PDA

View Full Version : Balance shaft delete?



H8PVMNT
02-05-2009, 06:24 PM
I've seen a few guys have deleted the balance shafts from their 5SFE. I'm rebuilding a 3RZ for an engine swap in a Toyota pickup and I was thinking of doing the balance shaft delete on it because on of the shafts is damaged and the bore for the bearing is totaly hammered... I'm thinking all I have to do is remove the shafts anr related components and plug up the oil holes somehow.

Anybody have some tech on this?

MrWOT
02-05-2009, 07:11 PM
Removing the balance shafts isn't a particularly good idea, they are there to counterbalance 2nd order harmonics. The engine will rev a tiny bit faster without them due to less mass, and I've never seen a smaller 4 cyl hammer itself to death before....

What I have seen is that on 2.4L-2.6L motors that the main bearings show much more wear if the shafts are removed, the longer the stroke, the worse the vibration, and the 3rz has a 95mm stroke...

I would ask on the tacoma boards to check on long term affects. I would advise having the bore honed and an oversize bearing installed and keeping. :shrug:

Kastigir
02-06-2009, 01:22 AM
Removing the balance shafts is a extremely popular, and reliability improving mod on a DSM. Not sure about Toyota motors, but are the balances shafts driven by belt?

H8PVMNT
02-06-2009, 02:09 AM
Removing the balance shafts is a extremely popular, and reliability improving mod on a DSM. Not sure about Toyota motors, but are the balances shafts driven by belt?

On the 3RZ I'm building they are driven by a chain from the crank independant of the timing chain. I know the Tacoma guys are doing this as well as a few of the 4x4 shops.

The balance shaft chain has several gears and tensioners/guides... Oddly, one of the guides broke off, fell into the crankcase, got bounced around by #2 pistion and ended up wiping out a balance shaft bearing. The system kind of did itself in!

VikingJZ
02-06-2009, 04:30 PM
I wouldn't recommend it.

I know the DSM guys run it, and Turner tried it with his Saab.

I just assume figure that it's there for a reason.

I would say, since Toyota obviously has some of the best engines out there, leave it in for reliability sake.

Luni
02-06-2009, 06:10 PM
5SFEs dont have balance shafts. They are like 3SGTEs, they just have a harmonic balancer which is known as the crank pulley.

MrWOT
02-06-2009, 06:17 PM
Generally, you only start encountering heavy vibration when the displacement on a 4cyl gets above 2.2L (in terms on the 2nd order forces), long stroke makes it worse more than larger bore.

Kastigir
02-06-2009, 10:15 PM
I wouldn't recommend it.

I know the DSM guys run it, and Turner tried it with his Saab.

I just assume figure that it's there for a reason.

I would say, since Toyota obviously has some of the best engines out there, leave it in for reliability sake.
DSM guys remove it because it's belt driven off the crank. If that belt goes, so too does your timing belt, and since the 4G63 is a heavy interference engine, so goes the head. It improves the reliability dramatically, and those who have done it claim they notice very little extra vibration.

Luni
02-06-2009, 10:34 PM
Ive done it on a 4G63 and didnt notice shit. It frees up like... 14 HP though. Those balance shafts are fucking heavy.

nuclearhappines
02-07-2009, 05:36 AM
In general:
It reduces the inherent harmonic vibration of an inherently unbalanced I motor by having a counter rotating weight.

Example the piston crank/rods/pistons weigh 10kgs and are rotating clockwise,
you attach 10kgs to that rotating counter clockwise.

The net result is all the 'clockwise' vibration is met with equal and opposite 'anti-clockwise' vibration and it smoothes the engine out.

Where it matters most is high rpm operation... you've seen after market pistons and rods advertise lower weight than oem parts, you've also seen crank performance machine shops advertise things like v-cut or knife edged cranks... the whole point of doing this is reducing the weight of the internals, which makes them more happy to accelerate faster (lower inertia), and more happy to stay longer at higher rpms (with lower friction losses) because in the end friction is a force that is directly propertional to weight * friction coeffecient so if the weight of the assembly falls by 50% then the friction is reduced by 50% ...

So , to make things simple, if you remove the balance shafts the engine will be less balanced but it may be more happy to rev to 9000 rpms.

Some cars even have balance shafts moving at double the crank rotation so when you are at 7000 rpms your balance shaft is at 14000 rpms. Think about how hard it would be to raise the redline up to 8000 rpms on a car like that (effectively spinning your balance shafts at 16000 rpms)... sometimes they take them out because they would rather not have a blance shaft designed for 14000 rpms running at 18000 rpms (like say on a DSM with a redline increased to 9000).

Freshnicity
02-07-2009, 06:11 AM
Ive never heard of anyone doing it on a 5sfe motor though

Kastigir
02-07-2009, 06:29 AM
Ive never heard of anyone doing it on a 5sfe motor though
That would be, because the 5SFE doesn't have them.

Freshnicity
02-07-2009, 06:48 AM
That would be, because the 5SFE doesn't have them.

Didnt think so.

Thanks for the verification

vip09
02-07-2009, 06:26 PM
5SFEs dont have balance shafts. They are like 3SGTEs, they just have a harmonic balancer which is known as the crank pulley.

SOME DO! I pulled a 5S-FE out of the junk yard for my 5S-GTE build and it had a huge gear on the crankshaft that turns the balance shafts that are mounted between the crank and oil pan.

I can take pics if you don't believe me.. ;)

Luni
02-07-2009, 07:32 PM
I dont believe you. Take some pics please.

MrWOT
02-07-2009, 07:51 PM
They do

nuclearhappines
02-07-2009, 07:53 PM
read this

http://www.babcox.com/editorial/ar/ar400108.htm

grayscale
02-07-2009, 08:17 PM
Yes, many of the 96^ Camry 5sfe(s) have them, easiest way to tell is if the crank pulley is solid.
Solid=balance shafts
Rubber damper in center of pulley=no balance shafts
I believe they did this on the 98-99 Celicas but I'm not positive.

H8PVMNT
02-07-2009, 10:15 PM
read this

http://www.babcox.com/editorial/ar/ar400108.htm


That's a cool write up, thanks! So some but not all 5SFEs have balance shafts. I read "deleted balance shafts" in somebody's signature here, that's where I got the impression that the 5S had them. I guess my '91 GT-S wouldn't though.

Luni
02-09-2009, 10:44 PM
Well Ill be god damned.

BiscutWheels
02-13-2009, 02:18 AM
I will agree that the 5S-FE did come with balance shafts, but I thought it wasn't untill the 3rd revision later in the 90's. I'm 99% positive it wasn't in the 92, 93 Celica's. I know it wasn't in the '93 MR2's, just had one in the shop and checked. If I had to place the year, it was the same year that the three bolt TB came in to existance for the 5S in the camry's, 97 or 98.

Nate