2005 Chevrolet Tahoe Shocks, Shock Hoops, Custom Mounts - Rosco P. DrivetrainPosted in Project Vehicles on July 7, 2015
The control arms and front suspension brackets that we’ve showed you in past installments of Rosco P. Drivetrain are just part of what’s necessary to keep our former law enforcement Tahoe on the road and trail. We also need shocks and springs that help hold the body and frame sprung weight (as opposed to unsprung weight) off the bumpstops, tires, and the ground. Sure, you know the rear suspension is being held up by a set of off-the-shelf Skyjacker 3 1/2-inch springs, and you know we’ve talked about coilover shocks for the front in the past, but we were not sure what shocks we needed both in terms of travel and body size. After a few emails and phone calls a few fancy parts from Sway-A-Way were on their way to our driveway where we could make sure they would work. Given our desire to keep the 2005 Tahoe road drivable yet capable off-road, Sway-A-Way sent us two 12-inch-travel, 2 1/2-inch-body, remote-reservoir shocks with mounting hardware to run dual-rate coils up front. Out back we will use a pair of 10-inch-travel, 2 1/2-inch-body, remote-reservoir shocks.
There are several steps we need to take in order to mount these shocks on the Tahoe, and that involves a few more parts and more than just a little bit of fabrication. With more help and guidance from our pal Rob Bonney from Rob Bonney Fabrication, building and gathering all the right parts was a cinch. Bonney helped us understand what needed to happen and either showed us how or helped us make the various parts. That means our Tahoe is almost standing on all four tires as we write this. We also got a chance to do some fender trimming up front and to go through that NP241C that we showed you in Part 2 at www.fourwheeler.com.
Next time we will be wrapping up a few loose ends of the project, like how we decided on coilover spring rates, and the gearing. With any luck we may just get some time in the dirt with ol’ Rosco!
With the four-link front suspension assembled under the front of the Tahoe, the next step was to add a stout hoop system and coilovers to the front suspension. Since we are building off the front framerails it was decided that adding a 1/8-inch plate to the area would be a good way to reinforce the frame. We started by making a template out of cardboard with tabs for the shock hoops (two top tabs) and one for the track bar mounting area. With the template in hand we went over to Rob Bonney Fabrication so Bonney could cut the 1/8-inch plates. He added the strategically placed holes where we can rosette-weld the plate to the frame.
To attach the plate, use large clamps to hold the plate flat and then tack it into place. To match the contours of the frame, you may need to do persuade the 1/8-inch plate with a hammer. Hammer, tack, hammer, and tack some more. The rosette welds will help ensure that the plate is one with the frame. The tabs fold over on the frame to add beef to the areas where the track bar and shock hoops will be welded on. Again, these tabs are attached using a hammer and plenty of tack welds. Once the parts are in place you can finish-weld the edges of the plate to the frame.
All of the force from the front axle and front suspension will be transmitted to the frame via the shock hoops. They need to be strong. We started fabricating our shock hoops by bending up two tubular hoops. Then cope the ends to match the surface of the tabs from the plate just added. The hoops, one per side, will be connected via bridge that runs over the engine.
With the shock hoops started we knew we would need upper and lower coilover shock mounts. Bonney cut us these tabs and allowed us to cut 8 1/4-inch sleeves on his lathe from some 3/4x0.120-wall tubing that has a 1/2-inch inside diameter. Once home we welded the sleeves into the tabs and added the tabs to the axle and the shock hoop.
We also used Bonney’s lathe to make a few spacers that are 0.30 inch wider than the misalignment washers from our 12-inch-travel front Sway-A-Way shocks. The spacers allow us to mount the shock tabs to the hoops and axle. That extra width allows the shock ends to slide in and out when we are installing or removing them. Also visible are the short runners that will go up from the hoops to meet the aforementioned bridge.
With both hoops temporarily tacked in place we moved on to building the bridge. The hoops and the main part of the bridge are made of 1 3/4x0.120-wall DOM steel tubing. The additional tube runs from the upper shock mount to the bridge to prevent the top of the hoop from twisting (like a torsion bar) as the suspension loads and unloads.
Once the shock hoops and tabs were all mocked up and the bridge was tacked together we removed the whole system so we could finish-weld without risking melting or burning nearby wires and hoses. Having the hoops and bridge out of the truck also gives a good idea of how it all goes together.
For the lower coilover shock mounts we first removed the factory Dodge lower coil perch from the AAM front axle using a plasma cutter. This 3/16-inch plate, again cut by Bonney, takes its place and helps tie the whole control arm mount and track bar bracketry back together. The two lower shock mount tabs are welded to the AAM’s axletube. This gives us all the uptravel we can get out of the coilovers. The slots along the sides of the plates allow us to weld the plate to the factory brackets below it. We also tested for clearance of the lower coilover coil mount. The blue painters tape on the shock body and shock end help prevent dings and scratches.
Up front we will be running 12-inch-travel, remote-reservoir shocks. Out back, Sway-A-Way’s 10-inch-travel, remote-reservoir shocks will fit with our Skyjacker lift coils and modified factory shock mounts. Both front and rear shocks are rebuildable and revalveable and will be charged with nitrogen once this thing is ready to roll. The shocks feature 7/8-inch Nitro-Steel shafts that are chip and rust resistant, steel bodies plated with zinc, and red anodized 6061-T6 aluminum parts.
For the rear shocks we cut eight 3/4-inch-long sleeves out of our 3/4x0.120-wall tubing. We drilled out the rear shock mounting holes to 3/4 inch. Using our spacers to allow room for the shock, we welded the sleeves in place.
With the 10-inch-travel Sway-A-Way shocks installed we just need to mount the reservoirs, charge the shocks, and tighten a few nuts and bolts. We notched part of the lower lip of the Tahoe’s frame to clear the inside upper control arm mount.
After last time we got a bit of flack from Editor Williams for deciding to run a bent rear track bar with two rod ends on each end. His argument was that the track bar would flop back up and down as forces changed. At first we thought we would just deal with that problem when it arose. Then we came across this cool 3/4-inch shanked bushing that replaced one end of our track bar. No more floppy rear track bar! (Floppy Rear Track Bar sounds like a great name for our next garage band.)
Our NP241C transfer case was from the junkyard, and we want the Tahoe to be reliable as well as fun so we got a rebuild kit from our local transmission shop. There are two NP241Cs,one with a thick bearing on the input shaft and one with a thinner bearing. We lucked out because our transfer case has the thicker and stronger input bearing. Rebuilding an NP241C is pretty simple relative to other transfer cases. Ours was in good shape but benefitted from new bearings and seals.
All along we have known we would need to trim some front sheetmetal to clear the 37-inch Micky Thompson TTC tires from National Tire & Wheel. We’ve spent lots of time trimming sheetmetal, and there is an art to doing it without the results looking butchered. By flexing the front suspension we were able to figure out how much metal needed to go. We ended up trimming out this piece of inner fenderwell. The tire will clear the outer fender when flexed and turned. We did the trimming using a plasma cutter and an air saw, and then cleaned up the cuts with our 4 1/2-inch angle grinder with a flap wheel.