Causes of Balance Shaft Belt wear?

[Devilsfutbol17]

I was just replacing my timing belt due to it having some damage. I found the culprit of the timing belt damage and will easily take care of it. But while I was down there, I noticed my balance shaft belt has wear on the wheel or drivers side of the belt.

It does look a little loose as shown in the video, could that cause the wear? I won't be pulling the BS belt until next weekend, so any help is appreciated.

[YouTube]B7U7nva3uXM[/youtube]

 

[92AWDHX40]

Im assuming wear and tear, if its old, remove it with a bse, no more issues, perhaps something loose tight let us know when you get to it with more information.

 

[talonDSMerr]

Check the tensioner pulley's condition and whether it is torqued correctly or not. Improper tension on any belt will cause premature wear.

 

[DSM1G90]

I also suspect a worn BS pulley - the bearings are tired.

The belt tension looks okey, but could be a smidge tighter-a quarter inch deflection is what you want where you pushed down on your finger...

Also, I've noticed belt scuff on the flange that is next to the sprocket. Make sure that the curve of the flange is going inward, not outward. For that outside edge will eat up into the T-belt if placed on backwards.

Good luck-DSM

 

[Devilsfutbol17]

Well I got it pulled off, but I haven't been able to figure out what caused the wear. I don't know when it was last replaced, but the water pump, t-belt, and the tensioner were replaces 18k miles ago.

 

[DSM1G90]

remove it with a bse, no more issues

(I like to see this "bse" mindset get under control by some users by not expressing their opinions on the mod since there are some DSM owners that like to have their bs assemblies left intact.)

..bet that edge tagged against the rear flange behind the main sprocket..since we couldn't see this wear on the pictures above, which were the outside edge of the belt..

Whoever did the belts that 18K ago, didn't do the install too well...

DSM

 

[TunaTalon]

A common reason for the balance shaft belt failure is the failure of the balance shaft bearings. Putting on a new, even super strong, belt will only result in the belt breaking with greater force.

Balance shafts are good when the bearings and the belt are good. With high mileage DSMs the balance shaft bearings are unlikely to be good.

At 183,000 miles the balance shaft bearings on my Talon were worn near end of life while the main and rod bearings were like new. I choose to replace the balance shaft bearings. Your mileage may vary.

 

[dondmon96]

I'd totally loose them anyways. My BS belt broke and almost grenaded my motor, so I got a nice pair of fish bats now.

 

[92AWDHX40]

Mines are gone, if it isnt there it cant break is my mindset one less belt replace, or engine issues later, mine was wearing, and wearing so i eliminated it all together no reason to keep it,not in my eyes.

 

[renogsx]

My bs belt failed got in my t belt which jumped timing and bent all of my intake valves. I have never had another motor with bs shafts in it for that reason. It is also my understanding that the bs shafts have poor oiling and by removing them the main bearings get more oil pressure. I also think it is a poor design to have one bearing in the block and a support for the shaft in the front cover as it would be very hard to ensure alignment between the two.

 

[HaveBlue83]

im @ a crossroads myself....i had a gates kevlar BS belt shred into two pieces after 250 mi after a redone head/16g/ timing belt, tensioner, and pullies were installed.

i dont know if the bs bearings are toast, or if its safe to put an OEM BS belt on amd run it.

the car has 161k on it and right now I'm doing the old " just run no front bs belt" way, but the vibrations/noise above 3,500 are not cool.

a BSEK would be lovely, but its gonna be a living nightmare to dig into an old motor for that.

 

[GRAVEDIGGER]

In most cases I believe it is a bearing failure that causes the bs belt to wear excessively and/or break. My reasoning for using the bse kit is simple... I don't want the bearings (whether they are new or old) in there turning at twice the crankshaft speed. PERIOD! 14k+ rpms is way too much for me to feel comfortable with, so I'm all about the bse. I've never felt that the little bit of vibration saved by having them was worth the risk of the bearings failing and having it take out the timing belt.

 

[marcman804]

im @ a crossroads myself....i had a gates kevlar BS belt shred into two pieces after 250 mi after a redone head/16g/ timing belt, tensioner, and pullies were installed.

i dont know if the bs bearings are toast, or if its safe to put an OEM BS belt on amd run it.

the car has 161k on it and right now I'm doing the old " just run no front bs belt" way, but the vibrations/noise above 3,500 are not cool.

a BSEK would be lovely, but its gonna be a living nightmare to dig into an old motor for that.

How do you run no front bs belt? I just ran into a little problem with my bs but i don't have the time to remove the engine to remove the bs.

 

[bmoha7321]

I've got 110k on my motor. The bearings look fine. My bs bearings looked like crap. I have been told they spin twice the speed of the rotating assembly. I eliminated the balance shafts. I see it as just a liability.

 

[HaveBlue83]

its a total liability. it killed my HKS272 cam, my pistons got hit, and bent my valves. the bs belt grenaded into my timing belt and it jumped the intake cam.

i just didnt put a belt back on after redoing it. I'm worried if i install another belt it will fly off again.

if i pull the motor i'd rather put a built one in back in.....see my logic.

 

[bmoha7321]

I wouldn't just remove the belt. The BSEK should be installed. If you just remove the front belt & leave in the rear you're running an unbalanced motor. Bad juju. The rear balance shaft should be replaced with a stub shaft. I don't see the difference in doing it on an "old" motor. There is some discussion as how best to eliminate the front balance shaft. Abandon in place or spin (or replace) the bearing to block off the oil feed holes. I abandoned mine in place after replacing the seal. I don't see it makes much difference. Won't leak that way. Bearing on flywheel side is hard to get to on block with internals installs. Much easier to do on bare block. I'm referring to a 7 bolt btw. I have heard it is easier with 6 bolt motor.
I have no problem with slight increased amount of vibration. The front balance shaft is oiled differently than the rear. The rear balance shaft is hollow and feeds oil to itself. I have heard from other DSMrs that upon tear down the front bs bearings look wornout while the rear bearings look fine... Possibly because the rear balance shaft gets its feed directly off the oil pump with nothing in between? I can't say for sure.
I do know my front bs bearings looked like crap. My front balance shaft tensioner pulley felt like crap. I feel better with those parts no longer being something I have to worry about. And let's face it our cars are pretty damn complicated. The simpler the better. Plus the balance shafts are supposed to be timed correctly along with the crank, oil pump & cams. More complicated to time. Timing with BSE very simple.

 

[HaveBlue83]

yeah, i drove mine for a week and i decided nogo on just removing the belt. a old tume dsmer told me to do it, said his has been like that for 5 years. well, mine isnt happy like that.

i'm guessing the bearings are bad & they stressed the belt. that or my other mechanic buddy didnt tension it enough.

 

[DSM1G90]

The simpler the better. Plus the balance shafts are supposed to be timed correctly along with the crank, oil pump & cams. More complicated to time.

Not really - just gotta know what you're doing and how to do it. It's not rocket science in doing balance belt/timing belt installs.

Granted, the shafts do spin twice as fast as the crank.

Thus, you look at the tach and if it's showing 3Krpms, they're spinning at 6Krpms.

How do these BS bearings fail if they're getting oil all the time?

along with really no heavy weight is on these bearings (and the shaft is supported in the middle to even out the weight on both ends of the shaft) in the first place being that they're suspended in a film of oil...

seems a little odd these would fail being that normal failure would come from oil starvation.

Only thing I can think of this failure is that they spin up too fast with not enough oil getting to the bearings, esp on startup, sudden bursts of high revs, and "jack rabbit" takeoffs.

-DSM

 

[HaveBlue83]

^^Agree. It makes no sense why bearings would go of they have oil plummed to them. Yes its twice the rpm, but small cc bike motors sit @ over 10k rpms regularly.

So if my BS spins freely and isnt sloppy in/out is it safe to use a belt? To pull a BS out to "check" is ...yeah

 

[bmoha7321]

Haveblue83. Not sure what you mean... You're still running with only rear balance shaft?

 

[TunaTalon]

The balance shaft bearings not only spin at 2X engine RPM but they are heavily loaded. The Eccentric weights on the balance shafts are sized to cancel the harmonic imbalance of the engine which is about 2500 pounds per piston pair at BDC and the loading is repeated at twice the engine RPM.

Please see Figure 19 of http://www.kidzuku.com/StrokeOrNot.pdf for the effect of engine configuration on imbalance forces.

And yes I got a little OCD when deciding to stroke my Talon or not.

 

[SlowChild3]

On my previous dsm I did the timing belt job. Once I got in the guts my bs belt was broke just hanging in there. My stomach twisted. I think im in the 1% to not trash my motor with a broken belt. I never noticed the vibrations with one operational shaft.

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[HaveBlue83]

bmoha7321, yes, I ran the car for a week (maybe 250 miles) with the front shaft installed with NO belt. I do not DD the car. I want to know how I can verify the bearings are OK without removing the shaft. If i throw another belt on there and it kills another head I'm gonna go bonkers again.


it seems 1g guys have less vibrations than 2g guys if they run without the front belt from what has been posted & from my buddies.

 

[bmoha7321]

No way I'd put another belt on there to the front balance shaft. How bad was the vibration with it off? Id say it is a sign of a good time do BSEK. Good time to do timing belt complete. Water pump, idler pulley and tensioner pulley.

 

[HaveBlue83]

^i did timing belt, BS belt, all pullies, tensioner, water pump, head, cams 16g, manifold, FMIC already. 250 miles later that's when it went...on the highway @ 5K RPMs. NO wear on the sides of the belt at all that I saw. it was literally ripped in 2 parts, the kevlar was shredded and pulled out.

i redid with another head, cam, timing belt, and am unsure on the belt now. if I yank the engine I dont want to put a stock 7 bolt back in. thats my dilemma.

the vibration was like stiff motor mounts at idle. over 3,500rpms you can hear/feel a vibrating noise. i didn't go over 5K with it like that, it was sending false knock signals. At 3K it wasnt really BAD, just felt.

my buddy with a 1g AWD & an HX-35 with no front belt didnt make that noise or vibration when I rode in it.