Q. Tony

Where can I go to look for unique, low-budget parts and accessories for my 1990 Camaro RS? It has 305 with a 700-R4 transmission. Keep in mind I want to convert to a manual transmission in the future. I purchased the car not too long ago, and I don’t know where to begin my search. So, I figured the best course would be to ask the professionals at Camaro Performers.

I have a subscription to your magazine and I like it ... for the most part. I’m a member of the Third-gen Mafia, if you catch my drift.

The RS is most likely going to be a long-term project for me and I don’t want to pour in a whole bunch of my hard-earned greenbacks.

Thanks,

Anthony P.
Via camaroperformers.com “Contact Us” page

A. Anthony,

C’mon, you know the staff here at Camaro Performers magazine likes third-gens. I, myself have owned two and plan on owning more in the future. We’re equal opportunity Camaro lovers. In fact, check out some serious devotion to third-gens in the Resto Shop column in the previous issue (October 2013). We include all the cool third-gens we can get our cameras on, and we’re always looking for more.

What kind of unique parts are you looking for? Are you looking for flashy parts or functional parts? Do you have a performance goal? Since you subscribe to Camaro Performers, you see all the advertisers and the parts they offer. If you are looking for used parts at a discount, you should check the auction and “list” sites on the Internet. Some pretty cool stuff can be purchased at really good prices. Car shows with swap meets are a good source for deep discounts, too. Salvage yards are another good source. We’ve seen some pretty cool parts on salvaged and wrecked cars. We once found a beat-up second-gen with a good engine for $300. It turned out to be a high-compression engine pumping out over 500 hp.


Q. Tony,

Back in the day, I bought a new 1978 Z28 with a 350 and a four-speed. Since the day I drove it off the lot it has had a bad vibration starting around 75 mph and gets worse all the way up to 90 mph, where the vibration doesn’t get any worse or better. The dealer changed the harmonic damper, rebalanced the tires, and may have changed out the flywheel.

None of these fixes worked. Over the years, I have replaced tires and rims, had the engine rebuilt (balanced and blueprinted) with 9:1 pistons and a mild Isky hydraulic cam. I have also had a new driveline built with a larger diameter tube. The engine runs like a sewing machine up to 5,500 rpm in Neutral. No vibrations. The only way I can describe the vibration is that it is related to the speed of the car and is a very tight or short-wave type of vibration. If the shifter is against the rear stop, the vibrations are transmitted to the shifter. If I move the shifter off the rear stop, the vibration goes away from the shifter, but is still present. There’s no vibration in the steering mechanism. I have not done anything with the rearend as far as troubleshooting. The car has never been wrecked, raced, or excessively abused. Any suggestions as what I may try next to troubleshoot this problem.

Thanks for your help.

Bill Pedersen
Via email

A. Bill,

WOW! It sounds like you’ve been pulling your hair out for a while trying to find this vibration issue.

One of my first thoughts was that the driveshaft may be out of phase (universal joints clocked 90 degrees off of each other). Properly phased universal joints are in the same clocked position in the front and the rear. Universal joints out of phase are not a common occurrence, but it has happened. Since you said that you’ve replaced it already, that turned into a fleeting thought. It truly sounds like it has to be in your rearend. Not the one you sit on. I’m referring to the one mounted to your leaf springs.

Have you attempted to check how “true” your axles are by using a dial indicator with the brake drums removed? An axle could have been machined improperly from the factory. An axle could be slightly bent. I used to work at GM, and I’ve seen some cars get seriously abused before they end up on the lot of a dealership. A Teamster or a truck driver could have taken your car for a joyride and hit a curb before you received the keys to your brand-new pride and joy back in 1978. Most likely you would have noticed the brake shoes on one side wearing more than the other. It doesn’t take much to cause a vibration like the one you’re experiencing.

If you haven’t already, check the pinion yoke on the rearend to see if it may have been machined slightly off-center. If the pinion yoke universal joint cups are improperly machined, the driveshaft could be whipping around and cause the car to shake at higher speeds. You would probably need to measure the runout of the rear of the driveshaft with a dial indicator with the car up on jackstands. This would allow you to rotate the driveshaft.

If the problem increases or decreases while accelerating or decelerating in the trouble range, you may have pinion angle problems. Also, check the angles of the driveshaft. Changing the ride height of your car can change your pinion angles and cause unwanted drivetrain vibrations. Since you’ve had this problem since you purchased the car, pinion angles are probably not your issue but still worth a look. You can measure the angle of your crankshaft/transmission output shaft as well as your differential pinion angles with a basic angle gauge. For best results, the car should be level (easiest to accomplish on a drive-on rack). A production leaf spring car should have about 3 degrees down on the transmission output shaft and about 3 degrees up on the differential pinion angle. These add up to 6 degrees of difference. Seven degrees is about the maximum for long universal joint life. Three down and three up should get you a pretty smooth ride. If you’re way off of these measurements, you can get some angle shims to adjust the pinion angle or you’ll have to figure out a way to shim the transmission mount to get it within spec. If your car was a moderate- to-high-performance Pro Touring leaf spring car, you can adjust the differential pinion angle to as much as 3 degrees down before you may start noticing chassis vibrations. The variation from stock and high-performance angles has to do with combating the amount of leaf spring wrap-up from applied power/torque.

Good luck!