vibration

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ERACER

ERACER

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Hey everyone. I'm new to the forum and am hoping to find some answers (other than the several I have gotten locally) on a vibration issue.
My car is a 74 Dart Swinger with a 318/904 and 8 1/4 w/ 3.90 sure grip.A few years back I rebuilt a 318 with forged flattops (can't remember brand or find paperwork) stock port J heads, Comp cams cam (280/480), LD4B intake, Holley 600, Hooker Super Comps, orange box ign, stock balancer, TCI 10" converter w/ Mopar 7/16 hole flexplate. Timing @ 32* full mech.
From the word go, this setup has had a vibration that is not evident at idle but increases with rpms. It is worst between 2000-2400. It vibrates when in park as well as when driving. I actually drove this for a few years like this and nothing ever came apart.
In the spring of '07 I pulled the motor to have it freshened and finally get rid of the shake. The machine shop told me everything showed normal wear and no signs of anything abnormal. I also had the tranny rebuilt telling him about the vibration. He also found nothing abnormal.
When everything came back, it all went back in the car and it didn't take long to discover I hadn't cured the problem. I then proceeded to try every possible balancer/flexplate/converter combo I had access to and nothing worked.
Spring '08, a guy I work with offers me his bone stock 360( w/ 75 casting date) until I can get mine staightened out. So I drop it in w/ a b&m 360/904 flexplate and the vibration remains.
I've talked to as many local mopar guys as I could find locally, but obviously to no avail. Any and all suggestions would be welcomed and appreciated. Sorry to be so long winded, but I wanted to give as much info as possible. Thanks
 
Jeepers............ Sounds like a gremlin..............

The only vibrations I've had issues with have been with internally balanced motors using an externally balanced harmonic, or torque converter.......and vice versa.

I've had the issue with 3 cars, and it was usually solved when we determined if the motor was balanced internally or externally, then examining carefully the converter and balancer to be sure if they did or did not have counterweights.

Internally balanced motors (IS yours balanced?) cannot use an externally balanced harmonic.......they will have weights bolted to the back side usually and result in vibration such as you speak of.....but converters also are neutral or balanced externally, and can add to the vibration.

We've solved 2 cars now with vibration by removing external weights on harmonics and converters.

You probably know this already, but it's all I can add to the mix from our experience. You need the right combination to have no vibration. 8)
 
318s never had forged pistons. Sounds like they didnt re-balance it.
 
Gotta be the driveshaft. I had a similar problem. I pulled it and took it to Denver Drivetrain, they changed the u-joints and balanced it as a unit and it totally cured it.
Cost $110.00.

Jim


Oh.......welcome to the site.
 
Yeah, you never know with rebuilds.........some guys just plain don't understand the internal/external variations on some of these motors, and cross parts that won't match......result, vibration.

I don't know of a 318 that was internally balanced........340's yes.......but those parts mix and match something fierce, and they get crossed up all the time and cause this problem.

My guess is that there's a mismatch on the harmonic and/or converter.......but you have to know what they did with the motor to know what to do with the externals.
 
ERACER said:
From the word go, this setup has had a vibration that is not evident at idle but increases with rpms. It is worst between 2000-2400. It vibrates when in park as well as when driving.



If it vibrates while in park also, that should eliminate the driveshaft.

Hmmmmmm, I'm stumped.
Click to expand...
 
Thanks for your responses guys. When I bought the car it was completely stock. The balancer and converter had no weights on them. I did try a balancer and flexplate for a cast crank 340 with no results. I could see a possible problem of not balancing after adding forged pistons but why the vibration with a completely different engine?
 
Sounds like the motor is hitting the chassy somewhere , or mounted solid ,maybe the exhaust is hitting, just some thoughts
 
I went back and read your post again and the car now has another engine in it and it still vibrates????? I`m stumped too, vibrates sitting still and you`ve changed out the engine, flex plate, torque converter??? The 360 is likely to be externally balanced and will need the appropriate torque converter. Do you have good motor mounts? Are they steel or rubber?
 
If your running the 360 with the b&m flexplate I'm going to assume you are using an unweighted converter right? That is the only way this combo will work. And you have the 360 specific balancer too?
 
63dartman said:
If your running the 360 with the b&m flexplate I'm going to assume you are using an unweighted converter right? That is the only way this combo will work. And you have the 360 specific balancer too?
Click to expand...
Correct, the converter is neutral and the balancer/flexplate are counterbalanced for 360.
 
Longgone said:
I went back and read your post again and the car now has another engine in it and it still vibrates????? I`m stumped too, vibrates sitting still and you`ve changed out the engine, flex plate, torque converter??? The 360 is likely to be externally balanced and will need the appropriate torque converter. Do you have good motor mounts? Are they steel or rubber?
Click to expand...
Yes, I've changed everything to 360 stuff. TCI told me all of their converters are neutral and the balance is made up in the flexplate, which I have from B&M. The mounts are rubber spool type and are in good shape
 
By weird chance, ignition system or ground problem??

Do you have access to put it on a scope.........Process of elimination...:banghead: :scratch:
 
I'm not familiar with the rubber spool mounts but, have you tried using a torque strap or even a turn buckle to temporarily lock the motor mounts just to see if possibly they are creating a harmonic through the chassis? It would be an easy thing to do and would eliminate the mounts.
 
6pk
I'm in the process of trying ignition solutions. It currently has orange box. I still had stock blue box but it wouldn't fire. Also had MSD off road just to try but was unable to get it to fire. I was just reading some old posts on that may have it figured out.
As far as a scope, my father's friend owns a garage and may have something. I'm assuming to diagnose an ignition problem?
 
63dartman said:
I'm not familiar with the rubber spool mounts but, have you tried using a torque strap or even a turn buckle to temporarily lock the motor mounts just to see if possibly they are creating a harmonic through the chassis? It would be an easy thing to do and would eliminate the mounts.
Click to expand...
I believe the spool mounts were a 73 and later piece? I have thought about your idea and its on the list of options.
 
Had a thought for if the ignition check doesn't pan out. The only part that is common to all the combos so far and rotates is the TCI converter.
 
I had another thought , it may be the fan blade or the water pump , try taking belts off and see if the vibration stops ,it may even be a belt pulley ,If it is a clutch fan they have been known to vibrate when going bad . Dane
 
I have tried it with just the balancer and no change. Haven't had a chance to try anything for a while, I was in a friends wedding this weekend so time was not there:sad10:
 
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