After devising a ridiculous looking tool consisting of fishing weights,
string, bamboo and duct tape. I carefully manipulated this gadget so as to
apply 6.4 lbs onto my fanbelt while measuring the resulting deflection with
my micro-calipers. After this exercise in futility, I realized that it will
be pretty much impossible to get any degree of accuracy in applying fan-belt
tension. I think I’ll just go with the recommended finger test…
snip <Here’s a suggestion – your pinky can deliver the 3.2lb with it just
to be uncomfortable; likewise for your forefinger and 6.4libs – who needs a
gauge?! No other fingers please gang. > unsnip
Dave Cooke '87 VDP (V12)
After reading the ROM - of course, after I had completed the job above
( I noticed that it is quite specific about fanbelt tension. ie: there
must be a deflection of 3.3mm when a load of 6.4 lbs is applied at the
point of the belt. This brings two questions to mind: a. How does the
hobbyist mechanic achieve this accuracy in fanbelt tension (I’ve been
thinking of somehow using my wife’s kitchen scales or my sportfishing
scale)…and question b. does anyone on the list know what the tension
the other belts should be (I can’t find mention of these tensions in the
or the archives) and perhaps more importantly how do I achieve the
'87 VDP (Cdn spec) 196,000km
According to my ROM (Edition 2 1985) The tension for the alternator
belt is 1.5 kg (3.2 lb) should give a deflection of 3.8mm (0.15 in) and
the air pump belt 2.9kgf (6.4lbf) should give a deflection of 5.6 mm or
in. Don’t know why it says lbf in this case. For the power steering pump
it’s 3kg (6.4lb) and 4mm(0.16in) , all the above for 12 cylinder engines.
I don’t see how you could do this and get results to the tenth of a
millimeter or how you’d measure the deflection to that degree of accuracy.
Tight belts put more strain on the bearings, so better to err on the side
of> looseness I think. The power steering on our '85 used to squeal like a
stuck pig on full lock, tightened the belt today as suggested in the
archives and no more noise!
The archives and FAQ will answer many queries on the XJ series…
To remove yourself from this list, go to http://www.jag-lovers.org/cgi-bin/majordomo.