DIY Electric Car Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
30 Posts
Discussion Starter #1
Has anyone seen issues with their motor starting to vibrate as the RPMs increase? I am guessing this is happening due to a slightly unbalanced hub/flywheel.

Any suggestions on how to diagnose/resolve?

I don't have a TAC attached so can't gauge the RPMs but it continues to get worse the higher the RPMs. Everything still works-- I am just having to run in a higher gear than is probably optimal in order to keep the vibration down...
 

·
Admin: 'one of many'
Joined
·
4,838 Posts
I take it this has developed and wasn't there from first installation.

My initial response would be to take the motor out and check if anything has worked loose or broken off.
If it is all still tight, clutch, flywheel, adaptor, I would put a dial test gauge on it to check for runout and to make sure it is still running true.
If it is I would then check the fan blades are all still there and that any balancing weights if any are still there.
Then arrange for it to be dynamically balanced, at full speed, and with each component added on as the balancing is done.


The balancing is important, especially due to the high speeds.
make sure the balancing shop spins the armature up to your max running speed and balances it first. Then add the coupler and balance, then the flywheel, clutch cover etc, balancing as each part is added.

With a mark to align each component, it can then be reassembled in the motor frame in the same configuration before refitting in the car.

Oh, just to add.
If you don't have a tach then you can work out the gear ratios and tyre rolling circumference and determine the motor speed based on road speed in one of the gears.
Also if your car has a speedo and a tach (not working) in the original instrument pod then often using 4th gear the speedo needle points to the same position as the tach needle would. So if you drove so that the speedo needle pointed straight up in 4th then the motor speed would be roughly where the tach needle would point to straight upwards too.
 

·
Registered
Joined
·
30 Posts
Discussion Starter #3
Actually it seems like it has been fairly consistent (only just recently got it up and running and the vibration has been there since the first time I took it out). Based on your comments it sounds like this is fairly common. Thanks for the steps for balancing-- I will pull the motor and see if that helps!
 

·
Registered
Joined
·
29 Posts
You should really try to get to the bottom of this as it could lead to other issues (bearing wear, sheared motor shaft, or tearing up the end-bell, or worse..) I have seen some adapters that were the cause, but I have not experienced a motor armature as the cause in the past 12 years - though it "could" happen..
 

·
Admin: 'one of many'
Joined
·
4,838 Posts
I have not experienced a motor armature as the cause in the past 12 years - though it "could" happen..
Armatures are pretty good and tend not to be at fault.

However, if it is damaged during conversion, either by accident or by poor machining work then that should be fixed along with the other checks.

Another area to look at is misalignment of the adaptor plate to bell housing.
 

·
Registered
Joined
·
1,378 Posts
A John Wayland trick is to put a washer under one of the pressure plate bolts, and move it to different bolts until vibration is minimized.

With mine, I took off my pressure plate and rotated it 180 degrees, problem solved.
Has anyone seen issues with their motor starting to vibrate as the RPMs increase? I am guessing this is happening due to a slightly unbalanced hub/flywheel.

Any suggestions on how to diagnose/resolve?

I don't have a TAC attached so can't gauge the RPMs but it continues to get worse the higher the RPMs. Everything still works-- I am just having to run in a higher gear than is probably optimal in order to keep the vibration down...
 

·
Admin: 'one of many'
Joined
·
4,838 Posts
A John Wayland trick is to put a washer under one of the pressure plate bolts, and move it to different bolts until vibration is minimized.

With mine, I took off my pressure plate and rotated it 180 degrees, problem solved.
That is a bit like trial and error balancing.
I used to do that with big off road tyres on my Land Rover to reduce the amount of balancing weight needed on the rim.
 
1 - 7 of 7 Posts
Top