an Omen in my garage... I was looking to get greater offset, and a paper box happened to have
the "message of the day" right there, on the box!!!
an Omen in my garage... I was looking to get greater offset, and a
paper box happened to have
the "message of the day" right there, on the box!!!
Above is a standard 88 front tire with typical offset of 40mm. with
lowering spindles, this WILL rub the fender. The scrub radius
of an 88 is about 1.3". Much less than on an 84-87, but.... this can
be improved, if one wants, by using a rim with a 50 or 55mm
offset.
so, here's the offset with a 7x17" Boxster rim with a 55mm offset
with 2" lowering spindles, the fender will not rub. The tires tuck
in nicely on my other 88 GT. (don't let the paintjob or nose fool you)
Even with Ryane brake hats which add a full 1/4" of unwanted
scrud radius, the rims reduce offset and scrub radius, the offset
is so
great.
with 2" drop spindles, and Ryane's lower A-arms, though, there is a
slight amount of rim-to metal rub at full lock in a parking lot.
I am pretty sure this would not happen with 1.5" drop spindles.
I have considered modifying the lower A-arms to relieve this problem,
but truthfully, it hasn't bothered me much in the last year or so.
So, here's the final product, which looks simple, but the following
pictures will show you some hoops you have to go thru to acheive this...
Boxster rims are 7x17" in front with a 55mm offset. The rears are 8.5x17"
with a 50mm offset. The whole plan was to use the existing hub's
mounting surfaces, NOT adaptor donuts with studs in them, which offset
the wheels out an inch or so. The other plan was to fit wider tires
in
back, w/o having them stick out, but also, to fit as large a rim as
possible, so the tire would be matched to the proper rim size.
The problem: Boxtser bolt pattern is 5x130mm. Fiero is 5x100mm. The
Boxster center bore is 75mm, as oppposed to the 56.5mm of the Fiero.
The front hub with 5x130mm holes drilled and studs placed juuuuust
fits the studs.
you would use an aluminum centering ring like most rim-makers supply,
to fit the larger
Boxster centerbore to the Fiero hub. This is a done deal for the front.
This is all it takes.
Concern was expressed by some people about the metal being so thin at
the flange edge of the
hole for the stud. (there's a scant 3mm of metal at the flange edge!!)
I talked at length to Daryl Armstrong at Ryane, who I trust with
these issues, and
our conclusion was that the forces working against the stud are "pull"
and the stud's "rotational direction".
if a stud is forced to bend outwards for any reason, you have a world
of other problems that have nothing to
do with flange strength, and whether the flange will break under these
conditions.
I drilled one hub for such a stud, and destroyed the stud by bending
it outwards using a long pipe.
I expected the flange to split open and let the stud fall out basically
intact.
the stud bent over before the flange edge gave up!!! not bad. the flange
metal is quite strong.
now, THIS is what it takes to be able to mount a rim with a larger
bolt pattern to a tiny little rear 88 Fiero hub
AND maintain it's stock mounting surface. You should be able to do
something like this for any
larger bolt pattern rim (Camaro, Vette, etc.), I just chose Boxster
because they are perfect for my plans, not too
expensive if bought used (about $700 a set).
I used the large outer aluminum ring which makes a nice, flat, even
surface for the rim to be fastened to. In the below picture, you can see
that the mounting surface would not be even, and strong, without the large
aluminum ring (which does not need to be centered, or machined carefully,
by the way--just the same level as the original Fiero's mounting flange
surface)
the left shows a stock 88 rear spindle/hub. The right shows the
hub with a larger bolt pattern
flange behind it. the hub centering ring is on the center hub. The
mounting surface on the right needs that large aluminum ring, to make the
moutning surface flat.
The black torx bolts go backwards thru the stock mounting surface and
hold the plate on the back.
Conversely, when you bolt the rim on, it also, holds the flange in
back, in place (the flange lug-nut bolts pull towards the rim and add extra
strength to the fastening of the backing flange plate to the stock flange
plate).
the brake hat must be drilled with some 3/4" holes to accept the black
torx bolt heads.
quite an involved peice of work. Now remember... this Whole
mess is being done because I did not want to use
the old 1" thick aluminum donut with the newer bolt-pattern on it,
which would make my rims stick 1" out from the darn fenders.
The taper for the lug-nut bolts on Porsche rims are different than the
Fiero rim-style. They have a rounder seat.
Titanuim lug-nuts from Porsche are insanely expensive....and the only
choice from Porsche. It just sooooo happens, that by doing a little
research, Honda lug nuts (for just about any Honda since 1980), are the
same size,
thread, and taper, and basically free, from any junkyard, and beautifully
chromed, to last just about forever.
now, how did the mounting
flange get there?.... the rear hub on a Fiero is a fixed peice, and
cannot be taken apart, right??
the 88 rear hubs are press-fit together!! This shows
the flange portion turned upside down (on the right) with the backing flange
bolted to it. The flanges can be taken apart from the hub portion, using
a hydraulic press, or careful even pressure, and modified however you want.
Then pressed back together after cleaning, re-packing, anything you want!!.
This is a big deal!!
a wider 255 tire going into the back of my 88 Fiero, without
hanging out.
look at the offset on these rims!!