I had my foot stomping the clutch pedal into the floorboard, so it's not like I didn't disengage the clutch completely. I was also fully stopped and parked in my garage. I wanted to have a friend check for the reverse lights with the engine running. Everything was nice and toasty from being driven. I shifted into reverse only to be greeted with a rapid and nasty grinding noise. I shifted out of R and went back in, and heard the noise again.

Is this something to worry about? I couldn't get it to grind all the time, just the two instances. My theory is that since it is a cable linkage setup, I may not have moved the shifter all the way over to the right. Any ideas? This isn't my first time driving a manual.

 

if you have the car in neutral with your foot off the clutch, push the clutch in and shift into a forward gear first, then into reverse. what happens is the input shaft in the tranny is spinning when your in neutral with your foot off the clutch, when you step on the clutch it will take a few seconds for the input shaft to stop turning. being reverse is non syncronized, it will grind if the input shaft is turning at all.

 

hey man good info


mine has done it since day one hasn't caused a problem (not every time) but with this new info im gunna try it out

 

he's exactly correct with his above post

one of my mustang friends told me the same thing, cause stangs get a similar thing when reversing.

 

Thanks for the info. I'll keep that in mind! Would it be ok if I waited like 1 second after I step on the clutch before shifting into reverse? Or do I need to go into a forward gear first?

I've never had a problem with my 07 GT's TR-3650. I can shift into reverse w/o grinding even if I had just stopped the car a split second ago.

 

just get in the habit of puting it into first then into reverse when backing up

 

Sharkey: I found this on GM's website:
http://media.gm.com/us/powertrain/en...n/09_MU3_n.doc

That claims all of the gears are synchronized:

FWIW, I've never had to shift into a forward gear with the Mustang's TR-3650 before going into reverse. I do have to shift into 2nd before 1st occasionally to prevent being locked out from time to time, but I've experienced that with the F35/MU3 as well. Since the GT's interior is so quiet, I can hear when the clutch is engaged or disengaged from the flywheel. The gearbox makes a rattling noise when the input shaft is spinning freely (in neutral) and becomes quiet when I disengage the clutch. The Cobalt is too noisy for me to hear anything distinct.

I'll keep an eye on the F35 and try out your suggestion.

 

ive driven plenty of vehicles that have syncronized reverse, it still doesnt fully stop it from grinding in certain situations. most 2000+ hondas are fully syncronized, but the design of it doesnt really do much and they will still grind. ive never had an f35 apart, however i know mine has always ground into reverse in the situation described above.

 

Thanks. I noticed the grinding only when I was able to shift into reverse from neutral very quickly. Once I tightened the backup light switch, the ball detent must present enough resistance for the pawl that it makes shifting into reverse slightly more difficult. This momentary hesitation probably allows the input shaft to slow down enough that the grinding doesn't occur. Nonetheless I'll be more cautious about this in the future.

PS, the stock gearbox fluid had a reddish dye and smelled more like a Mercon/Dexron III fluid than gear oil. I know the stock 75W-85 synthetic is pretty thin compared to the 75W-90 used in the SS/SC F35s, but this seemed more like an ATF. I hope GM didn't specify this new fluid just to boost fuel economy and ignore gearbox longevity.

 

used to happen in my mustang, i would go through all the gears starting at first then put it into reverse, hasnt happened in my cobalt yet

 

I was about to post to say that all the gears are synchronized. Sharkley said it right that it doesn't fully stop it. I get it on my LS on occasion.

 

Will the grinding eventually break the transmission? I have the same problem, last three times I went into reverse there was a bad sound. My mom said I might have been letting the clutch out too fast, but tonight I reversed and let the clutch out slow and eased on the gas and it sounded bad.
I would not describe the sound as a grinding but more of a pounding.

 

i have the same problem. The grinding only occurs when i first start the car and it settles to an idle. After the first time of going into reverse for the day seems like it doesnt do it anymore.

Now i just put it in 1st, then i go into reverse. Never grinds when i do this.

 

This is good info to know.

I've been told that 2nd-4th are synchronized, but 1st/Rev are not. 1st and Reverse are also the same shaft too I hear, just connecting to it in two different ways.

lol... Just saw how old this thread was.