Throwout Bearing vs Synchronizers

Read the FAQ and still not sure about something? Want to shift faster? Post here.
Post Reply
MacAttack
Junior Standardshifter
Posts: 59
Joined: Tue Apr 05, 2011 10:03 pm
Cars: 2011 Mazda2

Throwout Bearing vs Synchronizers

Post by MacAttack »

Here's a good question I think.
Maybe not.

I was reading a post on another site & one guy said he always shifts into 1st before the car comes to a complete stop, for example, at a red light. It's easier for the synchronizers to engage when they are turning slowly rather than when the car is at a dead stop. He said this will help the transmission to last a long time.

He also recommended never slamming it into gear. You need to put just the right amount of pressure on the shifter so it "falls" into gear. This also saves the synchronizers from excessive wear. This tip is probably just common sense.

Anyway he never mentioned the throwout bearing. I'm pretty sure I've read on this site that the bearing gets worn from holding the clutch pedal in?

So which is healthier for the transmission:
1. Shift into first when coming to a stop with the clutch pedal held down until go time
2. Shift into neutral when coming to a stop with the clutch pedal disengaged, then shift into first while stopped when ready to go
2011 Mazda2
MacAttack
Junior Standardshifter
Posts: 59
Joined: Tue Apr 05, 2011 10:03 pm
Cars: 2011 Mazda2

Re: Throwout Bearing vs Synchronizers

Post by MacAttack »

Here's another post I found. It's by someone that works for the South Bend Clutch company:

Maybe this will help with the confusion on what is considered the proper break-in for a clutch.

Normal driving ( you know, like when your Mother is in the passenger seat) is the perfect way to get the job done.

If you have the OFE series clutch and you are not drag racing, there really isn't a break-in period. Just install it and drive.

What is being accomplished during the break-in period is wearing down the clutch disc until 100% of the friction surfaces are making contact with each other. In most cases .005" will get the job done. The total wear for the life of a clutch is around .080"

Heat is the #1 enemy of a clutch. Slipping a clutch for more than 4 sec can generate 1100 F (depending on RPM) and break down the composite that holds the clutch facings fibers together.

Long clutch life is achieved by keeping the RPM's low on take off and engaging the clutch pedal smooth and quick.

Contrary to what many think, holding the clutch pedal down at a stop light is not detrimental to the TOB. These brgs are designed to run continually at low RPM. If the engine is revved while the clutch is depressed the TOB will heat up from the RPM's resulting in a shorter life span.
2011 Mazda2
User avatar
theholycow
Master Standardshifter
Posts: 16021
Joined: Tue Jun 24, 2008 1:36 pm
Cars: '80 Buick LeSabre 4.1 5MT
Location: Glocester, RI
Contact:

Re: Throwout Bearing vs Synchronizers

Post by theholycow »

It's a non-issue. The release bearing and the synchronizers are designed to do their jobs with normal driving, which can include either or both styles.

If I'm approaching a stop sign or other place where I expect to go again very soon, I put it in 1st while still rolling (just before stopping).

If I expect to sit there for a while I'm not making my leg hold down the clutch pedal when I have a perfectly good neutral I could use instead. Sometimes after that if I'm not paying attention and need to get into 1st quickly I'll bounce off of 2nd to use its synchro a little...not sure if that helps or not.

Yes, you should normally use just the right amount of pressure instead of forcing it past your synchro or slamming it in. Forcing it is abusive. It isn't going to destroy anything when you do it once (so don't freak out about a single overexcited shift) but will if you do it all the time.

I'm surprised to read that the total wear over the life of the clutch is a mere .080". That's 2mm. New clutches tend to be 8mm thick, with almost all of that being friction material and a thin sheet sandwiched in the center being a structural plate. I would have expected twice as much wear to be acceptable.
1980 Buick LeSabre 4.1L 5MT

Put your car in your sig!

Learn to launch/FAQs/lugging/misused terms: meta-sig
watkins wrote:Humans have rear-biased AWD. Cows have 4WD
User avatar
AHTOXA
Master Standardshifter
Posts: 14693
Joined: Sun Dec 23, 2007 6:31 pm
Cars: '19 4RUNNER TRD ORP
Location: Irving, TX

Re: Throwout Bearing vs Synchronizers

Post by AHTOXA »

I'll parallel cow on this one. I drive much in the same fashion.
'19 Toyota 4Runner TRD ORP
'12 Suzuki V-Strom 650
User avatar
six
Master Standardshifter
Posts: 4674
Joined: Thu Mar 16, 2006 4:45 pm
Cars: 2015 Chevrolet SS 6MT
Location: California, U.S.

Re: Throwout Bearing vs Synchronizers

Post by six »

As far as switching into first right before a stop, that really is a non-issue. However, if you want to follow that guy's advice, switch to first as late as possible before stopping at, say, a stop sign or a temporary stop. If approaching a red light that will not turn green any time soon, it's better to just shift into neutral and drive normally; no need to shift to first before stopping. The first-gear synchros are the strongest, and at a dead stop, only has to overcome the inertia of the input shaft spinning at idle RPM.
Image
2015 Heron White Chevrolet SS Sedan 6MT
User avatar
theholycow
Master Standardshifter
Posts: 16021
Joined: Tue Jun 24, 2008 1:36 pm
Cars: '80 Buick LeSabre 4.1 5MT
Location: Glocester, RI
Contact:

Re: Throwout Bearing vs Synchronizers

Post by theholycow »

six wrote:However, if you want to follow that guy's advice, switch to first as late as possible before stopping at, say, a stop sign or a temporary stop.
+1 Don't be holding it against the 1st synchro for ten seconds starting at 40mph, wait until you're at like 2mph.
1980 Buick LeSabre 4.1L 5MT

Put your car in your sig!

Learn to launch/FAQs/lugging/misused terms: meta-sig
watkins wrote:Humans have rear-biased AWD. Cows have 4WD
Charles421
Senior Standardshifter
Posts: 123
Joined: Tue Apr 05, 2011 11:59 am
Cars: 2011 BMW 335i Coupe, 6MT
Location: Philly, PA

Re: Throwout Bearing vs Synchronizers

Post by Charles421 »

This is how I do it.

If I can see no traffic on the road I want to turn onto, I'll go into 2nd and do a rolling stop (except when cops are around ;)). If you're moving, you really don't need 1st gear (in my car).

If there is traffic, I shift to neutral below 15MPH and coast; I shift into 1st right before I pull out from a stop.

And then there's times where I clutch in, hold it, shift to 1st, and go (if I have to wait 3 seconds for one car to go by).

I can't see how any of the above would hurt the syncs.
2011 BMW E92 335i: Le Mans Blue, M Sport, 6MT w/ CDV Mod, BMW Performance Exhaust + Style 269 19" Wheels
Post Reply