5.3 LS Swap into 91 318i

[DividedBeing]

By your own logic, if there were significant driveline stress from drifting, then drift cars would be popping axles left and right, just like drag racers. Since they don't, the driveline stress isn't such a big deal.

I almost hate to say this, but you do know that driveshaft torque is lower in 3rd gear than it is in 1st gear, right? 100 mph is going to be third gear in pretty much any T56 car (unless it has ZR1 gear$...). That means a 1.3 ratio vs. 2.66. That means that the "clutch kick" you describe involves at most half the driveshaft torque of a first gear launch... in reality way less than half because the speed difference between the crankshaft and transmission input shaft is way less in that situation than it is in a drag strip launch, which means the flywheel energy that can be dumped into the driveline is way less as well.

That is why I discount "driveline stress" from drifting.

Uh, don't know what to tell you, but drift cars break axles pretty often. I already told you I'm done with this slap fight. The motor mounts will work great and handle whatever I'm going to throw at them. Move along unless you want to discuss something else.

[The Dark Side of Will]

By your own logic, if there were significant driveline stress from drifting, then drift cars would be popping axles left and right, just like drag racers. Since they don't, the driveline stress isn't such a big deal.

I almost hate to say this, but you do know that driveshaft torque is lower in 3rd gear than it is in 1st gear, right? 100 mph is going to be third gear in pretty much any T56 car (unless it has ZR1 gear$...). That means a 1.3 ratio vs. 2.66. That means that the "clutch kick" you describe involves at most half the driveshaft torque of a first gear launch... in reality way less than half because the speed difference between the crankshaft and transmission input shaft is way less in that situation than it is in a drag strip launch, which means the flywheel energy that can be dumped into the driveline is way less as well.

That is why I discount "driveline stress" from drifting.

[DividedBeing]

Nice that you have no response to holes punched through the engineering analysis.

Traction = driveline mount stress. No traction = no driveline mount stress.

However, if there's so much stress on the drivetrain from drifting, then that means his static load analysis is completely inadequate to the use case and the mount arms survive by luck.

To be honest, from the way you came in hot and snarky, along with the fact that you're ignoring the stress from drifting and attributing 5 years of survival with that sort of abuse on the mounts without gusseting to "just pure luck," I don't really see much of a reason to respect your opinion at this point.

Clutch kicks and driveline lockup/re-engagement at 100 mph = major driveline stress.

It seems like you've completely ignored the fact that the load calculations I posted above are from an entirely different mount design that looks to be even weaker than the original mounts we were discussing.

I'm done with this slap fight though, man. Put as many gussets as you want on your mounts lol.

[The Dark Side of Will]

Nice that you have no response to holes punched through the engineering analysis.

It's you car, bolt whatever you want into it.

No matter what he's been doing with them, somebody else will do something else; see my comment on getting the T5 to live.
Traction = driveline mount stress. No traction = no driveline mount stress.

However, if there's so much stress on the drivetrain from drifting, then that means his static load analysis is completely inadequate to the use case and the mount arms survive by luck.

[DividedBeing]

WTF? How is this hating?



I will admit that I'm super fucking tired of keyboard engineers--mostly on BMW forums--saying "it's great because one guy used them for three seasons, so the design must be fantastic!". You know what? There are drivers who can keep a T5 trans alive behind 500 horsepower and there are guys who can break a T5 with 200 horsepower. Neither changes the fact that the T5 sucks.



Ahh, here's some actual meat. Looks like he designed for a 260# per mount static load case using engine weight. Where's the factor for engine torque? Where's the factor for dynamic loading hitting bumps? Where's the factor for dropping the clutch from 5 grand with slicks out back?
While he claims a 5:1 FS vs. the static load case, it's much more like 1:1 (or less! ) for dynamic loads, which can easily be 4-5 times the static load.

Hence my snark about spinning tires being a test of engine mounts... *TRACTION* is the test of engine mounts...



This means that the highest stress ends up acting on the relatively small portion of the weld. The circumferential weld means that there's no bead-end to provide a stress intensity factor, but there's still a relatively small portion of the total circumference that's experiencing the highest stresses in any load case. The way fatigue works, the mechanical configuration of a part can result in very high stresses at a small point. Depending on exactly how high the stress is and the amplitude of the cyclical stress from highest to lowest, just a few events of being stressed that much can nucleate a fatigue crack that will then propagate at lower stress levels.

While a gusset would still have the highest stresses acting on a small portion of the total weld, the leverage involved would make those peak stresses much much lower and thus be much less susceptible to fatigue.

Again, man. If the ungusseted version of these mounts can hold five years of drifting seasons with clutch kicks and locking up/re-engaging the drive train at 100mph repeatedly, I'm good to go on the gusseted version for $275. There's so much more stress on the drivetrain happening with drifting than just spinning tires. Also, a gusset in any direction helps in every direction to a degree. I don't know what to tell you though. The mounts are excellent quality, excellent value and they're going in my car because I believe them to be more than sufficient based on my use case and other designs I've seen.

If I'm mounting slicks to the car, I'm much, much more likely to blow either the axles or the transmission I plan on running. The car is never going to see a drag strip, but I've seen other people drag race their cars with the shittiest looking cobbled together, booger welded mounts and have zero issues with those. So yeah, I guess we'll just have to agree to disagree.

[The Dark Side of Will]

lol I'm not sure why you're hating on these mounts so hard and giving me snark, man. Maybe you're just trying to be helpful, but your tone isn't coming across that way. If five years of clutch kicks isn't enough to sell you on these mounts, when the set in question wasn't gusseted at all then don't buy them I guess.

WTF? How is this hating?

Those look like they are not gusseted in the correct direction.

I will admit that I'm super fucking tired of keyboard engineers--mostly on BMW forums--saying "it's great because one guy used them for three seasons, so the design must be fantastic!". You know what? There are drivers who can keep a T5 trans alive behind 500 horsepower and there are guys who can break a T5 with 200 horsepower. Neither changes the fact that the T5 sucks.

Yeah, I've got a major feeling I'm going to blow up my motor due to builder error or destroy several axles long before these mounts are ever likely give out.

Garrett actually engineered his mounts vs just slapping stuff together too. He measured all of the expected force on each joint, and they're more than sufficient.
I keep going back to his mounts, because to me, they don't even appear as strong as the mounts I'm getting.

Ahh, here's some actual meat. Looks like he designed for a 260# per mount static load case using engine weight. Where's the factor for engine torque? Where's the factor for dynamic loading hitting bumps? Where's the factor for dropping the clutch from 5 grand with slicks out back?
While he claims a 5:1 FS vs. the static load case, it's much more like 1:1 (or less! ) for dynamic loads, which can easily be 4-5 times the static load.

Hence my snark about spinning tires being a test of engine mounts... *TRACTION* is the test of engine mounts...

That's a lot of weld on a curved surface... I'd imagine it'd take a lot to break it... My E30V8.com mounts for my 302 look a lot worse, and there's at least 9.2 302 E30s out there!

This means that the highest stress ends up acting on the relatively small portion of the weld. The circumferential weld means that there's no bead-end to provide a stress intensity factor, but there's still a relatively small portion of the total circumference that's experiencing the highest stresses in any load case. The way fatigue works, the mechanical configuration of a part can result in very high stresses at a small point. Depending on exactly how high the stress is and the amplitude of the cyclical stress from highest to lowest, just a few events of being stressed that much can nucleate a fatigue crack that will then propagate at lower stress levels.

While a gusset would still have the highest stresses acting on a small portion of the total weld, the leverage involved would make those peak stresses much much lower and thus be much less susceptible to fatigue.

[DividedBeing]

That's a lot of weld on a curved surface... I'd imagine it'd take a lot to break it... My E30V8.com mounts for my 302 look a lot worse, and there's at least 9.2 302 E30s out there!

Yeah, I've got a major feeling I'm going to blow up my motor due to builder error or destroy several axles long before these mounts are ever likely give out.

Garrett actually engineered his mounts vs just slapping stuff together too. He measured all of the expected force on each joint, and they're more than sufficient.
I keep going back to his mounts, because to me, they don't even appear as strong as the mounts I'm getting.

[Elysian]

That's a lot of weld on a curved surface... I'd imagine it'd take a lot to break it... My E30V8.com mounts for my 302 look a lot worse, and there's at least 9.2 302 E30s out there!

[DividedBeing]

The irony of citing a video of spinning tires as evidence of engine mount durability...
What's the installed base? 5? 10?

lol I'm not sure why you're hating on these mounts so hard and giving me snark, man. Maybe you're just trying to be helpful, but your tone isn't coming across that way. If five years of clutch kicks isn't enough to sell you on these mounts, when the set in question wasn't gusseted at all then don't buy them I guess.

Again, take a look at Garrett's mounts and find me a single post where anyone had those break. What do you think is more likely to break? These mounts or the m10 bolt it's connected to? How about the 3 inches of mig weld on that guy's original factory subframe?

[The Dark Side of Will]

I posted in the other thread you responded to as well, but the guy who builds them has been running them in his tracked car (without gussets) for years without a problem. And if Garrett's will hold, so will these.



He's been doing this for five years with these mounts:

The irony of citing a video of spinning tires as evidence of engine mount durability...
What's the installed base? 5? 10?

[DividedBeing]

Those look like they are not gusseted in the correct direction.

I posted in the other thread you responded to as well, but the guy who builds them has been running them in his tracked car (without gussets) for years without a problem. And if Garrett's will hold, so will these.



He's been doing this for five years with these mounts:

[The Dark Side of Will]

Those look like they are not gusseted in the correct direction.

[DividedBeing]

Ok, I'm back at it with the videos. I've been sitting on this footage for a bit and just didn't have time to put it together.




I broke down and ordered some beautiful motor mounts from a guy on the BMW LS Swap Facebook group named Alex Volkman. Only $275 which was an incredible price for these things. I was going to build some, but these were at the perfect price and quality where I felt it was a justified expense. Really great dude, has a lot of excellent feedback on the group, and I can't believe he's selling them so cheap. They're coming in the next week or so.



Haven't even received my tax return yet, and I have all of it spent in my head for a CD009, Adapter Plate, T56 Bellhousing, and Shifter Relocation kit. Going to buy whatever else I can with what I have left.

[DividedBeing]

Took a break from the car there for about a week to get my gainfully employed work done, but I'm back on it and spending more money on this thing. Legitimately can't believe how comfortable I am just spending large chunks of money like this, but I'm dedicated to getting this thing finished.

Bought the Canton Racing 15-276 Racing/Drift oil pan so I can start test fitting the engine once I get it put back together this week.

Came out to around $352 new ordered on Ebay vs their website which is $430 or so.


Looks pretty solid and has cool trap doors to avoid oil starvation during heavy cornering/drifting and whatnot.

Have to use a GTO pickup for it, which I found on ebay for around $75

Also ordered their billet oil filter relocation attachment that goes on the pan (again, cheaper on ebay) and their oil pan stud kit from ebay as well.

Then I put together an oil filter relocation kit from ebay AN fittings/adapters , ebay AN line, and an ebay oil filter mount/bracket. Cost about $70 vs the $180-$200+ I was seeing from Sikky, Jegs, or Summit.

Crazy how much less expensive that sort of thing is if you just assemble it yourself.

[DividedBeing]

I know that feeling. I had my 302 running before the Sawzall treatment at least

See, that's where I went wrong lol. I might try to fire my 5.3 up on the stand once I get it buttoned up.