9" vs s60 vs zl1 rear upgrade
 

I apologize if this has been discussed before (I assume it has but searching 9" doesn't give me and solid results) but search wasn't turning anything up.

Planning out my next big upgrade. Eventual plan calls for a supercharger and probably mid 600's for rwhp. Car is an m6 so it'll see abuse. Looking to be as bulletproof as possible. I enjoy using the car as my toy and taking it to the drag strip.
I like the thought of factory reliability and parts engineering of the zl1 package but would really prefer deeper than 3.73's. (Currently had 4.10's that I sheared the pinion. 3,91's going in shortly to finish out the season). That's the only reason I'm debating something else.
So, assuming I go aftermarket, which way has everyone been leaning? I like the ease if gear changes with the 9", but is the parasitic drag that bad? Plus my car is heavy (convertible, 4200+ lbs race weight with me in it) so I still wonder if a 9" is strong enough? I'd love to have a couple different pumpkins to swap around, one with a spool for when I want to race/play, and one with a posi for road trips etc...
Or is the s60 measurably stronger over the 9" and the less parasitic drag make it that much better of a choice?

Thoughts? Opinions? Real world feedback from people who have been there/done that?

I went full ZL1 cradle with axles etc, cost/oem fit quality and availability/strength.

Different build with my Auto so I went 3.23s.....

If you are going PD Blower, you might not need as much gear.... and might end up preferring the 3.73 to avoid 5th gear.... I am not with real world experience, but consider the end goal. No question 4.10s and 3.91s are preferred NA.... supercharged still might like 3.91s, but vs 3.73 are they faster?

Consider this more of a bump than an answer!

ZL1 conversion will be the cheapest and perfect for you if you can stop at 650whp.

9" strong enough? Yes, go see what serious drag racers are using.
9" parasitic loss? More than the S60 and ZL1 but not enough for me to not go with one. The people worried about parasitic are probably bench racers or stuck on hp numbers and not performance. There was a thread on here where someone dynoed before and after a 9". The loss was 20-30whp if I am remembering correctly.

I have a gforce 9" and 3.25 gears and twin turbos and an m6. Even with a pretty good sized cam, it's peppy on the low end and turbos like having a load so less gear is better for them.

I used to have a Ysi and 4.10 gears. Not good for much but spinning the tires. Went back to 3.45s for a while and liked driving it a little more.

More hp/tq means you need less gear.

I'm PD 740 hp with DSS driveshaft, zl1 diff 3.73 and axles after 4L80e, seems to work real well for me.

I have the 3.73 ZL1 rear on my auto right now and working on getting the 4L80e.

I know most serious drag cars are running 9" rears. However, most serious drag cars don't weigh over 4,000 lbs lol. That was my reason for questioning it.
All this car will mainly be is a cruising play toy that will see occasional track use.
I'm honestly really leaning towards the 9" as I have two other project cars that I am running a 9" in so it would make things easier being able to swap pumpkins around between them for when gearing and differential type needs change.

What you appear to be saying is directing the conversation to say the least expensive route will work for you, and to go with the ZL1 differential with a 3.73. No need to spend more on the 9" or Strange due to the lack of beating on the car. On a supporting note, I do beat on my car, a lot... Take that info FWIW.

Oh trust me, I will be beating on the car. I take it to rolling burnout events, the drag strip, and just generally enjoy my driving experience. I want something that will be more or less bulletproof (yes, I realize anything can break, just looking for the least likely) so I can hammer down and dump the clutch without fear when the mood strikes. Cost isn't really that much of a factor. Not when you're talking a difference of a grand or so. If the aftermarket options are that much better then I don't mind paying. I suppose my biggest hang up with the zl1 combo is the lack of a deeper ratio than 3.73.
Dreksnot, what rear end do you have in your car?

Had a 3.73, too much wheel spin coming off the line at the track. Have the 3.23 now and it's better. Can still light up the tires if not being careful with the clutch.

If money ain't an object then I'd either go the 9" or S60 differential - then, you'd be set in the later parts of "Hey, I need more power!" kind of mindset (over engineer today for the power you'll add tomorrow).

I ran both the 3.73 and the 3.23 with my car.It's faster with 3.23,with the 3.73's it was shifting in 5th gear with my 6L90 tranny.

The ZL1 rear end has proven to be far and away the best value. It takes a beating. OEM quality. Quiet. Hard to go wrong. I think technically speaking the 9" is stronger so if you are drag car only...then maybe that's a better want to go. But the ZL1 rear is impressive. I've got it swapped into my 'charger SS.

I have a 2010, what is the most horsepower the rear zl1 diff can take and zl1 axles?. do I have to buy the whole zl1 cradle? This will be a street car. I like to do burn outs from time to time. and running aftermarket tires. I run 305 rear street tires. I would like to get into the 750 to 850 horsepower range.

I've heard the ZL1 rear can take up to 800, 900 or even 1,000rwhp. But that's all that "they" say, and you know how truthful "they" are and what credentials "they" have... I haven't heard of anyone grenading a ZL1 differential. Just folks, like myself, killing axles from time to time. I wouldn't recommend the OEM ZL1 driveshaft - get a good 1pc. Back to the axles, the OEM ZL1's have been pretty tough, and I've only broke several DSS 1,400hp axles. You don't need to get a whole cradle unless the price is right.

Thanks for the insight. what advantage does the zl1 cradle provide over a ss car? are you guys using the axle cooler lines to the rear axle too when upgrading? sorry for all the questions. with a manual trans that I have sounds like the 3.91 1le axle gears would be better then 3.73 zl1 axle is my thinking correct? thanks