boardkat
CAMtard
- Joined
- Nov 17, 2013
- Threads
- 45
- Messages
- 900
- Reaction score
- 569
- Location
- Lake Oswego, OR
- Vehicle(s)
- '15 GT
- Thread starter
- #31
Another quick update.
Got the MMI Adjustable Rear Perches on, but had two issues:
1.) 6" springs were too long
- 2000# 6"/2.25ID springs put me 3/8" higher than desired ride height, even with the perch being wound as low as it could go.
2.) 5" springs were too short
- 1600# 5"/2.25ID springs allowed me to get to desired ride height, but the perch was wound very close to the top of the adjustment range, introducing the very real possibility of upper/lower perch hangar interference. The picture below shows a safe ride height that would result in upper camber arm interference prior to the perch hangars hitting - which, unfortunately, was about 1/2" higher than I wanted to be.
After talking with Mike about possible interim solutions (given that there are no OTS 5.5"/2.25ID springs available anywhere), he sent me a set of 1500# 6" springs to try (less rate = lower ride height), as well as machining a few spacers to fit on the lower perch, would would give me an additional 3/8" of perch clearance (and enough adjustment to run a 5" spring at desired ride height).
Haven't had a chance to throw the 1600# 5" springs on with the spacers yet, but I can confirm that getting to desired ride height is possible on the 1500# 6" setup with a little bit of lowering still left.
All this said, I only had the 2000# 6" springs in hand for the NWR-SCCA Regional Pro Solo #1 @ Packwood, WA a few weeks back, so I did a quick alignment and ran 'em anyway.
Initial assessment: 2000# rear springs with a higher than desired rear ride height is not the right setup for a bumpy asphalt surface! The car was a bit of a mess. No surprise there of course, but I'll definitely be throwing them back on the next chance I get to run on a flat concrete surface with warm ambient temperatures to see how they do. For now, I'm actually going to throw a wrench in my known-good setup and begin experimenting with softer springs than I've run in a long time: 600f/1500r. We'll see how the car does this weekend at my home region OR-SCCA events, also in Packwood.
Ahead of that, I've had a chance to install a few other parts I've been meaning to get onto the car. The driveshaft vibration that I'd previously muted has progressively re-emerged since last season. Confident that the driveshaft itself is balanced correctly (I made sure Dynotech did this when I sent it back to get rebuilt after getting damaged when my diff carrier bolts failed last year), in tandem with a known good rear diff assembly (completely fresh build with new parts over the winter), and having already equalized the driveshaft/pinion angles previously (requiring 0.375" of spacers under the transmission mount), I've methodically tried the following:
1.) Get the car up on jackstands and pull the jumper to put the car in dyno mode
2.) Rotate the driveshaft at the pinion flange until vibrations are minimzed
3.) Rotate the driveshaft at the transmission flange until vibrations are minimized even further
I thought I'd try sometime a little different this time. Rather than any rotating, I added a worm clamp to the driveshaft as far to the rear as I could, suspecting that the new pinion flange may be the culprit. I proceeded to try different positions until magically, the vibration present between 65-110 disappeared COMPLETELY.
I suspect that the lack of any rubber in my suspension, poly/delrin diff/motor mount/subframe bushings, an aluminum diff carriage and a 1pc driveshaft all contribute to magnifying this issue in my case, but it's somewhat gratifying to finally overcome it again!
Also had a chance to put the Steeda Clutch Spring Assist & Perch Kit on.
One of the first mods I did back in 2015 was completely remove the stock assembly, given it's propensity to lock me out of high RPM shifts. However, I've always noticed a bit of play at the top of the pedal, and figured a little bit of extra insurance for my throwout bearing couldn't hurt! Happy to report that the installation was painless (< 1 minute, due to me having noting to remove), the fit and finish are excellent, and I no longer have any play from the weight of the pedal/gravity at the top. Wish all my problems were solved this easily!
I also finally got around to enlarging my strut tower holes. Ever since I switched from Vorshlag to JRZ camber plates - the Vorshlag design put the spring perches too low in tandem with the JRZ struts, reducing inboard space thereby increasing track and adapter requirements for wheel clearance, and requiring a stiffer front spring due to fender interference - I've been unable to adjust camber as easily as I used to, due to the location of the adjustment bolts. Fortunately, CAM has no restriction on making this sort of modification, so I took some measurements and had a friend waterjet me a steel template to use in tandem with a 3" hole saw:
Didn't take any pics while I was enlarging the hole, but hopefully you can see how it worked - unbolt and lower strut, place template below center hole, button back up and go to town with a hole saw located by the pilot hole with a drill bit.
End result:
Lots of room for socket activities!
My wallet and daily driven PS4S will be thanking me profusely for not having to endure that -3.75 camber and 1/8 toe out life any longer, thus saving them from an early trip to the trash heap due to accelerated inner wear!
Final thing to note: I picked up a co-driver for the rest of the season. Jim Boller, who warmed tires earlier this year @ the Crows Landing National Tour, will be driving with me the rest of the national event schedule, including the CAM Invitational and Solo Nationals in September. We really went through the ringer with all the oiling issues the car was having last month, so I'm excited to get another chance for us to thrash on a more reliable car for the rest of the year.
That's all for now, I'll be sure to report back ahead of the Packwood National Tour and Pro Solo events with the results of testing and tuning!
Got the MMI Adjustable Rear Perches on, but had two issues:
1.) 6" springs were too long
- 2000# 6"/2.25ID springs put me 3/8" higher than desired ride height, even with the perch being wound as low as it could go.
2.) 5" springs were too short
- 1600# 5"/2.25ID springs allowed me to get to desired ride height, but the perch was wound very close to the top of the adjustment range, introducing the very real possibility of upper/lower perch hangar interference. The picture below shows a safe ride height that would result in upper camber arm interference prior to the perch hangars hitting - which, unfortunately, was about 1/2" higher than I wanted to be.
After talking with Mike about possible interim solutions (given that there are no OTS 5.5"/2.25ID springs available anywhere), he sent me a set of 1500# 6" springs to try (less rate = lower ride height), as well as machining a few spacers to fit on the lower perch, would would give me an additional 3/8" of perch clearance (and enough adjustment to run a 5" spring at desired ride height).
Haven't had a chance to throw the 1600# 5" springs on with the spacers yet, but I can confirm that getting to desired ride height is possible on the 1500# 6" setup with a little bit of lowering still left.
All this said, I only had the 2000# 6" springs in hand for the NWR-SCCA Regional Pro Solo #1 @ Packwood, WA a few weeks back, so I did a quick alignment and ran 'em anyway.
Initial assessment: 2000# rear springs with a higher than desired rear ride height is not the right setup for a bumpy asphalt surface! The car was a bit of a mess. No surprise there of course, but I'll definitely be throwing them back on the next chance I get to run on a flat concrete surface with warm ambient temperatures to see how they do. For now, I'm actually going to throw a wrench in my known-good setup and begin experimenting with softer springs than I've run in a long time: 600f/1500r. We'll see how the car does this weekend at my home region OR-SCCA events, also in Packwood.
Ahead of that, I've had a chance to install a few other parts I've been meaning to get onto the car. The driveshaft vibration that I'd previously muted has progressively re-emerged since last season. Confident that the driveshaft itself is balanced correctly (I made sure Dynotech did this when I sent it back to get rebuilt after getting damaged when my diff carrier bolts failed last year), in tandem with a known good rear diff assembly (completely fresh build with new parts over the winter), and having already equalized the driveshaft/pinion angles previously (requiring 0.375" of spacers under the transmission mount), I've methodically tried the following:
1.) Get the car up on jackstands and pull the jumper to put the car in dyno mode
2.) Rotate the driveshaft at the pinion flange until vibrations are minimzed
3.) Rotate the driveshaft at the transmission flange until vibrations are minimized even further
I thought I'd try sometime a little different this time. Rather than any rotating, I added a worm clamp to the driveshaft as far to the rear as I could, suspecting that the new pinion flange may be the culprit. I proceeded to try different positions until magically, the vibration present between 65-110 disappeared COMPLETELY.
I suspect that the lack of any rubber in my suspension, poly/delrin diff/motor mount/subframe bushings, an aluminum diff carriage and a 1pc driveshaft all contribute to magnifying this issue in my case, but it's somewhat gratifying to finally overcome it again!
Also had a chance to put the Steeda Clutch Spring Assist & Perch Kit on.
One of the first mods I did back in 2015 was completely remove the stock assembly, given it's propensity to lock me out of high RPM shifts. However, I've always noticed a bit of play at the top of the pedal, and figured a little bit of extra insurance for my throwout bearing couldn't hurt! Happy to report that the installation was painless (< 1 minute, due to me having noting to remove), the fit and finish are excellent, and I no longer have any play from the weight of the pedal/gravity at the top. Wish all my problems were solved this easily!
I also finally got around to enlarging my strut tower holes. Ever since I switched from Vorshlag to JRZ camber plates - the Vorshlag design put the spring perches too low in tandem with the JRZ struts, reducing inboard space thereby increasing track and adapter requirements for wheel clearance, and requiring a stiffer front spring due to fender interference - I've been unable to adjust camber as easily as I used to, due to the location of the adjustment bolts. Fortunately, CAM has no restriction on making this sort of modification, so I took some measurements and had a friend waterjet me a steel template to use in tandem with a 3" hole saw:
Didn't take any pics while I was enlarging the hole, but hopefully you can see how it worked - unbolt and lower strut, place template below center hole, button back up and go to town with a hole saw located by the pilot hole with a drill bit.
End result:
Lots of room for socket activities!
My wallet and daily driven PS4S will be thanking me profusely for not having to endure that -3.75 camber and 1/8 toe out life any longer, thus saving them from an early trip to the trash heap due to accelerated inner wear!
Final thing to note: I picked up a co-driver for the rest of the season. Jim Boller, who warmed tires earlier this year @ the Crows Landing National Tour, will be driving with me the rest of the national event schedule, including the CAM Invitational and Solo Nationals in September. We really went through the ringer with all the oiling issues the car was having last month, so I'm excited to get another chance for us to thrash on a more reliable car for the rest of the year.
That's all for now, I'll be sure to report back ahead of the Packwood National Tour and Pro Solo events with the results of testing and tuning!
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