1999 honda prelude grinds gears when i shift into 5th gear when im over 50 mph. what would cause this?

sound to me like a basic sloppy shifter, did you inspect the shifter and all parts associated?
usually the synco dont stop shifts, only causes grinding
unless, it is shattered. (rare that)
it only matches speeds, so if cracked in half , you can shift by
double shifting , like racers and truckers did for years, "crash boxes"
RTM
http://hondatech.info/downloads/Auto/Manuals/Civic/

old car. 5th gear? is this M/T? 1987 ?
A/T? is 4speed

what does stopped working mean .
1: shifter fails to select 5 gear H pattern slot.
2: grinds?
3: cant force it to 5th with clutch depressed.? is free play at spec?
4: raise front wheels off ground, can you get in to 5th now? keyout and running?
5: can you get into 5th parked engine off, and select 5th and then start car in 5th with clutch depresses first step. then slowly very slowly attempt to move car starting in 5th, but dont finish, just feel the gear, feel that its there and not neutral.

not working ,says nothing at all.

One or more bad gear synchronizers in transmission

Sounds like the thrust bearing is worn to the bleep. Though I suspect it's not Synchromeshing. Some part of the Clutch mechanism failing critically.
See http://en.wikipedia.org/wiki/Manual_transmission#Synchromesh
http://en.wikipedia.org/wiki/Clutch
Did it run out of Oil? BUT then maybe damage has been done to both the internal of the Gearbox as well as the clutch, so yeah STOP driving it before more damage that can set you back a fortune

Hey I have a 1999 cavalier z24 5spd All my gears work except 5th while puttting it into 5ht gear as i let out of the clutch its grinding so i cannto put in 5th or it will grind, but at times it would work, but recently as Ive been driving I go to put it in 5th, there isn't a grind its as 5th gear is just netural NEED HELP geoff

It sounds to be like you have a syncronizer out on your transmission. This helps your gears mesh without grinding.

This depends as dose it do it when cold or hot.
2nd when you push in pedal and put in gear dose it go in clean or hard to select 3rd can you hear a grinding noise when pushing in pedal and noise goes
when you take you foot off the clutch pedal IF so then its the thrust bearing on clutch REPLACE ALL .4th if you push in clutch pedal and select a gear and let the clutch out if drive right out (replace)

gear linkage worn joints.

Hi James,
The grinding noises suggest to me that your brake pads have worn away, giving you metal to metal contact between the pad backing plates and the brake disc.

Can you explain more what you mean by "just revs when driving in 5th gear at 50 mph" ?

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