Re: TA Bolt questions

[tobyp@xxxx]

I am very glad to see one of the more respected contributors to the 
List, and to the Delorean community at large, adding comments to this 
ongoing discussion. I truly believe that everyone can learn 
something from focused dialog. I will agree that the incidence of 
total bolt failure due to fracture has a relatively low rate in the 
overall fleet. However, the bolt bending and corrosion issues have a 
much higher degree of incidence from my limited experience. I've 
personally had one break, and the other bend, so I am particularly 
sensitive to this. As I recall, in the seven cars that I worked on 
at the tech session that I mentioned, including my own, we found 5 or 
6 that were bent, 1 or 2 others that had wear grooves or other marks 
on the shank from joint component movement, and 2 or 3 other with 
corrosion and rust. So, on the low side, there were 8 bolts that had 
some form of challenge. The bolts in my car were fresh due to the 
earlier failures, but I put in the custom bolts anyway. Based on the 
analysis of my fractured bolt, using a scanning electron microscope, 
it would appear that any stress concentration could eventually lead 
to fracture. Corrosion pits, and wear grooves seem to be an 
invitation for a crack to start, particularly at stress levels that 
are high enough to cause yielding (bending and/or stretching). It 
would be very interesting to get a sense of how many owners have 
experienced TAB problems, ranging from wear, to corrosion, to bending 
and yielding, and to complete failure. My limited experience would 
suggest between 1/3 and 1/2 of cars currently in active duty. Those 
are pretty high numbers for a critical joint with no significant 
structural redundancy. Would a poll be useful? I don't really know 
the protocol because I'm relatively new to the list.

BTW - The current list of "interested parties" for the custom bolts 
is at about 40 - 41 sets. In discussions with Darryl at Specialty 
Automotive, a reasonable threshhold of 50 - 55 sets would give us the 
confidence to move forward with the necessary upfront investment. I 
will keep you all updated as the project nears a launch point. Let's 
keep up the good dialog.

Toby Peterson VIN 2248
Winged1 


--- In dmcnews@xxxx, "DMC Joe" <dmcjoe@xxxx> wrote:
> John,
>The trailing arm bolt failure problem is highly exaggerated and 
>actually has a very low incident rate. Yes; it should be of concern 
>to all owners who have not inspected and or replaced damaged 
>components.
> 
> DMC Joe
> DeLorean Help dmchelp@xxxx
> www.dmc.tv