If you ever run your car on a chassis dyno ....................

[tactransman]

... make sure the dyno operator knows what he is doing. This Road Runner had a fresh 727 in it that I rebuilt. He took it to a chassis dyno place and when he was running about 4500 RPM's ,he let off the gas and the guy on the dyno slowed down the dyno rollers way too fast and it threw the driveshaft out making a big mess.

The transmission case is broke almost all the way around and the rear end yoke is destroyed. 

[quagmire]

Wow, thats ridiculous.  I certainly hope that shop doesn't expect you to eat that repair!

[dutch]

wow.... did he have something to catch the driveshaft?

[tactransman]

wow.... did he have something to catch the driveshaft?

Yup,brand new Flow Masters! 

[tactransman]

Wow, thats ridiculous.  I certainly hope that shop doesn't expect you to eat that repair!

I am not eating it but my customer is.
We just got it out of the car,here is some better pics.

[dutch]

   I think it`s broken....

[ShelbyDogg]

Isn't that like running down the highway and slamming on the brakes? I don't see how it was the Dyno Operators fault. I've watched many dyno pulls and the drums are turning and are such a big spinning mass that they slow down at their own pace.  I've seen bad u-joints cause that kind of damage on the yoke and on the tailshafts.

[tactransman]

I would describe it more like spinning on a patch of ice and just as soon as you get ready to back off on the throttle,the tires come off the ice and hit dry pavement stopping them abruptly. 

[moparmaniac59]

Kinda like when I was speed shifting and hit reverse (by mistake) going about 35mph. I WAS going forward, but the car came to a screeching halt. The tranny didn't like it much!!


                                                     Matt B.

[71chally416]

I don't get a warm fuzzy feeling looking at the insides of that yoke. I wonder if that U-joint was moving around in there. Might just be the photo.
 

[wiging19]

So have you had a chance to tear it apart and figure out what you could reuse?  Looks like the case was toast.  Just looking at the end result makes me want to cry and it wasn't my car.   Though I could easily imagine that happening to me with the luck I've had with my car.   What a pisser.

[ShelbyDogg]

I bet that rear u-joint failed or shot a cap off then everything went out of balance and the driveshaft then went crazy spinning so violently that it shook the tail shaft, cracking it. I bet that was scary. I broke a tailshaft housing once because I had a 440 with 6-pack rods with the wrong balancer. The engine vibrated bad at high rpms. I was out cruising and jumped on it hard. The tailshaft cracked all the way around at the rear bearing.

When doing my race car burnouts, My tires were always spinning very fast out of the water, Then I would hit the brakes, while letting off the throttle, grabbing sticky race track. That's kind of like being on ice hitting dry pavement.

KSHE car show is May 3rd.  Lots of Dyno tests going on with spectators all around watching at eye level. Kind of makes me want to stand a little farther away now.  Going Terry?

Rob



 

[dutch]

I broke a tailshaft housing once because I had a 440 with 6-pack rods with the wrong balancer. The engine vibrated bad at high rpms. I was out cruising and jumped on it hard. The tailshaft cracked all the way around at the rear bearing.

Rob

hey Rob,
when I bought my car I only took it out once or twice for a short drive and it was vibrating pretty bad at say 40mph+ speeds . I had the feeling the driveshaft was out of balance but now I read this...     I have a 440 with 6-pack rods and you got me wondering if I have the correct balancer for it... I thought there were 2 types of those, cast and steel crank balancers... is that correct?
thanks,Bart

[71chally416]

When doing my race car burnouts, My tires were always spinning very fast out of the water, Then I would hit the brakes, while letting off the throttle, grabbing sticky race track. That's kind of like being on ice hitting dry pavement.

That's exactly how people roll the spags in their trannys and blow them up. I hope you don't come out of the water in 1st gear.

[ShelbyDogg]

I thought there were 2 types of those, cast and steel crank balancers... is that correct? thanks,Bart

This was back in 1978, But I found out there were 3 balancers. If you are out of balance, you will vibrate in neutral at high Rpm. Try to find the right balancer or pull everything out and take the rotating assembly to a balancer to add some mallory.

That's exactly how people roll the spags in their trannys and blow them up. I hope you don't come out of the water in 1st gear.

Raced for 10 years and some before that. I always did my burnouts like the Turbo Action instructions said.  1st or 2nd then quickly into 3rd, getting on the brakes while letting off of the gas at the same time so everything has a little load on it and nothing gets shocked OR doing a power burnout all the way to the line.  Only lost a sprag once when the 8-3/4 rear end blew up. Went to a dana and never lost one again. I also used the Cheetah non-LBA VB.