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

[ottawamerc]

Hi guys

My Charger is giving me some worries now and I'm trying to see if what I'm thinking may be the cause. History on the build, It is a 440 6 pack built from parts from all over North America, a 72 440 block bored .060 over, forged crank, LY rods shot peened and balanced, 10:1 pistons, a vibration damper that came with the crank and the torque converter was rebuilt/ altered but was the one on my car when it had the 400 in it. Here's where my worries kick in is the vibration possibly coming from a miss matched component? It's shaking pretty bad at around 100KMH kinda like a bad tire but a tight and constant shake Would I feel an engine shake if I reved the engine to the same RPM as cruise speed? or just under load...

Looking to you guys on if this could be the issue or help make this worry go away and maybe its a tire, hopefully although tires , rims etc are all new.

Thanks
Scott

[Cooter]

You say "When I had the 400 in it" Was the converter balanced for an external 400, with cast crank? (Were there little weights on the converter where you bolt it up to flex plate?)

Did you have machine shop Rebalance all those "mix and match" parts?

If it's the engine/converter itself, you should be able to feel the same vibration sitting still in park, and revving it till you feel it. Somewhere usually round say 1500-2300 RPM. I assume you didn't have this vibration until you built this engine correct? So, if you rev the engine till around the same speed as cruise, you should feel it if it's the engine.. but if not, and only does it at speed, under load, then you need look other places.

[ottawamerc]

Ok thanks Cooter, I think the weights were on the converter but I'm going to recheck tonight. I can rev the engine in neutral with no noticeable vibration, so I should be ok with the engine and tranny, maybe a drive shaft or tire issue?

[ottawamerc]

Ok I put he car on the hoist and checked the converter and there are no weights there, is that right? or should it be weighted?

[firefighter3931]

Scott, as Cooter mentioned ; the cast crank engines require an externally balanced torque converter. The balance is achieved by welding weights onto the Tq Converter so if you have an internally balanced engine (with an externally balance tq converter) those weights need to be knocked off to bring it back to neutral balance. 

If those weights are still in place then you need to remove 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.

[ottawamerc]

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

Wow that would be MUCH!!! better and possible cause the driveshaft is one of the "new/ used" parts that were installed. I did nothing to the shaft and u joints other than clean and paint. I had the car on the hoist and ran it at idle in gear and did a visual of the drive shaft and it looked true.. but who knows. I'll pull the drive shaft off and check the joints again.

Scott

[Dino]

My car had a minimal vibration when I reached 50 ish last year.  Before I had the chance to turn back the vibration got real bad and noisy, turned out the u joint failed.  How's your engine mounts looking?

[ottawamerc]

My car had a minimal vibration when I reached 50 ish last year.  Before I had the chance to turn back the vibration got real bad and noisy, turned out the u joint failed.  How's your engine mounts looking?

They are new.

[Dino]

My car had a minimal vibration when I reached 50 ish last year.  Before I had the chance to turn back the vibration got real bad and noisy, turned out the u joint failed.  How's your engine mounts looking?

They are new.

Did you do the driver's side mod?  If not do it now before you forget. 

http://www.dodgecharger.com/forum/index.php/topic,13216.0.html

[ottawamerc]

Ya I read the article after I did the swap, wished I knew before but its a pig to take in and out so fingers crossed

[MSRacing89]

If you had a vibration related to the wrong damper or flexplate, etc....you would most likely feel it sitting in the driveway under minimal load.  We just had a customer car with '72 block in it, had a vibration at 2500rpm with no load.  Turned out it had the wrong damper on there.  Once you get to the 70's era 440 block, you have to be real careful on the damper's.  Talk to 440 source and make sure your numbers are correct for the year.

[ottawamerc]

Not the best pics of the damper but this is whats there.

[MSRacing89]

http://store.440source.com/Dampers-Balancers/products/14/

You can read up on what the different types are here.

[RIDELIKEHELL]

My next job is to figure out why I have a bad vibrationg at 65-70 mph...shakes the steering wheel quite a bit but doesn't do it all the time  I've been told wheels,driveshaft etc....will report back my findings but for now will only go 60 mph 

[ottawamerc]

Ok update on my shakey shakey. I replaced the U joints and it is better but the vibration is still there. I'm going to send it back to the shop and have the new tires rechecked.


Scott

[Tilar]

You have the original balancer for that crank but you changed the Torque converter, I'm betting that is your demon. 

[ottawamerc]

You have the original balancer for that crank but you changed the Torque converter, I'm betting that is your demon. 

No the dampener was picked up along the line as I was gathering parts too but it is the right one for a forged crank (I think) I checked the converter and didnt see any weights and I think thats right?

[Tilar]

That would be right. The dampener looks right from the pic, the one for a later model engine is wider than the older internally balanced ones.

[firefighter3931]

Ok update on my shakey shakey. I replaced the U joints and it is better but the vibration is still there. I'm going to send it back to the shop and have the new tires rechecked.


Scott

The driveshaft could be out of balance or have excessive runout. Another area to look at is the front yoke and tailshaft bushing. Excessive play will cause vibration at speed.

Ron

[ottawamerc]

The front yoke has some play on the tail shaft but is that not normal?

[firefighter3931]

The front yoke has some play on the tail shaft but is that not normal?

It should have a very small amount of play.....you should just be able to feel it move ever so slightly. 

Pinion angle is another possible source for vibration. 


Ron

[ottawamerc]

The front yoke has some play on the tail shaft but is that not normal?

It should have a very small amount of play.....you should just be able to feel it move ever so slightly. 

Pinion angle is another possible source for vibration. 


Ron

So that brings me back to another question I had earlier about bushings / shims on my transmission rear support. When I reassembled I couldnt remember if they went on top or below like in the pic?

[ws23rt]

The front yoke has some play on the tail shaft but is that not normal?

It should have a very small amount of play.....you should just be able to feel it move ever so slightly. 

Pinion angle is another possible source for vibration. 


Ron

So that brings me back to another question I had earlier about bushings / shims on my transmission rear support. When I reassembled I couldnt remember if they went on top or below like in the pic?

Whether they go on top or bottom of mount bracket would make only slight difference. This could be answered by knowing your pinion angle.
Also it looks like the studs in the trans are short. You need full thread in the nut for the stud to be all it can be. If you need the shim you need longer studs.

[ottawamerc]

good point ws23rt

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

[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