 
     |
| Crankshaft replacement (Page 2/3) |
|
Cunnive
|
JUL 06, 08:50 AM
|
|
| 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?
|
|
|
|
fierofool
|
JUL 06, 11:51 AM
|
|
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
|
|
|
|
pmbrunelle
|
JUL 06, 12:04 PM
|
|
|
You need to change to 3.1 pistons to use the 981 crankshaft.
|
|
|
|
Cunnive
|
JUL 06, 06:40 PM
|
|
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?
|
|
|
|
pmbrunelle
|
JUL 06, 06:51 PM
|
|
| 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:
http://www.fiero.nl/forum/F.../HTML/143726.html#p4
|
|
|
|
Cunnive
|
JUL 06, 09:11 PM
|
|
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!
|
|
|
|
Raydar
|
JUL 06, 09:24 PM
|
|
| 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).]
|
|
|
|
pmbrunelle
|
JUL 06, 09:26 PM
|
|
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.
|
|
|
|
Blacktree
|
JUL 07, 12:53 PM
|
|
| 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).]
|
|
|
|
fierofool
|
JUL 07, 04:47 PM
|
|
|
Thanks, Blacktree for the correction. Wouldn't the 88 crankshaft also be a direct drop-in, along with a neutrally balanced flex plate?
|
|
|
|