have to have the ability to run a street wheel.
Now, if I could do it over again, I would probably spend the $ on a fab 9 and an alum center section, please let me explain why. 2 reasons: #1 gear choices, there's alot more choices and you can fine tune the gearing alot better, something that if you are going to stay on a limited power level (say under 550 at the tires) could help your cause. The 2nd reason, is if you are willing to spend the $ you can go lightweight and save alot of weight.
Gundrilling at your point, not really needed, but would help with limited power and if you can float it I would do it. If the car is 100% race, and you are going to buy rims, I would get the rims you want to run, then have it built to the width you need for where you want the tires to sit. Dish the rims so they're a centered wheel (15x10 with a 5 inch backspace, 15x12 with a 6 inch backspace) and then put the tire/rim in the car how you want it to sit, and build the rear to that. If you have the $, and can float it I would go fab 9, do an alum center section, 35 or 40 spline gun drilled star flanged axles, lw steel spool (alum ones don't last forever, but at a limited power level it may not be a concern at all).
When I redo the back of my car, that's on the list to do.... and if I can't float it, at least narow up the rear I have.
No problems at all, I took it apart last year figuring it was time after 3 years of being in the car and probably 200 track passes since it was installed... nothing wrong at all, and that was with a regular HD eaton posi.Spool and a gear change went in (wish I had left the gearing alone since the change didn't help anything at all other then dropping the rpm's, car ran the same) and it's been taking mid 9 second passes for a year with no issues.
Regular 33 spline moser axles, 5/8 studs, regular steel spool.
The studs are the one thing you should think about, I'd go with 5/8 unless you absolutely have to have the ability to run a street wheel.
Now, if I could do it over again, I would probably spend the $ on a fab 9 and an alum center section, please let me explain why. 2 reasons: #1 gear choices, there's alot more choices and you can fine tune the gearing alot better, something that if you are going to stay on a limited power level (say under 550 at the tires) could help your cause. The 2nd reason, is if you are willing to spend the $ you can go lightweight and save alot of weight.
Gundrilling at your point, not really needed, but would help with limited power and if you can float it I would do it. If the car is 100% race, and you are going to buy rims, I would get the rims you want to run, then have it built to the width you need for where you want the tires to sit. Dish the rims so they're a centered wheel (15x10 with a 5 inch backspace, 15x12 with a 6 inch backspace) and then put the tire/rim in the car how you want it to sit, and build the rear to that. If you have the $, and can float it I would go fab 9, do an alum center section, 35 or 40 spline gun drilled star flanged axles, lw steel spool (alum ones don't last forever, but at a limited power level it may not be a concern at all).
When I redo the back of my car, that's on the list to do.... and if I can't float it, at least narow up the rear I have.
06-28-2009, 02:20 PM
#18
The 12 bolt on on my car has been 9.80's with 1.3 sixty foots.it has a spool,4.10's 35 spline gun drilled axles. For rims i run a weld draglite 15x10 with 5.5in back spacing.I do have strange brakes as well .
06-28-2009, 02:38 PM
#19
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We have had 12 bolts with tons and tons of 1.3 60's all with stickshifts and heavy cars. Obviously a posi will not hold up at all you will need a spool and pro gear it will last alot longer.
06-28-2009, 03:14 PM
#20
Thanks for the post it was very informative....now i am thinking about the ( but i know they are usually heavier, and have more drivetrain loss than a 12 bolt...that is why i wanted a lightened 12 bolt...i do like the idea of centering the rim, is there any science behind that or just looks...
Time to go rim shopping too
Time to go rim shopping too
Plus, they look nicer
