Bemused and Confused

Last week I took the Rat in to a local shop to get the throw out bearing and clutch replaced. The clutch seemed to be in OK shape, but the throw out bearing was definitely on its last legs.

The job took them a bit longer than expected. They had a problem with the top two bolts that hold the transmission to the engine. Somebody, most likely my favorite PO, used the wrong hardware and had stripped out the threads on the housing. They had used US standard bolts instead of metric which generally use different thread pitch. This cost me more money because it meant more shop time. They had to drill out the bolts and then re-tap the housing.

I had the flywheel resurfaced and a new clutch put in along with the throw out bearing. I also had the rear main seal, the rear transmission output seal and the shift linkage seal replaced while we were there. It cost more than I would like, but it was still a good deal compared to what you could pay at other shops.

When I picked up the car there was no more whirring noise from the throw out bearing. The car shifted nicely. The stiff bushing and the new shifter hardware, which I had the shop complete putting in while the transmission was out, made for very precise shifting. Cool!

On the way back to the office, I started noticing a vibration. I hadn’t noticed it before the work was done. Hmmm, now what?

On the way home, I was almost scared to take the car up to speed. The vibration was quite bad. It followed engine RPM and not speed though. I thought at first it might have been a wheel that was out of balance, threw a weight off or something, or that the right rear wheel was coming off again. But, when I figured out it happened with the car in neutral and just revving the engine, well that ruled out the drive line and the wheels.

I called Ross at Horton’s German Car Service, the guys who did the work, and he told me to bring the car in. He was thinking that the exhaust was hammering against the belly of the car from my description of the vibration. I took the car in the next morning.

We put it up on the lift and checked out the exhaust. We could see one point where it was hitting the spare tire well back below the trunk. But, that was it. We started poking around in other places, revving the engine, looking for anything that might be vibrating against the body of the car. We couldn’t find anything. We realigned the exhaust and made sure everything was tight.

We did notice that the power steering and AC compressor pulley had a bit of a wobble to it. I told Ross I would take off that pulley since I didn’t need it anymore and also remove the viscous clutch fan to see if either of those were the problem.

Ross was great and spent over an hour with me going over the car. He wasn’t going to charge me for it, but since I couldn’t see a direct relationship between the work they did and the problem, I had him charge me his minimum shop fee.

Back At Home

I could still feel the vibration on the way home. It hadn’t gotten any better with the fiddling we had done.

I needed to drive down south and pick up my son so I switched cars to the Silver Sloth, my E46. Wow, what a difference. It felt like I was sliding into a giant limousine. The car was so quiet. It was smooth, refined, soft, soggy and a bit squishy. Ick. What a contrast. The Sloth is no real slouch either. It has a nice Bilstien and H&R suspension setup with a few other tweaks. When I first got that suspension I was thinking it was way too stiff and I wouldn’t be able to deal with it on a daily basis. Well, I have gotten used to it and after driving the Rat, the Sloth seemed like a soggy American built luxury car. But man, it is nice to drive. It is fun enough and it handles very well, but it is also quiet, comfortable and refined. Nice. That is the major reason I got the Rat for track duty. I didn’t want to modify my daily driver so much that it became something I didn’t want to drive.

On Saturday, I tore into the the Rat. I first removed the viscous fan. I plan on replacing it with an after market electric one. I removed the front PS and AC pulley and then did something stupid. I didn’t put the pulley bolts back in. I don’t know what I was thinking, I guess I thought the main bolt held the timing wheel/harmonic balancer in place. Well, it doesn’t. I tried to start the car. It turned over, fired up for a split second and then died. Whoops. Spencer popped his head into the garage and asked if I had broken something since it had made a “breaking” sound. Hmmm, I probably did break something.

It turned out that the timing wheel had popped loose and no longer spun with the crank shaft. This would of course immediately shut the engine down since it no longer had a crank shaft position signal. Good thing too. Luckily, there is a position stud on the mount where the wheel goes so it was easy to line it back up and reinstall it. If that stud were not there, I would have to get the engine over to TDC for cylinder #1 and make sure everything was lined up before I could reinstall the timing wheel. The original bolts worked fine, they were not too long after removing the pulley.

I checked around for any other problems, but didn’t find any. I started the car up and it fired up on the first crank. Wheew!.

I ran it for a bit in the garage, but it was too late to test drive. I thought that maybe the vibration had reduced, but I knew I would need to drive it to really tell.

Sunday morning, after the snow melted (yes, we had snow in April, very odd), I took the car for a drive.

The Silver Sloth with a skiff of snow on it

My back yard in April. Notice the flowers. We don’t get snow in the valley in April!

The vibration was still there as strong as ever. I drove it quite a bit and went and got some gas put in. The engine seems to be running fine. It responds quickly to the throttle and pulls well. But there are certain RPM ranges where the vibration gets pretty bad. Around 2800-3000 RPMs it starts kicking in pretty bad. It is really bad by 4000 RPMs.

After I got out of the car, my feet and butt were still vibrating.

I am now stumped. I think I might have to have the shop take a look at the flywheel. Resurfacing it may have gotten it out of balance. Or, there might be something out of balance in the engine. The PO had his father do the low end rebuild on it… like father like son?

Or, it might just be because of the hard engine and transmission mounts that I am using. I knew they would transmit a lot of noise and vibration, but this seems excessive. I watched my test drive video again but the noise on the recording is so bad that it is hard to tell if the vibration was there before the transmission work. I think that it might have been there, but not nearly as bad. I think I would have noticed it if it were as bad as it is now. I will have to talk to Ross again and see what he thinks. The worst case will be having to pull the engine and tear it apart. If it comes to that, it might have to wait for a while. I don’t want to be putting another couple thousand dollars into this right now.

The engine does seem to run well. Revving it up and listening from the engine bay sounds good. You can feel a small amount of vibration if you put your hand on the engine, but nothing that I would call bad. The engine revs quickly and runs smoothly. I can’t hear a miss at all.

If anybody has any ideas, let me know.