Grinding of Gears Causes Major Damage
Question: In the past year, somebody driving my Saab 900S attempted to shift into reverse while the car was still creeping forward. A couple of gear teeth were destroyed in the manual transmission. Needless to say, I am not happy. The Saab owner’s manual warns the vehicle must be fully stopped before shifting into reverse, but nobody really seems familiar with this peculiarity. My Saab dealer tells me it will cost $1,500 to $2,000 to repair the damage and that I would be better off just replacing the transmission. The instrument panel contains no warning.--H.R.S.
Answer: Very few manual transmissions have synchronized reverse gears. Synchronization is a system in the transmission that brings gears and shafts to equal speeds and allows a motorist to shift while the car is in motion.
There is an implicit rule of motoring that one should never shift into reverse while the car is going forward. It is one of those things that is taken for granted, and manufacturers assume motorists will not do it.
Saab installed a reverse-gear brake system in its cars in 1978, which helps equalize the speed and stop the transmission shafts when shifting into reverse. That helps eliminate the problem of gear grinding that occurs when shifting into reverse quickly after coming to a stop. But it does not permit shifting into reverse while you are still going forward.
One good bit of news for you is that the repair estimates you were given seem to be high. According to Saab’s guide for estimating repair labor, the job of removing and replacing the slider, reverse gears and related bearings should be about 12 hours. Even at a high labor charge of $50 per hour, that amounts to about $600. You should certainly be able to get the transmission fixed for under $1,000.
Q: I have a 1978 Lincoln Mark V, which has the original radial tires. My husband says before we leave on a long trip this summer, we should have new tires put on. I say no, because the tires have only 24,000 miles on them and there is plenty of tread. What do you think?--K.B.
A: The issue of when a motorist should replace a tire simply because of old age, rather than wear, is a touchy one among tire experts. Nobody wants to take an unnecessary risk, but nobody can agree on how old is too old.
You should certainly consider a number of factors in making your decision. Are the sidewalls cracked and worn? Is the tread worn evenly or is one side starting to go bald? Is any cord body exposed? Is there any evidence of belt or tread separation? Do the tires leak air?
Some manufacturers will advise that you do not need to replace tires simply because they are old. Similarly, some manufacturers do not recommend replacing tires that have high mileage if there is adequate tread on the tires.
You may want to have the tires inspected by a reputable tire dealer. If he recommends replacing them, you should insist on knowing specifically why he is recommending that you get rid of tires with good tread left. If you finally decide to buy new tires, you may be able to negotiate a trade-in for your old tires.
