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Med Case pinion angle measuring point

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    Med Case pinion angle measuring point

    I am chasing a nagging, continuing driveline vibration in my race car.
    I have the driveshaft out being checked for balance to eliminate that aspect but I am about 99% sure I am going to find the problem in the driveline angles and not in the driveshaft itself.

    I am looking for a measuring point on our Med Case Diff that is parallel to the pinion. Does anyone know for sure a point on the bottom of a Med Case Diff that equates to parallel with the pinion?

    There are 2 small machined pads just under the pinion end of the diff, then there is a 3rd one somewhere around the middle of the case on the bottom, there are also 2 threaded machined pads towards the rear of the diff that are unused on the E30 chassis.
    All of them yield different angle readings.
    The ideal method would be to measure from a flat side of the yoke, but that is encased in the rear subframe. Cannot get at it.

    My race car has a Tremec transmission and I am using a one piece driveshaft with a slip yoke on the front.
    We / I have mitigated a-lot of the initial vibrations from when this project first started but there is one nagging vibration remaining that starts blooming around 5500 driveshaft RPM and really develops at 6000 driveshaft RPM that I want to get out and I am sure its in refining the angles.

    In order to do that I need a reliable point to measure from that is parallel to the pinion to get the relationship to the transmission output angle then I can adjust by shimming diff and / or trans to get it correct.
    This vibration is being exaggerated at the moment because i have been running my 4.27 which has changed my driveshaft speeds in some areas of some tracks and now that vibration seems more evident.

    Thanks in advance for anyone that has any info.
    jimmy p
    Jimmy P.
    87 E30 M3 Prodrive British Touring Car
    88 E30 M3 Zinnoberot - Garage Queen
    88 E30 M3 Lachsilber - SCCA SPU #98
    92 M Technic Cabrio - S14 Powered!
    98 318Ti Morea Green
    04 Ford F350 Dually Tow Machine

    Can you post pictures of this? I may or may not be any help.
    91' 318is 90' 325is

    Originally posted by Sonny
    Buy the E30s, they ain't gonna last long
    E30 can make you, E30 can break you
    "He who controls the Nova's, controls the Boomers"