Replacing both brake shoes a smart move

Hey there, time traveller!
This article was published 12/03/2004 (8053 days ago), so information in it may no longer be current.

QUESTION — I have a 1986 Ford F150 pickup and have a question about the brakes. I recently had new rear brake shoes installed. Now, less than four months later, one rear axle seal has started to leak. I took the truck to the repair shop to have the seal replaced, and they tell me I need new brake shoes on both rear wheels. Do I need to have the brakes replaced again?

ANSWER — You do need the brake shoes replaced again. The set of shoes on one side is probably soaked in gear oil. Even if you wash the shoes in solvent, all the oil cannot be removed from the lining material. The oil will come out of the shoes during braking and cause the brake to drag or grab. This could cause a loss of vehicle control because of uneven braking.

The brake shoes on the other side may be good, but it is good practice to always replace the brake shoes for the complete axle. The amount of friction produced may be different between different types and manufacturers of brake shoes. Your Ford will have wear on the brake shoes on both sides, so putting new shoes on one side and seated in shoes on the other side can cause the truck to brake unevenly.

I have seen vehicles that have had brake shoes replaced on only one side, And the vehicle worked OK after it had been driven for a few thousand miles (kilometers), but braking was uneven at first. Brake shoes are pretty cheap, so why take a chance on your brakes? Replace both sides and be ready for that sudden stop.

QUESTION — I have a 1987 Pontiac Fiero with a 2.8-litre V6 engine. The car has been good transportation, but a while ago it started to buck or miss occasionally. I had a tuneup done but the car still bucks sometimes and it seems to be doing it more frequently. I have noticed that it always seems to happen while I am driving to work at about 30 mph (50 km/h). It seems fine at other speeds. If I step on the gas when the car bucks, it smoothes out and drives normally. I have checked the computer for trouble codes but there are none. Where should I look for problems?

ANSWER — Many parts and connections can cause driveability problems on fuel injected engines but I suspect you have a bad throttle position sensor. Your problem seems to occur at the same speed, which corresponds to approximately the same throttle opening. If you spend a lot of time driving at one speed, the throttle position sensor wiping contact wears a bad spot on the resistor. The voltage signal to the computer momentarily drops and the computer reacts as if you had closed the throttle. Fuel is turned off and the car bucks or hesitates.

I have seen this problem occur on throttle position sensors from various manufacturers. The clues are that it always occurs at the same speed, and it progressively gets worse with time. The fix is to replace the sensor.

Some cars require the throttle position sensor to be adjusted after installation to show a specified voltage. Your Fiero does not require this. Simply position the sensor on the side of the throttle body and tighten the mounting screws. The computer will look at the voltage signal from the sensor the next time the key is turned on and recalibrate itself for closed throttle voltage.

QUESTION — I park in a heated garage and my son told me to keep my gas tank full in winter. I only drive short trips. Do I need to fill it up every time?

ANSWER — Keeping your gas tank full prevents water condensation from forming inside the tank when you drive it outside. The water could then freeze and block the fuel line, stopping your car. It is wise to keep the tank full but you do not need to fill it every time you drive. Even though spring is near, adding gas line antifreeze is advisable. Water sitting in the bottom of the tank will mix with the gas line antifreeze and flow through the engine. This doesn’t harm the engine but will help prevent corrosion buildup and possible rust through of the gas tank.

Jim Kerr is an experienced mechanic, instructor of automotive technology and freelance journalist. You can e-mail questions to Jim at the address below.

kerr.jim@sk.sympatico.ca