Car: 2005 legacy gt wagon automatic high miles 200,000 Modifications: 9.8:1 pistons, h-beam rods, Sti crank, Megan up pipe, Cobb down pipe, vf52, Perrin silicone intake hose and inter cooler. Problem Description: any time I accelerate enough to make the back end of the car squat a fair amount, there is a loud growl in the rear of the car. It sounds like the driveshaft is dragging on the underside of the car... Recent Modifications/Maintenance: I have recently replaced ALL of the control arm/suspension bushings as they were all getting really tired looking. I bought the car with a grenaded motor. (About 10,000miles ago) I did all of the engine mods at that time, so it has made this noise ever since I have owned it. I am suspicious it has to do with rear differential mounting/bushings. I have THOROUGHLY looked under the rear of the car. I can see no “witness marks” on anything (suggesting that there are parts contacting each other). I see there are lots of bushing inserts for sale, for the rear diff mounts. The rubber ones in the subframe that have the gaps in them. Do these help? Is this what they are for? I think the bushing in the “saddle mount” at the front of the rear diff are looking pretty tired also. Can anyone suggest where to buy some good replacements? I only see the mount offered as a whole. *as a note, I generally try to keep this car nice and quiet and incognito. I’m not really a fan of poly bushings. Any help is greatly appreciated!
Get the rear on stands and pull on things. Check to make sure it's not a wheel bearing by pulling the wheel up and down (or pushing the top in and out / camber). Also check that the axles and driveshaft don't have a ton of play. I'd double check for any scraping/rubbing marks on the wheels, tires, wheel wells, mudflaps, struts, exhaust.. Ect. If a visual check comes back happy, check the dif oil in the rear (may want to replace it) for glitter or chunks of metal. Usually there's play in the axels if the dif is mechanically failing. Ive never had bad bushings make a growling noise, only thuds and bangs. Unless the dif noise is being transferred into the chassis by metal on metal contact. Try jacking the rear up by the dif itself and check the clearances between the chassis.
The carrier bearing in the middle of the two piece driveshaft perhaps? As for replacement bushings, not much help there sorry
https://imgur.com/gallery/crh4hCF https://i.imgur.com/a1rVZWP.jpg So this turned out to be the rear inner cv joint. I could have sworn it was the right (passenger’s) side. I removed the axle and inner boot to have look, and it was fine. However, the grease was old and dry looking. So I cleaned an re-greased it. Then for good measure, I did the same to the other side. AND WHAT DO YOU KNOW! The inner joint is grinding itself up! 1 new axle (on the driver’s side) and the car is mint! Or at least as mint as a 14-year old, 250,000mile car can be.
