Got the SHAFT!!!!!!!!!
 

Man...

Took my 69 Camaro to www.speedinc.com today to do the first live dyno tune since I put the car together. It has been running on a mail order tune since 2005. At that...it ripped a 12.5 at the quarter at 111 on C5 Goodyear runflats. It has carried me 11K trouble free happy miles...and been to the 1/8th mile many times. I am not shy about the throttle either when I'm out of traffic.

With all that said...I found out two things. First...all this time I have only had 85% of my throttle. I wondered why the car laid down a little at the top of the quarter...now I know why.

SECOND - MY DRIVE SHAFT SNAPPED at 6,300 RPM and destroyed the exhaust, some tunnel wiring, and the floor pan.

We rescheduled to finish it up on 5/14 - but I have to obviously fix it by then. I'm also a bit concerned about making the mid west challenge if I don't pull it together.

Funny thing is, I'm not mad about it. I'm glad it happened there...and not anywhere else. I almost drove the car the 150 mile one way trip to the dyno, but opted out as a buddy was giving me some mufflers for my wife's car that wouldn't have fit in the camaro.

Sorry for the long post. Now I have to try to make some lemonade out of the lemons.

Oh...before it broke it put down 362 hp at the rear wheels at the moment of breakage.

was that the original driveshaft or aftermarket one that came as a kit with the tranny? I had the u-joints broke on me long time ago when I did a burnout. Luckily the emergency cable kept the driveshaft from touching the ground.

Stock shaft that had been balanced and set to bolt to the 9" axle.

There is no evidence of rust or other damage to it. The trans mount is secure...and there is simply no other explanation.

The dyno guy said that sometimes when there is a little bend or unbalance situation in the shaft they will do this.

The drive line angle is good and I can't imagine the dyno put more stress on it than normal street driving.

Could be that depending on the rear gears and tranny combo -- your old stock shaft hit whats known as it's CRITICAL SPEED.

Do a little research on the subject. I think David Pozzi has some info on it on his website (can't remember). But my guess is that is the cause of the failure.

:cheers:

And Jim (the dyno guy) has a VERY heavy right foot, and some cool and fast cars!!

362 to the rear wheels is about 452 at the crank. Nice motor. Are you going with an aluminum driveshaft to replace your 2 piece?

Paul

If you dont mind me asking what are your engine specs, t-56? I'm running a cam only LS1 in my 69 and your got me wondering. Thanks

Holy crap,sorry to hear that...amazing how it tore @ only 6300.

The critical speed thing makes sense to me. The main part of the shaft after all is 40 years old - so between age and the magic frequency it let go.

I will tell you the engine sounded so sweet just before it came undone.

Engine specs:

stock short block - rebuilt with a ring/bearing kit. I bought it for $400 in 2005 as a take out from a stolen 2000 Trans Am that had hit the road bed and broke the pan open. It was starting to spin a rod bearing. I put a $160 crank kit in it and was good to go.

I bought a "stage III" SLP head/cam and 36# injector kit. It is a LS6 intake (non ported) and stock throttle body.

I put a set of non-emission Pace Setter headers on it and had to make some small changes to get them around the rack on the drive side - passenger side slipped right in.

Trans is a 4L60E out of a truck with a stock rebuild on the clutch/seals and a trans go shift kit. It is a TCI 2,800 stall converter with lock up.

All that is tied to a Ford 9" with a 3.5 gear.

For what it is...the whole combo was a major budget build. Nervous system is a Painless Harness on a 98 Camaro PCM.

I made some calls this afternoon. Hope to have a PSTD shaft soon and will most likely get a set of PYPES mandrel bent 2.5" exhaust and Race Pro mufflers.

The big issue is the floor. I'll post pics later when I can get them off the camera.

Here is what the bottom use to look like...and the motor. No bling under the hood.

http://mcspeed.homestead.com/files/c...k_complete.jpg

http://mcspeed.homestead.com/files/camaro_fisheye.jpg

same thing hapend to a friend of mine with a 70 charger.took out exhaust,transmision,bellhousing,driveshaft and the part of the u joint hit the dyno operator in the chest.

need me to get you a deal on a 3.5" aluminum one?

Sucks that broke like that.. glad you weren't in motion, could have gone badly..

The maximum Hp ever created by Chevy was 425hp. I doubt you have that drive shaft. Even if you did, it's seen better days. I'm also running a 3.5 inch aluminum shaft like Rupp.

What about steel or carbon fiber driveshafts? Can they handle high HP/torque?

Yep...talk to me. I put an email into PSTD out of Florida for some shaft suggestions. I have my wife's car on the lift right now with no wheels or brakes under it. Those show up this week, then it comes off and I'm hoping by next weekend I can have the Camaro up in the air to start the repairs.

I'll need to take a measurement for the new shaft - have to jack it up and get that today.

Time is going to be tight


Funny thing is...even at 425 hp or so...I never imagined the shaft being a weak link. Going over that...yes. We just wrapped up a 900 hp turbo trans am and got it out of the shop a couple of weeks ago. That one had a custom shaft from PSTD and it was also set up for living a 1/4 mile at a time. I just never imagined mine doing this.

Years ago I had a Jeep CJ7 with oversized tires and a 4.2 six. I snatched a gear hard going into second - chirped the tires and threw that shaft out on the road. Being 4x4, I locked the front hub in and limped it home.

You might want to add driveshaft loop. Dont know if it would have saved you from some of the carnage.

email me and I will check a "good guy" price over at IEDL.. Of couse I would need EXACT dimensions and what U-joints you are running.

[email protected]

Spun mine in the '69 to the 6800 chip on the dyno several times and made 431rwhp with a stock GM driveshaft,never worried about it before,maybe I should?:_paranoid

John - Like I've said many times about myself --- Better lucky than smart!:rofl:

The critical speed of a shaft is really important - and I don't think I ever encountered such things "back in the day" -- but now we're spinning motors to higher revs and with big gears (thanks to overdrive) and maybe we'll see more failures like this.

Luckily I think most of the folks on here that have done big engine swaps - are familiar with this issue - and most likely have already upgraded their driveline - if for no other reason than because they had to make a new one for the new rear and trans... (maybe Lucky AND smart!).

I was thinking back to my drag race days - and can't ever remember a discussion about this - but I was young - and maybe it was already taken care of (Obviously) by the constructors. Back then - all I can ever remember worrying about was the U joints... but they never broke either! LOL

Email sent....

FYI though....


The measurement form the metal lip of the rear seal on the trans to the face of the U bolt mount on the diff is 53 7/8” with the suspension loaded under vehicle weight at rest.

I used a conversion U-joint on this which allowed the use of the stock 69 shaft with the BRP mounts. The new shaft can have standard Ford joint which I think will be better as well. The diff yoke is 1 1/8” diameter and 3 5/8” from cap to cap (on the diff side). I think that is a 1350...but I can't remember for sure.

The 1350 U joint diameter is 1 3/16

My guess is your U joint is the slightly smaller 1330 - based on your 1 1/8 diameter.

Both the 1330 and the 1350 would measure 3 5/8 but the 1350 uses the larger bearing diameter.

just a heads up as i have seen it about a half dozen times at least, when the shaft brakes, rear end gears sheer or anything to cause the sudden rpm change in the trans you can hurt the transmission. i have had to rebuild a few because of it. make sure you have time to test out the trans before you leave on your trip incase you need to have it rebuilt.

1 was a turbo 400 and the other 5 were 4L60E in trucks.

Very cool! Back when I worked a parts counter I had a book that made me look smart in these areas! :lol:

I just ordered a universal loop kit and will put that in while I'm repairing the floor. Looks like it needs to be about 6" behind the front yoke.

Yikes...what am I looking for? Noise, slipping, hard shifting ?????

hey man, sorry to hear about the damage but I gotta say your car is super clean! love it!

noise and slipping, missing gear (most the time its the gear that it was in when it let loose). its different on them all just depends on what the trans wanted to do. one of the 4L60's lost 3-4 since they use the same clutch pack. the TH400 lost second. just go beat on it some to make sure everything works like it should.

:thumbsup: :thumbsup: That's one thing I can do! :lateral:

Here are some pics of the floor and exhaust damage.

By the way, I followed Jim's advice on setting up the throttle body (it was showing 1 percent at idle and not going to WOT. It idles down so much faster now...albeit through open headers at the moment.

You can see where it snagged the wires and emission hose as well as the battery cable. Let me ask you guys that have batteries in the trunk. Where/how is the safest place to run that cable??????

http://mcspeed.homestead.com/publish...~element68.jpg

Here you can see where it tore the seatbelt mount off the floor on the passenger side. It is only hanging by a thread. If the carpet was out you would see daylight.

http://mcspeed.homestead.com/publish...~element69.jpg

In the short run I am going to see if the local muffler shop can bend two short runs of pipe to replace the crushed pipe. I realize now my X pipe in the middle is way too restrictive. We built this exhaust to make servicing the car a breeze with multiple drop out sections on the bell clamps.

I'm thinking this is why certain racing organizations require a DRIVE SHAFT LOOP...

Ya think??

Man oh man....

BTW -- the safest way to protect you battery cables - is to not have your drive line break in two pieces! :rofl: Baring that, running them outboard on the "frame". Of course this question really can't be answered because it all depends. :cheers:

I set the cable up in this car just like all the Corvettes did from the factory did on the 3rd gen models. Running it along the side of the frame seems like an issue for any sort of T-bone accident which would likely short it out and cause a fire in a hurry.

I'm actually considering putting it back up front - except my air box is where the battery would go. I'd have to fit it in the driver fender front which would be kind of goofy too.

Sorry about the damage. When I had the battery in the trunk on my 69 (pass side), I ran the cables over the rear wheel well and up through the channel under the door trim plate. Used one of those battery cable posts you can mount on the floor (under the heater box) to pass it into the engine compartment. This way the cable was inside the car rather than exposed underneath.

I ran my cables through the car. Between the tunnel and passenger seat.

I just talked to Mark at Precision Shaft Technologies.

Based on the hp, PRM, and use of the car he is recommending a 3.5" steel shaft with the 1330 (FORD) rear joint that is good up to 700 hp.

You guys are right too. Without me telling him - he guessed exactly where it had broken and said it is a crictical speed issue. MAN...am I a believer now! While I have almost always had my shafts balanced, I haven't always upgraded them. I have had them shortened and lengthened before - but on "STREET" cars I hadn't sweated this before. On my Corvettes the shaft is more or less fixed as the diff is mounted solid and there is very little movement or issue. Also, they are substantially shorter. However, it could be cause there too to be aware of.

Aluminum would be cool - but just isn't needed.

Shaft will be here next week.

Okay...still mulling over the possible battery cable options. You can come up with a bad scenario for anything in terms of ways to short the cable or start a fire.

Did you guys know the new BMW's have pyro technology in their main battery cable? When the Airbag system senses a crash the main battery cable will blow a charge and kill the connection to the car. That prevents a live battery and cable from burning things down. It is a really cool concept until you have a BMW blow the cable...and you didn't know it had one...and you spend days and days and days trying to figure out why there is no power in the car!

I keep reading "cables" as in plural.... I would really hope that you guys are only running ONE cable - as in a positive - forward to either the starter motor or to a post/terminal somewhere up "front".

The whole car - body and chassis - is the ground... with a short ground strap from the batter to somewhere right close to where the battery is mounted.

I then run short ground straps - under the car from the block to the chassis - and another one from the body to the chassis.... so I have good grounds and I'm not relying on bolts and screws. Use a STAR WASHER under the ground - these are made to cut into the paint/primer to give you good metal to metal contact.

When I run cables or wiring thru the floor - I use a marine grade (west marine) bulkhead fitting. There are many types - and their use depends on what you're doing - where - etc. I like the water tight versions that you run the cable thru - and a nut threads on and clamps the cable and also makes it water tight.

BTW -- worrying about a fire in an accident is a bit overkill and over thinking. You don't drive this car daily - reducing your risk 100's fold - which is why your insurance is about 1/3 of your daily driver... yet the value of the Camaro is probably higher. Why? Because of the reduced exposure. Think about the millions of factory cars running around -- they don't or haven't - taken any particular action regarding battery started fires. Batteries are up front - in back - under seats - in trunks...

If you're really worried about that -- think about this - the two terminals are "exposed" -- what if you get in a wreck and the metal around the battery is crushed and shorts out the terminals....

I'm just saying - there's too many scenarios... Just put the battery where you want it and run your cables... :rofl:

By profession I am an auto insurance/collision research specialist. In other words, I spend a lot of time looking at crashed and burned vehicles from around the country. We search, research and try to determine defects that lead to fires, brake, steering...and yes...UNWANTED (can you say Toyota) acceleration failures.

Anyway - I see the worst of the worst and it tends to color my view of things.

As said - there is no perfect place to put the battery cable. Looking for the best of all possible bad places.

I got the loop today. It is a bolt up universal piece. It looks like it has a good area to go in but have to wait on the driveshaft. I do want to weld the two halves up when I'm satisfied. Ordered a new X pipe center section so we can rebuild the exhaust. Local shop doesn't want to build copies of the pieces that were damaged off the car.

Check out the June 2010 PHR "Getting Shafted" on page 68. There is a good explanation of critical speed failures in there.

New shaft came in last night. It is amazing how that extra 1/2" really looks more stout than the old one.

I didn't notice until last night the U bolts were also abused in the failure so I'm out to pick up a new set today at the 1330 joint at the diff yoke.

My loop is fairly tight to the shaft from side to side. I'll give it a good thrashing prior to the dyno and do a full review to make sure there is no paint transfer from the shaft to the loop from drivetrain shift. This is the downside to the bigger shaft and the tight tunnel in the 1st gen.

Hoping the trans is healthy still. If that is out...I'm out for the rest of the summer because I have no time to get involved in that for the next 90 days or so.

I ran my negative cable all the way to the Bellhousing. I also ran a ground strap from the bellhousing to the fireway. Can't think of a better ground than a bellhousing bolt. It's also 6 inches from the starter which is the biggest load in the system. When I researched it, the consensus was that running the cable was the best route. I'd rather ground through a 0-2 gauge high quality cable than 40 year old sheet metal and frame. :D More than one way to skin a cat.

No question or argument from me.... I just run a big cable from the block to the chassis - and another short run from the body to the chassis... when you stack up the dimension of the body - and the frame -- it's way bigger that 0-2.

I don't rely on the body mount points - or the bolts and tranny connection points to carry a ground... They're grounded securely with cable. We're doing the same thing - minus the long ground cable... so its SSDD..:rofl:

The KEY is that there are great grounds! People seem to discount the ground side of a circuit... somehow that word (Circuit) eludes them... :rofl:

The frame and sheet metal on Camaros are a little thinner than that hunk of iron in your garage. :unibrow: I still like my main ground right near the starter and fuse box. One body ground and it's done. After all, GM configured it through a block ground. The only major current draw in the rear is the fuel pump. I put the relay back there and grounded it directly to the battery. My way is better than yours....:rofl: :rofl:

I yield to the gambler...:hail: :hail:


I've got 1200 WATTS of big azz stereo amps under the back seat -- thus added a big azz ground back there... so have TWO big un's and everyone knows that two is better than one! :rofl:

We're talking CARS here -- BIGGER is always Mo' betta... Well... until you learn a few things that is. :lol: