Shakes at cruising speed ,,, bad parts combo???

[firefighter3931]

good point ws23rt

Oh and another thing I remembered I used the flex plate off of my old 400 too, are they interchangeable?

Is it a stock flexplate or aftermarket part ? If it has a B&M flexplate with the scallop cut-out that will make a big difference.

Ron

[ottawamerc]

It was the stock unit

Scott

[firefighter3931]

It was the stock unit

Scott

Stock flexplate is the same for cast vs forged crank so that is not the issue. 

The only difference would have been the weights which are added to the Tq converter which you say are not there and that leads me to believe the vibration issue lies elsewhere 



Ron

[ottawamerc]

Ok thanks Ron, I'm going to take my drive shaft in for balancing tomorrow to have it tested and the wheels in for a re balance too.

Scott

[firefighter3931]

Ok thanks Ron, I'm going to take my drive shaft in for balancing tomorrow to have it tested and the wheels in for a re balance too.

Scott

Good plan Scott....have them check the driveshaft for excessive runout before balancing. If it's bent at all just start looking for another one. 


Ron

[ottawamerc]

Ok I had the drive shaft inspected today and right away they noticed where the balance weight is up front it had been dented in, They tested for the runout and it was repairable and the found the balance to be way out too. Excellent service and price at this shop I highly recommend them, they also fixed it while I waited only 40 mins.http://ottawa-driveshaft-steering.com/

I'm going to give it a spin tonight I'll let ya know the outcome.

Scott

[firefighter3931]

Ok I had the drive shaft inspected today and right away they noticed where the balance weight is up front it had been dented in, They tested for the runout and it was repairable and the found the balance to be way out too. Excellent service and price at this shop I highly recommend them, they also fixed it while I waited only 40 mins.http://ottawa-driveshaft-steering.com/

I'm going to give it a spin tonight I'll let ya know the outcome.

Scott

Well that's great news ; not that the shaft was in need of some attention.... but that they found some problems and repaired them. 



Ron

[MSRacing89]

I would be looking at a bad U-joint first.  Bad drive shaft angles and U-joints will be show there stuff around 60MPH.

Check your drivshaft working angles while you are under there putting it back to together tonight.  Obviously you need to have the car under load if that is possible. Ideally you want to them to be under 3º.  If you have excessive working angles you will get a higher speed shimmy.

[Chryco Psycho]

http://www.youtube.com/watch?v=gmV4qwLfOMY
this will help

[ws23rt]

http://www.youtube.com/watch?v=gmV4qwLfOMY
this will help

A very good look at how u joints work. Some things that seem simple have unanticipated variables. In industrial applications a u joint needs a minimum offset in order to allow the needle bearings to fully roll. If not enough off set than the needle rollers would not roll and take a set in the race.

[ottawamerc]

Well I was out in it and pushed it to 80- 90 MPH on the hwy and ya its GOOD!   Thanks to all that coached me thru this, you guys are awesome. Best site ever.

[firefighter3931]

Well I was out in it and pushed it to 80- 90 MPH on the hwy and ya its GOOD!  Thanks to all that coached me thru this, you guys are awesome. Best site ever.

Excellent news  



Ron

[MSRacing89]

You are welcome.  Some of us have been through it....some more then others.  With all the mods on my car you would believe how much I had to change the driveshaft angles and parts to make it all work.  I run a 7º shim in the rear if that tells you anything!

[ottawamerc]

Ok So I have wandered a little farther down this twisty road of mine. In search of this shake I have of this week removed the transmission and returned it to the shop to have the tail shaft bushing replaced and the tail shaft seal done too as it was leaking now an indication that the bushing was fried While I had it out I figured well I might as well throw in a new torque converter and flex plate to see if that fixes the vibration. I replaced the stock although customized converter with a B&M holeshot 2400 stall converter and a B&M flex plate. I bolted it all back together tonight and tried it and there was some change in the acceleration with a reduction in vibration and also in cruise. The vibration would reappear in deceleration from high speed. One noticeable difference is that the shifts are smoother with this torq, not really what I was looking for but it does light up the tires quick I guess my next component to replace is the old vibration dampener. I'll keep ya posted.

Scott

[cudaken]

http://www.youtube.com/watch?v=gmV4qwLfOMY
this will help

Scott, did you watch the video? Have the pinon angle checked! I fought with this problem for 5 years in my Road Runner. Even had the tires balanced on the car at 80 MPH, could not get rid of the vibration!

Cuda Ken

[ottawamerc]

Ya I researched the heck out of it, I bought and angle finder too and tested it many times with findings there of trans down 2* drive shaft down 3-4* and axle up 2*. We seem to think it is coming somewhere ahead of the transmission now. I'm going to pull off all the V belts and try that and also maybe a new balancer.

Scott

[ottawamerc]

Ok Guys an FYI moment here.. I started out with a 50.5" drive shaft and after lots of research it looked like I needed a 53.18" drive shaft with my combo 71 Charger, 440, 727 and 9 1/4 axle. So I went and got one today from a parts guy and guess what? It's too ^%$#@&^ long!!! So anyone in the future that is building this combo in the future you will need a 51.75 or 52" drive shaft The 53.18 drive leaves about 5/8" clearance.

Scott