Story and images by Chirag Asaravala, John Dinkel and Day
Last month when we wrote our Feature Car piece on the Shelby
Automotive American Club (SAAC), we concluded that the organization
is full of enthusiasts who defy the clubs own admission that
its' members are not interested in working on their cars,
because they simply pay professionals to do so. In fact subsequent
to publishing the story we've received a flood of email's
from SAAC members nationwide who were eager to show us their
cars, which they themselves proudly built, race and maintain.
While we always knew that the regional and national clubs
were full of members who own all sorts of Ford muscle cars,
the least of which are genuine Shelby's, and we also suspected
that many of these guys are not only wrenching on their own
machines, but in fact leading the way in innovative modifications.
We had to look no further than own FordMuscle Forums to find
John Dinkel, aka "OpenTracker". John, a member of
the Northern California SAAC club, is known in the Mustang
open-track community as a highly adept fabricator of suspension
components -more on this in a bit. However it is not his engineering
skills alone that impress us, but rather his genuine desire
to help fellow enthusiasts out. As you'll see in this article
and the others in this series in future issues, John is completely
willing to share his secrets and designs so you can reap the
benefits of his innovations. Of course John doesn't mind either
if you choose to have his shop, Opentracker
Racing Products, build the products for you.
John Dinkel shows off his OpenTracker
roller spring perches.
Improving upon Stock, for Less
You might consider John's driving time around the circuits of
Thunderhill, Laguna Seca and Sears Point a sort of R&D facility.
His guinea pigs include the 65 coupe (pictured above, with his
wife driving), and the stable of other vintage Fords that occupy
his Carmel Valley ranch. When John noticed aggressively lowered
Mustangs breaking their shocks under aggressive track driving
he started analyzing the situation. He noticed that the stock
factory spring perches on Mustangs and most Falcons utilized
a high durometer rubber bushing, vulcanized to the outer bore
and also the center shaft. The result is a perch that takes
tremendous force to pivot, and while it may be suitable for
stock ride heights, when combined with lowered front ends and
altered upper A-arm
locations, the result was suspension bind. Not content with
having to pay big dollars for aftermarket Mustang suspensions,
he decided to design his own.
While researching the perches of other coil-on-upper-arm models
at the local Pick-n-Pulls, he came across some early Falcon
perches (see side bar) which utilized a bronze bushing and
Zerk fitting. The perch on these designs was free to rotate
on the shaft, eliminating bind. However the visible downside
to the bushing appeared to be accelerated wear on the shaft
and bushing due to the very limited range (less than 20 degrees)
that the perch and shaft rotate. We suspect this is why Ford
converted over to the rubber bushing perch.
Of course Ford isn't designing spring perches any more so
whose to say whether they could have, or would have, improved
further on the design. In John's analysis, the next logical
approach would have been to utilize a bearing; whereby the
load of the shaft is spread evenly upon the balls or rollers,
and allowing the perch to pivot with the motion of the of
John has produced over 50 sets
of roller spring perches since 2003.
John drafted up the design and produced his first set several
years ago. That set is still running strong in his families
daily-driver '64 Falcon. He produced several other prototype
sets for his open track car and to give out to fellow club
members. Since then he's produced over 50 sets for customers,
and an untold number have been made from his design which
he freely distributes. So far not a single one has come back
to him failed, and in many cases the perches have eliminated
broken shocks and other front suspension ailments. Those who
have tested them at the track have sung praises on how quick
and responsive the steering has becomes as a result of the
simple upgrade. Others have noticed improvements in the ability
to hold a line through a turn, as it is likely the old rubber
bushings allowed slight camber changes to occur on the inside
wheel under load.
Making your Own
We told you that John's first and foremost concern is in sharing
his knowledge and know-how with his fellow enthusiasts. He's
more than happy to help a fellow racer build his own set of
roller perches, and as you'll see on the next page, he's got
many followers who have successfully followed his recipe.