5sp manual swap and bsm delete drone

Anyone know what might cause this on a manual swap B5.5 at around 2200 RPM? Has a correct euro tdi tranny and a stage 2 tune. Maybe someone gutted the CAT. Could that cause it? Exhaust appears to be stock. Really annoying!

Mine does the same. I believe it's engine harmonics that the BSM "filtered" out. Now that the BSM is gone, you have to deal with it. Good/new engine and trans mounts could help. Also the Whitbread 30lb. flywheel could help.

I think it has Mats' 30lb flywheel and Kevlar clutch-smooth as silk. Interesting you have the same issue. My automatic car has none of this drone. I think I'm gonna try to source a new or used vw provided geared BSM module and put in it if the delete didn't permanently preclude doing that. I will deal with it. There are probably some geared engines out there to be had now that these cars are getting older and showing up wrecked and junked.Quite a few were upgraded including my automatic car. VW didn't put the BSM oe unless there was a damn good reason.

Actually, Volkswagen DIDN'T put the balance shaft in these engines with the manual transmission (which we did not get). So I suspect perhaps your issue is something different. But not sure.

Is this a noise, or a vibration, or both? Does it happen at a specific RPM, even sitting still? Does it happen if the clutch pedal is pushed in and the car put in gear but clutch not released?

How are the axles? Any change under load?

I purchased my car with the manual trans and original BSM. I deleted the BSM myself. I can say the harmonics/drone happened after the delete. This was my experience...

I also get the drone.


I think a heavier flywheel might help, i also have matts flywheel.

The drone causes enough vibration where i can hear tools rattle in the back floorboard.

It's a diesel. I live with it. This is the smoothest diesel I've ever owned. The car is equipped with enough sound dampening the monsoon system easily covers it up

A member in here is or was selling a bad tranny 05 with a geared bsm in johnson city tn. Id have snatched it up if he was closer. Had the factory vortex body kit and color matched my car.

oilhammer said:

Actually, Volkswagen DIDN'T put the balance shaft in these engines with the manual transmission (which we did not get). So I suspect perhaps your issue is something different. But not sure.

Is this a noise, or a vibration, or both? Does it happen at a specific RPM, even sitting still? Does it happen if the clutch pedal is pushed in and the car put in gear but clutch not released?

How are the axles? Any change under load?

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I put some Pirellis on it when I first got it so I'm swapping known quiet Defenders off my automatic car next week. I think the axles are aftermarket NAPA but that shouldn't be a factor in a manual car. The drone is always there in the 2000-2500 RPM range regardless of gear,load,speed, etc. I'm thinking of some subtle exhaust changes to see if I can at least move the drone to a diiferent RPM away from 70 MPH I'm mostly at. I'm surprised at the number of corroborations posting-delete must be a factor. I have sourced a geared BSM but the gears are damged. Would they be the same bsm gears as the skoda 2.0 European engine? BTW, it's mostly a sound. Don't feel much vibration if any. Thanks for piping in oilhammer.

Swapped the Defenders onto the car and they are quieter but didn't affect the drone. It's not loud but an annoying echo in my ears. All the factory sound deadening is on the car and I even added oe engine and Euro manual transmission splash shields with additional foam glued to them. I added 1/4" foam to the engine cover too. the engine mounts are dry and the tranny mounts are nice too. all the rubber mounts on the exhaust are good. Suggestions are welcome.

Funny you would mention that as it is my next move. I've seen various makes of vehicles with factory weights cantilevered off the exhaust. Thx. QuickTD. I'll get to the bottom of this.

50harleyrider said:

Funny you would mention that as it is my next move. I've seen various makes of vehicles with factory weights cantilevered off the exhaust. Thx. QuickTD. I'll get to the bottom of this.

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I've done this on another car of mine. You have to play around with the location. Some spots made it better, and some made it worse.

Also, in my B5.5 sedan, if I fold the rear seats down, the drone isn't as bad.

I also intend to clamp the exhaust to the body with a rubber lined clamp somewhere along the longest unsupported section of exhaust. This and most exhaust systems are floating with only hangers. That should change the natural frequency of the exhaust system up hopefully above my cruise RPM. I realize this approach assumes the exhaust is the culprit. Harmonics resonating from the engine block into the air will not be decreased. That takes us right back to the bsm need. Will report results.

Good news! I did all the above and the drone decreased some but not enough to suit me. When I got back to the garage after a test run, I decided to remove the engine cover and see any effect and sure enough the drone disappeared almost entirely. I suspect I had the area around the engine insulated so much that the remaining engine sound wave was getting forced through the firewall and into the cabin. That's all I can figure (doesn't make much sense but who cares). I'll slowly remove all the weights, hanger, and extra engine cover insulation I added one at a time to make sure they're not necessary. The oe hood insulation is all that's needed on top. Sometimes a little perseverance pays off.

Glad you got it figured out. I took my engine cover off the day I bought the car. Coincidentally a local member needed one so I gave it to him.

I'm so happy I polished my headlight covers and added HIDS today. WOW. All the B5.5 should have been oe HIDs.

It was slightly loose motor mounts. Torqued 'em down tight.