Engine balancing [Merged 6-7]

[Stock90GSXT]

Okay. I need some advice. I removed the balance shafts out of my 6bolt. I have heard two different sides.

1. The engine is'nt balance w/o those, so get the Rods, Pistons, and Crank,flywheel balanced

2. The engine is already balance w/o the balance shafts, they were just there to remove vibration so customers would'nt complain.

I was thinking. If the engine was vibrating. then its not balanced. I need imput from the people who have had experiance in removing the balance shafts. Is it worth it to balance the bottom end. Or is it a waste of money?. Keep in mind. I will be changing the perimeters by installing 95+ pistons on my 1g Rods. I know anytime you change stuff like that its recommended to balance the engine.

 

[AL92]

Ok guess putting in my energy suspension front and rear rollstop mount inserts!!

 

[steel_3d]

Personally I used my old pulley, since it was recently replaced. It ended up with a few drill marks, so I assume it wasn't perfectly balanced before.

 

[AL92]

Ok been driving the car a bit. I dont think it had much vibration at least not at idle but do get some noise not really vibration at 3000 to 4000 or so range.I also just cut off my clogged cat at same time and think it might be resonance not vibration.For sure things don't rattle or shake in my car so if anything its more a noise thing than a vibration thing.
My 91 fwd turbo with balance shafts also makes a lot of racket at about same rpm as my 97 with no balancer shafts and no engine balancing.
It also has no cat.

So can't really say the no balancing hurt me.I don't think noticed any big vibration or noise before I took the cat out.

I can cut the intown noise out by simply going to third instead of riding around in second. Second is nice as my turbo is right there when step on it and third have to downshift if want quick spool.
since it goes lower in volume by shifting up that would make it seem its not rear end noise not sure about the bearings on the driveshaft my last 92 awd had those shot and it made a lot of racket.

I am changing out my exhaust soon see if that changes much.

 

[AL92]

Oh also not sure if the poly rollstop inserts did anything much in the vibration department again things are not shaking in my car it just gets noisy past 3000 and that could be just no cat.

 

[twinkiemobile]

My friend an I just took apart his cylinder head. the walls look like they are perfectly fine. we're getting a bore gauge to make sure that everything is good, if we were to re-ring the cylinders would we have to get everything balanced over again? Or how about if we decided to take off the pistons and have the machine shop install std. bore 2g pistons, would we have to have the pistons/rods rebalanced, or would we have to have everything re-balanced?

thanks for any help you guys can give

- Jose

 

[Defiant]

If you change pistons, yes. Otherwise, no.

 

[twinkiemobile]

well if we change to 2g pistons would we have to balance the whole rotating assembly or just the pistons/rods?

 

[paper_clip_boy]

Not exactly. Im not a machinist but im pretty sure that when you balance the rotating assembly that you do not have the rods and pistons attached.

It is a good idea to WEIGHT MATCH the rods and pistons to within 1 gram of each other. This will help keep any harmful harmonics out of the system.

When you Balance the rotating assembly, you only balance the Crank, Flywheel, and sometimes the clutch assembly.

Talk to a local machinist, He wont charge you for advice.

 

[twinkiemobile]

ok, definately weight matched and ask about the balancing. I've read online that the rotating parts on an in-line motor are balanced separately unlike on a v-motor. So i just didn't know if i had to get the whole assembly rebalanced if we switched out to 2g pistons.

 

[paper_clip_boy]

A re-balance of the whole rotating assmebly is always a good idea. A good machinist, one who cares about doing his job well, can balance the Rotating assembly to much closer specs than what the factory has set without much effort. Blueprinting is also a whole other area of things.

Like i said, You are better of talking to a Trusted machinist in your area.

 

[Elvenhome21]

As long as the new rods and pistons are balanced equal to each other, and the old ones were balanced equal to each other. Then there isn't much need to have the crank rebalanced, unless if the new assmbly is heavier then the old rods/pistons, then it might be a good idea.

By going with a lighter assembly (rod/pistons) the crank bob weights are then just overbalanced, which in it self is a good thing for racing as long as its under 3-5% overbalance. New total reciprecating weight/ old recipreccating weight= total over/under balance.

 

[GVR4592]

As long as the new rods and pistons are balanced equal to each other, and the old ones were balanced equal to each other. Then there isn't much need to have the crank rebalanced, unless if the new assmbly is heavier then the old rods/pistons, then it might be a good idea.

By going with a lighter assembly (rod/pistons) the crank bob weights are then just overbalanced, which in it self is a good thing for racing as long as its under 3-5% overbalance. New total reciprecating weight/ old recipreccating weight= total over/under balance.

There is no need for bobweights when balancing an inline engine. When balancing is performed they weight match the pistons and rods; then spin balance the crank with the flywheel, pressure plate and harmonic balancer in place.

 

[Defiant]

well if we change to 2g pistons would we have to balance the whole rotating assembly or just the pistons/rods?

I'll try again.
If you change pistons, yes.

 

[fourreGsixty3]

Hope your using a dial bore guage, and not the T-scope ones...it takes lots of practice, and pacient's(sp?) to learn to use one accuratly...as well as a mic. Also like Defiant said BALANCE THE WHOLE ASSEMBLY IF YOU CHANGE THE PISTONS, if only putting new rings, then you wll be fine without the re-balance.

 

[GVR4592]

http://www.rpmmachine.com/engine-balancing.shtml

 

[my98GST]

The machine shop has my block right now. They were saying since Im going with a ROSS/Eagle rod piston combo, that my crank would need to be rebalanced. Do I REALLY need it done or what?

 

[MyÜberFastGSX]

I would definitely suggest having them doing. Atleast for the value of knowing that it was done.

 

[SnowBird]

Speedworlds machine shop is closed on saturdays, and thats only day I can go. I know some places arent set up to balance parts individually, just the crank. I need pistons pressed on rods, pistons and rods weight matched, and the crank, FW, Pressure plate, and pulley balanced. Im even wondering if I need my Flywheel balanced since its a brand new XACT streetlite, and the clutch is a new SBR clutch. So...is NAPA trustworthy, or should I leave work early to take it somewhere else? Thank you.

 

[my98GST]

Its another hundred bucks that i really don't have

 

[MyÜberFastGSX]

I'm currently $5000 into a 6 bolt build that I had estimated to cost around $3000.
I found out quickly that it's not worth it to save a little bit of money by cutting corners.

Read my thread called DO NOT BUY: Ebay Exhaust Manifolds.


I tried to save a little bit of money by cutting corners. Luckily someone warned me right before it was too late.

So I guess I'm passing on the favor by saying it'll cost you more in the end to try to save money now.

Good luck with your build from one DSM'er to another.

 

[SnowBird]

Where the hell are you getting it balanced that wants $100?!?! Ive heard $30 to $50 to balance a crank, only around $150 to balance the whole engine individually part by part.

 

[MyÜberFastGSX]

Yea, that was gonna be my next question. But I wanted to ask my guy first and make sure. But I thought is was closer to $50

 

[my98GST]

This is a very upper scale performance shop that does everything from hondas to a few Ferrari's and Porsches that run around my town. So far its 250 for: Hot tanking, breaking the bottom end down, boring/honing .020, and decking the block. I guess I'm going to have them balance the crank wile they're at it.

 

[MyÜberFastGSX]

It's probably the best thing.

Ask them if they can give you a little bit of a break on the price, and you'll send some business their way. That usually works.

 

[rst95eclipse]

I won't even think about using NAPA. Nothing against them as a company, but I'd only trust a builder that is known locally for good work - aka craftsmanship. Call up someone in your area that you've heard about and ask them if they can do the work, with the only problem that you can only drop it off and pick it back up on a Saturday. You'd be suprised how easy they are to talk to. Just don't let them push you around with "that's the smallest motor I've ever seen" or something along those lines.