Reached the stage in my timing chain replacement project where I'm ready to pull the harmonic balancer. Question is should I replace the harmonic balancer or reuse the old one? I've heard of harmonic balancers going bad and I certainly don't want to revisit this process of removing all the accessories and the front end of the motor. How long do harmonic balancers last (years and/or mileage) and how do you tell if they are about to go bad? Should I replace it while I've got everything apart? Thanks Paul
question on harmonic balancer
- Thread starter spstan
- Start date
PurpleBeeper
Member
Good question. They don’t wear out often, but I have had one on a Ford go bad once. Sure, why not replace it? Make sure you get one that’s correctly balanced for your motor (likely neutral balance, but check) You replaced the seal in the timing chain cover where the harmonic balancer goes through, right?
In normal use, harmonic balancers have a very long life. They are usually re-used with timing chain changes.
Going bad? Many talk about the outer ring "slipping" such that setting the timing is difficult, BUT rather than "slip", their usual mode of failure is the outer ring moving rearward such that it can even touch the timing cover itself. Such movement IS definitely visible, exposing the rubber interface between the hub and outer ring in the process. So, as to ultimate mileages? I've had several Chrysler V-8s with past 150K miles and the same production balancer they came with. No movement of the outer ring evident.
If any movement happens, it will be over a long time. Not sudden by any means.
Of course, do NOT use the outer ring to pull on when you pull the balancer off of the crank nose! Use the normal crankshaft damper puller and three bolts to do that deal. After the center balancer bolt is carefully removed.
Similarly, the nose of the crankshaft should have a tapered lip that the balancer should be installed against for it to be fully "on". When hammering it back on, it might seem like it is on far enough, but you can tell by the sound of the mallet when it IS on far enough and against that lip on the crankshaft nose. When done, install the damper bolt and torque to specs, even if a breaker bar is needed.
Enjoy!
CBODY67
Going bad? Many talk about the outer ring "slipping" such that setting the timing is difficult, BUT rather than "slip", their usual mode of failure is the outer ring moving rearward such that it can even touch the timing cover itself. Such movement IS definitely visible, exposing the rubber interface between the hub and outer ring in the process. So, as to ultimate mileages? I've had several Chrysler V-8s with past 150K miles and the same production balancer they came with. No movement of the outer ring evident.
If any movement happens, it will be over a long time. Not sudden by any means.
Of course, do NOT use the outer ring to pull on when you pull the balancer off of the crank nose! Use the normal crankshaft damper puller and three bolts to do that deal. After the center balancer bolt is carefully removed.
Similarly, the nose of the crankshaft should have a tapered lip that the balancer should be installed against for it to be fully "on". When hammering it back on, it might seem like it is on far enough, but you can tell by the sound of the mallet when it IS on far enough and against that lip on the crankshaft nose. When done, install the damper bolt and torque to specs, even if a breaker bar is needed.
Enjoy!
CBODY67
Unless it's obvious that the rubber has deteriorated, use the old one.
IIRC, your car is a '75 or '76 (helps to state that) and now you're getting into finding the correct external balanced balancer that matches the rotating assembly. That may be more difficult than you think.
If you decide to change, have the original rebuilt. It will be much easier. I've never used these guys, but have heard good things. DamperDoctor
IIRC, your car is a '75 or '76 (helps to state that) and now you're getting into finding the correct external balanced balancer that matches the rotating assembly. That may be more difficult than you think.
If you decide to change, have the original rebuilt. It will be much easier. I've never used these guys, but have heard good things. DamperDoctor
Justin Plant
Well-Known Member
I just replaced the one on my Camry yesterday. 25 yrs old, 216,000 on the clock. Was it age or mileage? The one on my 75 Dodge looks great, 49 yrs old and 48,000 miles you be the judge.
Probably both... Rubber doesn't age well and rubber that's been subject to heat under the hood ages even worse.
CB; I got the crank bolt off with an old electric impact wrench I bought on E-Bay (Millers Falls). Do you know what the torque should be when I put the bolt back in? I don't think a torque stick will fit. Paul
ynst
Member
383 and 440 should be a neutral balance damper. 400, on the other hand, are externally balanced so the dampers are NOT the same as the 383/440.
Is the rubber cracking? Can you wiggle the outer rin at all?
You can get it rebuilt at https://www.damperdoctor.com/ . I just had them rebuild the damper on the 265 cid six in Tex Smith's old '48 Chrysler 7 passenger sedan. They can rebuild yours or exchange it for one in stock.
Personally, I'd go for the rebuild because the OEM balancing holes will match your rotating assembly. If your engine has been rebuilt in the past, the OEM balancing is out the window though (unless the shop re-balanced everything).
Is the rubber cracking? Can you wiggle the outer rin at all?
You can get it rebuilt at https://www.damperdoctor.com/ . I just had them rebuild the damper on the 265 cid six in Tex Smith's old '48 Chrysler 7 passenger sedan. They can rebuild yours or exchange it for one in stock.
Personally, I'd go for the rebuild because the OEM balancing holes will match your rotating assembly. If your engine has been rebuilt in the past, the OEM balancing is out the window though (unless the shop re-balanced everything).
I'll agree on the 383, but the 440 used a few different dampers.
The early forged crank used a neutral balance while the forged six pack/heavy rod used an "external balanced" damper. The cast cranks used "externally balanced" balancers too... One for the regular rods and one for the heavy rod engines. I don't even pretend to have figured out what fits what with the cast iron crank stuff....
This is a decent ID page. Harmonic Dampers 440 Source.com
With the OP, once we get into cast cranks and unknown rods, it's just best to not tempt fate and use the original.
Well, not so fast. There are all sorts of balancer combinations depending on the application. A 383 has two different ones.....a forged crank type which is for internally ballanced engines, and the oddball '71 2bbl. cast crank balancer which is for external balance. A 400 cast crank balancer is externally balanced, but, slightly different than the 383 one due to the different bolt pattern for the pulley. It should interchange by slotting the pulley, but, I haven't tried that combination personally. The 400 with a forged crank uses the same one as and 440-4 350HP with a forged crank and will interchange with a 383 forged crank by modifying one pulley hole to match the different (even) bolt pattern on the balancer that all engines have from '72 onward. '71 and older engines have one offset pulley bolt. A 440-4 375HP, and a 440-6 use an externally balanced damper different than all the others to match the heavier rods in those engines. A 440 cast crank has a different one also that actually has "use with cast crank only" cast into it's hub.
This is the stuff that makes my brain hurt worse than it normally does... And why I say "rebuild the original" because that can of worms is best left unopened.
I didn't know that about the 71 2bbl crank! I would have said all the 383 cranks were forged. Learned something new today that I'll forget about next week.
I am going to replace mine soon with timing chain and gears....and some of the new ones, like the one I will get from 440, has a bolt in weight. So, you do not have to understand, research or figure out. Just pull the OEM, look for a weight on the back side, and do the same on the new one. The external weight is easily seen on the damper, and in my case, I think I will remove from the new one.....internal balance on 383???
Lefty ; I showed the balancer to my race car driving neighbor and he said it needs replacement cause the rubber is cracked. I respect his opinion but I will post pictures to see what the rest of the board thinks. Paul
Plymouth man
Member
Can you put a aftermarket balancer on a 77 400
Again, finding a replacement with the proper offset balancing for the cast crank is going to be a challenge. Yes, 440 source makes one that is supposed to work with the cast crank, but really the question is if you want an offshore built piece that might work or do you want to go with the original that is built to work with the crank in the car? Also note that 440 Source doesn't have the best reputation for some of their parts.
IMHO, you are going to save a lot of frustration and probably $$ in the long run by having the original rebuilt by someone like https://damperdoctor.com/index.php?route=common/home
To explain... In the 70's, Chrysler went from forged crankshafts to cast crankshafts. Along in the mix came a heavier connecting rod for some cars too. These cranks presented a problem that in order to balance them, they had to add additional weight to the harmonic balancer and the torque convertor. Before that, the forged crankshaft, small rod engines used a harmonic balancer and converter that didn't need the extra offset weight.
So... Now you have different combinations of balancers that takes someone at a higher pay grade to figure out what fits what and things you read on the internet about this subject aren't the most accurate. Chrysler was known to do some mixing and matching over the years so you could drop the pan and check what rods and crank you have if you really want to know what is actually in the engine... AND that is why I say to get the original rebuilt and then everything fits, everything balances so there's no engine vibration etc. I may not know everything, but I have built a big block Mopar or two over the years....
John; have you ever rebuilt an harmonic balancer yourself? Damper dudes wants $139 for the project and I can't see where it's that complicated. Paul
I have never rebuilt one myself and I think it's something left to the pros. Just thinking about it, it would have to be cleaned up, the timing mark aligned to the keyway and then assembled with new rubber (I think they use silicone instead of vulcanized rubber).
$139 isn't that bad... There has to be a couple hours work there.
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