M6/MN12 Diff Breakage
Thread Starter
Safety Car
Joined: Jun 2005
Posts: 4,977
Likes: 256
From: St. Louis Missouri
M6/MN12 Diff Breakage
What kind of tires can we get away with? What 60fts? I've been a long time owner of f-cars and know the factory rear ends couldn't hold a slick with a manual tranny (leaving hard). How about the Vettes?
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 31
From: Central Florida
I launched a stock C5Z on MT ET Street Radials at up to 5200 rpm for passes #300-#350 . About 250 of the first 300 passes were on BFG DRs launching at 3600-4200 rpm. Plus 50 passes on stock tires. Never broke anything.
But if you
(1) add more than 30 or so rwhp
(2) add a strong-clamping aftermarket clutch and/or
(3) launch at >5400 rpm
the breakage risk goes up significantly on both DRs and MT bias-ply.
So, at that point hardening of the rear becomes prudent.
I should add that driver error during the burnout or launch can break an axle or differential even at stock power levels no matter the tire. run.
Ranger
Le Mans Master
Joined: Nov 2003
Posts: 8,308
Likes: 157
From: NJ
It depends on the power-level, specific mods, and "how hard is hard."
I launched a stock C5Z on MT ET Street Radials at up to 5200 rpm for passes #300-#350 . About 250 of the first 300 passes were on BFG DRs launching at 3600-4200 rpm. Plus 50 passes on stock tires. Never broke anything.
But if you
(1) add more than 30 or so rwhp
(2) add a strong-clamping aftermarket clutch and/or
(3) launch at >5400 rpm
the breakage risk goes up significantly on both DRs and MT bias-ply.
So, at that point hardening of the rear becomes prudent.
I should add that driver error during the burnout or launch can break an axle or differential even at stock power levels no matter the tire. run.
Ranger
I launched a stock C5Z on MT ET Street Radials at up to 5200 rpm for passes #300-#350 . About 250 of the first 300 passes were on BFG DRs launching at 3600-4200 rpm. Plus 50 passes on stock tires. Never broke anything.
But if you
(1) add more than 30 or so rwhp
(2) add a strong-clamping aftermarket clutch and/or
(3) launch at >5400 rpm
the breakage risk goes up significantly on both DRs and MT bias-ply.
So, at that point hardening of the rear becomes prudent.
I should add that driver error during the burnout or launch can break an axle or differential even at stock power levels no matter the tire. run.
Ranger
I've run mt et streets and launched hard for a few hundred passes.
I've broken the rear once and output shafts 2x. The tranny/rears are quite strong imo. Most guys go with hardened left output shaft. I wouldn't change anything until it breaks. The stock trannys have been proven to hold up to alot of abuse. Don't beef it up unless you have a problem. Many 60' times in the low 1.4x's with 3.90's and 4.10's
Thread Starter
Safety Car
Joined: Jun 2005
Posts: 4,977
Likes: 256
From: St. Louis Missouri
I'd definitely consider 1.6x 60fts 'leaving hard' for a mostly stock car. I'd be happy with high 1.7xs.
I've read there were differences between the 01 and 02-04 Z06 clutches. I don't know *what* the differences are but I presume the 01 clutch doesn't hold up to the abuse as well as the newer clutches?
I've read there were differences between the 01 and 02-04 Z06 clutches. I don't know *what* the differences are but I presume the 01 clutch doesn't hold up to the abuse as well as the newer clutches?
Last edited by Tech; Aug 4, 2007 at 01:16 AM. Reason: typo
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 31
From: Central Florida
^^^ Tech, I had 150 passes on a stock 2001 too. On BFG DRs I cut some 1.70 60'. Never broke anything on DRs or stock tires
The clamping force of the Z06 clutch was given 7% more clamping force when the HP was increased from 385 to 405 in 2002.
Ranger
The clamping force of the Z06 clutch was given 7% more clamping force when the HP was increased from 385 to 405 in 2002.
Ranger
Melting Slicks
Joined: Sep 2003
Posts: 2,911
Likes: 1
From: Augusta GA
St. Jude Donor '05-'06
I'd definitely consider 1.6x 60fts 'leaving hard' for a mostly stock car. I'd be happy with high 1.7xs.
I've read there were differences between the 01 and 02-04 Z06 clutches. I don't know *what* the differences are but I presume the 01 clutch doesn't hold up to the abuse as well as the newer clutches?
I've read there were differences between the 01 and 02-04 Z06 clutches. I don't know *what* the differences are but I presume the 01 clutch doesn't hold up to the abuse as well as the newer clutches?
Now running bias plys and hard launches, the shorts are mid 1.4s to 1.5s, but I have broke 2 3.90s. Like above, dead hook or wheel hop can be very bad. It will show the weakest link.
Good luck man!
Dave
