Carnage at the dyno... need some advice

[Pronto]

I'm interested in that as well. I want to buy the complete package ready to go in the car.

Ya, once you finish other damage a strong driveshaft is in order. I'm at the point where I don't trust mine.

 

[Grumpy]

Is that the "pro package" with both front and rear yokes/u-joints or the one with only the front? At what ET do you feel the rear yoke is nessassary?

http://www.dennysdriveshaft.com/c49_grand_national.html ... BGN-3.5-NRPRO .. they arn't cheap.. Check the other ones posted here an see what they are for price.
I really don't know what ET range.. Hey I am a Buick guy that runs stock junk to the max We did have a 3" alum one in Melissa's car.. Now she has done mid 1.4 short times but it isn't a violent launch (NO wheelie's ).. Car just takes off. We are upgrading the rear end so we figured it was time to get the "good stuff" .. Clear as mud right

 

[Grumpy]

Ya, once you finish other damage a strong driveshaft is in order. I'm at the point where I don't trust mine.

One of the old guys from NH "Stan" .. Silver T like yours.. rolled into the throttle on the highway.. ran it up to about 120 (well lets say he was moving) .. Let off to slow it down the BOOM !!! Broke the driveshaft, murdered the floor, cut a brand new 3" KB exhaust in half. I forget what else it did. So this is "food for thought"

 

[Pronto]

Humm. Seems like a common factor is letting off (unloading the driveshaft?) suddenly. I really don't want to experience a broken driveshaft, especially at speed...

 

[87gnguy]

One of the old guys from NH "Stan" .. Silver T like yours.. rolled into the throttle on the highway.. ran it up to about 120 (well lets say he was moving) .. Let off to slow it down the BOOM !!! Broke the driveshaft, murdered the floor, cut a brand new 3" KB exhaust in half. I forget what else it did. So this is "food for thought"

Hmmmm..... Sounds kind of like what happened to me. Exept I was on a dyno. Good thing it didn't happen with the car actually moving at the 120mph you stated. Well, I'm going to call around and start pricing parts Monday and see how much $$$ I'm looking at. Needless to say the wife is PISSED!!! LOL. I told her not to sweat it, it's only a driveshaft and about $200

 

[DailyDrifter]

Edit..................Put a Driveshaft loop in the car !!!

 

[chopped39]

Strange makes driveshafts as well. chromemoly with 1350 joints

 

[Grumpy]

Edit..................Put a Driveshaft loop in the car !!!

remember NHRA only requires the front one. FAST cars have front and rear..

 

[motorhead]

You were making that kind of power and running it through a stockish trans, stock driveshaft (with no loop) and running stock suspension in the rear and this is a surprise? You really have to consider the weakest link and over compensate for the power you are (or plan on) making. Glad you are safe; but all and all this was the result of being cheap and ignorant.

I have a 3" chrome moly DS and HD u-joints in my low-12 second car for a reason.

 

[Pronto]

remember NHRA only requires the front one. FAST cars have front and rear..

Exactly. We don't know what 87gnguy has so why is everyone jumping on him? If he has front loop that would only help the car from pogo sticking if the front u-joint blew at speed. I've seen cars with all the good stuff still drop a driveshaft or bust a tranny. No doubt this was an expensive lesson that everyone can learn from.

 

[jdpolzin]

I've got carnage of the same laying on the garage floor. My problem was an aluminum Nodular 3rd member in a Ford 9". It ripped the helicoils on the pinion support out of the aluminum case and then the Denny's driveshaft pretzeled and destroyed a brand new CK TH350 trans! Scarey stuff right there! This was at the track not a dyno

 

[87gnguy]

Exactly. We don't know what 87gnguy has so why is everyone jumping on him? If he has front loop that would only help the car from pogo sticking if the front u-joint blew at speed. I've seen cars with all the good stuff still drop a driveshaft or bust a tranny. No doubt this was an expensive lesson that everyone can learn from.

Yes, this was a learning experience and has nothing to do with being cheap or ignorant as "others" have stated. A driveshaft loop is on the list and will be installed, probably two of them, but in this case it wouldn't have done any good since the DS broke off at the rear yoke. It would have just kept the it from hitting the floor anyway. The whole point of this thread is to find out what the best way to spend my money fixing this and to let others know what can happen if your components don't work well together. This was the first time the car has been dynoed or even driven this hard since the motor was installed back in October and there are no track passes so we had no idea it would make this much power. Thanks to everyone's comments and advice that do not include name calling or insults. For the rest of you... I'm bigger than that to even comment.
Thanks,
Casey

 

[84BuickGNYorkPA]

Casey,

Thanks for posting this up, guess I should be shopping for a better drive shaft & U-joints also....

Chuck

 

[laz]

Hey Casey sorry to hear about this it sucks . I would tell u to get Pst driveshaft here in fl and pretty good prices . I can hook your up with a trans if you need one let me know . It looks like you broke the rear too have u looked at it yet ? Laz

 

[87gnguy]

Hey Casey sorry to hear about this it sucks . I would tell u to get Pst driveshaft here in fl and pretty good prices . I can hook your up with a trans if you need one let me know . It looks like you broke the rear too have u looked at it yet ? Laz

Thanks Laz, DJ says good things about you. I haven't really looked at much of anything yet. I know I'm going to need a trans, DS and rear yoke. You know what? I'll just get your number from Dan and give you a call

 

[Rebel]

Casey, just a thought. I know it seems the differential is discounted, but especially on a a dyno, the rear and rear driveshaft flange are put in circumstances they are not designed for. Plus, the diff is now transferring energy to the coast side of the ring/pinion. For that small time of decel, I can't help but think as the u-joints are at there acceleration angle, you quickly decel as you let off the gas and the driveshaft "binds", the weak link now being the flange. Definitely a better built driveshaft would endure, out on the street it might not be the same. It just reminds me of a four wheel drive vehicle with four different circumference tires.

 

[87gnguy]

Casey, just a thought. I know it seems the differential is discounted, but especially on a a dyno, the rear and rear driveshaft flange are put in circumstances they are not designed for. Plus, the diff is now transferring energy to the coast side of the ring/pinion. For that small time of decel, I can't help but think as the u-joints are at there acceleration angle, you quickly decel as you let off the gas and the driveshaft "binds", the weak link now being the flange. Definitely a better built driveshaft would endure, out on the street it might not be the same. It just reminds me of a four wheel drive vehicle with four different circumference tires.

You've made a good point here. The more people I talk to, the more we are thinking the driveshaft is the culprit in this whole thing. I've got the website of a very reputatble driveshaft company that's not too far from me so I'm going to be talking to them about one of their chromoly ones (or whatever they would recommend for my application) as well as some hardened yokes. I'm also in the process of finding a stage 2 transmission and two driveshaft loops. Thanks everyone for the advice, I've learned alot from this experience. Anybody know of a good reasonably priced stage 2 trans? LOL
Casey

 

[2toneregal]

What are the specs of your motor and what mods have you done?

 

[87gnguy]

What are the specs of your motor and what mods have you done?

Most of it is in my signature. But basically, it is a standard 109 block with steel crank, fully studded/girdled bottom end, J&E Pistons, K1 Rods, Bored .030 over. It has a custom ground roller cam by Don Cruz (he wont' tell me the specs on it but I know it's a good one). It has roller lifters and 1.55 T&D Roller rockers, Champion head with the Champion port matched intake. The turbo, injectors, and the rest of the mods are in my signature. Hope this helps.
Casey

 

[QUIP'6']

my friends car did the same thing on a decel at the end of the track. bent and twisted in the middle and snapped