Cloud9...68

I've heard from a reliable source that the Lindsey 3-piece crossmemebr isn't suitable for a track car. This disappoints me greatly, as I've had my heart set on one (thus cutting out about 85 hours from the job to get to the oil pan, and eliminates the need for an alignment afterwards - what was Porsche thinking?) for my 92 968, which I'm in the process of converting to a mostly-dedicated track car. It's also ironic, because Lindsey developed them primarily for track use, seeing as a track car would need to have its bearings replaced more frequently than a street car. To me, the flanges Lindsey welds in, allowing the unit to be held together with bolts, would tend to make it stronger, not weaker, so I'm wondering what experience people, particularly those who track their cars, have had. Thanks.

thirdgenbird

interested in one as well...

zerMATT951

I've seen several mentions of cracked 3-piece crossmembers, but I just spent some time searching and could only find one real thread with evidence on the topic. I'm wondering if this concern is one where there was one problem and now several people are poo-pooing the idea?

Here's the thread that I found, but the pics don't work:

https://rennlist.com/forums/944-turb...over-pipe.html

Either way, this particular incident seems to be an isolated one because of a missed weld during the conversion that Mike Lindsey fixed when it was brought tomhis attention. Does anyone else know of a thread where examples of cracked units were displayed?

67King

I can't see why anyone would do it on anything BUT a track car.

The flanges will introduce crack initiation points for a fatigue failure. So while the weld may be stronger than the cast crossmember, the failure mode is different, and because of the shape of it, it would likely be more prone to cracking.

Having said that, I made one myself for my car, and installed it when I did the bottom end last Fall. I used a mill to make the cuts, ensuring uniformity, and had a professional welder do the welds (I only mention this because I don't want anyone getting the idea that good results from a quickie DIY project are attainable without the right equipment). Although I am aware that it is now more prone to a fatigue failure, I trust it much more than the bearings, and even if I only get one bottom end change out of it before I notice any cracks, it will have been worth the time. It is a HUGE time saver, IMHO.

So if you can't read between the lines, I'd highly recommend getting one, and just inspecting it for cracks (if you can get some penetrant dye inspection stuff, all the better!) when you replace the bearings. It will pay for itself in one use.

zerMATT951

Are there any other subframe stiffening options for these cars that would help to reduce the stress on the crossmember (1 or 3 piece)? I know that Turbo S cars have some type of stiffening, but I've never crawled under one to see what Porsche did. If it's a bolt-on piece, is that something that can be added to earlier cars? I know that a strut tower brace is pretty much a requirement for track use, and I'm sure that helps the crossmember a little, but are there other options to stiffen things up?

MAGK944

There are a few companies making lower chassis braces, rsbarn, deutschnine, brey-krausse. There is some flex down there so they would have an effect on track cars.

http://www.rsbarn.com/968chassisbrace.html

http://www.deutschnine.com/mm5/merch...uning-handling

VaSteve

I saw seen it firsthand. I know the guy that bought one, installed on his car, sold the car to another guy I also know. The second guy had the car apart at the local club race for an emergency oil pan replacement (something else broke and poked a hole in it).

The were cracks all over the crossmember near the welded ends. Too bad too, as I think it's a neat idea.

jaje

I had a Lindsey 3 piece cross member on my car for 2 race seasons. It held up well and did not have any cracks in it by the time I had to remove it (illegal in 944-Spec). I know of a couple 3 piece crossmembers that cracked and broke but they were not Lindsey units (where welded up from a local shop here).

Cloud9...68

Thanks for all the responses. So it sounds like the gist of it is that there is a history of some problems with 3-piece cross-members, but there is also plenty of evidence of trouble-free use. I'm hoping that the problems happened early on, and that Mike has addressed and corrected them. I did inquire at a couple of local machine shops as to having my existing x-member turned into a 3-piece unit, and both places said it is actually a huge undertaking, requiring the fabrication of a special jig, which would bring the job into the $1500-3K range, which is 5 - 10X what Lindsey charges.

My car has both a shock tower brace, and an RS Barn lower suspenion brace that connects the two castor blocks, which will hopefully take some strain off of the cross-member. I'm also planning to install a rollbar/partial roll cage, which will further stiffen the chassis and reduce flex. Having removed my cross-member twice now, I would dearly love to go to the three-piece X-member. I'll definitely talk my concerns over with Mike Lindsey before taking the plunge, though.

Rich Sandor

As far as I can recall there was discussion that there was a BATCH of the 3-piece units that were failure prone and that it was alleviated in later batches.

Cloud9...68

That's exactly what I hoped was the case. Thanks.