Like the title says, how much weaker and prone to break are 4.10 gears compared to stock 3.42? I'd love to have some 4.10's but I've heard theyre weaker and I do not want to increase my risk of breaking my rearend...

 

sorry thats a new one on me. Where did you hear that?

 

The 4.10 pinion has 10 teeth where the 3.42 has 12 teeth. The smaller pinion will obviously take less abuse, however it is usually the ring gear that fails first.

I dont know how to really say how much weaker the 4.10 is, other than it is a bit waeker. From what I have read those guys that have run sticky tires with the 4.10 have blown up the 10 bolt more times than not.

I have the 4.10's and have never had an issue with hard launches on street tires.

HTH.

 

So "theoretically" a bolt on 99 z28 m6 will be safe to run 4.10's with some hard launching here and there with street tires? Do the rear end girdles actually help?

 

Girdles will do little. If the rear will break is hit and miss. Some guys break them stock, some running 11's. Its a crap shoot, take your chance if you want.

 

Again mine has survived lots of hard launches and abuse on street tires. I have the girdle and solid spacer in place of the dinky crush sleeve to help out some. These mods help a bit.

I think if I put stickies on and launched at 3K or less then the 10 bolt might hold up for a while.

There is no "safe" period with the GM 7.5" 10 bolt behind an V8 f-body let alone running 4.10's.
Its a crap shoot.

 

I had an 01 SS 6speed with 4:10's and blew it up twice, just bolt ons meaning exhaust and intake. But now in my Z i have 4:10's and no issues so i guess depending on what brand and how much abuse is the main factor. The gears does mulitply torque so there is more stress on top of it has less teeth. I broke mine in my SS goin from 1st to 2nd gear change so my situation might be different.

 

The key word in this thread is "street tires". Not putting on a sticky tire is the biggest thing you can do to prolong the life of your rear end, short of not driving hard. Hard shifts still put a huge amount of strain on the rear though.

 

x2. im more afraid of breaking my rear end on the shifts than the launch. My clutch BITES on the shifts, i chirp 4th consistently. IMO thats worse than just holeshotting on street tires.

 

Interesting point.
I have a custom clutch that grips very well. When I "power" shift I do release the gas, this helps to prolong the rear end as well.

I try to avoid chirping tires when shifting, might save that for the track. I can grab 2nd and 3rd if I want to but this stresses the gears severly. It must take one hell of a clutch to grab a 4th gear.

The key is to "power" drive it smart, avoid the stickies and things should be fine. My 4.10 gear has held for two years plus I fire on it all the time.

 

I had Richmond 4.10's in my car, and broke 2 teeth off the pinion gear, while road racing the car (not street racing, I mean racing out on a road course! ) ... as well, this was behind the A4 tranny! But the thing was, coming out of EVERY corner, the tranny would make a hard down-shift into 2nd (which also lead to my 4L60E dying a couple weeks later! ).

 

so LS1 have a 3.42 stocked? i always thought they where 2.??. never really looked it up. what do i need to install 3.73 gears? installation kit?

 

i broke my 3.73 motives on a 1-2 on street tires on the street.. but ive launched stock 2.73s several times at the track at 3-4k with a twin disk dead hooking with no problems with those gears.. at around 5k i broke an axle like a tooth pick but the gears are still fine, fixed the axle and am still running on that rear 3.42s are gonna definatly have strength advantige but NO 7.5 gears are worth a damn IMO and if you do get them too hold something else will go.. especially that LS1 driveshaft or POS torsen