'88 Fiero Balance Shaft (Page 1/1)
Nhertz1613 OCT 07, 08:40 PM
Howdy, My name is Nathan. I've got an '88 2.5/5Speed Fiero I picked up for $800 a few months back. Ran great with what I thought was a slight engine knock, turns out the balance shaft assembly was failing. Bought it anyways cause there was VERY minimal rust on the inner metal body, subframes, battery tray, under the battery tray... you name it. But being new to the Fiero world, "Iron Duke" world, and just GM world (minus LS Motors), I figured I'd ask rather than assume stuff. Lol

My questions are...

Has anyone successfully shaved the weights off the '88 Balance shaft assemblies to allow them to "reliably" run without grenading themselves? I know the '87 Has the same setup minus balance shaft assembly, with a normal oil pump. I just don't have one around me for sale that doesn't need rebuilt, or overly expensive.

Has anyone found a possible bearing that fits in the balance shaft housing in case of needing to rebuild one?
Raydar OCT 07, 09:43 PM
The balancer is largely made of "unobtainium".
There were rebuilt pieces being offered, a couple of years ago, but those have since dried up.

One of our club members (Top Notch) I believe, rebuilt one, a few years ago, but I don't remember the details. I'll see what I can find.

This may be useful to you.
http://gafieroclub.org/docs/BalanceShaft.pdf

[This message has been edited by Raydar (edited 10-07-2020).]

Nhertz1613 OCT 07, 10:35 PM

quote
Originally posted by Raydar:

The balancer is largely made of "unobtainium".



Thanks a bunch for the response. I assumed that was the case. I was originally looking at doing some sort of bushing for it, but I have no clue what material to use. I've recently found someone selling a good balance shaft assembly that is used, hence the thought of machining the weights off the shaft and gear portion and making the best efforts to get it "zeroed" in in hopes to keep from ruining the bearings a second time, and keep my oil pump operational.

That file you attached will help tremendously if the weight machining does not work, though. Very specific tolerances.
theogre OCT 07, 11:11 PM
Find 87 engine. Has ~ same everything but w/ "old style" Oil pump and filter w/o balancer.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Nhertz1613 OCT 07, 11:33 PM

quote
Originally posted by theogre:

Find 87 engine. Has ~ same everything but w/ "old style" Oil pump and filter w/o balancer.




I'd like to. But nobody has one for sale that doesn't need a heavy rebuild, or overly expensive.
gjgpff OCT 09, 01:06 AM
Hi Nathan,
What are the symptoms that suggest to you that the balance shaft is going? What are you hearing/seeing/feeling?
I've got the same kind of Fiero and I'd like to be on the lookout.

Thanks,

------------------
Geoff Gibbons
1988 4cyl Manual

Raydar OCT 10, 09:24 PM

quote
Originally posted by theogre:

Find 87 engine. Has ~ same everything but w/ "old style" Oil pump and filter w/o balancer.




I tossed this idea around for all of a few minutes. Was thinking an 87 block and lower end (since the crank is essentially the same as the 88, and "heavier duty") with an iron "775" SD head bolted to it.
The 775 head is not the "maximum effort" head. It uses the stock Fiero intake and exhaust gaskets (and the hardware mates up, IIRC) and might actually not stress the lower end enough to just kill it, outright.
But I went in a different direction.

[This message has been edited by Raydar (edited 10-10-2020).]

Nhertz1613 OCT 24, 12:02 PM

quote
Originally posted by gjgpff:

Hi Nathan,
What are the symptoms that suggest to you that the balance shaft is going? What are you hearing/seeing/feeling?
I've got the same kind of Fiero and I'd like to be on the lookout.

Thanks,





Had a very weird knock from the lower end so I stopped driving. It sounded like rod knock but it was WAY faster than rod knock. I pulled the pan after removing the engine and could wiggle the shafts around a solid 1/4" where the bearing should have been.


I decided to shave down the two weights on the shaft and the press fit gear, I'll upload a picture when I get back to work and show what I'm talking about, and get an opinion on it from you guys. I don't think it's going to "stop" it from happening, but may at least mitigate the chances of it happening with the large amount of weight that used to be spinning around. The closest '87 2.5 to me is about 180 miles away, and I only drive a Jetta, so it's Probably not going to fit in the trunk. And the lady is probably not keen on a greasy engine in the back of her tan interior car.

[This message has been edited by Nhertz1613 (edited 10-24-2020).]