I have a quick question regarding ARI 3.1 stroker motor. I purchased a car that was said to have had one installed and was bored out making a 3.2... I have been trying to track a vibration in the car not knowing if its engine related or suspension but all bushings are poly and all eng/ tran mounts are new... Well to get to the point .... I was under the car trying to track an oil leak and I was looking at the flex plate and it deff has weights on it... Now I thought you needed a neutrally balanced one for an 88+and correct me if I'm wrong but wouldn't that be one with 0 weights on it.....if that is the case is there anything I can do without having to pull the trans out... The vibration is deff there gradually more as the rpms go up so in my head this makes sence... It's bad enough that my tail light screws on the drivers side keep loosening and I have a crack in the drivers corner rear panel next to the screws on my gt
The flexplate will need to be removed. You can probably make your existing one work by removing the balancing weight, and having it re-balanced. But it won't be as simple as just removing the weight. It will actually need to be re-balanced. Otherwise, you'll end up with the same problem all over again.
It might actually be cheaper to just buy the correct flexplate, instead of having a machine shop re-balance your existing one.
You're probably wondering why you can't just remove the weight from your existing flexplate. There's a good reason for this. The externally balanced flexplate is not just a neutral-balance flexplate with a weight added. It's actually built to a different balance, with the weight added to fine-tune it.
You can drill the spotwelds and knock the weight off. (I've done it) Then what you have is the same as if you buy a new neutral balance flywheel. I work in an engine building shop, and I do the balancing. All flywheels have too much weight variation. For that matter, so do the cranks.
Originally posted by larry mimbs: You can drill the spotwelds and knock the weight off. (I've done it) Then what you have is the same as if you buy a new neutral balance flywheel.
This may be true for a Fiero flywheel, but not the flexplates. The external-balance flexplates have 4 big holes in an asymmetrical pattern, whereas the neutral-balance ones have 3 big holes in a symmetrical pattern. If you take the balancing weight off an external-balance flexplate, the flexplate will still NOT be neutrally balanced, because of the asymmetrical hole pattern.
Edit to add photos of the two different flexplates:
[This message has been edited by Blacktree (edited 09-08-2013).]
Finding/ buying isn't the issue... I'm planning an overdrive swap in the future but didn't want to have to pull the tranny for any reason till then.... Any way of verifying in fact if it is a 3.2 or just a 2.8
If it shakes so bad you cracked body pannels I think you have answered your own question. Are you sure the block is a 2.8? Look to see if there is a place to bolt a starter on the back side of the engine, if so then it is likely a 3.1 RWD engine and will need a newtral FW. Larry
As stated it wasn't ever said to have been a 3.1 block I was told the motor was rebuilt and bored using an ARI kit... The crack was there prior to my purchase and the engine only had a cpl hundred miles... I've put an additional 1800 on it since I bought it... Not sure if the vibration is in fact from the engine all I saw was weights on the flex plate which either tells me it's the wrong flex plate that can explain the vibration or its not a 3.2 and the vibration is somewhere else
Short of pulling the pan I don't know of any way to tell for sure what you have. I would tend to believe what the seller told you, every thing you say points that way. If you could find an inspecton camera that will fit through the oil drain plug you could look at the crank and know for sure unless someone put a windage tray in it like a 3100 has. Larry
I think you are lucky to find the problem, that is probably why they sold the car. It is really quite an easy fix, you can probably do it by just dropping the rear of the cradle down and pulling the transmission while supporting the engine with a 4X4 across the strut mounts and some chain. Larry
Mark, you may be thinking of 186, which is what 981 looks like upside-down.
Edit to add: there was also a casting number 268, which IIRC is interchangeable with the 981 crank.
The 486 was in a Marshall crankshaft kit I was thinking about getting several years back. Dunno, maybe they were reading it upside down! Could be the 486 was the early Transport TBI 3.1 crank.. In any event, I didn't buy it as I might wind up with a welded up rod journal in one of those kits.
Well either wating guess I'll just start looking for the parts for either the overdrive swap or piece together the stuff to drop a 5 spd in it.....I'm really certain that it is the wrong plate in the car which is no biggy but if the tranny has to come out to replace it it sure as hell ain't gonna go back in(. 3pd tranny with no 1st gear). I could use the extra gear / gears anyways since I do a lot of trips in this car for my military...plus I figure if I'm upto 25 mpg on this motor and missing a gear and having a balance issue that is shine can't be helping mpg any having an extra gear and hopefully smooth running motor should help on gas and performance some
well it took a long time to be able to getthis into a garage to do this but i finally got the pan dropped
first off it definately has the center piece on the crank with the notches but comparing it to the picture above in this topic it is not nearly as large diameter...in the picture it looks fairly close to the edge of the block where as mine deffinatly has alot more space their
also the car doesnt knock and oil pressure is always around 60psi but the rods do have some front to back play ...is this normal .. i mean i can slide them on the crank just a littlebit side to side....no up and down play