Discs-G0-Rear
Q: I have an '01 GMC Sonoma regular-cab pickup with the 4.3L V-6 and five-speed manual transmission. I've lowered the truck and fitted it with 18-inch wheels and tires. I have the 3.42:1 Posi-traction rearend. I like driving fast on country roads, so I've taken kind of a sports car approach to the truck. I'm happy with the suspension and engine, but I'd like to upgrade the brakes by installing rear disc brakes. I don't care for the rear drum brakes.
Would it be possible to install the rear disc brakes from an S-10 or S-15 4x4 on my truck? Can I still my current brake lines and emergency-brake cables?
Matt Brown,
Dallas
A: The general answer is yes, with a few cautions. Your drum-brake truck uses the same style four-bolt backing plate flange as those used on disc-brake rearends. You need to be sure that the axleshaft end is the correct diameter to fit tightly and align the rear discs. If the fit is either too tight or too loose, some machine shop work will be necessary to get a proper fit.
You will need some new brake lines along the rear axlehousing. Just like your front disc brakes, the new rear discs require short lengths of flexible brake hose between the hard line and the calipers. With your current drum brakes, the hard lines go all the way to the back of the wheel cylinder.
You can most likely use your current parking-brake cables. There is probably enough slack to handle any minor differences between your old drum brakes and new disc brakes. If your old cables won't work, replacing them with correct cables isn't a big deal. You can buy new cables at your local GM parts department or get some wrecking-yard cables. We'd spend a few more dollars and get new cables.
When shopping for your rear disc brake assemblies, try to find a wrecking yard that understands what you're doing. Explain your project and be sure you can trade for another set in case there are any unexpected fitment problems. A knowledgeable dismantler has the reference sources that should be able to pinpoint the right donor vehicle. You're most likely to find the rear disc brakes on a 4x4 pickup or SUV, but you might also find them on some extended-cab two-wheel-drive pickups.
It's possible to find an entire disc-brake rearend and install it. If you go this route, be extremely accurate about your measurements. You should be able to use a rearend from a '99-'01 4x4 or a '98-'02 two-wheel-drive S-series truck or SUV.
Less Lugs
Q: I have a '92 Nissan King Cab pickup that I'm trying to build on a tight budget, since I'm still in school. One of the first things I'd like to do is convert from six-lug to five-lug wheels. A friend told me that the trick deal is to swap for Toyota hubs. If this is so, how difficult would it be for a novice like me to do? Is the swap the same for both ends of the truck?
Jeremy Johnson,
via e-mail
A: The good news is that Toyota five-lug hubs will fit on many mini-trucks, such as Nissan, Mazda, and Mitsubishi, because they use the same front wheel bearings. The bad news is that we wouldn't recommend that a novice do this swap. Any time you're dealing with front suspension and brakes, you're dealing with your safety. We suggest you find an experienced shop that has done this swap before.
For your truck, an '89-'95 Toyota five-lug hub and rotor will bolt right on your spindle. You need a grease seal to adapt the Toyota hub to your spindle. A good old-fashioned auto parts store (the kind that still does machine work in the backroom) should be able to find the right seal. Your truck will also need a spacer between the spindle and the brake caliper so the caliper will bolt up properly. Depending on the spacer thickness, you may also need longer mounting bolts.
Out back, you have two choices. The less expensive course is to find a competent machine shop (notice how important a good machine shop is to this whole swap) that can re-drill your existing axle flanges to the Toyota five-lug pattern. The more expensive option is to install a complete Toyota rearend.
The easiest choice of all is to find some six-lug wheels that you like. When you consider the cost and hassle of converting hubs, some of those six-lug wheels might start to look a lot more attractive.