I was recently presented with a problem involving the original steel wheels and tires on my Spitfire. The problem was caused by one tire blowing the sidewall out (impact related). Unfortunately for me, it was a Yokohama A509 tire that is no longer made. Consequently, I was left with three nearly new tires, and no replacement option for the fourth. As always, I saw this as an 'opportunity to make lemonade out of lemons' and started considering my options, all of which are dictated by monetary restraints. I thought about buying two Yokohama AVS Intermediates, and running a pair of them with the A509's, however I was also aware that my stock steel wheels were bent and out of round. How should I proceed?
When discussing this issue at a local LBC club gathering, a TR7 friend offered his older set of alloy wheels for a reasonable price. They would come complete with tires already mounted and bargain priced as well. This would solve my bent wheel problem as well as my need for tires and stay within my affordable money limits. I knew the wheels he was offering, liked the look, and agreed to purchase them. This is where the adventure begins.
I had nothing wrong with my original wheel
studs and lugs. However when attempting
to bolt on the TR7 wheels, I couldn't use the
original Spitfire lug nuts as they didn't
match the TR7 wheels. I'll detail this
problem more in a minute. The TR7 lug
nuts were needed as they are matched with the
wheel, and were a 12 mm x 1.5 lug which did
not match the 3/8th wheel stud on the
Spitfire. The difference between the
wheel stud and nut on a TR7 wheel and the
Spitfire wheel stud and nut is significant,
not only in size, but function.
Let's take a moment to discuss the difference between LUG-centric and HUB-centric wheels. Using lug nuts that are rounded at the inward point centers a lug-centric wheel when the taper mates with the counter-sunk taper of the wheel stud opening. Lug-centric wheel studs and nuts is the configuration the Spitfire uses.
Wheels that are centered by the open
center hole on the wheel's hub are
hub-centric. This is the method that
the TR7 uses to mount and center its
wheels. The hub extends, in most cases,
into the open hole on the wheel center and
matches it's opening. Additionally, the
lug nuts are also matched with the wheels, as
the lug nuts are usually a longer cylinder
shape that inserts straight through the
matching lug opening.
OK, since I was obviously going to replace the lug nuts, why not consider replacing the wheel studs as well? Better yet, why not make them a more standard, and somewhat stronger 7/16th inch stud with a 20 thread? The end result allows me to use the TR7 wheels and easily find a lug nut that matches as a larger selection exists.
At this time I recalled seeing one
Spitfire related website that documented this
alteration. I used this information as
my starting point, and now that my project is
completed, this is what I can share with
The wheel studs that closely match the
Spitfire, (in my case, a 1979 Spitfire) are
actually counter-referenced with a 1971-1974
Mercury Capri II. Let it be known, the Wheel
Tite #28020 part number given on the webpage
I referenced was no longer valid.
However the young man at my parts store spent
a considerable amount of time measuring my
Spitfire studs with a micrometer and then
looked through his supplier books until we
found what we both believed would work well.
These studs are made by Dorman, part number
610-175 and are not easily available, but
were ordered and received in two days.
The lug nuts themselves were hanging on the
rack, which is precisely why I elected to
replace my wheel studs. Now, I have
easily obtainable and sturdier wheel studs in
a more common 7/16th X 20 format
Now before I detail the actual actions
used to accomplish this project, let me offer
1. I am not a mechanical genius, and my
methods certainly fall within
2. I do not hold myself out as an expert,
your results may vary, proceed at your own
After putting my car on jack stands, and
removing the old wheels, the first major step
in this project is to remove the original
wheel studs. I discovered that this
could be accomplished without removing any
major moving suspension parts. The
front studs are easily removed and the new
studs installed without dismounting
anything. The rear studs can only be
removed and reinstalled with the brake drum
off. See your manual for removing the
brake drum. After the brake drum is
off, then the hub can be rotated so the stud
can be positioned into an open area avoiding
the brake cylinder and springs. I was
able to remove one hub, however, which made
this process a bit easier. It is
possible, as mentioned above, to complete the
conversion without removing the hub.
Removing the studs requires you to use
your own judgment here regarding the proper
method. My Shadetree method was to put
some hardwood against the end of the stud and
then proceed to hammer them out after a
presoak of WD-40. Keep in mind, WD-40
and brake pads/rotors do NOT co-exist well
for obvious reasons, be careful. I had
no difficulty removing any of the studs in
this manner, however your results may vary as
I mentioned before.
Installing the new studs takes patience,
and again, the method I used may be
questioned by some. I elected to pull
the lug through the hub using a washer(s) and
a new lug nut. On the front hubs I
inserted the new stud to the shoulder where
the knurls start to engage. I then
positioned a washer over the end of the stud,
tightened the lug nut finger tight, and then
slowly tightened the lug nut while checking
the head in back to ensure it was pulled in
straight. Note: you will want the
washer to be a matching 7/16th washer to
assist with aligning the stud. (see Pictures
below) This method worked for me,
consistently with all sixteen studs.
The rear studs require a bit of
alteration to ensure the stud head does not
come in contact with the rubber boot of the
brake cylinder. I choose to defeat this
problem by inserting the threaded part of the
stud into a junk piece of radiator hose with
an inside diameter of 1/2 inch that I had
recently discarded. I could then hold
the stud while I reduced the height of the
stud head on my bench grinder. (The
rubber hose also kept me from burning my
fingers on the heated up stud as well as
giving me some additional distance between my
knuckles and the grinding wheel.)
shape of the head resembles a mushroom.
The outer edge or dome of the stud is the
part to pay attention to. I merely
removed some height, and then rounded over
the edge a bit to provide the proper
Installation of the rear studs is the same
as the front studs. Inserted from the
rear, washers added, the lug nuts pulled them
in square. Spin the hub and ensure
clearance between the stud and rubber
boot. Additionally, after the job is
completed and the wheels have been mounted,
please remember to once again remove the
wheel and check clearance once again by
removing the brake drum and checking the
brake cylinder boot for rubbing.
There are a few items to note with this project. If you are not comfortable grinding on the stud heads and feel the studs will be weakened by doing so, then don't do this project. Also of note, the heads of the studs have a 90-degree angle between threads and base of the head. The originals are tapered at 45 degrees, which fit into the beveled hub in a countersink position more securely. With that understanding, use your own judgment.
Lastly, if you have been told that TR7
wheels are a straight bolt on, you have been
misinformed. IF... the wheel has the
same backspace or offset as your original,
then overcoming the hub-centric vs.
lug-centric obstacle is the only
hurdle. After my stud replacement, I
mounted my new wheels and promptly discovered
the TR7 wheels have a different offset and
actually increase the width of track.
Not only that, but the 185/70 tires were 'too
tall' and with the additional change in
offset I have significant wheel rub.
Enough that the car wasn't able to be driven
until I resolved that problem, which was
quickly rectified by mounting some 185/60
size tires. I did have to roll the
inner front wheel wells just a tad. I'm
very pleased and personally think the end
result is worth the effort.