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Reinforcement issues when switching to solid mounts

Discussion in 'E90/E92/E93 M3 (2008-2013)' started by Vikas76arya, Oct 24, 2018.

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    Vikas76arya

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    A few months (and 12 track days) after changing to solid transmission mounts, I noticed that my transmission mounting bracket broke. I had a race shop reinforce the bracket which will solve the issue.

    I also switched to solid engine mounts and am wondering if I need to reinforce anything in that area as to prevent another similar issue.

    This winter, I am planning to switch to solid subframe and differential mounts; same question applies there.

    I would appreciate any advice about what type of reinforcements are needed when changing to solid engine, subframe and differential mounts.

    Thanks - Vikas Arya
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    • Technical Service Advisor

    charlson89

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    Do you have any other mods to the vehicle or plan to?
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    MGarrison

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    I'd say beware the slippery slope of the infinitely possible performance mods, at least not without some goals, plans, or budget in mind. With the stories I've heard/seen of others with ripped subframes from solid bushings, or other pieces cracking/tearing, it's worth keeping in mind that solid bushings pass whatever stresses a flexible bushing absorb, handle, or are subject to, on through to whatever it's mounted to, which... was never engineered by the factory to handle those kind of stress factors - resulting in stress-related failure, in time.

    So, if solid bushings all around are the plan, I'd say it would be no surprise to find other things needing additional repair and/or reinforcement. Which calls in the question of evaluating if the trade-offs of any particular mod justify the gain. The more track-oriented you make the car (generally), the less streetable it becomes, at least in terms of performance vs. everyday practicality & comfort. It's all too easy to mod oneself into a great track car that's certainly street legal but beats you to death in regular driving, at which point you don't want to be second-guessing whatever mods or their justification. Different car of course, but I went with poly bushings for most things on my E30 so there would be some give, to minimize the chance of other component lsuffering damage & needing repair. Another thing, just switching to poly subframe mounts substantially upped the drivetrain noise from the diff into the cabin - can't imagine that'd be any different for your car, I'd expect it would be no surprise to find the interior noise level upped dramatically with solid rear carrier & diff mounts. If part of the point of the mods is improved lap times, that's most relevant to racing competition - if you're sticking to non-competitive driver schools, it's perhaps worth considering how much fraction-of-a-second type mods might be justified, particularly if where you're at in the learning curve and experientially means more practice & seat-time has the potential for greater improvement and lap-time gains than say, things like immediacy of transitional response.

    As for specifics for reinforcing your chassis, not much I can be specific on there without specific experience to go off of - perhaps take a look at the Turner Motorsports & Bimmerworld websites, which I'd figure would have chassis-reinforcement kits for what they've found are known problem areas or issues.

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