11.8 @ 124... and then something went *SNAP*

[treynor]

Brief update -- was up at the Sacramento test 'n tune last night to finally run my car properly.
1st run, my first ever on slicks, I launched at 3000 RPM and nearly stalled leaving the line, spent about a second climbing back into the powerband, and ended up running an 11.78 @ 123.8 with a 1.90 sec 60'.
2nd run I launched at 3500, but still nearly stalled the engine (I think I'm not on the gas hard enough as I let the clutch out), 1.895 sec 60, and then right after the 1-2 shift there was a *snap* from the back end and the engine revved freely. I pushed in the clutch and coasted to a stop, and the tow vehicle came out and pulled me back into the pits where we surveyed the situation.

There's nothing obviously broken under the car. Half shafts and driveshaft appear intact. However, when I put the car in gear and let out the clutch, the driveshaft spins but the wheels do not. I'll have a diagnosis and more observations shortly.

As I told my companions afterwards... "That's racing."

 

[Bill/APEX Motorsports]

My guess is the pinion gear snapped...

 

[Tom Welch]

Ben,

You should have been racing in Texas. That kind of breakage doesn't happen there. LOL!! Launch at 4000-4500 off the bottle for optimum 60' times. Hope its nothing serious.

Tom
Http://btrviper.com

 

[Steve Miehe]

I agree with Bill. Sorry Ben, but the pinion shaft probably sheared. That's my 2 cents. Keep us all updated.

 

[treynor]

Update:

Fortunately, it appears to be just the left side half-shaft U-joint nearest the diff. I say "appears" because the U-joint is definitely broken, but I won't know if there's any other damage until we get under the car, have a better look, and replace the U-joint. Assuming nothing else is amiss, we'll be putting something stronger in there and giving it another go in about 10 days.

ObNote: launching on slicks is totally different from launching on street tires! Even though I had the RPMs in the right ballpark for the launch, I'm not hitting the gas as I release the clutch (street tire habit) and thus the engine stall at launch. Given the launch, and my conservative shift points & speed for the first run, the fact that I ran 124 mph gives me a prayer of seeing 11.1 @ 126 on motor once I get everything (car, and especially driver0 sorted out. Woo hoo!

 

[SoCal Rebell]

I hope your mishap turns out to be minor, didn't you have HD half shafts? Let me know what the outcome is. And like I said last week you should launch between 4,000-4,500 rpm. Bummer about Famoso I was looking forward to it.

 

[bad viper]

If you are not using Unitrax HD half shafts
then I suggest using them I've done more than a few 4500
launches with more than 50,000 miles on their halfshafts.

 

[FRANK]

As far as some earlier posts in this thread...I cannot imagine shearing a pinion shaft. Cars that are front wheel drive or have independent rear suspension ****. I have seen so many blown CV joints and half shafts over the years. When was the last time you have seen someone blowing up a Ford 9" or Dana 60? Just my opinion here...For one, I am sure the unit is super strong and the likelihood of it shearing is nill. Maybe losing teeth on the gear ring...but I had a feeling as soon as I read the post that a half shaft busted. The easiest diagnosis would have been to just jack the car up and run the car with the rear wheels off the ground and see if the rear wheels spin or if the shafts coming out of the case spin.

 

[TOOOFST]

Treat it like a chick on the first date.1st base ,2nd ect.Try running your sticky's with 15-17 pounds.You'll spin off the line some ,happy mph and break less parts on your streeet car,lower pressure as needed.Most people work backwards and break stuff.

 

[pauls]

If your bogging the car to the point of stalling your killing every part from the wheels to the flywheel. No halfshaft will stand up to that abuse. If your running slicks you must either drive it out and hammer it or launch at HI!!! RPM and ease the clutch in to soften the hit and keep the RPM up.

 

[treynor]

My car's running a real 600 RWHP on NOS and 530 off. I'm running very conservative NOS jets for the moment. The only run I've completed so far was on motor, with a bogged launch and conservative shifts. I expect I'll run low 11s @ 125 on motor once I get the launch right and speed up my shifts, and run mid/high 10s @ 130 on NOS.

Regarding launches, it must be that a launch where the tires do not spin involves less peak force than a launch in which they do; thus I do not follow the logic that I'm "killing every part" with my launch. However, I do intend to do my next launch at a higher RPM with more clutch slip to keep the car in its powerband.

 

[Doug Supercharged Vipers]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by FastFreddie:
Im not a drag racer, but i still dont get it. How does BTR sell a package that is GUARANTEED to do 9 second runs, and yet it doesnt make as much power as your car does.
I mean would a stock viper with 200 shot run 9's??
Im running close numbers to you and expect very similar number in a couple weeks when a couple more mods are done with. With a small sot of NOS aslso, i should be right there at 600RWHP, i should be able to run low 10s maybe 9's with slicks (of course with the proper track experience)

<HR></BLOCKQUOTE>FastFreddie -
Respectfully, don't expect 10's that easily in your car.
It does take more power and effort to get your older R/T to run into the tens than the newer Gen II suspension and weight factor cars. It's a challenge to do it in a pre '96 car, but a lot of fun getting there.

Good Luck,
Doug

 

[Tom Welch]

Freddie,

I do not offer a guaranteed 9 second package, YET.......

We are testing some cylinder head upgrades over the next few months which should give enough extra power to put us in the 9's considering the lack of drag racing efficiency of the viper chassis.

A package should we do one, will be different for different year and model vipers.

I will say though that at present with the average mph of our car being 137, we are already making plenty enough power to run 9 second times. Chassis efficiency is what the viper lacks. That is what we are going after next. Thats all I have to say about that!

An honest comparision of tuner packages should start with the dragstrip MPH. That is what dictates a cars horsepower, not the elapsed time. A Levin car that runs 145+ mph should be running low 9's but again the lack of chassis efficiency is holding him back. Very few vipers have exceeded 140 mph in the 1/4 mile.

Tom

 

[Doug Supercharged Vipers]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Tom Welch:
An honest comparision of tuner packages should start with the dragstrip MPH. That is what dictates a cars horsepower, not the elapsed time. A Levin car that runs 145+ mph should be running low 9's but again the lack of chassis efficiency is holding him back. Very few vipers have exceeded 140 mph in the 1/4 mile.

Tom

<HR></BLOCKQUOTE>Tom,
Your on the right track but for us it's a little different. As you know I have been plagued with clutch problems *only* when I run on the track and try to launch above 3000 rpm. We have tried a "well known" performance clutch and spit-it-out on the first pass at a prior track event. That encouraged us to go back to a stock clutch for the time being.

I am open again for suggestions to try a better clutch that we haven't tried yet.

Regards,
Doug

 

[Tom Welch]

Freddie,

Chassis efficeincy is measured from a combination of all of the drivetrain components behined the engine. As Doug stated, his clutch didn't get the job done. His MPH is indicitive of a low 9 second car, but due to the lack of efficeincy of his chassis he has to leave the line easy which costs him valuable time towards a correct run elapsed time wise.

The cars weight really does not come into play when you have mph above 135 because you have the horsepower to move the vehicles mass through the quarter mile. Yes, lighter weight does help and a rule of thumb is; for every 100 lbs of weight removed, take a tenth of a second off of your elapsed time.

To achieve an efficeint chassis in my opinion for drag racing purposes, one would need to scrap everything from the flywheel back and start over. An Automatic transmission, 9" torque convertor with about 4000 stall, solid axle type Dana 60 series rear end with aftermarket spool and axles would send Dougs car deep into the 9's even at stock weight. My car would run 9.60s with an efficient chassis equipped as above.

The best case scenerio would be for Dodge to manufacture two different drivetrain choices for the viper, dragrace equipped as above(no secret to Dodge as they did this years ago)and the current car for road racers. Until that day comes.....which may never happen, most are spending far too much to attempt to turn an Orange into an Apple.

Like I said earlier, we don't have a 9 second package, YET. But a mildly modified viper with the right drivetrain and nitrous WILL run 9 second times. Think about it, for the price of my competitors half shafts you can buy a complete rear end that will never break!HMMMMMMMmmmmmmmm. Good things take time, especially when you have two jobs....but Im workin on it!

Tom
Http://btrviper.com

 

[pauls]

YES!!! A 2001 version of the Dragon Snake!!! The MPH on our cars shows how ineffective the chassis is for Drag Racing. Stock Vipers run 120MPH thats close to 11.00s in a leaf spring Mopar. 126 is a 10.5. If I could just put in an auto with OD without cutting the car, it would be in there.

 

[GTS Dean]

Food for thought from an alignment freak...

The chassis inefficiency at the rear is the sum of numerous little things. Among them: bushing preload on the wishbones, lateral tire scrub throughout the range of motion, dynamic toe change (both by geometry and by deflection), anti-squat geometry, relative motion in all the splined yokes and u-joints/CV joints. Shock spring rate and internal valving can pick up nearly a tenth. Additionally, there are more gears and inertia losses in the tranny than needed for a quick trip down the dragstrip.

Once you have upgraded the halfshafts, shocks/springs, monoball wishbone pivots, paid extra attention to alignment, done some judicious bracing of suspension pickup points and going back to Dexron III in the tranny, you might pick up 4 tenths ET and some MPH. This is because you are transferring weight more efficiently and keeping the tires square to the track surface more of the time down the track.

 

[Tom and Vipers]

For what it is worth....

I have raced Dana 44's with the 4 spyder gear TwinTraction differential. The weak link in that rear end is the spyder gears. You can break these on 7" cheater slicks if you have any wheel hop.

The TracLoc uses 2 spyder gears with a larger pitch diameter - so I would guess the load carrying capacity is equivalent. My guess is that the spyders would break long before you could snap a pinion shaft.

That's my 2 cents worth....

 

[Tom Welch]

Freddie,

The main reason is BECAUSE IT WON'T SELL! A friend of mine, Tony Darwin(also known as Sir Hiss)performed a driveline change which was fairly extensive and included an engine swap. He is forever haunted by those who heckle him about his engine and transmission.

I may in the future install an automatic trans and dana 60 series rear end with 4 link suspension in my own viper using the v-10 engine, just because I want to. This will surely get me launched from any viper events where I am faster than my foes because of a more efficient chassis-----thats not factory. It is not rocket science, 135 mph with a 1.40 or faster 60' time is GUARANTEED to run a quarter mile elapsed time of 9.7 or faster, GUARANTEED. People just don't want to make that kind of change, at least not enough of them to warrant the R&D to market a product and make a profit.

Tom

 

[Mike Brunton]

You know, one of you guys with a fast Viper needs to let me drive the sucker. I am a very giving person, and although it would be a great stress on me, I will do my best to get the best performance out of your car - and I will not charge you!

But seriously...

Ben, is this your 1st time on slicks? Man, I ran an 11.81 tonight with only 118.15 (just checked.. was 118.15, not 118.51 like I said before). My 60' is 1.829 on that run... what is different between how we drive? I've got a slower 60' time, 5mph less in trap speed, yet I have an identical ET. The only explanation is that I am getting down the track quicker than you, even though you are running more MPH than me. I think I need to teach you how to shift like I do

. The ONLY place you could be losing that time is in your shifts - nobody believes me, but I'm telling you it's in the shifts. Ask Mike P - he will vouch for me here

I'd like to hear all about your run - can you post the timeslip maybe? Or the #'s at least - curious about your #'s as you went down the track.


So who'se going to hire me as a driver? Come on guys!

 

[treynor]

Mike,
Yes, that was my first run ever on drag tires -- actually M/T ET Streets. It's very different from launching on street tires. I've since gotten a bit of practice, and can routinely crack off 1.82 sec 60's on cold tires. Launching with hot tires and my stock rear gearing still requires more practice, because there's enough traction to stall the engine if I don't slip the cluch quite a bit on launch.
It's a shame I won't be able to practice for a couple months now, since I think I'd be able to get low 11s at this point. However, when this round of mods are done I should routinely run &lt;10.8 @ &gt;136, so I'll bide my time...

 

[Mike Brunton]

Ben,

You will get used to the ET streets in no time... I wish I could get consistent 1.8 short times in my car, but I *can* occasionally get 1.7 short times (and that is on stock tires at stock air pressure), so I must be doing something somewhat right.

I guess what I was getting at is that on your run where you got 11.8, you had a better 60' time than me, and 5mph more trap speed, yet our ET's are identical. So you launched harder than I did, and you have more power and attained a higher speed, but we covered the 1/4 in the same amount of time. So, somehow I was making up time on the track on you, even though you have more power and launched harder. The *only* place I could have made up that time is on the shifts. You must shift a LOT slower than I do, to have more trap speed, a better launch but the same ET.

I'm just suggesting that if you work on your shifts, and get them lightning quick, you will pick up 2-3 tenths in ET. Venom Lover was out visiting my way a few weeks back and I had told him the same thing. We went for a ride and I demonstrated it for him, and I think he agrees it works and is good for a bit of ET and MPH on the track. These Vipers are VERY sensitive to being shifted slowly - if you do that, you lose a TON of time and speed.

Just something to think about. If you're out this way (Boston), I'll take ya for a ride and show you. Or better yet, bring your car and I'll show you firsthand

Hope it helps... just trying to be constructive!

 

[Kid97GTS]

Mike,
Are you powershifting - i.e., barely slipping the clutch on shifts? If so, aren't you worried about grenading the clutch? Also, how much traction are you losing on your shifts, particularly the 1-2 and 2-3 shifts? The more power I add to the car, the worse the traction on the 1-2 shift seems to be since I can't really control the amount of power being laid down as I could on the initial launch.