Current FFR Bilstein Shock Issue!

Hoofa · #1 (**permalink**) 09-14-2008, 09:19 AM

For the people that like a little vodka in their Koolaid, What do we think about my nuts? I'm not an engineer, but I can make or break anything.. I believe in them enough to send them out for free... In the hopes that St. Peter will overlook some of the other stuff...

mrmustang · #2 (**permalink**) 09-14-2008, 03:18 PM

Quote:

Originally Posted by Hoofa

For the people that like a little vodka in their Koolaid, What do we think about my nuts? I'm not an engineer, but I can make or break anything.. I believe in them enough to send them out for free... In the hopes that St. Peter will overlook some of the other stuff...

Hoofa,

Attached is what was originally posted by me in regards to a Bilstein shock failure, clearly the pictures are no longer on my server that accompanied this post, but the facts and the third party (without a financial hook in this battle) analysis (from a shop that rebuilds Bilstein shocks for race teams all over the country) show what the real issues were. After reading this analysis, you might want to reconsider sending out the nuts.

Bill S.

Originally posted 03-25-2006, 09:34 AM on FFcobra (and still located on their server, maybe this one as well):

"Ok, let's start off with the Bilstein shocks as submitted by Marty D. who wrote to me the following:

"the shocks were mounted with body up on the front suspension. Lower control arms are from Fortes. I had some spacers between the spring hat and the heim joint to prevent any interferance from occuring with the lower arm. When I looked at the shocks I couldn't see any signs of contact between the arm and shock. There are about 5k miles on the shocks. Many of those miles were on bumpy back roads driven at speed."

Ok with that out of the way, let's look at cause and effect with the following four photo's:

From the looks of things, there was not only some unusual lateral loads (wear on the outside of the lower spring seat and threading), but my shock guy (a custom rebuilder and master WD for Bilstein, QA1, Carrerra, and Pro Shock) sent me the following email:

"From the shock it looks like the center to center of the mount on that car are at 14.5 " center to center this will allow a 5" stroke on the shock and looking at the shock, also looked like there was only 2" of shock left when the car is at ride height so that means there is only 2" of shock available to extend so constant battering on that shaft at full extension is what caused that shaft to rip off. By no means was that a shock manufacturers fault but a poor choice of mounting a street car should have at least 7" of shaft length to deal with at ride height 3/1-2 " of shaft for bump and rebound the reason that some other shocks might get away with the constant beating full extension is that the QA1 shocks pro's and carrera shocks use a thicker shaft that is much softer than the bilstein but this still does not make it right".

Just thought you would like to know his thoughts on first glance, he is going to take them completely apart in the next day or so to check the valving to see if anything failed there as well. If he finds anything else of interest, I'll let you know."

mrmustang · #3 (**permalink**) 09-14-2008, 03:27 PM

Original post here:
Third party shock failure analysis with pics

Original post on ffcobra:
http://www.ffcobra.com/forums/showthread.php?t=154461

Again both posted the same day back in 2006 .

Here we are in 2008 with the same issues, so the question remains, what is the difference between then, and now?

Bill S.

Hoofa · #4 (**permalink**) 09-14-2008, 03:46 PM

That is the only concern with my nuts. That they steal a little travel. The next batch I'm making are going to be significantly shorter. After I broke them I figured out that I don't need the sleeve to be nearly as long. Basically it comes down to the lesser of two evils. If the shaft is going to be taking a beating anyway, I'd rather the beating is on an area that has 40% more material and isn't scored. My new nut without the magic washer should only steal about 3/16" of travel. Can you ask your Shock guy about the nuts? I can't afford new shocks, I blew my wad on my nuts....

mrmustang · #5 (**permalink**) 09-14-2008, 04:23 PM

Quote:

Originally Posted by Hoofa

That is the only concern with my nuts. That they steal a little travel. The next batch I'm making are going to be significantly shorter. After I broke them I figured out that I don't need the sleeve to be nearly as long. Basically it comes down to the lesser of two evils. If the shaft is going to be taking a beating anyway, I'd rather the beating is on an area that has 40% more material and isn't scored. My new nut without the magic washer should only steal about 3/16" of travel. Can you ask your Shock guy about the nuts? I can't afford new shocks, I blew my wad on my nuts....

Hoffa,

Look at this line again:

also looked like there was only 2" of shock left when the car is at ride height so that means there is only 2" of shock available to extend so constant battering on that shaft at full extension is what caused that shaft to rip off.

Again it's an over extension of the shock shaft itself that is most of the problem as the shaft vs travel is not long enough and it over extends causing the failure. Not the opposite of maximum contraction of the shock shaft. Still unsure what effect your shock shaft nuts would do in this situation, not sure I would want to test it out either.

As for asking the Master WD rebuilder about your solution, he is now 130 miles away and I cannot just stop in and ask him. I will send him a copy of your pictures and will post his response here if I get one.....

Bill S.

Hoofa · #6 (**permalink**) 09-14-2008, 04:41 PM

If you study the breaks, you can clearly see that it is caused by many small side loads. There will be side loading throughout the range of the shock. The nut transfers those loads to a much more robust area of the shaft. With no scores in it. I'm going to go break something, I'll be back...

lineslinger · #7 (**permalink**) 09-14-2008, 04:33 PM

Quote:

Originally Posted by Hoofa

For the people that like a little vodka in their Koolaid, What do we think about my nuts? I'm not an engineer, but I can make or break anything.. I believe in them enough to send them out for free... In the hopes that St. Peter will overlook some of the other stuff...

Just so I understand correctly, by beefing up the stress/break point on the rod by encasing it in a longer heavy walled nut is that intended to strengthen the break/stress point?

If indeed this is the intention would not that stress be passed on to the next weakest point in the "link" and cause potential fracturing or over-stress that point as well?