As you may know the infamous “clunk” that comes from the rear of our cars (04-07 CTS-V) when the clutch is pushed in at slow speeds is caused primarily by a failed bushing the front of the rear differential. The reason for the failure of these bushings is that the OEM bushing material is very soft and this bushing is under tremendous load when the vehicle is under acceleration.
This Block was developed to assist the differential bushing in supporting the front of the differential at this time. This polyurethane block is formed to fill the void in the sub frame above the differential bushing. When installed, the Diff Block and the differential bushing work together to hold the differential in it’s correct position during hard acceleration and prolongs the life of differential bushing.
Installation is very simple, no tools are required if installed during a differential bushing replacement. Once the differential is dropped down to replace the differential bushing, this Block is simply pushed up in to the cavity in the sub-frame above the differential bushing, that’s it, reinstall the differential, the Block is now captured in position.
When purchasing the differential bushing in RED you do not need a diff block, the red bushing is rigid/stiff enough on its own.
Ryan Holloway –
Simple and effective, very easy to install when putting in the new carrier bushing.
Bert Foster –
I installed this piece along with the differential bushing and it works beautifully. I did not notice an increase in cabin noise as some have said will occur. Do yourself and your car a favor and get these pieces.
JR (verified owner) –
You have to disconnect and lower the driveshaft at the differential while it’s still in place to install this (GM service instructions warn not to drop the driveshaft below 8 degree decline). I did this by unbolting the 8 allen screws and then using a hammer to knock the driveshaft loose from the little press fit (not much force). Once this is done and then you drop the differential from its three bolts, this differential block will fit into the space DIRECTLY ABOVE the front bushing in the space where the it is mounted into the subframe. Use a hammer and large punch to get bushing block into place (some lube couldn’t hurt). Those allen screws get tightened by doing every other one around the driveshaft at 44 lb-ft with blue loctite.