Keep the balance shaft?!?!??

[drcolt]

I am in the middle of changing cams to performance cams and I figured to replace the timing belt and all seals and pulleys and waterpump, etc....... remove balance shaft. or not. I dont know the history of the motor I have. All I know is the donor car had over 530K kms on it.
I then recalled this was talked about a few years back, found this site, http://www.jackstransmissions.com/pages/keep-your-balance-shafts


That article makes a lot of sense. I believe BS failure is improper maintenance. I do have the kit for deleting, but now I am thinking I might just keep them. I am not after big hp. I do want a nice driving motor, although there is nothing smooth about the colt!

This should be a good read for new dsm owners.
There have been nissans that have had issues with knock at high rpms when balance shafts have been removed.
Porsche makes their motors with BS, as well as many other manufacturers of large displacement 4 bangers.

 

[Bo0sTeD 4G63]

Remove the balance shaft.

 

[ThunderChild]

stubby is waay more reliable than running a cut down shaft.

Curious, why do do you say this?

 

[19Eclipse90]

But running a stubby with helical gears has proven to cause side loading, and you can't put the straight cut gears in the helical case. A buddy of mine might have a straight cut case in his garage. Hoping he does, otherwise I'm gonna buy that shaft to keep the driven gear supported.

I'm not picking on you but I've seen it posted so many times and I disagree with it so here it goes...

By "side loading", if we mean thrust loading, this really doesn't make any sense. The interface of meshing helical gears will inherently produce forces in the axial direction (thrust loads) but a journal bearing like that for the rear shaft in the block does nothing to provide support to counter those axial forces. Journal bearings are only supportive in the radial direction. If thrust loading is occurring and causing damage with a stubby shaft and helical gears, switching to the turned-down shaft will do nothing to change that.

If the issue is that the timing belt is too tight, sure, the rear balance shaft journal can help prevent contact of the gear and case. Notice again the first part of that sentence and realize this is not due to axial forces or side loading. If the timing belt is too tight, it does not matter what gears are in the case; helical or straight-cut gears would see the same fate.

Obviously open for discussion on the topic, but that's my perspective.

 

[chrysler kid]

Some one just explain to me why the water pump isnt driven by the timing belt.

Why couldnt the oil pump be driven directly off the crank shaft like in the ls1 blocks. Hell it would almost be easier to have the oil pump mounted on the front of the crank shaft and lose a rib on the harmonic balancer for better clearance in the engine bay to make up for the oil pump being down there.

So lose a rib on the balancer by making the water pump timing belt driven, add the oil pump on the front of the crank behind the balancer.

We're all just back yard mechanics trying to put on our engineering hats. If it was designed a certain way I tend to keep it the factory way

Hell why not just delete the balance shaft belt and just add another drivers side lower motor mount

Ok im done rambling

 

[SNAKE_15]

If it makes you feel better, I deleted my balance shafts and used an oem stubby shaft with the stock 7 bolt helical gears. I daily drive my dsm and never had any issues or felt a difference after the change besides a negligent increase in vibration.

 

[gsxitement]

I'm not picking on you but I've seen it posted so many times and I disagree with it so here it goes...

By "side loading", if we mean thrust loading, this really doesn't make any sense. The interface of meshing helical gears will inherently produce forces in the axial direction (thrust loads) but a journal bearing like that for the rear shaft in the block does nothing to provide support to counter those axial forces. Journal bearings are only supportive in the radial direction. If thrust loading is occurring and causing damage with a stubby shaft and helical gears, switching to the turned-down shaft will do nothing to change that.

If the issue is that the timing belt is too tight, sure, the rear balance shaft journal can help prevent contact of the gear and case. Notice again the first part of that sentence and realize this is not due to axial forces or side loading. If the timing belt is too tight, it does not matter what gears are in the case; helical or straight-cut gears would see the same fate.

Obviously open for discussion on the topic, but that's my perspective.

I'm just putting forth what I've read. Several big names in the 4G community say that the stub shaft with helical gears is an issue, and all evidence I've seen I.E. pics of failures that all look like the failure I had, leads me to believe nothing to the contrary. Luckily for me, a buddy had a 90 cover with straight gears that he's sent to me so hopefully that does the trick. I'm always open to discussion about figuring more about these motors out, so don't think I would ever assume you're picking on me, unless of course there's some insults thrown in there . But discussing ideas on ways to keep this issue from happening is always a worthwhile discussion. Now. That being said......you're wrong!!!! Lol!!! JK JK!!!!! But I do see your point. And seeing how it's almost always the belt driven gear that shows more sign of failure than the smaller driven gear, that Definitely leads to some proof of the top gear not really needing the support. We'll find out at the end of next season when I pull the motor apart after 11 races

 

[ThunderChild]

Im not saying the stubby shaft is for sure a failure point; its a factory part after-all. But i dont like the idea of a 1.5" piece of metal shaft being the only thing supporting my t-belt when it has alot of other load variables to consider. The race shaft really has little-to-no drawbacks, save a minuscule amount of drag. Choose whichever you like, but I'll go with race-shafts in my future builds.

 

[ceedawg]

I'm just putting forth what I've read. Several big names in the 4G community say that the stub shaft with helical gears is an issue, and all evidence I've seen I.E. pics of failures that all look like the failure I had, leads me to believe nothing to the contrary. Luckily for me, a buddy had a 90 cover with straight gears that he's sent to me so hopefully that does the trick.

FACTS

I also see all the Top Dogs using raceshafts ,Boostin,Kiggly,GSC so it only makes sense to me that it would be the way to go. I am certainly going to have the front of the motor broken back down and have the race shaft installed what does one have to lose in that case.

 

[chrysler kid]

Oh I didn't mention, I hate the bse kits because 99% of the time they're installed wrong and cause major oil leaks because they increase oil pressure exponentially, which causes more oil leaks.

And then you don't even know if the BSE was done properly unless you remove everything to look inside the damn motor to see what the previous owner did or didn't do

So yeah, I'd rather buy a clean car with balance shafts than an unknown can of worms with an eBay kit causing oil leaks from everywhere that gets brushed off, like oh all old cars have oil leaks. Or oh dsm's always leak oil. Well that's bullshit and your bolt on car is made worse by a back yard bullshit modification because you shade tree dsm mechanics think the delete is actually a mod. It's not, leave them in there for God's sake.

 

[Lou98GSX]

i agree leave them in . leave them out more vibrations , things loosen up ,oil leaks more problems .

 

[jinscho]

Oh I didn't mention, I hate the bse kits because 99% of the time they're installed wrong and cause major oil leaks because they increase oil pressure exponentially, which causes more oil leaks.

And then you don't even know if the BSE was done properly unless you remove everything to look inside the damn motor to see what the previous owner did or didn't do

So yeah, I'd rather buy a clean car with balance shafts than an unknown can of worms with an eBay kit causing oil leaks from everywhere that gets brushed off, like oh all old cars have oil leaks. Or oh dsm's always leak oil. Well that's bullshit and your bolt on car is made worse by a back yard bullshit modification because you shade tree dsm mechanics think the delete is actually a mod. It's not, leave them in there for God's sake.

Serious question, I'm currently building my 7 bolt and opted to delete the balance shafts.

Are your feelings towards the removal directed towards the eBay kit and improper installation? Or do you truly think it's just not worth removal?

I originally planned to delete the balance shafts, as I almost lost my 4G64 shortly after I purchased the car due to a broken balance shaft belt. I didn't want the risk on my 4G63t after spending quite a bit of money on the rebuild, so I opted for the STM BSE kit, and even went so far as purchasing the BSE spacer for the crankshaft so I'm not half-assing any part of the removal.

I haven't installed the BSE kit yet, and after reading through this thread I'm beginning to second guess the decision.

 

[m_0ney_pit]

if you want to keep the balances shafts and have more power planned get the gates Kevlar timing belt + Kevlar balance shaft belt kit it's only like $30 more than just their Kevlar timing belt.

I've seen and used one of the kits the Kevlar balance belt it's just as nice as there timing belt. Part number is t167rb wish they sold just the balance belt alone though