2nd gear Grinding Manual Transmission

[linuxology]

2009 Mazda 5 w 140,000 miles on it. My wife's primary vehicle and now every time she drives it she is grinding second. To the point, that I am going to be looking for something new for her to drive. I want to keep the car though. If I double clutch it seems that I am able to drive it without grinding second the majority of the time. Downshifts can be difficult to pull off at times dependent on terrrain and driving. All other gears switch with no issues. Does this primarily mean the synchro or second gear is busted? The clutch is original as well. The transmission fluid only has ~30,000 miles on it. What would you do if this was your car to attempt repair?

 

[bullwinkle]

What MTF are you using? I had issues with synchros and GL-5.

 

[linuxology]

I'm using the Ford Honey. XT-M5-QS.... thinking about putting redline in. Really don't have anything to lose, though I ran this prior as well with zero issues it seemed.

 

[vwmaniaman]

My 65 VW beetle was doing that too till I added one quart of Lucas trans oil. I changed the oil and added the quart at that time. I could not believe it fixed it.

 

[bullwinkle]

I would try either Red Line or LiquiMoly GL-4-at this point you don’t have a lot to lose, neither one will make it any worse. I have RL 75-90 in the xB, and LM 75-90 in the Corolla (& just changed my brother’s Sentra Spec-V to RL 75-85), all of them are working well, all are over 100K now.

 

[paulo57509]

Just because it's easy to do. I'd check the clutch hydraulics to be sure there's no lost motion someplace.

It may not improve the situation, but I'd try the Redline MT-90.

The Legend has a 2nd gear like yours (double clutch to downshift). Redline MTL improved it somewhat but as the miles continued to accumulate it isn't doing much for it now. Miraculously, I found a synchro set for it and rebuild kits are still available but I sorely lack the motivation to tear into it.

 

[demarpaint]

I would bleed the clutch to completely exchange the fluid and see if that helps. Brake fluid goes bad, taking on moisture, and as a result grinding when shifting gears or going into reverse happens. I have an M5OD transmission in an 88 E-150, and if I don't bleed the system to completely exchange the fluid every few years grinding will happen.

 

[Ursatdx]

Mobil1 makes a full syn GL-4.
Might be worth a try.

 

[JavierH19]

I would bleed the clutch to completely exchange the fluid and see if that helps. Brake fluid goes bad, taking on moisture, and as a result grinding when shifting gears or going into reverse happens. I have an M5OD transmission in an 88 E-150, and if I don't bleed the system to completely exchange the fluid every few years grinding will happen.

Had that happen to my manual 95 f350. Mechanic told me about doing that and I was confused as to how that could fix it but did it anyway. Somehow fixed it.

 

[demarpaint]

Had that happen to my manual 95 f350. Mechanic told me about doing that and I was confused as to how that could fix it but did it anyway. Somehow fixed it.

Contaminated old brake fluid will reduce the distance the clutch disk moves away from the flywheel when you step on the clutch, causing it not to fully disengage, especially after driving a while when things get hot. It can happen occasionally, but when the fluid is real bad it can happen all the time. Driving it that way will eventually cause excess clutch wear and can damage the transmission. It is cheap enough and easy enough to try and if the synchros are good, and the clutch is good it more than likely solve the problem.

 

[JavierH19]

Contaminated old brake fluid will reduce the distance the clutch disk moves away from the flywheel when you step on the clutch, causing it not to fully disengage, especially after driving a while when things get hot. It can happen occasionally, but when the fluid is real bad it can happen all the time. Driving it that way will eventually cause excess clutch wear and can damage the transmission. It is cheap enough and easy enough to try and if the synchros are good, and the clutch is good it more than likely solve the problem.

I didn't know the clutch was just that close to the flywheel. Enough so that a miniscule amount of distance caused by fluid would still make it touch slightly. Makes sense, I just figured clean fluid operated faster.

 

[atikovi]

The first gen Honda Insights are notorious for 3-2 grind. There is a simple mod to the syncro eliminate it, no parts required, but of course the trans has to come out and be taken apart.

 

[demarpaint]

I didn't know the clutch was just that close to the flywheel. Enough so that a miniscule amount of distance caused by fluid would still make it touch slightly. Makes sense, I just figured clean fluid operated faster.

The clutch disk is up against the flywheel all the time. It moves off when you step on the clutch, but not that much. Years back Ford had problems with the clutch master cylinder moving when stepping on the clutch pedal in their E and F series vehicles. The movement was caused by the floor flexing, causing the clutch master cylinder to move slightly, causing the clutch not to fully release too. Same symptoms different cause. They made a kit that beefed up the floor in that area. My brother welded a plate on mine to strengthen it and stop the flex. Not many people were aware of that problem, but if you got under the truck and watched the clutch master cylinder while someone stepped on the clutch you'd see it move if the floor needed reinforcement.

 

[NormanBuntz]

About 12 years ago I had the same 3rd to 2nd gear issue in my 1987 Alfa Romeo Spider Veloce, known to develop this condition. I changed to Shell Spirax synthetic gear oil, and the crunch disappeared.

 

[linuxology]

Contaminated old brake fluid will reduce the distance the clutch disk moves away from the flywheel when you step on the clutch, causing it not to fully disengage, especially after driving a while when things get hot. It can happen occasionally, but when the fluid is real bad it can happen all the time. Driving it that way will eventually cause excess clutch wear and can damage the transmission. It is cheap enough and easy enough to try and if the synchros are good, and the clutch is good it more than likely solve the problem.

Sorry so brake fluid can have an effect on the clutch???

 

[Number_35]

Sorry so brake fluid can have an effect on the clutch???

The clutch is hydraulic (rather than being cable-operated).

It's easy to bleed - the clutch slave cylinder is easily accessible with the vehicle up on ramps.

 

[linuxology]

The clutch is hydraulic (rather than being cable-operated).

It's easy to bleed - the clutch slave cylinder is easily accessible with the vehicle up on ramps.

So it could be a possibility that only one gear would be effected? I'm sure its possible and an easy try.

 

[Number_35]

Lots of good advice from others so far - replace the MTF with a good GL-4 synthetic, and bleed the hydraulic clutch system.

I've used both Redline and Pennzoil MTF in our '09 Mazda5 with good results.

It's also possible that the linkage is on the way out. The steel cables do stretch, and can eventually break.

 

[Number_35]

So it could be a possibility that only one gear would be effected? I'm sure its possible and an easy try.

The symptom on our Mazda5 was an increasingly soft clutch pedal, followed by difficulty shifting. We had set out on a trip in the winter, and it got bad quickly. We turned back and limped home with me double-clutching to make the shifts. I bled the clutch, and all was well.
Water in the fluid had partly frozen.

 

[linuxology]

The symptom on our Mazda5 was an increasingly soft clutch pedal, followed by difficulty shifting. We had set out on a trip in the winter, and it got bad quickly. We turned back and limped home with me double-clutching to make the shifts. I bled the clutch, and all was well.
Water in the fluid had partly frozen.

Thanks. I will try all recommendations and report back. Step 1, bleed brake fluid, Step 2. Change transmission fluid. I appreciate all of the comments.