Anyone else out there blow their LS6 @ 15000 miles, lol? If ya ain't breaking something your not going fast is my motto. Though I have been lucky with the gear box and rearend (just a stock shaft), we just try to make sure there is a little slip of the tires each pass.

Have you guys been putting your fast times up over at the Vetteforum?

Robert

 

no, I went 20,000 before I killed my LS6..You win that one Robt !! I was getting quite a bit of spin as I was still 2 psi higher than normal..didn't matter this time. That was a brand new RPS unit too..go figure !!

I did post my time last year on the cam\heads area. 11.33 under Pittman.

Pit

 

man Pitt, that sucks about your breakage. I don't understand how the clutch is "hitting hard" as you say, we have the same clutch and mine doesn't do anything like that. its very smooth and easy to modulate/slip.

I like to think of the clutch as a fuse to the driveline. if you can slip it and ride it out a little bit on the launch until your finally moving and the tires are hooked your doing good. what you don't want to do is dump the clutch at any RPM no matter what. you need to be able to tell exactly when the clutch starts to grab and thats where you want to leave your foot before you launch. this clutch is stong and can handle many hard launches but it needs to slip ever so slightly when launching so you don't send all the power/shock of the launch to the next weakest link in the drivetrain cause it ain't going to be the clutch that breaks, that sombich is beefy.

when I launch the car I like to remove all the slack in the driveline, here is how I do it. pull up to the tree and trip the first blub. once the first blub is triggered I put the clutch to the floor with the car in first gear and SLOWLY start to lift the clutch pedal until it creeps the car forward a little bit, THAT is your enguagement point. Once the car starts rolling forward enough to trip the second beam you push the clutch back in just a touch so its not enguaged anymore but also not released. Now you are fully staged and ready to launch, from there its just a matter of applying the correct amount of throttle while releasing the clutch pedal at the same time.

 

Thanks for the info Boost. Now for the prize question. Are you tellin me you pulled that 1.41 sixty foot easing the clutch out ? Holy crap !!!

Pit

 

Yea man, let us in on the secret?
I do my launches a little different. I come from the J-Rod School of clutch dumps from hell, lol. Actually, it's just short of a full on dump. Getting close to 300 passes on stock gear box and rear end with Aussie clutch, so the effort to have a little tire spin has paid off, though may have cost me a 1.4x 60? Them damn rears are not cheap and many have gone through more than one so... Still looking to go 16" tire and wheel to help with torque absorption, but the 17" and ET Street have been great so far. I always start with my psi in the 10/12 range to help with wrinkle wall effect. Should have seen how close my rim came to contacting the roller at the dyno with my new 7xxrwtq, lol, at about 10psi.
Robert

 

no secrets here, anyone can do it... 10.5psi is what I shoot for.

one important thing is to dial the pressure in while hot. after a burnout and full pass get back to the pits and set your pressure were you want it. after every pass make sure to check it and adjust if needed.
also, make sure to keep your tire out of the sun if possible, it can throw off your pressures by a few psi which is huge. thats all common sense stuff, not like anyone didn't know it already, but little tricks like those add up on the big end.

Pitt I'm sure its been mentioned before but its worth repeating; you need to get a drag pack on that car!

 

Thanks Boost. Yeah I know, a DP would be nice if I could quit buying clutches, tranny's (and rear end & motor).

Man, you guys are killen me...10.5 psi...I was at 13 when she snapped. Gotta get in a few more "town" street miles ...maybe that will help out with the first gear slip I need !
I probably should just buy a Vette Shell..this thing just sits in the garage broke down most of the time anyway !!

Pit

 

Pittman, first off congrats on the numbers and new setup, it looks sick. I was wondering if you knew the reason for the dropped valve on the original motor? You break a valve spring? What springs where you running and can you list your cam specs on your original setup? Also, were you running stock valves or aftermarket ones?(for both your old and new setup) Sorry for all the questions, looks like you have one mean ride.

 

Hey 1-8,
I will pm you the story and info tonight after work.
Pit

 

Awesome. Thank you

 

Heres a story... about a guy named Pittman and his dropped valve (please sing in giligan island format, it will be more humorous )

 

hEY-hEY -HEY....Thant is not funny Bruce !! You better go knock on some wood fast...lol

Pit

 

AlwaysInBoost can come out easier(less RPM and less aggressive clutch/throttle tecnique) because he is making so much more torque and hp at lower rpms. I bet he launches @ around 4000rpm. (i'm sure he'll chime in on this). It will be a different technique for you PIT, but trying different things will eventually allow you to find out what your car wants. Track prep and conditions also play a significant role in how one launches. That clutch you guys are running is a great piece. I know that a twin will feel/act slightly different on a S/C car with some serious hp/tq. You basically eliminate the dreaded spin bog with the s/c wheres the typical 450 h/c car needs to figure out a way to power thru the bog with a measely 400rwtq. The way to do this is to air up tires/or possibly lower launch rpm which is kindof counterintuitive. This will take time to figure out with your setup. It should be easier now that you have some more grunt/torque, but you will need to be fairly aggressive on the throttle during the launch. You will figure it out, just don't be afraid t experiment with tire pressure/launch rpm/launch tecnique and write it down so you know what you did last.
That clutch is good for a mid 1.45 in your car with elevate tire pressure(~15) and a 4800 rpm launch on a good track in an m6. That's why I would encourage you to keep the tire pressure up esp in the beginning to help prevent breakage while your figuring out the clutch. You can try bringing the pedal just below the engagement point (like AIB does) and see how the car reacts. It will cause the clutch to hit easier,less shock to the tires ,(in essence more slip). That may be a good balance to go with the extra tire pressure. To ge the low 1.4x's you can't have any bog which can be difficult to achieve. The advantage you have is the m12. As soon as I went to the m6 it took alot more finess to get the low 1.4x's but it's possible.
Remember when you figure out how to avoid bog, or spin-bog, you will be there.
I guarantee the sweet spot for your car/setup will be different than most everyone elses. By watchin' the vid's it proves you know what your doing and your very close.
Keep at it, I just wanted to give you some more food for thought.

 

Look at how an AT car launches, you don't have to nail the tires hard off the line. a lot of those AT guys are just rolling out of the hole off idle and still getting good 60's. I'll bet you can come off the clutch @ <2k RPM & pull an awesome 60' as long as you give it enough gas as to not bog. launching is all about being able to keep the nose up thru first gear and yet not lose traction.

also remember Pitt, if you spin off the line and THEN hookup you can still break parts. you want to avoid any sudden shock to the driveline. whether its from the initial launch, losing traction and all of a sudden finding it while still in the throttle or just shifting hard. traction WILL find the weak link in your setup. I've broken driveline parts on other cars just from losing traction and all of a sudden getting it back again. thats why, like I said in another post, I like to think of the clutch as a fuse for the driveline.
Learn to modulate that along with the gas pedal and your golden.

 

Thx for the info guys. I did start writing my launch rpm and psi on the back of eack time slip. I must admit..I'm going to be gun shy for awhile now (unless I get some spare case donations....anyone ??) !! I could have handled the ring gear, but the case cracking is gonna give me nightmares.

I will get back out there ASAP. The whole thrill to me is the launch, first and second gear..the rest is ho-humm waiting on the motor to wind up. That is why I love the m12\390 gear..no time to think..all just reaction.

I will keep you guys posted with results. I have had 2 years of bad clutchs..this McLeod may be the horse I need to ride !

Rob, here is a pic of 25 runs on a PRS Stage 4+....I had 400 rwt, not 1,000 !!!
Almost worn completly flat.
http://i160.photobucket.com/albums/t...e/DSC01280.jpg



Pit

 

Hey Pitt dont get discouraged!!!!!!! It could be worse you could've ran say 11.0x 12times now!!!!!! I have my stock 3.42 rear diff sitting in a plastic bag just incase something like this happens. I have a friend selling his 4.10 rear but that doesnt help you Theres gotta be a couple rears on CForums.

 

Bruce, That is crazy..11.0 - 12 times !! All you ever needed was a 10 mph tail wind !!

Yeah, I will start watching for a deal on a diff...I have seen them before.

Pit

 

Ok guys,
I had a little luck. My diff blowout was the ring\pinion and one side cover cracked. The fluid leak was from a blown seal. The ring gear had 3 large chunks out of it (about 5 teeth in each spot) and the pinion gear had 2 large hunks out of it. I do believe the DTE brace held it all together. I will Order some parts and get that puppy on the road soon !!

Pit

 

Here is a pic of the damage. It did eat the case inside a little but I can smooth it out and should be ok.
http://i160.photobucket.com/albums/t...e/DSC01291.jpg

Pit

 

Ouch. Sorry to hear. Are you doing your own diff build?

I broke my diff last week too and am looking into this.