In April of 2004, I decided it was finally time to bite the bullet on new suspension. I had been researching for a long while, and a group buy came up on bimmerforums for the KW coilovers. I was looking to buy the KW V3, so this was a perfect opportunity.
I should note up front that while I drive my roadster regularly in the summer, it's not exactly a daily commuter. It's also very rare for me to have a passenger. The roadster is my 'fun' car. My point being that if it was my dailyy driver, it's unlikely I'd run coilovers.
Why KW? I've read good reviews of them. I think they're hard to beat for dual adjustables in this price range; I got the whole set for $1668.75, with free shipping. The strut housings are stainless steel; they should be reasonably light and corrosion-resistant for Michigan weather and my dirt road.
I seriously considered a Ground Control setup. The deciding factors were the stainless steel strut housings and reviews.
Note that part of the changes here include the Ireland rear subframe bushings, since the rear subframe in our cars has a lot of play with the factory bushings.
I wanted adjustable camber plates in front, and went with the TC Kline ones. The Ground Control ones looked nice too, but Pat Avakian said they were hard to keep quiet.
I installed Rogue Engineering rear shock mounts.
I also installed Racing Dynamics sway bars.
I am currently running TC Kline SmartDesign coilovers and rear springs/struts. This is because I broke a swaybar end link in the front and blew one of the KW coilovers.
I've really liked the handling with the KW V3, but the reality of Michigan roads has taken a toll. I've decided to order TC Kline SmartDesign suspension.
I ordered new adjustable swaybar endlinks from Turner Motorsports.
I found the Project Kics R26 lugnuts at www.daliracing.com for $129. Other places that might have them in stock:
Evasive Motorsports sent me email to tell me that the Project Kics R26 lug nuts aren't in stock and it could be months before they have them. I cancelled the order and ordered black lugnuts from Turner Motorsports.
I tweaked my camber in the rear to be -1.1 degrees on the passenger side and -1.4 degrees on the driver side. I also checked my total toe in the rear, it's .5 degrees toe-in which is exactly the factory specification. Note that I like less camber in the rear to minimize my tire wear on the street. I ran something near these numbers for the last set of tires and they wore very evenly. I'd like to go back and tweak the camber on the passenger side a _tiny_ bit, to get closer to being even with the car unweighted.
I touched up a few spots with black spraypaint, nothing special. I also ordered 2 more aerosol cans of Eastwood Rust Encapsulator.
I removed the subframe and one of the Ireland trailing arm bushings tonight. I then installed a stock bushing. The BMW tool is critical here; it works very nicely. I used a 50/50 mix of alcohol and water to lubricate the bushing for installation. I'll do more tomorrow, and take some pictures.
I'm also going to deal with the fuel tank strap cushions. The plan at the moment is to use heatshrink to hold them in place, probably McMaster-Carr 2595K8. I'd also like to use a better material than the foam BMW used... McMaster-Carr 93275K36 looks right.
The only work that remains to be done in assembling the rear end: put the wheel well liners back in, put the wheels on, and tighten the struts and the subframe mounting nuts. I then need to put the undercover back on and put the DME cover back on (these were off for gauge/sender work).
Today I removed the subframe and the second set of bushings. I took some measurements, in the interest of having Randy take a shot at making some Delrin AF bushings.
|Steel sleeve O.D.||.752" (19mm?)|
|Steel sleeve length||2.70"|
|Polyurethane flange O.D.||1.41" (36mm?)|
|Polyurethane flange thickness||.355" (9mm)|
|Polyurethane body O.D.||1.063" (27mm)|
|Polyurethane total length||2.70"|
I lubricated the second set of bushings (driver side), and reassembled the subframe. I now need to do some priming/painting of the differential pendants, since I scraped some paint off of them the last time I had the subframe out.
If I have enough gear oil around, I'll probably install my differential temperature sender while I've got the subframe off. It will require removing the differential cover, and redrilling and retapping the sender hole in the cover. I need to get a 1/8 NPT sender in there, but to do that I need to go up to 1/4 NPT since the existing hole is M10. I have adapter bushings, so this isn't a problem.
The torque values:
|rear rotor to hub||16 Nm|
|subframe support brackets to chassis||21 or 30 Nm?|
|differential cover bolts||77 Nm|
|rear lower strut bolts||77 Nm|
|caliper carrier to trailing arm||65 Nm|
|caliper guide bolts||30 Nm|
|transmission mounts||42 Nm|
|driveshaft to final drive||64 Nm|
The bummer is that I seem to be missing my passenger side brake pad retaining clip. Otherwise the car would have been driven tonight to settle the suspension and take rear toe and camber measurements.
The aluminum rod ends from McMaster-Carr are very nice, and they have as much swivel as the RD rod ends (maybe more). See the Pictures section.
I ran into a couple of hitches. One is that the connecting hardware for the RD endlinks is larger than stock, and won't fit through the holes in the trailing arm tabs. So I need to ream out those holes and touch them up. The second issue is that the new endlink hardware doesn't have cable guides for the parking brake cables, and the stock guide brackets need a little tweaking to use them.
Finally, I didn't really like the looks of the end links that RD sent; the ball doesn't move very freely, and the races are plastic (I'm guessing a PTFE-lubed fiber-reinforced plastic). So as an experiment, I tried to powdercoat them. One end survived, one end had the race expand out of the housing.
I have a number of choices to replace these. For now I've ordered some anodized aluminum ones and some 316 stainless steel ones from McMaster-Carr. The aluminum ones are rated around 4,000 lbs. of static load, have chromed 52100 steel balls and PTFE-lined high-carbon steel races; no lubrication required. The drawback: only 12 degrees of swivel. I'm not sure what the balls and races are on the stainless steel ones, but I know they require no lubrication. The stainless steel ones are rated around 3,000 lbs. of static load and have 19 degrees of swivel. Both are 3/8"-24 thread, and the dimensions match the ones that RD sent.
I also ordered some 17-7 PH stainless steel 1" OD washers to replace the lower bushing washers on the endlinks, since the RD ones won't fit between the gussets Randy welded. 17-7 PH is high-strength, has excellent fatigue properties, and good corrosion resistance (not as good as 304, but better than 410, 420 and 431). I also ordered some 2.25" long 3/8"-24 grade 8 bolts (super corrosion resistant coating) and nylon-insert locknuts to replace the M10x1.5 bolts that came with the RD endlinks.
If I wind up totally screwed on using the non-metric rod ends, I can order metric stainless steel M10x1.5 rod ends from McMaster-Carr.
Most of the endlink hardware I wanted to powdercoat is now done. Support triangles for the top of the trailing arms, a pair of the washers for the urethane bushings, and the U-shaped metal pieces. I also finished coating one of the parking brake guide brackets; the other will get done tomorrow. I put the RD swaybar in the mounts on the crossmember, using the new powdercoated C-shaped brackets. Now I wait for the new rod ends to arrive from McMaster-Carr.
Unrelated, I ordered some Wheel Wax, some Meguiar's NXT Wax, and 2 sets of microfiber towels from autogeek.net. Figuring Randy might want some Wheel Wax and more microfiber towels, one of the sets of towels is for him, as is one of the tubs of Wheel Wax.
I also powdercoated the exhaust hangers, in light gray. No idea how long this will last because I don't know how warm they get. If it doesn't last, I'll buy some new ones and powdercoat them with the high-temp powder.
I managed to burn myself pretty good tonight, left hand fingers and thumb. I fumbled a pie pan taking it out of the oven and caught it with my unmittened hand so that Myles wouldn't get burned. Ouch, typing is not much fun right now and tomorrow is going to be painful at work. The oven was at 400F. No severe blisters yet, but I did this about 10 minutes ago. I've lost my appetite for the pie. :-)
I also powdercoated the marked side of the Ireland trailing arm bolt heads, one side of the keyed washers, and the non-contact side of the nuts.
It's been about a year since I put the Ireland subframe bushings in, and other than some surface rust, they look brand new.
I finished powdercoating Clint's TC Kline captive frames.
Also, my KW struts have a different thread than the stock or Koni struts; M12 versus M14. So I bought some thin bushings to fill the gap between the TC Kline bushings and the strut rod at the top. The bushings I bought were Teflon-lined, not by choice but because they were the only ones I could find in the right inner and outer diameter.
I set the caster at maximum and don't expect to change it. I checked the camber at both extremes. It looks like I've got about -2.07 at one extreme and -3.4 at the other. Of course, I've got new S-03 tires (235/45-17 on the front, 255/40-17 on the rear), and haven't readjusted my ride height. The car had been on jackstands for almost 4 weeks. So we'll see where I wind up once the suspension has settled and I set my ride height again. Ride height right now appears darn close to where it was before the tire and camber plate work; about 23.125" from the bottom of the rim to the lip of the fender. To the floor it looks higher, since the tires have full tread and they're slightly taller. I suspect I'll wind up lowering the front to around 22.875" once the suspension is settled.
I siliconed the flanged bearings to the RSM bushings washers. Worked great, they're very snug but I know I could yank them off if needed. I cut the hole in the ragtop liner on the passenger side and inserted the trim plug. It looks perfect, the trim plug looks almost exactly like the plugs that hold the ragtop liner to the sheet metal. If I powdercoat them black with some gloss reducer, someone would be hard pressed to distinguish them.
The bad news here is that these plugs don't grab well. So I've decided to go the slightly larger ones, and I'll cut the prongs off and JB Weld them to a 1" O.D. MDS-filled nylon bearing. This will also permit fairly big goofs in cutting the hole in the ragtop liner; the new plugs have a head diameter of 1.3125".
5 lbs. of light gray polyester TGIC powder arrived from Caswell. It looks nice, but it's hard to tell with powder until you've cured some on a part. I'll do that tonight (probably the handle of one of my height adjuster tools, or maybe one or more of the tools in my trunk).
It looks like a 1" ID nylon bearing would work nicely to cover the top of the shocks in the rear, with a trim cap on top. They need to be 1.25" long. Looks like McMaster-Carr P/N 6294K72 is perfect.
Today I will be setting the front ride height to 23.125" (from bottom of rim to lip of fender) on both sides. This is higher than I want to be, but will save my tires until I'm ready for an alignment.
I powdercoated Randy's Rogue RSM reinforcement plates in Caswell 'Black Magic' TGIC powder.
I turned the driver's side coilover height adjuster lower by 1/2 turn, and the passenger's side lower by 2 turns. This should bring my ride height just below 23.125" on both sides, with the locking set screw on the height adjusters facing outboard for easy access. No idea what my toe is at (yet), but I'll check the camber (car unweighted) after it settles.
After settling, my ride height is just a hair under 23.125" on both sides in the front (seats not weighted). With my very crude measurement tools, camber appears to be around -1.5 on both sides. This doesn't seem right to me, so my tools are probably too crude.
I ordered a variety of different types of trim caps to try to use to cover the holes I'll be cutting in the ragtop compartment liner to access the rebound addjusters in the rear. I ordered them from McMaster-Carr.
I also ordered a silicone plug kit, masking kit and some light gray TGIC powder from Caswell.
With a friend's help, I installed the driver's side coilover. I then pulled the passenger side strut and got the KW installed on that side. I then put the Rogue wheel spacers on. I took a picture of each side, then put the wheels on and lowered the car to see where I am on ride height and space between the tires and coilovers. It looks like 5mm spacers would work, which is good to know. With the suspension not settled, my ride height is actually higher than it was with the stock suspension (23.5" versus 23.375"). I suspect it'll settle between 22.5" and 23". Currently I have the rebound damping set 1/4 turn from full soft, just like the rear.
It's raining on and off here, but I took the car for a short test ride anyway, to see where the ride height would settle in and get a rough idea of how stiff it is up front for Michigan roads. I'm happy with the spring rate; it's firm but not a bone-rattling experience. More stuff rattles in the interior, but it's far from a cacophony. It will be a heck of a lot more fun to drive hard. It's time for better tires, either S-03's or PS2's.
Interestingly, the driver's side settled only .25", to 23.125" (from bottom of rim to lip of fender). This is so close to my stock height that it's unlikely to have a significant effect on tire wear. Of course I want to go lower, but I will leave it as-is until I get the KMACs in and get to Randy's for an alignment or borrow his tools. I have not checked my toe yet on either end, nor the camber in front.
Since I'm not working on the battery box, I'm going to install the coilovers on the front today. I'm about to start, it's 4PM now.
After getting the driver's side strut out and getting the spring compressed, I realized I didn't have a 21mm deep socket. I went to Sears to get one. All they had was 12-point, and no 22mm impact sockets. So I bought the 12-point, 1/2" drive. I also picked up a long 3/8" drive ratchet and a long swivel-head 1/2" drive ratchet. For some reason I can't find my old second set, and I like having more than one set around w/o breaking out the air ratchet.
Then I couldn't find my 6mm allen wrenches. Didn't matter, I put the 21mm socket on the impact wrench on low speed, and the nut holding the strut together came off with no trouble at all.
I then assembled the upper strut bearing to the KW V3 coilover. I packed the upper strut bearing with Phil Wood waterproof bearing grease. Not what I'd normally use, but my grease gun is empty and it was my last cartridge of wheel bearing grease. The strut bearing still had some clean factory grease, which I did not remove. The Phil Wood should work fine, it won't be in there that long since I plan to get the TC Kline adjustable camber plates at the end of this season. I used a new dust cup, as well as a new support washer (replacing the one sent my KW). I did something a little odd, using the KW-supplied washer on the top side of the upper strut bearing. This was done because the KW nut is smaller in profile than the stock nut (19mm versus 21mm nut).
So, the driver's side coilover is ready to go in. Right now the ride height adjuster is set to 30 turns from the bottom (i.e. 30 turns from the lowest setting). I still have the helper spring installed, and it looks like I'd have to cut some of the dust cap on the coilover to get rid of the helper spring.
While I was in the driver's side front wheel well, I put some black RTV silicone on the nutsert that Randy installed for me to hold my ISSPRO EVM oil pressure sender. It's stainless steel so it's not rusting, but since we drilled through the sealant, I figured better safe than sorry for my strut tower. The silicone should help prevent moisture from getting to the sheet metal.
I removed the stock swaybar end link on the driver's side, cleaned up the end of the swaybar, and installed the KW swaybar end link on the swaybar.
It looks like my rear ride height hasn't dropped very far, but I won't know until I drive it and it settles in. The ride height adjusters are near max at the moment. I'm being conservative here until I get to the work in the front. I'm aiming for about 1.25" of drop in the end, but we'll see where I wind up. Since I haven't yet installed the KMAC eccentric trailing arm bushings, I can't drop the rear very far yet w/o eating up the inside of my tires.
On my first test drive, I had the rebound set to four 1/4 turns from full soft. This is too hard for Michigan roads, but is very nice performance-wise on smooth roads.
For my second and third test drives, I set the rebound to one 1/4 turn from full soft. This is fine on Michigan roads, and doesn't give up much on the performance front. Squat is dramatically reduced, as is roll in the rear. This is a huge relief from the ragtop weight that's up high, and makes the car feel much more planted.
Ride height has been reduced by about 1.25" in the rear. I will probably go down another .25" when the front is done.
I ordered rear shock mount reinforcement plates from Rogue Engineering.