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New Exhaust for the F-22 Stealth
After several false starts, I finally managed to remove the old exhaust system on the 325is and install the new cat and muffler I’ve had since August. All of the DIY postings I’ve read on e30 exhausts have said the same three things: 1. Don’t try this without a lift; 2. This thing is long; and 3. It’s heavy. Right on all three. You can do it with the car on jack-stands, but be prepared for a lot of up and down work. It helps to have a couple of extra stands to support the exhaust; an extra jack to move it up into position; and a skateboard to help guide the exhaust under the car.
Bolted together, the old cat and muffler weighed in at 60 lbs. The new one came in slightly lighter at 55 lbs. The mufflers are essentially the same, but there have been some changes to the mid-pipe over the last 20 years. Catalytic converters are much more efficient and much smaller now. The old one also had an elaborate heat shield that rotted away.
The e30 exhaust system has basically three parts. A pair of very short exhaust headers (which I didn’t remove); a mid-pipe with the O2 sensor and cat; and a pipe and muffler section.
I’m not sure I understand the basic design principles involved though. The BMW 6 cylinder engine has two exhaust headers. The new pipe has an X-pipe at the O2 sensor, but then the two pipes continue to the cat. Before the cat, they go through a Y-pipe and enter a larger diaper tube into the cat. That larger pipe is perhaps 2 1/2 inches in diameter; the other pipes about 2 inches. Then there is another Y-pipe and back into two smaller diameter pipes to the muffler. Why not a Y-pipe at the O2 sensor, then a single pipe all the way back? That has to be a lighter design.
I guess I don’t have to understand it to appreciate it. The new system sounds great and seems to have a bit better throttle response, so the redesigned cat must be more free flowing. Also when I walk up to the car, I don’t have to look at the old crappy muffler any more. Yeah.
New MINI Suspension
I got the MINI back from Frederick Motorsports last night. I had Scott install the new adjustable Konis along with the replacement camber plates. I also had to have the front muffler replaced. It’s too soon to really offer an opinion on the new struts. My impression is that the ride home was smoother and less harsh, but that just may be because I want it to be so. I still have to figure out how I’m going to make the adjustments. Notice that the camber plate slot is smaller than the diameter of the Koni adjustment tool. Nothing is ever as easy as it seems.
The Thud was definitely gone as the front left strut is again attached to the chassis and doesn’t ride up and down in the receiver as you can see in the photos of the old camber plates.
The rear shocks are also adjustable, but to make the adjustment, you have to drop the shock, make the adjustment and bolt it back in. I’ve heard most people just leave it on the middle setting and play with the adjustment in the front to achieve the desired balance. I’ll start there and see where it goes.
New Camber Plates
The replacement camber plates arrived from IE today. The adjustable Konis arrived earlier in the week. Hopefully I’ll have a chance to get them installed next week. When you compare the two photos, you can see how the urethane failed. I’ve been told they have improved the manufacturing process so these are not as likely to fail as the previous ones.
Things that go Whump in the Night
I am always amazed by the chain of events that leads to discovery. This past weekend, I was getting my MINI ready for winter. We don’t get a lot of snow here in Maryland, but when you car is only a few inches off of the ground, it doesn’t take much to slow you down. I figured the splitter would act like a dive plane in the snow. With that in mind, I decided to take off the splitter, close the brake duct holes, reinstall the fog lights, and trim a inch off of the bottom of airdam to gain some more clearance.
I had the car up on jack stands with the front wheels off. I remember looking down into the center bore of the camber plate (photo above) on the driver’s side, thinking it didn’t look quite right. I compared it to the other side and noticed the gap was about twice as large. I figured there must be some movement in the receiver, and since I had been working on the hub, maybe the downward pressure had made it droop. Then, as I reinstalled the wheel, and was pushing down to tighten the lugs, I heard a “whump”. The bearing had dropped out of the receiver. Even I know enough about suspensions to think, “not good….”
Sure enough, the urethane bushing had failed. The bearing was still attached to the top of the strut, but the strut was no longer attached to the receiver. From the machining that appears to have taken place, it looks like it has been loose for a while.
I talked to the manufacturer and they are going to replace the camber plates. That’s good news, and the car is still drivable, but I have to be careful to avoid large potholes. Once I line up the bearing, and lower the car to the ground, the weight of the car along with the compression of the spring keeps it seated, even when I jack the car up again. I can make it fail, but I have to put a lot of pressure on the hub to drop it out again.
So this presents an opportunity: If I’m going to have to have someone reassemble the struts, I might as well replace the shocks. (Quiet: Rationalization in progress.) I’m not yet good enough to really take advantage of coil-overs. Plus at $1200-$2500 I can’t afford them anyway. I’m thinking about 3 options:
- Koni Sport. The yellow Konis are adjustable. The fronts can be easily changed through the center bore of the camber plate. The rears are a little harder to use since you have to remove the shock to adjust them. I’ve heard good things from people who set the rears to the mid setting, then adjust the fronts to suit conditions. Soft for daily driving or in the rain. Hard for autocross/track. Designed to work with lowering springs.
- Koni FSD. FSD stands for frequency selective damping. That’s a fancy way of saying that the have a softer rebound rate for a quick (high frequency) compression such as seams on the highway or a pothole; and a hard rebound rate for slow (low frequency) compression such as on a smooth track. Sort of a cake/eating thing. They are not adjustable, but they compensate for the two primary goals of the daily driver/occasional racer.
- MINI JCW. The JCW suspension is designed to work with shorter springs which should help with the harshness of using stock struts on lowering springs. They aren’t adjustable and they don’t offer two distinct damping rates, but they’re OEM.
I’m leaning toward the Koni Adjustables. If I can dial out the harshness of my current suspension, then maybe people won’t worry about their fillings when they ride with me. The ability to make adjustments gives me something else to play with (or blame) next season. That’s a bonus.
Catching up with Fall Track Days & Progress on the BMW Stealth Project
I haven’t been keeping up with blogging so I’ll try to catch up with a few things in this post. With the economy in a tailspin here in the US, I’ve put my BMW project on hold for a while. There are a couple of advantages to this strategy: It preserves cash should we have to throw everything in the Volvo and head to Mexico; and if I wait until January, then the BMW will qualify as “historic” according to the great State of Maryland and I can skip the Maryland State Inspection (and associated fees).
Since I’m not making any progress mechanically, I thought it would be a good time to even out the flat black paint scheme. Here you see it before the attack of the black spray bombs.
And here it is afterward. You can see how far I’ve gotten by looking at where the door meets the rear quarter-panel. From that point back to include the roof remains to be painted. My goal is a uniform satin finish. Sort of Stealthy.
Back in October, I went to the Fall Driver’s School at the Shenandoah Circuit, Summit Point, WV.
It was a great three days of track time, but at the end of the first day, my friend hit the wall at the start of the main straight.
He and his passenger were both unhurt, but his 2005 Corvette was totaled. I was actually quite surprised how well the passenger compartment held up. He dropped a wheel off the outside of the turn going 85+ MPH and skidded across the track hitting the opposite wall with the car rotated about 110 degrees. Both airbags deployed as the car ricocheted off the wall. Now you know why I’m working on a dedicated track car.
