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View Full Version : roll pins in a stock balancer for strength?



22lbsofboost
01-17-2006, 08:13 PM
this is what my machinist tells me they used to do with small block chevy balancers they were prone to failure. he says 3 or 4 around the perimeter of the balancer will hold it together forever. i think i have him talked into drilling and doing this to my stock balancer. he turns his dirt track car to 8000 rpms and he has yet to sling one out in several years he says. could this be an affordable way to reinforce our balancers? has anyone done this with adverse effects?

Terrible Juan
01-17-2006, 08:34 PM
this is what my machinist tells me they used to do with small block chevy balancers they were prone to failure. he says 3 or 4 around the perimeter of the balancer will hold it together forever. i think i have him talked into drilling and doing this to my stock balancer. he turns his dirt track car to 8000 rpms and he has yet to sling one out in several years he says. could this be an affordable way to reinforce our balancers? has anyone done this with adverse effects?

Somehow the fact that it is called a "balancer" would tell me not to add any extra metal to it, but thats just me.

22lbsofboost
01-17-2006, 09:02 PM
i was sure to ask him about this and he says he cant tell a difference either way, they just dont come apart(which would be good) . the material you are removing would be partly compensated for by the steel roll pins, and it is a negligabe amount to begin with, but hell im no engineer, what do i know. i do know that different motors need different weight in different places on a balancer to be vibration free. maybe ill drill, then ill weigh the shavings, and compare that to the weight of the roll pins:D

anyhow im gonna try this hopefully by the end of the weekend, so if it works, and it feels good, ill post all the pics i take during the procedure

Mike8675309
01-17-2006, 09:58 PM
If you understood what a balancer does, you would understand that the pins could not possibly serve that function and allow the balancer to work.

Two piece balancers are specificly designed with a specific elastomer that works in concert with the two pieces to dampen any resonate frequencies that develop in the crankshaft. thus the two haves can't be coupled to each other otherwise the elastomer would be doing nothing but taking up space.

If these frequencies are not damped, they could escalate to the point that the crankshaft resonations create a stress crack.

There are new one piece balancers that use a fluid inside them to dampen the vibrations and another new style called a rattler that uses something else. These are nice in that they dampen vibrations at all frequencies rather than at some predicted, critical, frequencies that elastomer balancers can only achieve.

7birdslater
01-18-2006, 02:34 AM
So everyone with a 1 piece BHJ balancer must be in big trouble? There are too many success stories. Also, I heard the BHJ weighes a bit more anyway. I hope the roll pin idea works out, I have a factory balancer just waiting for some some experimental treatment.

David Neibert
01-18-2006, 09:32 AM
So everyone with a 1 piece BHJ balancer must be in big trouble? There are too many success stories. Also, I heard the BHJ weighes a bit more anyway. I hope the roll pin idea works out, I have a factory balancer just waiting for some some experimental treatment.

Mike is correct and the BHJ balancer isn't a one piece design. It has an elastomer ring just like the stock unit. What makes it better is the steel inner hub instead of the weak aluminum one used on the factory balancer.

David

Mike8675309
01-18-2006, 10:42 AM
Have your mechanic cut the stock balancer in half and see if he can verify that the inner and outer ring have a position that will allow them to be interlocked by roll pins. I'm pretty certain they don't. The Cars he's familiar with at the track may have had a part of the inner core that fit inside the outer core allowing roll pins to lock both sides together.

TCI has a nice presentation on their Rattler that could give you a good understanding of what balancers do and how they do it.
http://www.tciauto.com/tech_info/seminars/rattler/Rattler_Seminar_files/frame.htm
And their FAQ section:
http://www.tciauto.com/tech_info/rattler_tech.htm

7birdslater
01-18-2006, 01:50 PM
Wow, I learn something new every day. All the pics ive seen of the BHJ look like a single piece.