Do syncronizers wear out in manual trannies?

[TylerL]

Originally Posted By: TallPaul

Oh yeah, if the clutch is worn out or warped from abuse, it may not release completely even if the hydraulics are okay. That will cause grinding going into gear.

That's my guess.

 

[OVERKILL]

Originally Posted By: GMFan
I'd say synros will wear out if you downshift gears without rev-matching.

If I'm driving 45 mph and come to a red light, I'll brake, and then shift into neutral just before the engine would stall (~10mph). Only when I have to give it gas will I shift into the proper gear to accelerate. I only downshift to slow down in snowy or icy weather. Otherwise, I let the brakes do the slowing down.

Downshifting to slow down in everyday driving definitely puts more wear on the drive train, clutch and transmission....of course if you drive a stick shift like 95% of the population. For those that rev-match, the wear and tear won't be too much.

My friend has a 2003 Mustang Cobra SVT and he blew his syncro in 2nd gear. He has to double clutch to get into 2nd, or just go from 1st to 3rd.....he beat the [censored] out of his car and it has 29k miles on it.

So, manual transmissions will last almost forever, as long as you don't drive it like a fool or abuse it. If you grind your transmission or spin your tires a lot, be prepared to replace your transmission.


Wow, he buggered a T-56! That's an expensive problem.

 

[grampi]

Originally Posted By: zrxkawboy
The shifting problems didn't appear with the gear oil change, did they?


Yes they did, which is wierd because you'd think if anything, it would shift smoother with the new oil in there.

 

[grampi]

Originally Posted By: XS650
Originally Posted By: grampi
I've noticed the transmission in my '99 Corolla is starting to become more difficult to shift.


Does it make grinding noises when you try to shift or do you just have to push a bit harder?

It sounds like you are having to push a bit harder, if that's the case, check out the clutch hydraulics, most likely the master cylinder if there is no external leakage.

If it's hard to press into forward gears but grinds going into reverse, then the clutch isn't fully releasing when you press on the pedal.


No grinding, I just have to push harder, or usually what I do is fish around more to get it to go into gear because I don't like forcing it. It's definitely become more "notchy" feeling since I changed my transmission oil.

 

[mstrjon32]

Originally Posted By: TallPaul
You man be able to live for years with it like that. Suggest you get some Redline transmission fluid in it for better wear protection to preserve what's left. My F150 has been notchy in some gears and it's just a matter of holding the lever against the slot until it eases in. If I try to jam it in too quick may grind. Not hard to drive. Typically on downshift I will blip the throttle to raise RPM so as to reduce the work of the syncros.


I assume you realize that bumping the throttle as you downshift does nothing to save synchro wear unless you actually let the clutch out to bring the intermediate shaft up to the higher speed and then push it back in before you shift into gear. Just bumping the throttle, shifting into gear, and then letting the clutch back out may make for a smoother shift but doesn't do anything for synchro wear.

On the colder days my Jeep can be quite stubborn with the 2nd gear upshifts and will grind a bit as I go into second. I can double clutch it, skip 2nd, or try and ease it into 2nd (also bad for synchros, but eh)--what I do depends on how lazy I'm feeling. Often I just skip it and go right for 3rd, especially if I'm not accelerating up a hill or something. Oddly, it downshifts into 2nd no problem, only fights me on the upshift.

The clutch fluid could also probably stand to be replaced and bled.

 

[labman]

Maybe it is stupid of me to say so, but my 77 LUV still shifts fine. It is just short of 140K, but seldom put 2 miles together without a stop. I have had to replace 2 clutches.

 

[rpn453]

Originally Posted By: grampi
Originally Posted By: zrxkawboy
The shifting problems didn't appear with the gear oil change, did they?


Yes they did, which is wierd because you'd think if anything, it would shift smoother with the new oil in there.


Not if the oil is too slippery. Did you use a GL-5? Try a GL-4 specifically designed for manual transmissions, like Redline MT-90 or Amsoil MTG.

 

[TallPaul]

I must say, my manual transmission shifts pretty good for 160,000 miles, the first 60 of which the previous owner must have been abusive (trailer hitch holes in frame, clutch badly abused and was burned and warped, rear pinion goes out 20,000 later), and with about 85,000 on current clutch. I suspect that having had MolaKule's Syncroglide fluid in it for the past few years has been a good thing and is part of it's present good performance.

 

[grampi]

Originally Posted By: rpn453
Originally Posted By: grampi
Originally Posted By: zrxkawboy
The shifting problems didn't appear with the gear oil change, did they?


Yes they did, which is wierd because you'd think if anything, it would shift smoother with the new oil in there.


Not if the oil is too slippery. Did you use a GL-5? Try a GL-4 specifically designed for manual transmissions, like Redline MT-90 or Amsoil MTG.


Toyota recommends GL-5 so that's what I used.

 

[brianl703]

Yes, they sure do, and they wear out faster if some dumb [censored] forces it into 1st gear at 45MPH.

 

[grampi]

Originally Posted By: brianl703
Yes, they sure do, and they wear out faster if some dumb [censored] forces it into 1st gear at 45MPH.


While I certainly don't do that with this car, I did it once with my Dad's AMC Gremlin back in the 70's (I actually shoved into 1st at about 60 MPH). He was pi$$ed (and I don't blame him) as he had the have the clutch replaced.

 

[D189379]

Originally Posted By: eljefino
Originally Posted By: D189379
I've never experienced or even heard of a manual trans failing.


You can blow many manual transaxles (and autos too) by spinning one tire and sending the differential pin through the casing.


I don't doubt that it can be done, but usually it is a result of serious abuse. Most auto's on the other hand seem to explode if you look at them funny.

Now that I think about it, I did have a buddy who destroyed one by red-lining his car in neutral and just jamming it into 2nd gear. Not too sure what he thought would happen?

 

[TallPaul]

Originally Posted By: D189379
Now that I think about it, I did have a buddy who destroyed one by red-lining his car in neutral and just jamming it into 2nd gear. Not too sure what he thought would happen?
Maybe it wasn't a matter of what he thought would happen, but what he'd been smoking?

 

[cornfused]

On the toyota forum I am on, It is common knowledge that although they say GL-4 or GL-5 that the gl-5 is too slippery for the syncros and we only use the gl-4. I just put redline mt-90 in mine and it helped slightly, I am referring to tacoma transmissions tho,should be the same?

 

[grampi]

Originally Posted By: cornfused
On the toyota forum I am on, It is common knowledge that although they say GL-4 or GL-5 that the gl-5 is too slippery for the syncros and we only use the gl-4. I just put redline mt-90 in mine and it helped slightly, I am referring to tacoma transmissions tho,should be the same?


When you say the GL-5 is too slippery for the syncros, what exactly does that mean? One would think the more slippery the lube the better.

 

[Hirev]

Originally Posted By: grampi
I've noticed the transmission in my '99 Corolla is starting to become more difficult to shift. I'm paticularly having a harder time shifting into 1st gear when coming to stop signs, and downshifting into 2nd gear (like when turning corners). Upshifting isn't as bad, and shifting into the higher gears (3rd, 4th, and 5th) don't seem to be any worse than they ever were. In case you're wondering, I just changed the transmission oil about 1000 ago and used a synthetic blend 75W90, which is the recommended weight.
I bet shifting is worse the colder the transmission oil is? Had at least one manual transmission Toyota around since the mid 80s. I know what you are talking about.

Tried many brands of gear oils in Toyota manual transmissions over the years, some are noticeably better than others. But the best I have used so far, as far as shifting quality is Amsoil Manual Transmission & transaxle gear lube 75W-90 API GL-4. Well worth it IMO.

 

[grampi]

Originally Posted By: Hirev
Originally Posted By: grampi
I've noticed the transmission in my '99 Corolla is starting to become more difficult to shift. I'm paticularly having a harder time shifting into 1st gear when coming to stop signs, and downshifting into 2nd gear (like when turning corners). Upshifting isn't as bad, and shifting into the higher gears (3rd, 4th, and 5th) don't seem to be any worse than they ever were. In case you're wondering, I just changed the transmission oil about 1000 ago and used a synthetic blend 75W90, which is the recommended weight.
I bet shifting is worse the colder the transmission oil is? Had at least one manual transmission Toyota around since the mid 80s. I know what you are talking about.

Tried many brands of gear oils in Toyota manual transmissions over the years, some are noticeably better than others. But the best I have used so far, as far as shifting quality is Amsoil Manual Transmission & transaxle gear lube 75W-90 API GL-4. Well worth it IMO.


How much is that stuff a qt?

 

[rpn453]

Originally Posted By: grampi
When you say the GL-5 is too slippery for the syncros, what exactly does that mean? One would think the more slippery the lube the better.


One would think so in most applications. But that gets thrown out when performance relies on friction between two surfaces to function properly.

Here's an excerpt from the back of the Red Line 75W-90 GL-5 gear oil I used in my LSD-equipped Pathfinder:

Originally Posted By: Red Line 75W90 High Performance Gear Oil GL-5
. . . Supplemental friction modifier additive is usually not required for limited-slip differentials, but can be used if chatter occurs. Red Line 75W90 is used for high-speed and high-torque conventional and racing applications. This product is not designed for use in most manual transmissions, since the extreme slipperiness may cause gear clash.


RedLine 75W90 GL-4 gear oil (MT-90) is much different:

Originally Posted By: Red Line MT-90
. . . Most gear oils, ATFs, and motor oils are too slippery for proper synchro engagement - which causes gear clash when shifting . . . MT-90 has a coefficient of friction which is perfect for rapid synchro engagement and allows high-speed upshifting and downshifting . . . This product is not designed for use in a rear-wheel drive differential which requires a GL-5 lubricant.


Differentials and manual transmissions have different requirements. A ring-and-pinion differential is subjected to higher loads and requires more extreme pressure protection than a manual transmission. That extra protection makes the oil too slippery for synchronizers. Generally, you can't have a gear oil that is optimal for both.

 

[widman]

It helps when people are more specific. "Slippery" has a lot of meanings. Both GL4 and GL5 have the same hydrodynamic friction coefficient. But GL5 has more sulfur/phos additive (double the GL4) so the GL5 has more boundary lubrication, making harder for the synchronizers to stop the movement and sync the gears.

Also, since the sulfur/phos additive is chemically bonded to the surfaces, when it does scrape itself off the bronze synchronizers, it pulls some of the bronze with it, flattening them

.
GL4 is still recommended by many, but most cars are going towards products with zinc/phos additives (polar, not chemical adhesion) and sometimes friction modifiers that change the dynamic friction coefficient as the surfaces approach each other in rpm.
In this picture, the synchronizer is so worn that it completely hits the end of the cone, barely making contact.

 

[wantin150]

Just my .02. Use a mix of 50/50 Redline MT90 and MTL. Should cost you about $30 or so. ALL of my Toyota's with aftermarket mt fluid are notchy when cold. After they warm up, it's smooth as silk. And that is WITH the MT90 alone. I'm due for a swap in about 1500 miles in my Matrix and will be going with the 50/50 mix.