As those of us who one x300’s with broken seatbelt buckles know, these
things are rare as hens teeth. Jaguar no longer supplies them, and there
are few left in the used market. Unfortunately the design changed for the
more plentiful x308, so those are not available for retrofit. Sometimes
shaking debris out of them gets them working for a while, and sometimes it
doesn’t.
Well I finally took mine apart to see if it was repairable:
http://www.jag-lovers.org/snaps/snap_view.php3?id=1304995782&n4=
Taking the buckle off is trivial with a few hand tools. I won’t enumerate
the process here except to say that the seat must be unbolted from the floor
(torx screws), the buckle shaft unbolted from the seat (torx head bolt), and
the open circuit seatbelt wire disconnected from the harness (a bit of a
struggle).
Once that has been accomplished, the two plastic halves covering the
mechanism can be separated with some moderate prying. I had a brittle
plastic alignment pin break on me, but the perimeter of the cases click lock
together, so there should be no problem if one or two snap.
As it turns out, the return spring in mine had fatigued, broken in half,
collapsed upon itself, and jammed the mechanism. As far as I can see,
there’s very little to go wrong inside the mechanism except for spring
fatigue. Finding a replacement turned out to be non-trivial as the random
spring assortment sets I found (Harbor Freight) simply did not contain a
spring of the correct specifications:
The spring must exist in a slot that is 0.266" OD max, and must extend to at
least 0.9" free height. It must be able to compress to 0.27" or less
without buckling side to side. It must be able to respond to many repeated
compression cycles without fatiguing. I believe the original spring may
have been double tapered / slightly barrel shaped. Along the way to these
measurements I tried several springs, even cutting the end off of one that
was too long. I ended up finding the right spring to fit the bill with
the help of Maria Bran of Century Spring. http://www.centuryspring.com
The spring pictured in my repair is part #3115 (although I believe part #
DD-43 -spring steel - would have also worked.)
Part# 3115 Specs: 0.25" OD, 1.00" Free Length, 1.3 Rate, 0.78" max
deflection, 0.23" solid height, 0.018" wire dia, 11.5 coils, closed ends,
Music Wire
FYI, the minimum order from Century Spring is $40 and I currently have a
surplus of a few springs.
Another possible solution may be to acquire a 2000ish GMC/Chevy buckle from
a pickup or other vehicle. My local Jag mechanic noticed that the buckle
from his truck was a click-lock fit for the x300 tongue. At least with the
spring repair, an insurance company isn’t likely to question you for
modifying the OEM safety equipment in case of a questionable accident.
Hope this post helps a few people…
Paul Kobres
85’ Silver V12 XJS
96’ Sapphire VDP
Columbia SC
