Hello Racers, this is a general break down on what I feel is important to inspect on your 1/8 offroad truck or buggy to keep it running at peak performance after a hard weekend of racing. Most may think that factory drivers are constantly building new kits for major events during the year, maybe some do but the majority of us don’t. This will help you know what to look for when you decide to go through your car and clean it up or replace parts. Its difficult to say exactly when this should be done because the types of tracks you race on determines whether or not it should be done often or not so often. Obviously more often the better. Before attending an event, preparing your car should never be overlooked, especially racing nitro.
Drive-train (axles, differentials, gears and bearings)
Axles should be replaced when you noticed the pins are worn flat, bent or has slop in the joint. Some manufactures offer a tool and pins to save money than completely replacing and axle. The flat surface of a worn pin creates friction in the out-drives and will cause the car to handle inconsistently and could wear your out-drives out sooner. If I notice this and I am attending a smaller event, most of the time I would just flip the axles from the left side to the right side and vice versa. Completely replacing the axle is still best however I haven’t had any issues flipping the axles. Any degreaser or brake cleaner works good on cleaning the axle joints up, don’t forget to re grease. Be sure to wear protective gloves and mask (you don’t want cleaners absorbing into your skin and inhaling the fumes).
These days differentials hold up pretty well on most buggies and truggies. When inspecting the front, center and rear diffs it is good to look at the conditions of the ring and pinion gears, the groove of the out-drives, if the diffs are leaking, the groove inside the diffs that the cross pins are guided by and the bearings. Keep an eye on the teeth of all the gears especially the front and rear pinions, replace if you notice chipping or wear to the teeth of all the gears in the car. Tip: Try to keep gears that touch each other together for the life of those gears, premature wear or loud gear mesh is why I try to keep those gears together. Out-drives should be replaced (or you can flip them left to right like the axles) if you see a notch or groove in the slot for the axle pin. I have seen many axles snap or bend because of a notch in an out-drive. This happens because as your suspension moves up and down the axle pin is slideing in and out of the out-drives and that notch will lock the axle pin and not allow it to move correctly in the out-drives. Be sure to always use a little grease on the neck of the out-drives before you slide it back into the differential. Leaky diffs can be annoying and fixing the diffs so they never leak is sometimes difficult. Some tips for leaky diffs is to sand the surface slightly of the diff housing where the gasket touches, replace worn gaskets, the squish of the o-rings inside the diffs (Some manufactures make sightly tighter fitting o-rings such as protek r/c) and try not to overfill with diff fluid.
The outer hub and clutch bearings usually will wear faster than the internal bearings of the differentials and pinions. Tip: balancing your tires will make your hub bearings last longer as well as your hubs and arms. Unless you race on an extremely clean track, I have never been a huge fan of oiled bearings I have always preferred using grease if your concerned with the life of the bearings. Clutch bearings should never be used without any lubrication, oiled clutch bearings can cause the clutch shoes to slip and using grease instead is harder for the lube to get onto the clutch shoes and bell. Replace any bearing that feels gritty, sometimes you can carefully pull the seals off the bearings and use brake cleaner to flush out any old oil/grease and dirt, re lube and press the seals back into place (I don’t recommend doing this for clutch bearings, its best to just replace). Engine bearings should be replaced immediately if you hear any hi pitch whistling while the engine is at an idle (be aware that it could be a dried out clutch bearing sometimes).
Shocks (shock boots, shafts, o-rings/bladders, pistons, shock bodies, shock ends and caps, springs)
Shock boots are the most important part of the shocks to keeping all the internal pieces working properly and the life of the internal pieces. Shock boots are used to keep all the outside elements from entering the shocks as well as scratching shock shafts. Replace shock boots if you notice any tear or hole in them, if there is no problems with the boots soapy water works best to clean them (stay away from brake cleaner as it could dry out the rubber). Replace shock shafts if they appear scratched or bent. You can tell when to replace o-rings by feeling how smooth the shaft slides in and out or if your shock oil appears dirty. Over time silicon shock oil can make o-rings swell and they should be replaced. Replace shock bladders if your shock caps are leaking or if the bladders are torn (careful not to over tighten the shock caps). Shock pistons do wear out over time, they tend to rub against the shock body and eventually you’ll get slop between the outside of the piston and shock body. Also if you notice your shock oil is not clean this could be due to you wore past the hard anodizing of the shock body or dirt entered through the o-ring assembly (this can cause the shock body and piston to wear faster than normal). Replace the shock ends, caps or cap inserts if you notice slop. Shock bodies should be replaced if they got dented or worn past the inner hard anodizing. Shock springs can be difficult to tell if they need to be replaced, one way to tell is if one of the front or rear springs are longer or shorter than the other side. Having alot of time on a set of springs will change the rate as well. Don’t get lazy on replacing shock boots, in the long run it will save you money on replacing other parts inside the shocks and keeps those parts working properly.
Plastics (arms, hubs, inserts, linkages/tie rod ends and bulkheads)
Lower arms should be replaced if you notice any cracks in the webbing, out of round hing pin holes, or warped (meaning if they are bowed or twisted). If my arms don’t have any of those issues I will clean them with soapy water and clean the hing pin holes with a pipe cleaner. WD-40, Pledge, and UpGrade plastic cleaners will make old dried out plastic look new again (just be sure to dry off the plastics good so dirt or dust doesn’t collect on them). If you notice a lot of play between the plastic linkage/tie rod ends and the ball that snaps inside they should be replaced to keep your car working properly. When to replace a front or rear bulkhead? If you ever stripped out a ring or pinion gear this could cause the plastic inside bulkheads to warp and there is more of a chance that those gears will strip again. Replace the bulkheads if a screw striped the plastic inside a hole (any hole). Keep an eye on if the bulkheads are tweaked, a good way to tell is if the shock towers don’t look strait or your ride height isn’t the same left to right (this also could be caused by a bent hinge pin, twisted chassis or bound up shock). Caster blocks, rear hubs and hing pin inserts should be replaced when they become sloppy.
Chassis and Hing Pins
A twisted or tweaked chassis is never good and it is extremely difficult to get your car to handle correctly again without replacing the chassis. I like to completely disassemble all parts bolted to the chassis and place it on a flat surface and see if twisted, a bowed chassis isn’t good as well but not as bad as a twisted one. I also keep an eye on how thin the rear of the chassis gets, I have worn them down so much in the past where dirt can enter the inside of the bulkhead and cause premature wear to the ring and pinion gears and bearings. On most cars the inner hing pins hold up pretty well, its the smaller outside ones to keep an eye on so they are not bent. If I have a bad wreck on the track before I run next I will check to see if I bent a hing pin or chassis, a good way to tell if its bent is to roll the pin on a smooth surface and see if its true or if its a hing pin that has an allen hex on the end you can put your wrench in and turn the hing pin while its in the hub and see if the hub rocks back and forth or side to side (if it does its bent), if your hub uses setscrews loosen those first.
Engine (air filters, engine bearings, glow plugs, clutch, exhaust pipe/header, and gaskets)
Replace air filter foam as often as you can, don’t cut corners on this and use a hi quality air filter oil. Keep the air filter boot clean as well when pulling your car apart. Engine bearings should be replaced immediately if you hear any hi pitch whistling while the engine is at an idle (be aware that it could be a dried out clutch bearing sometimes). If you are having engine tuning issues, replace your glow plug first before doing any drastic tuning to the carb. A way to tell also if you have a glow plug that works but you want to see if it needs replacing is to fire up the engine, let it get up to temp and while at an idle put the glow igniter on and if the idle seems to rise, you should replace the glow plug. When you have a brand new clutch its good to measure the diameter of the shoes when they are installed and save that number, when you notice the clutch not working as well as when it was new try to remeasure the dia. again before running next, doing this will hopefully tell you so you know before hand (some clutches will slip when they get worn down and some will bog down the engine, it depends on the brand/type). Your exhaust pipe and header should last a long time if its not bent or dented, keep an eye on the holes for the manifold springs (these can eventually wear past the outer material). One of the best ways I have found to clean a pipe is to find a crock pot (that you’ll never use for cooking again) and fill with antifreeze and let it heat with the pipe and header over night, all the exhaust build up should flush out easily with some brake cleaner (thanks to Barry Baker for that tip)! Exhaust gaskets should be replaced if they have become hard, cracked or you notice exhaust leaking after you run.
Thanks for taking the time to read this and more in depth tuning and tip blogs are to come!