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Crankshaft replacement by Cunnive
Started on: 04-24-2020 08:41 AM
Replies: 23 (555 views)
Last post by: Cunnive on 09-11-2020 08:04 PM
Cunnive
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Report this Post04-24-2020 08:41 AM Click Here to See the Profile for CunniveSend a Private Message to CunniveEdit/Delete MessageReply w/QuoteDirect Link to This Post

Hey folks,

I am in the process of rebuilding my 2.8L and I figured since I am replacing every part in the engine, I might as well replace the crankshaft.

Anyone have a recommendation for a replacement crankshaft? I'm not looking for anything performance-wise but something that is close to or slightly better than OEM.

Ty
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Report this Post04-24-2020 11:21 AM Click Here to See the Profile for RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
If you are replacing the crank, do a 3.1 crank and pistons. They're pretty much a straight drop-in. The block and rods are the same.
You'll be pleased with the torque increase.
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Cunnive
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Report this Post04-25-2020 12:38 PM Click Here to See the Profile for CunniveSend a Private Message to CunniveEdit/Delete MessageReply w/QuoteDirect Link to This Post
Unfortunately I already purchased replacement pistons and connecting rods for my current crankshaft so I would need a replacement for what works without needing to get matching pistons.

I see the engine tech crankshaft on rockauto is out of stock so was wondering what other brand or replacement would work.
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olejoedad
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Report this Post04-25-2020 12:47 PM Click Here to See the Profile for olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
How many miles are on your engine.
If the crank is not damaged, why would you want to replace it.
A seasoned cast crank is stronger than a new cast crank, simply because it is seasoned.
Magnaflux your old crank to check for cracks, if it's not, then use it.
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Report this Post04-25-2020 10:05 PM Click Here to See the Profile for RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
This may not exactly address your question, but here goes....
I don't know what year your 2.8 is, but if it's an 85-87, you can swap in an 88 crankshaft. You will need to also replace your flywheel or flexplate, to a neutrally balanced piece. A flywheel or flexplate for most any FWD 3.1 will work with the 88 crankshaft. The later (neutrally balanced) flywheels are much easier to find than the earlier (weighted) pieces.
Hope that helps a bit.

[This message has been edited by Raydar (edited 04-25-2020).]

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pmbrunelle
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Report this Post04-25-2020 10:17 PM Click Here to See the Profile for pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by olejoedad:
A seasoned cast crank is stronger than a new cast crank, simply because it is seasoned.


I don't know how the seasoning helps things, but it is an intriguing idea.

The 80s BMW F1 turbo engine blocks were apparently sourced from used road-car engines.
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Report this Post04-25-2020 10:51 PM Click Here to See the Profile for wftbSend a Private Message to wftbEdit/Delete MessageReply w/QuoteDirect Link to This Post
Engine blocks as raw castings used to be left outside for a few months before machining. My late Uncle, that worked on WW2 aircraft told me all factories did this and he called it seasoning as well.

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Report this Post04-26-2020 09:26 AM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by wftb:

Engine blocks as raw castings used to be left outside for a few months before machining. My late Uncle, that worked on WW2 aircraft told me all factories did this and he called it seasoning as well.



correct.

Cast Iron is odd stuff. As it cools it builds up internal stresses. If you machine it right away, the part will slowly warp and probably take your machining out of spec. Each part will have it's own requirement for 'seasoning', but a used part has already done all that and will maintain accuracy better than a new part.

[This message has been edited by Gall757 (edited 04-26-2020).]

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Cunnive
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Report this Post07-06-2020 01:56 AM Click Here to See the Profile for CunniveSend a Private Message to CunniveEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by olejoedad:

How many miles are on your engine.
If the crank is not damaged, why would you want to replace it.
A seasoned cast crank is stronger than a new cast crank, simply because it is seasoned.
Magnaflux your old crank to check for cracks, if it's not, then use it.


The thrust bearing was eating away at the walls too much and has made it too close for comfort to exceeding the recommended specs. I also found a tictac-sized piece of metal stuck inside an oil galley when I took out the crankshaft so I want to just replace it entirely.

My machine tech told me I need a Cast #817 for my 2.8L 86 fiero engine

Is there any crankshaft out there I can search for that would be a straight replacement?

[This message has been edited by Cunnive (edited 07-06-2020).]

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fierofool
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Report this Post07-06-2020 07:34 AM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
As Raydar said, you can get a neutrally balanced crankshaft for a (Beretta) 3.1 FWD engine and use your old rods and pistons or the new stock 2.8 rods and pistons you just bought. The shorter stroke of the 3.1 will give you much more torque. It's all a drop-in, except you'll need to replace the flywheel or fexplate. In that case, a 91 Beretta piece is readily available through Rock Auto.
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Cunnive
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Report this Post07-06-2020 08:50 AM Click Here to See the Profile for CunniveSend a Private Message to CunniveEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierofool:

As Raydar said, you can get a neutrally balanced crankshaft for a (Beretta) 3.1 FWD engine and use your old rods and pistons or the new stock 2.8 rods and pistons you just bought. The shorter stroke of the 3.1 will give you much more torque. It's all a drop-in, except you'll need to replace the flywheel or fexplate. In that case, a 91 Beretta piece is readily available through Rock Auto.




Is this the right one?

I am also swapping out my transmission for the 4T60. Do I need to do anything to this transmission for the Beretta crankshaft?
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Report this Post07-06-2020 11:51 AM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'm installing a 3.1 engine into my 86. It's a factory engine, but the block is essentially identical to the 2.8. It has the 981 cranshaft in it. That was how we determined that it needed a neutral balanced flywheel instead of the counterweighted 86 flywheel. Something way back, though says that the reluctor wheel might have some interference with the block. Some of the other guys like olejoedad might be able to answer that question. The 4T60 transmission is quite strong enough for that engine.

Raydar, does he need to change to 3.1 pistons or can he use the 2.8 pistons with the 3.1 crankshaft? If not, the 88 cranshaft and 3.1 flexplate would be the way to go
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Report this Post07-06-2020 12:04 PM Click Here to See the Profile for pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
You need to change to 3.1 pistons to use the 981 crankshaft.
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Cunnive
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Report this Post07-06-2020 06:40 PM Click Here to See the Profile for CunniveSend a Private Message to CunniveEdit/Delete MessageReply w/QuoteDirect Link to This Post

So if that's the case, what crankshaft would be a direct replacement to the original crankshaft that will allow me to use 2.8 pistons?
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Report this Post07-06-2020 06:51 PM Click Here to See the Profile for pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Cunnive:


So if that's the case, what crankshaft would be a direct replacement to the original crankshaft that will allow me to use 2.8 pistons?


The answer to this question is in this previous post:
//www.fiero.nl/forum/F.../HTML/143726.html#p4
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Cunnive
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Report this Post07-06-2020 09:11 PM Click Here to See the Profile for CunniveSend a Private Message to CunniveEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by pmbrunelle:


The answer to this question is in this previous post:
//www.fiero.nl/forum/F.../HTML/143726.html#p4


Ok thanks. Sorry for the trouble, this is a first for me so I am being overly cautious. So a Fiero 88 crankshaft would be the direct replacement is what i'm understanding.

It also sounds that if I swap out the 125C transmission for a 4T60 then I probably don't need to worry about the flywheel/flexplate.

ty all!
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Raydar
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Report this Post07-06-2020 09:24 PM Click Here to See the Profile for RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Cunnive:


Ok thanks. Sorry for the trouble, this is a first for me so I am being overly cautious. So a Fiero 88 crankshaft would be the direct replacement is what i'm understanding.

It also sounds that if I swap out the 125C transmission for a 4T60 then I probably don't need to worry about the flywheel/flexplate.

ty all!


If you don't completely understand all the variables involved, you can never be too cautious.

If you want to keep your 2.8 pistons, then yes, go for the 88 Fiero 2.8 crank.
Use an 89 or later Beretta or Cavalier flexplate. (It will probably call for a 3.1. They should be the same.) It should not have any sort of balancing weight on it.

Edit - If you use a 3.1 crank - any 3.1 crank - you will need to swap over to 3.1 pistons as well. The rods, however, are the same.
Based upon your most recent responses, I'm assuming that's not what you are planning to do.

[This message has been edited by Raydar (edited 07-06-2020).]

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Report this Post07-06-2020 09:26 PM Click Here to See the Profile for pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
It's OK to ask twice for confirmation, considering that being wrong can be an expensive mistake.

But when a correct answer has been provided, there's no need to rewrite the same answer again slightly differently; the original correct answer can be referred to.

Where possible, I find it is good to adhere to the DRY principle:
https://en.wikipedia.org/wi...%27t_repeat_yourself

I am not sure about the automatic transmission flexplate stuff, so I will leave that to someone who is better-versed in that.
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Report this Post07-07-2020 12:53 PM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierofool: As Raydar said, you can get a neutrally balanced crankshaft for a (Beretta) 3.1 FWD engine and use your old rods and pistons or the new stock 2.8 rods and pistons you just bought. The shorter stroke of the 3.1 will give you much more torque.

This is incorrect. First of all, the 3.1 crankshaft has a longer stroke than the 2.8 crankshaft. That's where the extra displacement comes from. Second of all, the 2.8 pistons are too tall to use with the 3.1 crankshaft. If you did that, the piston would crash into the cylinder head, and that would ruin your day.

Since the OP already has new 2.8 pistons, he needs a 2.8 crankshaft. The '85-87 crankshaft (i.e. externally balanced) would be a direct drop-in for his engine.

 
quote
Originally posted by Cunnive: My machine tech told me I need a Cast #817 for my 2.8L 86 fiero engine

This is correct.

I see a crankshaft kit on AutoZone's website (with bearings) for about $205. Link: https://www.autozone.com/in...0540/212889_187284_0
RockAuto sells the same thing, but it appears to be out of stock. You may be able to find it elsewhere, but I got lazy.

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

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Report this Post07-07-2020 04:47 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks, Blacktree for the correction. Wouldn't the 88 crankshaft also be a direct drop-in, along with a neutrally balanced flex plate?
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Report this Post07-07-2020 05:35 PM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
I think the OP just wants to replace the crankshaft. But yes that will work.

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

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Cunnive
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Report this Post07-07-2020 11:48 PM Click Here to See the Profile for CunniveSend a Private Message to CunniveEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Blacktree:

I think the OP just wants to replace the crankshaft. But yes that will work.



Thank you for the input!

I did find the crankshaft on RockAuto and AutoZone but both places are out of stock. AutoZone shows it in stock but when you add it to your cart, you get the "Item not available" message.

I did however find a replacement on https://proenginerebuilders.com - it's a little more pricey but hey, better than nothing!

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Report this Post07-08-2020 11:11 AM Click Here to See the Profile for MarkSSend a Private Message to MarkSEdit/Delete MessageReply w/QuoteDirect Link to This Post
You might try these guys:

https://engine-parts.com/pr...2-8l-crankshaft-kit/

They've taken heat for their 3.4 short block conversion but for a reconditioned crank, they might be fine.

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Report this Post09-11-2020 08:04 PM Click Here to See the Profile for CunniveSend a Private Message to CunniveEdit/Delete MessageReply w/QuoteDirect Link to This Post

Hey hey!

So I got my replacement crankshaft from this link https://engine-parts.com/pr...2-8l-crankshaft-kit/

and it looks good but I noticed something that I wasn't sure about and wanted to ask yall





The top crank is the old Fiero crank while the bottom one is the new one. It doesn't appear like that part is held in by anything other than friction so would I be able to just pull/wedge it out?

If so - anyone got tips on removing the pin from the old crank and installing it on the new one?

Thanks!
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