As most of you known, it seems that about half of the 2000-2005 Bonnevilles have some degree of front end shudder at 60 to 70 mph. Mine was solved with cleaning of the stock rims on my 2002 sle. The rims had large lumps of debris and brake dust, some lumps the size of wheel weights. I have never seen this much harden debris on wheels before, and I have owned a lot of vehicles in my 60 years. It seemed especially strange given the overall excellent condition of the car when purchased.

I recently replaced the stock rims with new ones because the stock rims continued to rust from the pitting cause by the debris. I tired to sand and seal the stock rims but it just did not work and a bit of shudder returned at about 60 mph. New rims, tires balanced but the small bit of shudder (about 15% of the amount from the original problem) was still present. I was going to get the tires road force balanced when I found a shop that had the right equipment.

Last week as part of my regular maintenance, I siphoned out 2 quarts of transmission fluid and replaced with 2 quarts of new dextron III. I started to do this with my cars with automatic transmissions years ago after having to rebuild several transmissions on late 1980s and early 1990s front wheel drive cars. I took the Bonny for a spin and it drove like new, no shudder at any speed. I drove it some every day for a week and no shudder.

I recall some people on the forum had the shudder problem sovled after some transmission work. I had the transmission fluid and filter changed when I purchased the car, but a regular transmission fluid drain only gets about 50% of the old fluid out. I think that the last 2 quarts of fluid did the trick.

If you have the shudder, you may want to give this a try. Dextron III is no more expensive than motor oil so this is not expensive and you should be able to siphon out 2 to 4 quarts of fluid in less than 20 minutes with a $15.00 pump that you can get at the local auto parts store. The transmission tube will easily accept a 1/2 inch outside diameter hose.

Hope this helps, even if this does not work for your shudder its good for your transmission.