rear end vibration
#2
V8 Miata Enthusiast
I would start by doing the mod Jason talks about here https://www.v8miata.net/build-thread...ion-162/page5/. It is post #44.
Bolting the transmission crossmember to the floor pan helps to take out vibrations inherent to the drivetrain.
Bolting the transmission crossmember to the floor pan helps to take out vibrations inherent to the drivetrain.
#3
Administrator
I would start by doing the mod Jason talks about here https://www.v8miata.net/build-thread...ion-162/page5/. It is post #44.
Bolting the transmission crossmember to the floor pan helps to take out vibrations inherent to the drivetrain.
Bolting the transmission crossmember to the floor pan helps to take out vibrations inherent to the drivetrain.
-Jason
#6
Jim Stainer
That and check the relative angles of the diff pinion and trans and make sure they are within 3 degrees of each other. Remember this does not mean that the driveline has no angles, it just means that if you were to make an imaginary line through the center of the diff and the center of the crank they should be within 3 degrees of parallel to each other in all dimensions (the known ones at least 8-B ).
-Jason
-Jason
#7
Administrator
A digital angle gauge like carpenters use to set up table saws works perfect. They are about $40. If your smart phone has a fairly square outer shell you can use it and a free app instead. Your looking for no more than 3 degrees of difference.
-Jason
-Jason
#8
V8 Miata Zealot
You may just have a tire vibration. If you have a driveline vibration at 75mph, you should also feel it around 40-45mph. Be sure to drive the vehicle at least 20 miles before any work is performed in order to eliminate flat-spotting on tires.
#11
V8 Miata Participant
Basically, you want the engine/trans shaft and the rear end pinion shaft to be parallel. The easiest way to measure that is to put your angle finder on the pinion flange, note the reading, then go to the front crank pulley and measure that. They should be the same. If not, its usually easier to adjust the rear.
The attached drawing should show the idea. It shows the engine/trans and the rear to be "level", that's not important, they just need to be parallel. IE if the rear of the trans is slightly down, the front of the diff should be slightly up.
It's considered good practice to have a small angle in the system to keep the ujoints working slightly, otherwise the rollers don't roll and can wear in one position.
Mike
The attached drawing should show the idea. It shows the engine/trans and the rear to be "level", that's not important, they just need to be parallel. IE if the rear of the trans is slightly down, the front of the diff should be slightly up.
It's considered good practice to have a small angle in the system to keep the ujoints working slightly, otherwise the rollers don't roll and can wear in one position.
Mike
#12
Jim Stainer
Great idea to measure off the crank pulley! I was thinking it would be tricky to get a good reading from the trans yoke but will try both. I find it interesting that there is not one word about this subject in any of the build manuals I have read yet it seems to be a critical issue. (Monster, Flyin Miata and Boss Frog) Thank you!
A friend sent me this which I think is also helpful.
A friend sent me this which I think is also helpful.
Last edited by charchri4; 05-17-2013 at 10:23 AM.
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