Recently Jeff had done the Arning (Shelby) drop on his car which lowered the front end by 1/2" resulting the tire rubbing against the fender lip as well as increasing ground to header interference. Before he started spending lots of money experimenting with different coil springs, he decided to consult with suspension guru John Dinkel of Opentracker Racing Products.
John had recently developed a simple yet effective modification that moves the front spring perch outboard by 1". When you move the perch closer to the ball joint, you get a better motion ratio that makes the car ride better and it happens to also raises the front of the car approximately 1/2" which was Jeff's current concern (tire/fender clearance and header clearance).
John knew that we were working on Jeff's car at my work this past Saturday so he sent us one of his prototype templates on Friday overnight (Thanks John!!) to arrive while we were there. Unfortunately we ran out of time on Sat after playing around so long with the caster and camber alignment project, so Jeff and I came back on Sunday to start the perch relocation project.
Moving the perch requires drilling new holes in the upper control arm 1" outward. The template that John loaned us, fastens to the current perch holes in the arm. The template has two additional 1/8" holes located where you will be drilling the new holes. Here's some photos:
Here’s a photo supplied by John of another arm with a relocated perch:
Jeff's car specs: '67 Mustang with Eibach progressive coil springs (free height 12-3/4"), 1" poly upper coil spring spacers, Opentracker Roller Spring Perches, stock style upper and lower control arms and KYB GR-2 shocks.
Though John mention that you can move the current perch outward keeping the perch, coil and shock assembly together, he learned that Jeff had some of ORP’s original perches which John wanted back for destruction testing which put a wrench into the plans. Since Shag had new ORP perches, we simply removed them from Shag (sorry Buddy) so we could finish the project and off we went removing the shocks, shock tower caps springs and perches.
Once the coil spring and spring perch has been safely removed from the upper control arm, the template was attached to the existing perch mounting holes. Using a 1/8" drill bit, we drilled the two pilot holes in the upper control arm; removed the template and gradually opened up the pilot holes in a couple of steps ending with 3/8" holes. John warned us that depending of the mfg of the upper arm, we might not be able to have the perch’s bolts enter from the top due to possibly not having enough room for a socket underneath. Since Shag's new perches had no splined perch bolts we easily ran the bolts up from the bottom securing at top with a nylon locknut. If one wanted, they could remove the original splined bolts from the perch’s shaft and then run them up from the bottom.
Once we reassembled everything, we dropped the car back down and chose to recheck both camber and caster which did infact become altered during our perch project. After tweaking the caster and camber again, Jeff took the car for a quick spin to settle the front end.
Results: He gained 9/16� in height up front. Goal was 1/2�. Very happy
For those who consider doing this keep in mind the importance of safety when working on coil springs.
Here's a before and after shot, keep in mind we are only talking 1/2"
Before:
After:
Summary:
Since so many have or will be doing the Shelby drop which might affect the height, I felt it was pretty important to publish this project in order to give people another idea on how to obtain some of the height back without going out and spending lots of $$ on new springs. For those with stock or the reproduction rubber bushing perches, you will probably encounter a situation while trying to attach the bottom of the shock to the perch since the perch is very stiff and will not want to easily rotate. It might be a good time to
Buy some new roller ones.
Looking for a way to increase height was never Johns intention. This is a typical bi-product of another idea.
Thanks to Jeff and John for all their input and help.
Craig
John had recently developed a simple yet effective modification that moves the front spring perch outboard by 1". When you move the perch closer to the ball joint, you get a better motion ratio that makes the car ride better and it happens to also raises the front of the car approximately 1/2" which was Jeff's current concern (tire/fender clearance and header clearance).
John knew that we were working on Jeff's car at my work this past Saturday so he sent us one of his prototype templates on Friday overnight (Thanks John!!) to arrive while we were there. Unfortunately we ran out of time on Sat after playing around so long with the caster and camber alignment project, so Jeff and I came back on Sunday to start the perch relocation project.
Moving the perch requires drilling new holes in the upper control arm 1" outward. The template that John loaned us, fastens to the current perch holes in the arm. The template has two additional 1/8" holes located where you will be drilling the new holes. Here's some photos:
Here’s a photo supplied by John of another arm with a relocated perch:
Jeff's car specs: '67 Mustang with Eibach progressive coil springs (free height 12-3/4"), 1" poly upper coil spring spacers, Opentracker Roller Spring Perches, stock style upper and lower control arms and KYB GR-2 shocks.
Though John mention that you can move the current perch outward keeping the perch, coil and shock assembly together, he learned that Jeff had some of ORP’s original perches which John wanted back for destruction testing which put a wrench into the plans. Since Shag had new ORP perches, we simply removed them from Shag (sorry Buddy) so we could finish the project and off we went removing the shocks, shock tower caps springs and perches.
Once the coil spring and spring perch has been safely removed from the upper control arm, the template was attached to the existing perch mounting holes. Using a 1/8" drill bit, we drilled the two pilot holes in the upper control arm; removed the template and gradually opened up the pilot holes in a couple of steps ending with 3/8" holes. John warned us that depending of the mfg of the upper arm, we might not be able to have the perch’s bolts enter from the top due to possibly not having enough room for a socket underneath. Since Shag's new perches had no splined perch bolts we easily ran the bolts up from the bottom securing at top with a nylon locknut. If one wanted, they could remove the original splined bolts from the perch’s shaft and then run them up from the bottom.
Once we reassembled everything, we dropped the car back down and chose to recheck both camber and caster which did infact become altered during our perch project. After tweaking the caster and camber again, Jeff took the car for a quick spin to settle the front end.
Results: He gained 9/16� in height up front. Goal was 1/2�. Very happy
For those who consider doing this keep in mind the importance of safety when working on coil springs.
Here's a before and after shot, keep in mind we are only talking 1/2"
Before:
After:
Summary:
Since so many have or will be doing the Shelby drop which might affect the height, I felt it was pretty important to publish this project in order to give people another idea on how to obtain some of the height back without going out and spending lots of $$ on new springs. For those with stock or the reproduction rubber bushing perches, you will probably encounter a situation while trying to attach the bottom of the shock to the perch since the perch is very stiff and will not want to easily rotate. It might be a good time to
Buy some new roller ones.
Looking for a way to increase height was never Johns intention. This is a typical bi-product of another idea.
Thanks to Jeff and John for all their input and help.
Craig
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Some of us like to turn our cars