HoLLo

iTrader: (17)

I daily drive a 26" 315/35/18 Toyo drag radial. Cam makes peak power at 6200, I shift about 6500.

Jadedbird

iTrader: (27)

Im a big fan of "if it aint broke, break it then fix it"

So im considering pickin up some used 3.90s for my 10 bolt.
I dont feel like dishin out 3k for a rear right now (plus alot of people have started to complain a out the 9" rears--both whine amd quality)

So i guess ill stick to this 10 bolt and run it until she breaks. But right now.. Shes whining so loud that i can hear it on the interstate over open headers...

Jadedbird

iTrader: (27)

What series gears do our cars have? 2 or 3?
I found a decent price on a 3 series but you need like a spacer kit if our cars are 2 series..

How long does it take to swap some gears? I got two friends in auto tech school amd were all gonna have a weekend getaway in the garage with our cars and tear **** up.. Figured id put new gears in it while shes up in the sky..
I cant decide if i want 373s or 390s...
Its stock bolt ons with 315 nittos in the back.. Soon to have a 6.0 (i hope)

01MAROONz2890

i'm also going run a 26" tire but i dont see 1/2" really changing the ratio all that much ya know? and to the guy above if your an m6 you have a series 3 carrier however keep in mind that if you or your buddy's havent done a rear before its probably wise to let someone else do it. they can be a pain to setup without the correct tools and if you mess it up your basically out a set of new gears

wrd1972

iTrader: (12)

I disagree on the 10 bolt. I actually pulled mine before I ever broke it, which already had 4.10s, solid spacer and girdle. I painted it black, made it look like new and sold it for $400 on the boards and put that money toward the nine inch.

HioSSilver

iTrader: (8)

yeah that's not a bad gear for your car if your full weight. But it won't take long before you could run over top that gear. You should trap near 118 now which would put you past your peak power.

BTW....good lookin bird. Track times?

redbird555

iTrader: (14)

should i consider 4.10's then? i run a 295/35/18 26" tire and i shift at 6500 as is. or would the 3.90s still suit me better

LS1T56FTW

iTrader: (3)

Really? Can I see the test data? How much misalignment was allowed during the test? What torque did each of them fail at?

Oh, you mean that you just heard that by word of mouth? That's what I thought.

There are tons of theories out there as to what is stronger and what is not. The 10 bolt rear is weak and will break with enough power. There are tons of ways to "make these rears stronger" and choosing a different ratio is not one of them.

redbird555

iTrader: (14)

actually its pretty evident some gears are weaker than others. 4.10's are weaker than 3.90s and 3.90 weaker than 3.73 etc. The numerically larger ratio you have the teeth on the ring gear become smaller and so does the pinion. more teeth+same surface area= less strength no 2 ways about it.

does that mean 4.10's will shatter and 3.73's wont? no. however they do make it weaker so in theory adding 3.73's or 3.90s instead of 4.10's will make the 10 bolt stronger than it would have been with the shorter gear.

LS1T56FTW

iTrader: (3)

1. What you said above is not always true.
2. The difference in strength under load (WITH DEFLECTION) taken into account is so minimal that all gear sets mentioned above would break under equivalent loads. The thickness of the tooth has very little to do with the strength of the gear set as a whole if you are edge loading the tooth and strip the teeth off due to that failure mode, which is how these rears break (probably 100% of the time - but I cannot prove that) most of the time.

Jadedbird

iTrader: (27)

I actually agree with redbird (no offense) because when i was speaking to a few shops about a 12 bolt, 9 inch, and the possibilities of beefing up the 10 bolt, they also said that higher gears become weaker... As to what extent, they didnt say, but nonetheseless they too believe that the high ratios are a bit weaker.

HoLLo

iTrader: (17)

Yeah, I really do think the 4.11s are perfect. But I'd be hard pressed to put them in a 10 bolt due to its weaknesses. With the 9", I had no doubts. I'd like a 28" slick with 4.56s, but I've decided to go with a D1SC boosted build next year, so I'll be putting in some 3.50s or 3.73s.

Thanks. No track times. Only been to the track once with this car, and it broke the driveshaft on the first pass right after I installed my 9". Haven't been back since, it's too far of a drive.

HioSSilver

iTrader: (8)

If your still on the 10bolt and staying with a stockish height tire then go 3.90's.
You seem like a smartass.

I've had them both. I went from breaking ring gears with the 4.10 to breaking axles with the 3.90's. Seems to me the 3.90's are stronger. Don't ya think?

Besides that my car went faster with 3.90's.

HoLLo

iTrader: (17)

^ and to add to that. Really, a different ratio doesn't mean CRAP for the amount of metal in the ring and pinion. It's the teeth ratio. Some higher ratios make that happen with less teeth. Less teeth = more metal = stronger gears. The torque multiplication is what hurts stuff.

HioSSilver

iTrader: (8)

^^^yep

41r/10p (4.10) gears are not as strong as 37r/9p (4.11) I had both. I broke 2 sets of 41/10 and never broke the 37/9. I sold them in good shape to a board member. The thicker ring gear teeth of the 37/9 gearset held up better.

But to be honest unless a car has a peaky cam and/or is heavy the 4.10/1 gear is just a bit much for a street car with stock height tires. It ends up hurting trap speed some. We put 3.73's in a buddies mild bolt-on car, it went 11.96 @ 116.3. I like mph.