Project Update for April 20, 2011: So we don't end up with 8 events and a lot of modifications in one thread update, I'm trying to do them more quickly. Over the last week we only did one suspension update to the car, but it took a sizable amount of work over 2 days. Then I took the car to a local autocross last Saturday. That was a train wreck for me, with a course layout that was super tight/narrow, and the Mustang was a bear to fit through the gates. Pretty much wasted a day, but I did get some cold and warm weather data on the Toyos (none of it flattering). Then this week we've located some 18x10" track wheels, bought another set of STX tires to test with, and another new part for the Mustang arrived. Read below for more.
The front suspension on the S197 Mustang is pretty basic stuff: McPherson strut, spring mounted on the strut, with a beefy steel Lower Control Arm (LCA) that has two big rubber bushings. These bushings are very mismatched in size, with the rear unit being
as big as a beer can and the front somewhat smaller, but they are at least lined up on the same axis. This means they are
single axis of rotation bushings, which is a good place to use poly or nylon materials, especially if the bushings are large, rubber, and soft.
Our durometer hasn't arrived yet so I wasn't able to measure how soft the LCA bushings were, but the OEM rubber depressed easily by hand. Feels like a giant marshmallow, and I read somewhere that it was full of fluid as well. This is great for ride comfort and quiet, but will deflect badly under load, and we had noted some wheel deflection in some close-up pictures of the suspension under heavy loading. Toe change, camber loss - its never good for dynamic suspension geometry and overall handling to have super soft, large, compliant suspension bushings on a car. We began to look at solutions for the LCA bushings and more bits of this chassis months ago.
S197 poly Mustang bushings we now carry (click thumbnails for larger images)
Since there was almost no model coverage overlap between Powerflex (which we already stock/sell) and Energy Suspension, we went ahead did a buy-in with Energy a few months back. The initial stocking order had all of their S197 Mustang bushing kits in it, and they finally arrived a week ago. Energy had no idea if their "2005-2007" Mustang bits and pieces fit the later cars, so we bought everything to check for ourselves. We have been testing these bits on our 2011 and I can report this so far: Their front LCA kit works on the '11 GT, as does the track bar kit (panhard bar bushings), and it looks like the upper rear control arm kit might work (but we might go another route there). The shifter bushing kit most certainly does not fit the new Getrag 6-spd on the 2011, however.
Poly LCA Bushing Install -
http://vorshlag.smugmug.com/Instruct...y-LCA-bushing/
So the lone modification we did to the Mustang last week was the bushing replacement on the front LCA. Let me tell you up front - this was not a quick, easy or fun job to perform. Our tech AJ fought with this install for part of 2 days, and we had the right tools, a lift, a press, had all done poly bushing installs many times - everything stacked in our favor. The OEM Mustang front LCA bushings (especially the fluid-filled, gigantic back ones) are some of the nastiest I've ever seen.
Just getting the LCAs out of the car took a good bit of work. The front bushing bolts are blocked by the giant electric power steering unit, which had to be unbolted and slid forward (he left the steering shaft installed). Even then the bolt
barely came out. For the bushing swap, we followed the Energy's instructions. This says to "apply heat to the outer shell", to break the bond of the rubber to metal, but we resorted to cutting and burning the bushing out of the outer sleeve. Then cut the bushing remnants from the inner sleeve (both sleeves are re-used). Nasty, messy work. The damn fluid was under pressure, too. We used heat, then fire, then drills and a saws-all. Maybe spent 5+ hours getting the first LCA done. The second LCA went a lot smoother...
This time AJ and Matt teamed up and used more heat and brainpower than we did the first time. With the LCA held in the vice, one of them used the torch on the metal while the other pulled on the bushing housing (with a water bottle nearby to put out the small flash fires that flared up). This process took some time but eventually, with enough heat and pulling, the outer sleeve pulled clean off the bushing. No time wasted cutting the bushing up or cleaning up the outer sleeve. The inner sleeve worked almost the same way, with careful heat and pressure.
The inner sleeve has a knurled section that has to be sanded off, as the bushing slides over that when its installed. We also went the extra step and, after the bushing was pressed into the outer sleeve (only) we drilled a hole and tapped the outer sleeve for a grease zerk. Then installed the inner sleeve (which can stay pressed onto the LCA the whole time). Now we can go back and grease the bushings easily - to keep them from squeaking later (a common complaint on poly bushings when the original grease gives out). We don't show the front bushing in this install gallery but it was smaller and easier to swap.
After a quick check of the toe (nothing changed) AJ and I loaded the Mustang into the trailer by 8 pm Friday night, ready for the autocross the next day.
April 16th NTAXS Autocross
We had found a local autocross on Saturday I could attend (co-driver's Amy and Costas were both out of town) so I tried to enter on Thursday... but it was full at 65 entrants already. I said as much on FB and
within 2 minutes (gotta love the internet) had a friend willing to sell me his entry (thanks Jason!), so I was in. NTAXS is what remains of an S2000 autocross club, and they cater to mostly S2000 and Miata drivers. This event was to be held at Texas Motor Speedway bus lot (slick sealed asphalt I've autocrossed on at 40+ events in the past, so I know the surface well), and normally Jarrett J sets up their courses - who does most of the local autocross courses for other clubs as well (and does an excellent job).
So I towed out there early and it was pretty cold in the morning, mid 40's and 10-20 mph winds. The surface was going to be slick, but it was predicted to get into the mid 70's that afternoon. With 4 runs in the morning and 4 more after lunch, I'd at least get some varied track temperature runs on the Toyos. Walked the course with Chris Ledbetter and we both groaned at the extreme tightness of some gates and oddly tight corner layouts... this course was made for a
NARROW car. Sure enough, another course designer had set-up the course (his first), an S2000 driver, who ended up hitting cones on 4 of his 8 runs himself. Lots of DNFs, lots of cones felled, etc.
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