Author Topic: Vibration (Read 8315 times)

allntexas · « **on:** January 12, 2006, 06:53:23 pm »

I got my new billet flywheel, heavy duty starter, and brass counter weights from ARC today and installed them. When I started the motor it seemed to have a shake to it that it never had before. I took it on a test run down the street and back and when I got back the bottom oil seal had come completely out and was on top of the pulley and the oil was dripping from the bottom of the engine. Is this normal to have some vibration of the motor with the brass counter weights? Could it have shook hard enough to cause the oil seal to come out, or maybe I just didn't get it installed correctly? Any input would be appreciated.
Dennis Drake
IMOW, S/P, B/P
#168

George Herrin · « **Reply #1 on:** January 13, 2006, 01:16:31 am »

Are you using the ARC rod and short skirt piston? Have you ever had a balanced motor before other than the stock syncro. It is a single engine and being so you can never balance one completely at all RPM. IT will shake a bit at low rpm but not enough to blow the bottom seal out. You probably didn't have it pressed in far enough. I have built a couple using the brass setup and had no problems. Best balance I have seen yet.

allntexas · « **Reply #2 on:** January 13, 2006, 07:44:02 am »

George, this is my first experience with a balanced motor. I am still using the stock rod and piston. It is not a violent shake, but is a vibration at lower RPM's, so I was concerned. Just wanted to make sure it was normal and that I had not installed the weights incorrectly. I figured that I did not get the oil seal in far enough or that it may have been a faulty seal. Thanks for all your help. I always read your posts to get as much information about this sport as I can gain. Hope to be able to meet you some day, maybe at the national race in Avery, Tx.

George Herrin · « **Reply #3 on:** January 13, 2006, 09:14:02 am »

Well stock parts will shake a tad more than if using the arc rod and short piston they brass weights were designed for. But it is good to knwo that it will work with the stock stuff. Gives racers a cheaper option. This Race in Avery is on my races I want to make. It depends mainly on how the funds roll this year and how many double weekends arise Nationally. But as a single event weekend Avery believe it or not is even closer for me than The Bristol Race. Gotta make that one its in my home state. LOL Glad I could help.

arcbilletrod · « **Reply #4 on:** January 30, 2006, 01:41:33 pm »

Maybe check to see if the flywheel is seated properly on the crank? If the key gets caught in there, sometimes it can keep the flywheel from going down all the way. But then, you would have an alignment problem with the starter gear.

It is getting late in the season for this, but you could send the crank/rod/piston and counterweights to Doc and have him balance it.

I don't have any experience with one that does not have our brass balance weights, so I wouldn't know if what you are feeling is normal or not, but the word I hear is that the engine should have better balance with the brass weights than without.

You do have them pinned to the crank counterweights, right?

allntexas · « **Reply #5 on:** January 30, 2006, 06:40:46 pm »

They are pinned to the same dowels that the original weights were pinned to. I intend on purchasing the billet rod and short skirt piston as soon as the extra funds are available to me. It only shakes at low RPM's, so I hope that the new rod and piston will solve that. Took it to a test and tune a couple of weekends ago and it shook the bolts loose that hold the steering in place and it shook the battery hold down loose too. Guess it was a good test and tune. Wouldn't want that stuff coming loose in a race situation. Thanks for all the help.
Dennis Drake
#168

George Herrin · « **Reply #6 on:** January 31, 2006, 12:01:58 am »

All reading this keep in mind these brass weights are designed to work with the billet rod and short skirt piston. So using it with the stock rod and piston it will vibrate more so than with the billet rod and psiton. I do feel it will work with stock parts but the low end vibration will for sure be more than you will experiance with the billet rod setup.

mightymowe · « **Reply #7 on:** January 31, 2006, 11:46:42 am »

We had an 11 Hp briggs that did'nt have the removable weights and it had pounded the bearings on the syncro balancer,we just took it out to see what would happen. The engine had a vibration at an idle and a vibration at a point in the rpm range about 4000(we dont know exatly,no tach) then it smoothed out and seemed fine. We only ran it in a few races then blew the spider gears out of the transaxel, we thought the engine would blow but it did'nt and it still seems to work. do you think that the eccentric lobes on the crank were acting a little like the add on counterweights.

George Herrin · « **Reply #8 on:** January 31, 2006, 02:21:45 pm »

It will to some extent but not near enough. Most times you remove the counter balances it will shake so bad you cannot see straight. But whats a bad vibration for some may not be so bad for others.

allntexas · « **Reply #9 on:** February 01, 2006, 07:28:24 pm »

Did not mean to imply that the new parts are responsible for the nuts and bolts coming loose. These were parts that I had neglected checking for over a year of racing. The vibration is only at low RPM's and is not violent. I am tickled to death to be able to have them in my motor and will order the new billet rod and short skirt piston in about a week (I hope). The acceleration and deceleration are quite significant with just changing the flywheel and crank weights.
Dennis Drake
#168

George Herrin · « **Reply #10 on:** February 01, 2006, 07:56:28 pm »

NO NO Dennis you misunderstood my post. I said that just for others to know what everything is designed for. Hey if it works with the stock stuff GREAT. More budget friendly for lost cost racers. Lease forgive me if I said something that seemed worng or harsh. I have been curious to know how it would work with the stock parts and been wanting to try it but hey no need now you have. Keep me posted on the difference when you install the billet rod and piston.

allntexas · « **Reply #11 on:** February 01, 2006, 08:07:51 pm »

No problem. I reread my post and I made it sound like it shook so hard that it shook those parts loose and I wanted to let everyone know that it was from neglect and not from the flywheel or weights. I have since gone over the mower with a fine tooth comb and I believe she is ready for the next race in Nacogdoches in February. Don't want to have to fight a loose steering column during a race situation. Was kind of scary just in a test and tune. Good luck this weekend and keep the rubber side down
Dennis Drake
IMOW, S/P, B/P
#168

George Herrin · « **Reply #12 on:** February 02, 2006, 12:24:24 am »

Well I can promise you if there is a spectacular wreck, I more than likely will be the one doing it. If and when I do it generally is a wild one. I hope not, I still ain't 100% from last year. I hope to bring home a win each day!!!

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Author Topic: Vibration (Read 8315 times)