Posted By: domingo
Using a solid hub instead of a damper? Will this fix it - 11/04/14 03:50 PM
HI!
I have a rotating assembly for a HEMI that has been balanced using a solid HuB instead of a vibration damper (no elastomer or fluid).
I was wondering if by using one of these gilmer pulley and belt setups I would absorb the harmonics just like on Blower equippped engines? My engine is gonna be naturally aspirated.
http://www.ebay.com/itm/Mopar-Chrysler-B...b97&vxp=mtr
Posted By: B G Racing
Re: Using a solid hub instead of a damper? Will this fix it - 11/04/14 05:27 PM
If the solid hub is a neutral balanced hub(no offset weight) then it dosen't matter what hub(neutral balanced) you use.Usually any internally balanced assembly is balanced without any neutral balanced componants,(dampners,flywheels,etc.).The dampners have two functions,one to dampen any harmonics and the other is for torsional twisting of the crank under loads.The heavy balancer or dampener helps bring the crank back to centerline alignment as the front of the crank tends to twist ahead of the true centerline.It offsets the twisting load.Heavy loads like turning of a blower act similarly and you don't need a heavy balancer.With this being said,because of the tremendous loads placed by pressurized cylinders and heavy fuel loads as well as heavy rotational loads is is why you find cracks in most all cranks used in these applications.If your not turning any accessories with the crank then you can get away with a lite balancer an hub.Balancers with no dampening effect will allow any harmonics from the cam and valve train to effect the crank.If you are running a N/A engine with a solid hub and balancer it would be wise to run a belt driven cam to interupt those harmonics.
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/04/14 09:17 PM
Thanks for the reply Bob!
Well, let me explain a lil bit further...
Thing is I haev enough parts to put together a 500 cid HEMI from parts I have sitting on the shelf.
All these parts came as part of package deals or freebies when I bought some cars...so they came at practically no cost tome...still these parts are seconds, or brand new parts that got machined etc in a way that I woukd probably havent done, or had done....but they are what they are....either they remain on my shelf collecting dust, or I assemble them together and build a HEMI at almost zero cost to me.
Turns out that the rotating assembly I have is a 4.375" stroke bryant billet crank, childs and albert pistons and stock rods polished, resized and w new bolts installed. but the thing is that these have been already balanced by cutting the crank counterweights and then by having an offset balance flywheel and solid hub installed. The hub has a considerable offset balance, and the whole rotating assy has been balanced like that.
Yes, I could get a new balancer, new flywheel etc, rebalance and do it "right" but that will mean added costs which I dont want to incurr in since these are all "junk" parts.
So...having said this, I suppose that a way to make this work without having a time bomb is to use that gilmer pulley setup and then getting the belt driven cam gears???? Now that seems like I could do....
My total cost on building this hemi will only be labour, gaskets, bearings and piston rings. most everything else I already have! -cracked but welded heads, they dont leak, used rocker arms, the rotating assembly mentioned, a new MP siamese water block that had the core shift issues and says not to bore over 4.31", etc.
Be nice to build a HEMI that will last for at least a while and not spending much in putting it together....
Posted By: Locomotion
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:48 AM
I've always heard that solid hubs also crack cranks. It is out of my "familiarity zone" and it's been done without issues, but I tend to be over-cautious.
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 07:57 AM
I think Im just gonna take a stab at it....
Better trying and seeing it blow in a thousand pieces rather than keep the parts collecting dust on a shelf forever!!!
Lets see how it goes...
D
Posted By: Twostick
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 09:01 AM
A stock damper would be better than a solid hub. Solid hub equals broken crank sooner than later.
As was said earlier, if the rotating assembly is neutral balanced then just get a neutral balance damper in whatever brand you like. It will NOT require you to rebalance the rotating assembly.
Kevin
Posted By: B G Racing
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:16 PM
Can you show us a picture of your weighted hub?Keep in mind this is nothing new,when Chrysler added the heavy rods and pistons to the 6 Pack engines they balance them this way.Just buy a cheap aftermarket dampner or use a stock one and have it offset balanced to your assembly.A good machinist should be able to determine how much weight and where it needs to be placed on the dampner,just remember to use the weighted flywheel with the balance process.We had a machine shop that took a neutral balanced stock dampner and offset balanced it to an external assembly buy first removing a lot of material from the heavy ring then spun it on the balance machine adding the weight where it was needed with a couple of slugs of heavy metal
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:46 PM
OK guys! Here go the pics!!!!
As you can see somebody was dead set on making things lighter
Here are the pistons
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:46 PM
nuther one of the pistons
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:48 PM
polished stock rods, they also went kinda crazy shaving off the balance pads....I corrected them to make em weight the same on both sides with my rod scale but some were not possible to equialize perfectly, still, no worse than a set of untouched stock rods....
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:49 PM
Now here is the 143 tooth flywheel and dual disc clutch assy. Check out how they machined it to lighten it and also check out the chunk they took out making it external balance....
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:51 PM
Now this is the killer....the damper.
Dont know why they went into the trouble of making a damper that looks exact to a stock street HEMI damper on the outside....its machined out of a solid piece of steel. The went "concourse show poodle correct" on the external appereance of the damper!!!! Its machined out of a single piece of billet steel.
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:52 PM
Now this is the backside of the damper....and the heavy offset balance chunk of steel bolted to it.
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:54 PM
Here are the turned down counterweights on the crank....you can still see the chunks of mallory in the counterweights, when it was turned down some portiones of the mallory were shaved away
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:55 PM
Do you think I risk these coming loose? Should I weld them to secure them in place? If welding, what should I use???
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:56 PM
I think its a Bryant Billet crank...here are the markings....can anybody confirm what I have here?
Posted By: domingo
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:56 PM
It reads PRO CRANK on one of the counterweights
Posted By: dogdays
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 06:59 PM
A belt drive on the camshaft will NOT protect the crank. There isn't enough mass on the other end of the belt to have any damping effect on the crankshaft. The belt does dampen the vibrations going to the camshaft, which is why some have found 20+ hp by switching from chain or gears to belt.
Back in the day, chevy 283s with forged cranks did not have dampers. 3" stroke, 200hp or thereabouts.
My Poly 318, 200hp, 3.31" stroke, did not have a damper on the end of its forged crank.
Dirt track racers have tried over the years to use solid hubs instead of the heavier dampers, because the dampers are additional rotating mass to accelerate. But they found out that the cranks, even decent forgings, would break. To finish first, first you have to finish. I remember reading about the need for dampers back in the '70s, and that was with 3.5" stroke cranks.
Now, if you have an engine with a solid hub and a big supercharger hanging on it, connected by belts, I can see how the rotating mass of the supercharger, the horsepower drag of compressing the air, and the flexibility of the belt would serve as a damper.
But take that belt off and I guarantee, you'll break the crank. It may take a while, but it'll break.
R.
Posted By: B G Racing
Re: Using a solid hub instead of a damper? Will this fix it - 11/05/14 09:13 PM
All the Bryant cranks we have seen and the ones here in the shop have Bryant stamped on the front counter weight.It appears that the counterweights where excessively cut for piston/block clearence and externally balanced because too much was removed to be able to internally balance it.Those street hemi rods are questionable at best,years ago we would go through 3 to 4 sets to get 1 good set.So if you have some way of checking them like magging or zilego(penatration) testing it would be a good idea.That flywheel maybe matched to the clutch and external assembly.
You must ask yourself,"when is a deal not a deal" and do you want to "risk the time and effort" for a "hopeful chance of success"My advise is not to use any of the stuff but if you want to take a chance have the crank checked before anything,that might be the deciding factor.
Respectfully Bob
Posted By: dthemi
Re: Using a solid hub instead of a damper? Will this fix it - 11/06/14 03:10 PM
Just to cut to the chase. Don't run that pulley set up instead of a damper. The blower pulley/belt set up works because there's around 30 +pounds of rotating rotors and gears in the blower that provide the damping effect through the belt, that is under constant strain. No rotors, no damping.
Posted By: B G Racing
Re: Using a solid hub instead of a damper? Will this fix it - 11/06/14 04:58 PM
most race hemis used the thin dampner similar to the 440. Just machine it and offset balance it like your solid hub is.I suggest you do some checking to find if that flywheel was balanced to that dual clutch setup
Posted By: Oyvind Mopar
Re: Using a solid hub instead of a damper? Will this fix it - 11/06/14 07:31 PM
If you are just going the cheap way, you can buy a chinese damper for 360 that has attachable weights inside. It is simple to adapt it to the hemi, my