Page 18 - Spring 2018 GMC Vintage RVing

Technical Corner MAINTENANCE, PARTS, TIPS, INNOVATIONS AND MORESpring GMCMI Convention Tech Sessions>> Aligning and Adjusting the GMC’s Steering Column| Alex FerraraNothing scares Alex more than a coach that has the wrong or mis-adjusted steering gear. Why? During this presentation, Alex showed the audience several examples of broken ball joints. These problems, if left unattended, result in bad stuff happening. Alex is on a mission to get as many coaches as possible to drive safely straight down the road without constantly having to fight the steering wheel. Then he proceeded toshow how to make sure the steering mechanics are set correctly.First, the steering gear box is unique to the motorhomein that it has internal stops.If the steering gear comesfrom any local auto partsstore, it will not have thesestops so when turningsharply right or left the onlything stopping the travelare stops on the knuckle.The extreme pressure exerted onthe ball joints at that point can causethe ball joints to crack. Furthermore, Alex explains that if the steering gear is not adjusted properly similar problems can occur. He then spent time explaining and demonstrating how to properly adjust the steering gear to ensure it ison “high point”. As a “field trip” Alex demonstrated (on several coaches} the procedures necessary to check and correct problems withthe steering system.>> Upgrade Designs:Three Point Seat Belt, Quad Bags, Reaction Arms | Rick FlanaganRick is an engineer by trade and has been a GMC Motorhome owner for many years. He has used his talents to help deliver unique high quality (and safe) products to the GMC Community. In this discussion, he described how the three point seat belt system is designed. The unique mechanism he developed to attach the 3rd point to the sideof the motorhome allows for easy installation and adjustment for different seat configurations.Aftermarket air bag systems have become available out of necessity when Firestone discontinuedthe manufacturing of the original air bags. Rick looked at several alternatives for using 4 bagsand came up with improvements to eliminate shortcomings in those designs. The resulting Quad Bag System has become the top of the line air bag replacement alternative.Braking is another area that has been a challenge. The original brakes, when properly adjusted provide adequate braking but with onedisadvantage, the rear most wheels tend to lock up during a panic stopcausing the tire to “flat spot” resulting in an annoying“thump, thump, thump”. This “weakness” resultedin a lot of smart guys working on a way to minimize this issue whileimproving overall braking capability. The reaction arm braking system was the result.During the presentation, Rick explained the development of the system and the testing he was involvedwith to finalize a product. At Applied GMC, where the testing was conducted, they wore out sets of used tires. Rick shared videos of many stops highlighting the differences between a stock setup and the reaction arm system showing that with the reaction arm, the rear most tire would not “lock up” but contribute strongly to stopping the coach.>> No-Nos for our 425s | Manny Trovao Manny has been rebuilding the 425 transmission for the GMC Community since 2000. His current count is well over 900 units. In this presentation, Manny related some of the things you should NOT do in order to minimize damage to the transmission. Do not run low on transmission fluid. If you are low, then the pump could end up pumping air which will lowerfluid pressures causing bad things to happen. When going down a steep grade, do not shift to second gear at high speeds. If you are goingAttendeeCommentWas better than I expected. Plan on attending another Convention. Thank you. member three years, first Convention18 GMC VINTAGE RVING MAGAZINE | GMCMI.COM