Hey everyone,
I'm having some issues tracking down the cause of my rear diff issues. So here's the backstory:
I purchased a used 2003 Cobra IRS unit that was blown up from a hard launch with slicks. I ended up nabbing a used center pumpkin to replace the blown unit (I didn't rebuild the center diff at this point).Because this was going into a T-45 transmission instead of the T-56, I reused the pinion flanged from the '97 cobra SRA housing and mated it up with a shortened aluminum Ford Racing driveshaft. I replaced the DSS level 5 halfshafts with some used OEM '03 half shafts with about 30k miles on them and mated them with new Ford racing hub bearings. All bushings were replaced with the FTBR delrin kit while I had everything apart. I put everything in and torqued to the prescribed specs from FTBR. I drove it around to listen for anything unusual and it drove like a dream. That weekend I took it on a rigorous drive through some canyons. A couple of weeks later, it started popping, chattering, and making all kinds of noise. Several months later, I had the center pumpkin rebuilt at a local shop keeping the stock 3.55 gears and filled with Royal Purple rear diff fluid (Note: minus Ford racing friction modifier). Just yesterday I went through all of the bolts and they were loose by about 30% of the prescribed torque specs. I tightened them back down to spec and it seemed to have stopped the popping noise that happened when backing out of my driveway with a curb. I will also note, that I haven't checked pinion angle, only set the front aluminum spacers to what Bruce recommended in his video.
Now, onto the problems...when coasting in neutral, it chatters. When decelerating, it chatters, rattles and almost sounds like something is loose in the back. When shifting, there's a loud, metallic clunk. I've put the rear of the car on jacks and rotated the wheels forward and backward and I'm able to recreate the clunking. There's no play in the cradle or center diff. To settle the road noise and gear whine, I just purchased the MM poly bushings for the front and rear mounting points on the subframe cradle as well as front and rear bushings for the center diff. As far as the loud clunking and chattering, what could be causing this? Is the fact there's no friction modifier causing the loud clunk? I think it could be causing the chattering but it almost seems like something is loose. Can someone help guide me in the right direction? The way it feels when driving, the clunking and chattering are probably related.
I'm having some issues tracking down the cause of my rear diff issues. So here's the backstory:
I purchased a used 2003 Cobra IRS unit that was blown up from a hard launch with slicks. I ended up nabbing a used center pumpkin to replace the blown unit (I didn't rebuild the center diff at this point).Because this was going into a T-45 transmission instead of the T-56, I reused the pinion flanged from the '97 cobra SRA housing and mated it up with a shortened aluminum Ford Racing driveshaft. I replaced the DSS level 5 halfshafts with some used OEM '03 half shafts with about 30k miles on them and mated them with new Ford racing hub bearings. All bushings were replaced with the FTBR delrin kit while I had everything apart. I put everything in and torqued to the prescribed specs from FTBR. I drove it around to listen for anything unusual and it drove like a dream. That weekend I took it on a rigorous drive through some canyons. A couple of weeks later, it started popping, chattering, and making all kinds of noise. Several months later, I had the center pumpkin rebuilt at a local shop keeping the stock 3.55 gears and filled with Royal Purple rear diff fluid (Note: minus Ford racing friction modifier). Just yesterday I went through all of the bolts and they were loose by about 30% of the prescribed torque specs. I tightened them back down to spec and it seemed to have stopped the popping noise that happened when backing out of my driveway with a curb. I will also note, that I haven't checked pinion angle, only set the front aluminum spacers to what Bruce recommended in his video.
Now, onto the problems...when coasting in neutral, it chatters. When decelerating, it chatters, rattles and almost sounds like something is loose in the back. When shifting, there's a loud, metallic clunk. I've put the rear of the car on jacks and rotated the wheels forward and backward and I'm able to recreate the clunking. There's no play in the cradle or center diff. To settle the road noise and gear whine, I just purchased the MM poly bushings for the front and rear mounting points on the subframe cradle as well as front and rear bushings for the center diff. As far as the loud clunking and chattering, what could be causing this? Is the fact there's no friction modifier causing the loud clunk? I think it could be causing the chattering but it almost seems like something is loose. Can someone help guide me in the right direction? The way it feels when driving, the clunking and chattering are probably related.
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