theedge

You dont feel comfortable with four bolts on the crossmember (which can be grade 12, fairly tough, nevermind being an actual bolt and nut) but youll happily support the 400+ pound engine with four of the same sized studs/nuts, in a way that has more than the engine weight pushing down on those four little studs and nuts due to simple physics?? And god knows what those studs are mounted in, probably just the floor pan. And theyre in stretch, unlike the four on the crossmember. Its there for lateral structural bracing, not holding up the engine. Figured id point that out, since youre busy bashing LR for trying to improve the crossover Porsche designed to hold the engine up to make life easier, while youre stupidly using a little structural brace that was never designed to support the engine, to support it WHILE youre working on it, and with leverage in the equation.

Youre certainly the dim bulb on the christmas tree.... A hypocritical dim bulb too.

ibkevin

What timing!

I was just under the car yesterday inspecting things for a Malibu fun run in the morning, and the center section is still in correct alignment and the band clamp joint is still tight! Good stuff.

I don't track my car, but 99.9% of the people that know me will tell you I drive pretty aggresively. Last event was in Oct blasting canyons with the 928 crowd, tomorrow will be the 99X T/TT crowd. In order to do that the turbo has to stay spooled and the car is continuiously flexing through the turns.

DanG

Are you guys going to the www.supercarsunday.com meet first, or just heading out on your own? I can't wait to get the new M3 out there.

ibkevin

That's typically the point, I'm going to see some old friends and shoot some pics for our "weather challenged" listers. I started doing this when we meet at VCR and it was less structured and more enjoyable.

Back to out regularly scheduled topic....

Skip Wolfe

First off - bolts are stonger in tension (stretch) than shear, and second, Chris was talking about using the torque tube crossmember for working on a car, and the concern about the 3 piece cross-over bolts are regarding the stresses it would see while in use which will be a lot more than the static stress it would see on jack stands. While, I don't share Chris' concern regarding the 3-piece bolts (haven't run the calcs but the stress would be spread over 8 bolts in single shear and would probably be fine), I am concerned about the potential of the welds being the weak link. Also Chris stated that the LR crossover was a good idea, just questioned the price, which is valid. One could probably have a good exhaust shop do the same think and save money, but I'm guessing that for most people the $50-$75 you might save is not worth the hassle.

As far as the dim bulb comment - Chris' tech info has always been spot on, so I'm not sure where you coming from.

Tom M'Guinn

Agreed.

theedge

My impression is that he was referring to the arched black crossbrace, which is really the only thing there that he could be referring to.... Which was never intended to support the engine IMHO. If he wants to rely on that to support the engine while hes wrenching on it, then by all means hes free to. I certainly wont be getting under any engine "supported" like that though, and that is the basis of my comment. That thing is merely a body brace, and using it to support 500 pounds at the end of the torque tube (hence some leverage acting with that 500 pounds) and then getting under there and working seems profoundly dim to me.

Bri Bro

Second that.

Back on subject, Chris, I would like to see the pictures please.

reno808

ME TOO reno808@gmail.com

Zero10

Stupid question time....
Why are we taking about shear force on the 8 bolts that hold the 3 piece crossmember together?
The middle piece does not hold anything up. There is no vertical force pushing down on it, so why would there be any shear force on the bolts that hold it to the pieces beside it?
Now, the pieces on each side are being pushed down on very hard by the weight of the engine, and are only supported on one side, so I can imagine them trying to pull away from each other. To me the only force on the 8 bolts that hold the crossmember together would be tensile, and not shear.

Also, it was mentioned earlier about the torque tube crossmember having the same size bolts are the front crossmember. I do not believe that is accurate, I thought the torque tube crossmember was a little bolted in assembly that is attached with 4 M6 (maybe M8) nuts to the floor pan? Are we talking about something different?

Skip Wolfe

Good point. For some reason I was thinking the motor mounts bolted to the middle section of the 3-piece which would put the connector bolts in shear but the mm are on the end pieces so you are correct in that the would be in tension. I was responding to theedge's post regarding them not being in tension and ran with it without thinking it through - my bad.

Zero10

Okay cool. I thought I was losing my mind, lol.

SeaCay

Took a tour of Chris' shop while driving the '89 back from MD. He does great work. GREAT work. Judging by what I was looking at there, and our conversations, his opinion holds a lot of water with me.

Ski

100% correct on his work and knowledge. However, I think what got all this cross ways was what started about convenience and end user turned somewhere - as many threads do.

If I had his experience, tools, lifts, I too might be proned to view it different. However, since I do all my work on 2 ton or 6 ton jackstands, I like the ability it gives me for future endeavors.

Chris Prack

Thanks for your input. You are certainly entitled to your opinion. I am not sure why you feel the need to personally attack me but you did and I could not care less. I will stand behind (or underneath) my comments and experience. Experience that covers over 25 years as a wrench, close to 20 with Porsche, Porsche factory training and the countless hours of fabrication and design, that have put my customers at the front of the field in PCA, NASA and SCCA. This is what I do, everyday, week in and week out, year after year. I am not just a weekend warrior with access to the internet to spew my "knowledge" all over people that couldn't care less.

It's bull **** like this that has kept me from posting here. The overwhelming majority of my post count was from several years ago and has tailed off since due to this kind of crap. It is really not worth it to me. Why don't you post what you do for a living and we can comment on that.

None the less here are links to the pics. Thanks for sharing.

http://i33.photobucket.com/albums/d9...ler/Rlpic3.jpg

http://i33.photobucket.com/albums/d9...ler/Rlpic2.jpg

http://i33.photobucket.com/albums/d9...ller/Rlpic.jpg