My recently acquired '85 B350 with a 360 has a vibration problem and it's most noticeable in neutral when revved up and also at low speeds. It also has a leaking rear main seal. I've installed new motor and trans mounts and it has the proper 360 harmonic balancer. The 4 bolts on the flex plate are present and tight. I suspect that someone has put in a newer trans from a 318 and the converter is weighted and the engine is 'double-balanced' and
is causing the vibration. My manual says that the middle #'s of the trans number series is the date code. This trans date code is "8606". Does anyone know if this means a June 1986 build date for the trans? My local Dodge parts guy says he can't tell me what year it is from the numbers!
Would changing to a 318 harmonic balancer solve the problem?
Would appreciate any help!
Dodgevanman
11-16-2006, 11:39 AM
Actually the 360 torque converter needs to be coutnerweighted since it's externally balanced. I betcha the torque converter is bad. Me and buddy of mine just replaced two converters in two seperate trucks because of bad converters...and this is after we thought it was the harmonic balancers.
VanMoreSon
11-16-2006, 11:49 AM
Thanks for the quick reply! I'm not clear on the balancing thing. Aren't the 318 and 360 just opposite? And if you switched a trans from one to the other, without changing converters...wouldn't it upset the balance?
Also, would the 727 from my '77 B300 (also with a 360) fit the '85? I know it wouldn't have the lockup converter but that's OK for now.
Dodgevanman
11-16-2006, 02:52 PM
Yes...the 318 is internally balanced, so the torque converter will not have any weights on it. The 360 is externally balance so the torque converter will have weights on it. The balancers are different between the two as well.
The transmission will bolt into the '85. The mount is the same as well.
VanMoreSon
11-16-2006, 08:56 PM
Well this weekend I'll just have to pull it out and check. The bad converters you changed out...what else did they do (slip,leak,etc.)? Or did you change them ONLY for a vibration problem?
Dodgevanman
11-16-2006, 10:14 PM
Nope...just a vibration problem. Must have been an internal thing.
You don't need to remove the whole transmission to see if there's weights on the converter. Just remove the inspection cover and turn the engine over by hand. As the converter turns you'll be able to see the weights (if there's any there). One thing I just thought of. Check the condition of the harmonic balancer...if any of the rubber has come out or if the "outer" ring has spun around, then this can cause a vibration as well.
The trucks we replaced the converters on received brand new Mopar balancers and well, you know the rest :)
VanMoreSon
11-17-2006, 09:38 AM
OK, will check for the weight...I thought they were on the back side of converter. If it has a non-weighted converter, can the weight be added without pulling the trans? How do you know how to position them? And are they spot-welded on?
Again, thanks!
Dodgevanman
11-17-2006, 11:52 AM
I don't think the weights can be added while the converter is in the vehicle. Not sure of the position of the weights exaclty but I do kow that they are spot welded on. At least all the ones I've seen are. Mopar Performance sells a kit with the weights.
