I have just done a front suspension overhaul on my 1988 XJ12 which included new
front springs. Previously the sagging was a couple of inches off spec and something
had to be done. Comparing the original and the new free lengths showed that the
new springs were 3/4" taller. The old setup had 3 spacers at the bottom and one
at the top. I elected to remove one spacer, given the difference in free legth,
and, after everything was complete, was rewarded with a ride height just about
spot on - checked after a trip round the block and into town to get the alignment
sorted.
However after a couple of hundred miles it has sagged back down to just about its
previous level. Even adding that extra spacer, to the maximum of 4, wouldn’t bring
it back up to the level it was directly after the rebuild. What’s up here?
I did have to replace the anti-roll bar as it was XJ6, not XJ12, are there any other
XJ6/XJ12 differences that would make this happen if someone had put in an XJ6 subframe
after a big shunt (it also has an XJ6 bonnet). Would the all new, stiff bushings that
went in, along with new lower wishbones, hold it up for so long and let it sag after
a few hundred miles?
I didn’t think a spring had any kind of property that would cause this?
True spring steel shouldn’t sag even after years of supporting a car, so it
sounds like something was wrong in the installation process. It’s hard to
imagine a defective spring, but who knows, maybe?
Alex
79xj6L SII
Cosmo wrote:>
I have just done a front suspension overhaul on my 1988 XJ12 which included new
front springs. Previously the sagging was a couple of inches off spec and something
had to be done. Comparing the original and the new free lengths showed that the
new springs were 3/4" taller. The old setup had 3 spacers at the bottom and one
at the top. I elected to remove one spacer, given the difference in free legth,
and, after everything was complete, was rewarded with a ride height just about
spot on - checked after a trip round the block and into town to get the alignment
sorted.
However after a couple of hundred miles it has sagged back down to just about its
previous level. Even adding that extra spacer, to the maximum of 4, wouldn’t bring
it back up to the level it was directly after the rebuild. What’s up here?
I did have to replace the anti-roll bar as it was XJ6, not XJ12, are there any other
XJ6/XJ12 differences that would make this happen if someone had put in an XJ6 subframe
after a big shunt (it also has an XJ6 bonnet). Would the all new, stiff bushings that
went in, along with new lower wishbones, hold it up for so long and let it sag after
a few hundred miles?
I didn’t think a spring had any kind of property that would cause this?