Why the bolts Fail!
https://www.youtube.com/watch?...
The Bolt Saver II Bushing kit is for the rear differential bushing on the BMW X3M, X4M & x3 M40i's. The Bushing supports the mount bolt in 3 modes:
1. The aluminum insert removes the slop built into the oem insert removing the “running start” the differential had at bending or breaking the bolt.
2. The Bolt Saver Bushing removes the distance from the differential mount flange to the rubber in the oem bushing. This removes the leverage the force had to bend the bolt and transfers the bending moment force closer to the mount location converting it into more of a shear force.
3. The Bolt Saver resists the movement of the mount bolt in both compression AND Tension. It resists in compression by the very hard and strong 75D shore hardness polymer material and it resists in tension by the dual carbon fiber rings inside of the polymer to reinforce it and limit give.
Bolt Saver II Kit for BMW X3M and X4M rear differential bushing mount bolt. The in creased strength of the new carbon fiber infusion process makes Bolt Saver II even more desirable that the original version at no additional cost.
This kit works with your OEM bushing. You do not need to press out the OEM bushing and you do not need to press in the new Bolt Saver II. You must remove the aluminum OEM insert as it has too much play and makes the bolt wobble. The Bolt Saver II kit includes a much thicker and much stronger replacement insert sleeve that has a tolerance that removes the excess movement and stabilizes the mount bolt. The Bolt Saver Doughnut adds significant support in compression strength that supports both the bolt and prolongs the life of the OEM bushing. The Bolt Saver II is an excellent alternative for those who want the OEM quietness combined with the compressive strength of Poly.
Doughnut Bushing only without aluminum sleeve.
The doughnut only option is very popular due to the fact that you do not have to remove the oem aluminum insert to use the doughnut alone. The doughnut alone is still VERY effective and for stock vehicles that are not launched or tracked it can be a permanent fix if not abused.
Because of the easier installation procedure, many have opted for this option with zero complaints. The in creased strength of the new carbon fiber infusion process makes Bolt Saver II even more desirable that the original version at no additional cost.
For persons who already have a sleeve and just want the
Bolt Saver II Bushing Doughnut.
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