Steve; the Alpine does have a nice X member frame as well as rails forward
of the firewall to which the cross member is bolted.
Jacking points were mentioned to you a day ago and this is all correct.
Also, you can floor jack this car and also position support stands under
any portion of the lower cross member, lower A frames, side frame members ,
rear axle housing and rear springs themselves. This car is light and those
various places can handle the weight without deforming or bending.
Avoid jacking under the thin wall portion of the rocker panels or other
actual body sheet metal.
I see NO reason not to trust four properly placed stands or supports.
use of drive-on ramps is OK and certainly are solid but they encroach too
much around the front car area and hamper certain work areas.
------------------
Rich; you mentioned using BR60x13 tires with 42 and 45 psi front and 40
psi rear. No wonder you slide around a lot !
These are radial tires and as we know, they look somewhat bulged or
underinflated when set at recommended psi.
The idea of the radial (which makes it so much better than a bias ply tire)
is that when a radial is inflated PROPERLY, it will not lift it's trear off
the ground in a hard corner and will instead just keep it's tread hard on
the ground and allow the side wall to flex over to one side.
A bias ply tire in a hard corner, keeps its sidewall rather straight but
lifts the tread off the road.
To get a better handle on this, stand up with your shoes a few inches apart
and just lean your body to one side. The shoes remain flat on the floor but
if you had ridgid ankles, you would have tipped up or lifted up the outside
edge of your shoes, like tilting a statue off it's base.
Now....when you air up a radial way too high, you make it act like a bias
ply tire. It cannot flex and keep it's "footprint" on the ground properly.
Also, whenusing too much air, the front-rear length of foot print is
shortened a lot . The result of all this is as you alreadu found ! No grip
and lots of skidding.
By law, tires are marked on the side with their MAXIMUM load carrying
capacity when aired up to a certain MAXIMUM pressure. This marking is
misunderstood by far too many people in the tire and garage business.
The marking represents a max pressure you "could" use if you had to carry a
max weight on that tire.
A typical text may read: " Max allowable weight 1020 lbs (at) 35 psi
inflation". This sidewall pressure marking is NOT the pressure you would
normally inflate the tire to for road use!!!
By law, cars sold here after approx 1972 (?) must display a sticker telling
the tire pressures (cold temps.) for normal driving and normal loads. If
the mfr. wants some increase in pressure for heavy loads or high speed
driving, this must also be on the sticker !
Your BR60x13 certainly won't have normal footprint size nor flexible side
wall action at the pressures you have used.
I am rusty on this subject but will guess you need around 24 psi front and
22 psi rear (cold setting) to obtain proper "radial tire grip". Perhaps
some reader with current data or tire industry technical book can reply
here and supply the actual correct data if I am off a bit.
Also be aware....different brand tires as well as different construction
variations makes for different psi requirements (2 ply, vs. 4 ply , steel
vs nylon or rayon cord belts etc. etc.).
----------------------
Jarrid; your interesting comments re. lifters require me to offer the
following comments .
When you state that regrinding the lifter base to obtain the "concave"
affect, this is not correct. Due to being positoned off-center from the
cam lobe, the lifter is expected to be rotated by the cam lobe. This
results in the lifter receiving equal wear all around it's base but also
gives the lifter a "concave" wear pattern which we would NOT want to
intentionally put back onto the lifter.
The cam lobe is ground dead flat (not rounded in any way) and we need a
dead flat lifter to carry the extreme pressures present all the way across
the cam lobe evenly. After long use, the lifter and lobe will of course
have worn into a slightly curved shape but they MUST start out flat when
new .
I found it also interesting that you "never saw Alpine lifters without
pits". Well of course we all have seen pits but I would say that most
lifters I have seen were without pits and could be refaced and made
serviceable again. Hmmm...wonder where all the badly pitted Alpine lifters
have gone to?
Now for the last point you raised (and it is one I failed to comment upon).
This matter of the internal cup shape base in the lifter and the bottom of
the push rod which rides in it.
The radius machined on the push rod bottom is NOT designed to match the cup
radius in the lifter. This intentional difference is done to create an
"interference angle" which in turn gives "line contact" between the parts.
In my opinion, the burr or ridge you may have seen in a few cases on the
push rod is of no importance and does not result in any change in valve gap
after the engine has miles on it.
Due to where this exists it would not be seen by the eye but by the use of
some machinists "blueing" called Prussian Blue paste, we can apply the blue
to degreased parts, assemble them and note the area of contact.
When I have been concerned over a slight little ridge worn on the rod base
I did check out a few rods by this method and found the ridge was not
making contact at all and that only a nice polished spherical ball area on
the push rod base was in contact with the lifter . Result... no wear
expected nor found later and no early readjustment of valve gap required.
Re. the cost of case hardening lifter base if major regrind was done and
too much metal had to be removed....The lifter is cast iron, not steel and
all that needs to be done is to buy some gunsmiths hardening powder and the
one I use is called Casinet from Brownells catalog.
The lifter base is simply heated to a red glow with a torch and the powder
applied . It provides a high carbon case hardening of unknown depth but
then we don't need more than a few thou. So I feel this is so cheap that
anyone could afford a couple bucks for the powder and this makes
rehardening lifter bases not as costly, as you suggested.
Dick T.
As we both know....there can be exceptions to just about everything which
we write about or try to share with others. There is rarely a clear
black/white condition. Our various opinions are the results of our own
experiences, tests, investigations, and mistakes. Readers don't have to
accept anything we say but are at least benefited by having seen the
comments and they in turn are then alerted to conditions they may not have
even considered. They can then check out their own cars to see if what they
have read here applies to their own situation.
This archive was generated by hypermail 2b30 : Tue Sep 05 2000 - 09:55:58 CDT