I think that my engine is out of balance. It runs great and idles perfectly but I am getting a vibration as the rpms increase. The vibration is the worst around 2k to 2.5k rpms but is still there just not as annoying at higher rpms. I know it is not the u-joints before anyone goes that route. The vibration is there whether the car is moving or just reving the engine while parked. This engine is a new rebuild from Atkins. I have been messing with it for a year now and have installed new motor mounts hoping that this would help but has not. If the engine is out of balance what are my options for fixing this thing before I have bearing troubles?

 

Have you checked your ignition?

 

Have you checked your tranny mount? I had the same problem and it was most noticeable at about 2K-2.5K RPM, especially out of gear sitting still. Replaced it and smoothed right out. Mazdatrix has them for about $30.
Todd

 

could also be the fan clutch.

 

I had a similar problem that was a mix of my tranny mount and my clutch...

 

Yeah, it could be the fan clucth. My engine did the same. Guess what, it was the water pump. Grab the pullys and see if the move side to side. If they do. $40 and 4 hours of work.

John

 

Thanks guys for a couple of things that I have not looked at yet. I will definately check out the fan clutch and the water pump. I do not think that ignition is a problem. My timing is right on and I have good spark at all four plugs.

Keep any others ideas coming!

 

Fan assembly mounting spacer. I lost a bolt that holds the clutch to the spacer and the spacer ended up hellaciously bent. The vibrations drove me nuts. I have the spacer that's a thin piece of metal rather than the longer, thicker one.

 

An incorrect Flywheel match can also create that symptom. Have you swapped flywheels during the engine mod?

 

So does it still do it with clutch in sitting still? The reason I ask is I had put a new engine in the car 3 months ago, hideous vibration after about 2500 rpm, thought wrong counter weight, lightened flywheel, gear box mount, clutch the lot. Foot on clutch still there eliminated all bar counter weight.
The problem was the timing was spot on, but under higher revs the leading spark was too weak to bridge the gap, this manifested in a all out onslaught of vibration through the whole car.
If I were you and I could get my hands on another dizzy or ignitor, I'd try it .
Cheers Sue

 

Well, I checked the water pump pulley and the fan clutch this afternoon and both were good. I will check the tranny mounts when things dry out here a little more. I did not change the flywheel. The motor came with a resurfaced flywheel already installed from Atkins Rotary. I will swap out the dizzy and ignitors tomorrow and see if that has any impact but I have my doubts. I am kind of beginning to think that the flywheel was messed up (either the wrong one or was not resurfaced properly). I hope that is not the case but am getting a sinking feeling that is the problem.

Any other ideas?

 

If it is the flywheel,youll need to pull the trans,and get the number off it.Compare it with the chart of flywheel specs on Mazdatrixs' FAQ page.That's provided your sure about the year of your engine,which will determine the weight of the rotors and thus the required flywheel.
It could be that Atkins installed the wrong flywheel or front counterweight.Or the year of the engine isnt what they/you thought it was.Tough to say for sure, since you cant inspect or weigh the rotors when the engine is assembled!

 

Ok, I pulled the inspection plate today and looked at the engine side of the flywheel. According to Mazdatrix there should be no numbers on the flywheel for a 79-80 engine. Mine has the following numbers on it (KD24). Does anyone know what these numbers are. Is this the wrong flywheel? I did not see these numbers listed for any of the flywheels on the Mazdatrix website.

 

So, anyone have any ideas on those numbers?

 

Bump.

Does no one have any idea what those numbers mean on the engine side of my flywheel????????????