Well, it depends on what you mean by saying the 'gears grind in reverse'...If the noise is while you are trying to shift INTO reverse, and if your Saab is around the 1995 vintage, then it is a common problem caused by the stretching of the non-adjustable clutch linkage cable:
The 1995 Saab (and maybe a year either side of it) used a cable from your clutch pedal to the clutch arm off the transmission. As it gets older it stretches. Reverse is the gear that will start grinding first as the cable stretches and the clutch is not actually being fully dis-engaged. Eventually the grinding will get bad enough you will have trouble shifting into reverse, and then start having grinding when shifting into 1st gear too. At least that's what I experienced.
You might be able to buy 6 months if you are a little handy, but making a "shim" out of a fender washer. Take a fender washer and cut a slit in it, wide enough that you can slip it over the internal metal cable of your clutch cable where it goes through the metal arm out of your transmission. Put it on the side toward the front of the car, between the 'ball' end and the metal arm. (You will have to also bend the washer into a semi-circle shape.) This will in effect shorten the cable, because you will have moved the arm about 1/8 inch closer to the firewall. When I did this my grinding disappeared.
But it's a stopgap. 6 months after I did this the cable started to stretch again, A LOT, very quickly, and within one day's commute snapped completely, stranding me and I had to have the car towed.
The REAL solution is to replace your clutch cable NOW before it stretches so far it breaks. If you have a dealer do this, there is an engineering change that will have them put TWO washers in place instead of the ONE washer that was originally stock...somewhat postponing the trouble from occurring again. It's pricey, take a big wallet.
This was a design flaw...it is the only cable operated clutch I am aware of that had NO provisions for adjusting the length of the cable! SAAB eventually realized it was a poor design, and by the time they came out with the 9-3 model they converted to using a hydraulic clutch instead of a cable clutch. (I'm not sure when this change was done...maybe in the 97 model year, but that's a guess on my part.)
good luck,
Paul H.
PS: I was told by the dealer my clutch had more pedal pressure than it should have, which made the problem appear quicker. They said it was due to a part that was not lubricated properly when the clutch had earlier been replaced, and they could fix the problem but it would involve as much labor as a clutch job, so I should have the clutch replaced at the same time. Their estimate was over $2000 to do this work...I sold the car before it became a problem again.
The gears will quickly grind down to junk, and you will need a new transmission.
The transmission might grind on an '88 Dodge Colt because it is very low on transmission fluid. It might also grind because the gears are damaged or stripped.
Of course it will you idiot. Think about it... while the car is going forward you slap it into reverse and the gears need to stop turning the other way BEFORE the can turn the other way around or it will grind all the gears and then you have just ruined your transmission
bad transmission
There are a few reasons for a transmission to growl. It could be that the vehicle is low on fluid, and the gears are starting to grind, it could be that there is dirt within the system causing it to grind as well.
Sorry to say that you probably wrecked the syncro in some of the gears if it is only in between certain gears
I would guess that your clutch or transmission are bad. Hope that is just the clutch.
It depends on the context. One meaning can be someone who drives a truck, referring to the fact that they shift the gears and sometimes the gears would grind. Another meaning can be a vehicle with a manual transmission. Of course, the real meaning would be the person or machine that actually grinds the gears during the manufacturing process.
im assuming that its an automatic,if so then its just because your transmition is messed up,or your rear gears(not the trans gears)are damaged.
Synchros in a manual transmission are used to slow down the gear before it is engaged so it doesnt grind
Manual transmission only: Probably broke your reverse gear or grind up the gear to much and it won't go into gear. Could need a new clutch or thrust bearing does it crunch trying to get it into gear if yes then its probably the clutch
clutch is worn out