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      08-14-2012, 04:53 PM   #90
Second Lieutenant

Drives: M3
Join Date: Feb 2010
Location: USA

iTrader: (0)

Originally Posted by tibra1 View Post
Your posts are rife with misinformation and takes away focus from the real issue. The bolts are not at fault here, rather the rubber mounts that house the bolts which flex. Several performance shops have already developed solid or delrin cased mounts which unitize the diff to the sub-frame and eliminate the flex caused by the diff during hard driving.

So you argue the bolts are at fault? Yet these shops who have spent the time and effort to CNC the uprated diff mounts have not also machined new bolts to go along with their mounts????????? you would think machining bolts that are partially threaded wouldn’t be too complicated for them to do right? Yet they haven’t. :

The reason they have not and no one else has is there is no need for using partially threaded bolts if you unitize the diff to the rear sub-frame with solid or stiffer mounts than OEM. So fortunately we don’t have to wait for someone to machine these in their garage b/c the use of these bolts is moot if you use the solid mounts. Again as with all suspension stiffness uprating there will be some measure of NVH increase.
Using a fully threaded bolt in single shear where only one of the parts is threaded is poor detailing. The threaded portion of the bolt should be excluded from the shear plane. If including the threads in the shear plane is unavoidable then the bolt capacity should be determined using the root thread area instead of the gross bolt area.

Originally Posted by mitch32 View Post
The bolts are also in shear which is a terrible design, should be in tension since a bolt is strong that way, why is there only 1 bolt on top? Anything that requires any real strength will have the bolts in tension/compression, its design/engineering 101.
Bolts designed to resist shear are completely acceptable and standard in the engineering world. You've probably driven over many bridges where the steel girders are spliced together with nothing but bolts in shear. Check the AISC Steel Manual that structural engineers use to design steel structures, they have page after page of tabulated shear resistance values for different types of bolt/bolt groups/eccentric loadings to make connection design easier.

Last edited by oldmanstyle; 08-14-2012 at 05:02 PM.