BonestockZ06

Ok, so I see countless c5's at the track ranging from 1.6x to 1.4x 60' times and I wonder, why aren't they braking anything?

So, I ask and to my surprise, almost all guys cutting the 1.6x and above 60' claim to be in stock form (according to owners). I was under the impression that the c5 rears were very fragile in stock form. Are guys just plain lying? or are they just getting lucky and are running on borrowed time? Or are c5 rears stronger than what they are made out to be? The guys in the lower ranges have built rears, so that explains that situation.

I'd like to cut better 60' but I'm always so scared of braking something, thats why I always slip the clutch and never launch over 3500k rpms, but This method has never resulted in anything sub 1.8x my personal car.

So what are the basic rear mods that will enable me to launch over 3500k and have a little piece of mind? Or is it true that a stock rear it's up to withstand higher launches?

Some schooling would be greatly appreciated. If possible, I would like for you to post your best 60' and what your rear consist of..

REDGAR

I consider the rear gears a consumable like tires.

I have a best 60' of 1.37 and spend most of the year in the low 1.4s and my rear is built by The Vette Doctors.
It is an A4 and launches are at 2100 which I think helps them live a little longer.

Joe_G

You have to slip the clutch and let it take the abuse. It will take it you'll be surprised. Proper fluid maintenance and removal of the clutch pedal spring are necessary. If you dump the clutch you will be leaving on a flatbed. If you wheelhop you better get out of it or you will also risk the flat bed.

Most of the rears I've seen broken at the track, and I've seen several, were on street tires wheel hopping. Drag radials at 18 lbs give you some give and take the shock.

Since I got the cam I have to launch at 4800 - 5000 or so and cannot go below 4500 or I bog.

Here are some great launch and clutch tips:

www.rangeracceleration.com

PRE-Z06

I've cut a best of 1.64 on stock rear w/ only 4.10 gears(no hardened shaft) launching @
4k-4500rpm depending on track prep and a 1.74 w/ 3.42 and 4.5-5k rpm launch(remember I have the mn6)...Dr. Ron cut a 1.59 on a completely stock rearend as far as I know launching @ 5-6k rpm

BonestockZ06

I need to know the low down on these rears. My knowledge on this subject is lacking and thats where my interest lies. I do appreciate however that you posted and are attempting to contribute.

Now, are you running a 100% stock rear? What has been your best 60'?

BonestockZ06

Is the MN6 stroger?

Joe_G

I absolutely did answer your question. You asked why some people get 1.4's and don't break and others break. It's not the rear as much as it is the driver. The rear lives or dies based on what you do with the clutch and what tires you use more than anything else. If you want to build a DTE stage 5 with everything possible look at DTE's website and like everything else let your wallet dictate your purchase. Side step your clutch on street tires and wheelhop down the track and that $3500 rear will break and take your trans with it.

I have 3.90 gears, hardened left shaft and DTE brace to save the transmission mainshaft if the rear breaks. Best 60 is low 1.6's.

GARY2004Z06

Something will be taking the power to the ground and its transmitted shock. A smooth clutch release can help mitigate some of this. I understand that ET Streets will also help. As for 60's, here's some #s I know.
My car bonestock on F1s launching at 3600..........................1.75
My car on DRs with hardened left shaft launching at 5000.......1.63
Dr. Ron on ET Streets launching at 6200..............................1.58
Jrod on F1s..................................... ...............................1.72
Robz on DRs launching at 6500.................................... ......(Priceless)

ChopperLoco

...keep in mind,that most of the guys with the really good 60' times are autos.

dogboy

Auto with 3:42's, 3,500 stall, MT DR's lauch about 2,000 rpm best 1.67. Stock rear end

BonestockZ06

I like this answer much better. Thank you very much..

Dr.Ron

I have cut a 1.58 60' launching at 6200-6300rpm's, but I had a performance clutch in. My rear was stock except for a hardened output shaft & a DTE brace on. They CAN brake as well, as I saw personally at the track Monday on an average launch.

I broke BADLY once w/ just DR's, an intake & a tune. The car dead hooked & it was carnage!
I also cut a 1.71 60' on stock F1's w/ just an intake & a tune.I think that was launched at like 4000 rpm's, but w/ a good amount of clutch slip by me.

As stated above, you need to slip the clutch in the C5's, something not afforded with the C6 clutch! Also, track prep must be above average.

The C5 rears will hold up so long as you don't go clutch dumping or dead hook a high rpm launch!!

Ron

GARY2004Z06

Not on my list.

BonestockZ06

Thanks Ron, you pretty much summed it up for me.. I take it driver error is the biggest factor generally speaking.

Now I see how Joe_g's first comment relates to the entire equation. I think for my power levels a hardened output shaft and brace will be suffice. My driving skills will dictate the rest.. Thanks again guys.

ChopperLoco

...i'm hoping this will work for me too!
Dominic

ChopperLoco

Impressive,I will try to get there with a six gear also!
Dominic

chaase

Auto w/3.42, 2800 stall and MT D/Rs, launch around 1300rpm best 60' 1.67. All stock except for left hardened output shaft (I think its the left one).

The output shafts tend to be the weaker link in many cases. Your best bet to survival is probably a transmission brace and hardened output shaft.

Joe_G

I would say that's a great plan. Don't leave out the drag radials.

Dr. Ron, quick point on the C6 clutch, my buddies and I have had great luck with the stock ls2 clutch at our < 450 rwhp levels, it is actually easier to slip than my c5 z06 clutch. I'm waiting for the day that mine goes but once I removed the spring (I take care of fluid before and after each event) that thing is so reliable, letting me hot lap 5000 launches 3 in a row if I like. I'm amazed at it 250+ runs now (and knocking on wood).

Now the C6 Z clutch in my buddy's c6Z is another story...his is not holding up to launches at all. Of course he put in a cam and at 520/500 he can't expect it to. He's a great driver, 1.4's were not uncommon for him in his C5Z with stock clutch. He split his C5 DTE Stage 5 all the goodies rear case after 3 years and hundreds of 1.5 launches, on a particularly hard 1-2 powershift on a track prepped for Pinks later that day. He's Retrotech, you might remember him.

PRE-Z06

mn6 has lower (numerically) gears vs the mn12 (c5z06/c6z51)...3.90 rearend gears+mn6=overall gear ratio of mn12 w/ stock 3.42 gears...didn't realize dr. ron had a hardened shaft and brace...I would think stiffer gears help w/ the torque multiplication and actually put less strain on the rear

Dr.Ron

The C6Z clutch is terrible for launching!! lol

I had a hardened shaft & brace on my C5Z06, AFTER I broke earlier on in my ownership!
My C6Z is stock.

Ron