How long can you drive with a noisy throw-out bearing?

In My Humble Opinion
1

My throw-out bearing started squealing a couple of weeks ago. I’ve scheduled a clutch replacement but the parts don’t arrive until next week. Should I park the car or drive it until the parts come in?

2003 Subaru WRX
211,000 miles
Original drivetrain components including original clutch.

Some (searched on the wrx boards) threads speak of doom and gloom. Others don’t sound so alarming. Is the sound simply annoying, or is it trying to tell me there’s something ready to blow up? The friction disc is working very well, btw.

The bearing is only whining/vibrating for 1.5-2 seconds during a start… hardly much time to generate and transfer a lot of heat. I wouldn’t think it’d be much of an issue until I was stuck in b-to-b traffic. Of course, with the low-rpm (idle) pull of that boxer engine, I still don’t have to clutch it much.

What say you?

2

The bearing only gets used for a second or two when you shift, I would think there would be plenty of warning if it got really bad. I have never heard of one coming apart but I guess that’s possible. All the ones I have seen are pretty well enclosed, it’s not like the bearing balls were going to drop out. Just keep the revs down on that fun ride.

I once drove my TR3 home with no clutch, so you can make it without declutching if absolutely necessary. Mine was just the slave cylinder, or whatever they call them today.

You have to start in 1st, then match the revs for each shift and let the synchros handle it.

Dennis

3

Bearing failure tends to proceed like a hyperbolic curve (the lower one in this illustration). The rate of deterioration is slow for a fair while, but the worse it gets the faster it gets worse. When the deterioration “turns the corner” it’s a very short time to total failure.

So, how long can you drive before it fails? That depends on how far you are from the “corner” on that graph. It’s can be difficult to determine, but when you notice the symptom getting worse at a noticeable rate it generally means you’re close to or entering the corner.

4

Once the noise starts turning to a growl you have very little time left.

5

The same could be said about my wife…

6

<rimshot>

Getting the clutch in and out as fast as possible at the lowest RPM will be easiest on a failing, or even failed bearing. A growl means a seized or rough bearing, which will start eating up the clutch fingers, but you have to count on replacing the pressure plate anyway.

7

You can drive until you wreck the clutch. Even then if it’s seized you may be able to force the transmission in and out of neutral. Of course you don’t want to do that, so you should get it fixed soon so other parts don’t get wrecked making it a more expensive repair in the end. YMMV

8

If there’s four components in the average clutch, the only one that can be counted on to last through one or more replacements is the flywheel.

Doing a clutch service at the first sign of wear-related trouble might let you reuse the pressure plate without rebuilding or service, but good economics usually says to replace it after a normal lifespan along with the friction disc and TO bearing.

By the time a TO bearing gets noisy, damage to the pressure plate fingers is already likely.

9

That’s good feedback; I appreciate it, everyone. I especially liked the curve presented by GaryT. I’m going to predict that I’m still a ways from the “corner”. I arrived at this prediction based on the fact that the bearing’s only whining right now; it’s not growling, yet.

I’ve ridden many motorcycle miles on dirt and pavement w/o a clutch, but I’ve only shifted a few gears without it in the car. Point is, I’m sure it’s possible, though I hope I don’t have to go down that road (pun intended).

I’ll plan to leave the Suby parked, but I won’t fret if a situation arises in which it needs to be driven. It’s given me an excuse to drive the old car anyway. It needed some love, too.

AB, I’ve scheduled the entire clutch to be replaced, including the friction disc, pressure plate, t.o.b., and flywheel.

Thanks for the laugh, doc!

10

I know of a case where the fork ended up bent because of poor alignment. Maybe that was an exceptional case but I still wouldn’t let that problem go on too long. Maybe I’m overly cautious and it really couldn’t get much worse. I’m just an “If it is broke then fix it” guy.

11

You should be fine. And I hope you are also replacing the pressure plate and clutch?

Any time I do a clutch job, I replace the throw-out bearing, pressure plate, and clutch. Perhaps this was not done the last time the clutch was replaced?

Note driving with your foot on the clutch can cause a throw-out bearing to wear out prematurely (I’ve been told.)

12

That’s correct, and in some cases it can cause the clutch disc to wear out too fast. It’s wise to avoid resting a foot on the clutch pedal.

13

I concur.

Do not forget to replace the pilot bushing/bearing in the flywheel as well. The flywheel may need to be resurfaced. I try to reuse the flywheel as it is one of the main items that affects the dynamic balance of the engine.

Make sure that you are not “riding the clutch” as this is hard on all of the components that make it work.

14

It’s a worthwhile skill to practice. Clutchless driving isn’t that difficult, but does take a touch that varies from car to car. Better to learn your car’s idiosyncrasies before you absolutely need it.

However many shifts your bearing has left, you’ll get more total driven mileage out of them if you only use the clutch to transition from stopped to moving in first gear. Then shift clutchlessly for all accelerations and decelerations, finally shifting clutchlessly into neutral as you coast/brake the last few mph to your next stop.

15

Another thing that does it is sitting at stop lights with the clutch pedal depressed. It’s better to shift into neutral if you’re going to be stopped for more than a few seconds.

16

When my TO bearing started to whine a few years back, I drove clutchless as much as possible until I could get it fixed, then had the whole clutch replaced because the main cost was the labour rather than the parts (particularly so on the model I had at the time). So basically, what everyone else said.

17

Driving without using the clutch for a long period of time, say two years, can lead to some other issues.

BTDT, I have a 1959 Ford pickup with a 223 CID six and a four speed granny tranny. First the throw out bearing started to squeal, I just drove it using the clutch only for complete stops. I did as others have suggested, except, I rarely came to a complete stop as I could creep along at less than 1 MPH in granny gear. Think long red lights.

Then the clutch failed, (after 6 months), it was fully engaged at all times. I still drove it, however, to get started on any trip, I started it in gear & drove away. After a while (1.5 years?), the starter would just spin & not engage with the flywheel. I had worn some teeth off of the starter ring gear. The short term fix was that when this happened, I would pop the hood & turn the engine 1/4 turn by hand to get away from the worn out teeth on that gear.

No excuse really. I was working two jobs & going to college, but I had plenty of time to fix it.

After I graduated, quit both jobs, & got some sleep, (two months?), I fixed the issues. It was not that expensive, but it did take some time. I did a complete clutch job. New clutch disc, pressure plate, pilot bushing, throw out bearing, starter ring gear, & rear crankshaft seal were installed. Along with having the flywheel resurfaced. Oh & I had the starter rebuilt as I knew that I had been abusing it as well.

Since the original 1959 clutch lasted until 1997, I figure that the new one will last at least until 2025. I know because I have the maintenance records for the truck from when it was new. It should go longer as I have not abused the new clutch like I did the old one.

I am not proud of what I did, but sometimes you have little choice.

18

Machines are meant to be used up. Lots of perfectly good clutches and transmissions go their grave when the body work they’re installed in gets rusty or bent enough.

Sounds to me like you used every part of the starter / clutch / trans system to the utmost. IOW, It’s not dead until it’s thoroughly dead from end to end. Well done.

19

Hey, Thanks! :slight_smile: