The short version... Motor is stock 305 one piece RMS. Pulled the 700r4 that was slowly dieing but NO VIBRATION and replaced it with a WC T5 with new counter balanced flywheel and yes the auto flywheel had the butterfly weight as well, clutch assembly, flywheel bolts and clutch etc.... got all the parts from rockauto. So install everything (including correct pilot bushing) and start it up and at idle no vibration but above 1500rpm its shakes/vibrates bad.... decided had a flywheel so got another new counter balanced flywheel and also new clutch assembly and it shakes/vibrates at 2000rpm..

Im at a total loss. The vibration happens moving or standing still with clutch in or out.. ive checked all the bolts that i ordered and all seems good.. Im miss my car and missing out on all the cool car stuff that goes on this time of the year and taking my boys to see.. Please help and thanks..

 

should need a 0 balanced flywheel not counter balanced what year is your motor i looked up 87 305 and it never shows counter balanced flywheels

 

This is not correct: the 1-pc RMS motors ALL have the rearmost INTERNAL balance weight, the one that was previously on the flywheel flange of the crank in the 2-pc design, on the flywheel instead. It's a quite small weight, only acoupla ounces. Since this is an INTERNAL weight, the flywheel WON'T be described as "counterweighted", "unbalanced", etc. Those words are not appropriate to this situation.

The ONLY SBC that requires an "unbalanced" flywheel, in stock form, is the 400. Non-stock ones, specifically 383s, sometimes do as well; but not any stock ones.

OP, the best advice I can give you, is to put all that talk and worry about "counterweight", OUT OF YOUR MIND. Just concentrate on the word "stock". The STOCK flywheel for 86-92 Camaro/Firebird is all you need, without muddying the waters with all that other. You will find that there are 2: one is lightweight, about 16 lbs or so, for the TPI motors; the other is MUCH heavier, probably 21 - 22 lbs, and was used for the
(even) slow(er) cars, LG4 & L03. You'll Probably find the light one MUCH more enjoyable to drive, even if you still have the lesser motor in your car.

 

Its a 91RS stock 305 one piece RMS.. Ive triple checked that the auto flywheel is "counter balanced" and replaced with a new "counter balanced" 153 tooth manual flywheel. I'm aware there is a neutral balanced flywheel but not sure why i would use it if my auto flywheel was counter balanced.

 

your auto flex plate has the weight welded to it and a flywheel is not made that way and is balanced differently then a flex plate

 

yes thats correct.... and the manual flywheel was cast with a counter weight and then balanced.


counter balanced flywheel #1

 

Did you "clock" it properly? Notice the dowel pin location.

 

yes. they are what i call idiot proof, and so is the clutch assembly. Also used new hardware on the flywheel and clutch assembly and the new pilot bushing from the clutch kit.

I hate to start guessing at this and throw parts at it but..... It was a beautiful night in TX and i wanted to go cruise and listen to VH at absurd levels but i cant..

 

Post a pic of the 305 flexplate showing the weight.

 

this is the one pulled from my car... it has the counter balance weight.

 

Well, I'll be damned. There it is..... and in the correct location.
I had a theory, but this shoots that idea to hell.
Sofa???

 

There’s no such thing as Van Halen at absurd levels...as a younger man, I saw them twice in concert.

 

I won’t say how long ago that was....but the ticket only cost ten bucks.

 

It might be a trick of the lighting...but several of the bolt holes on that flywheel picture look chewed up....like it wobbled against the bolts on the crank flange. Anyone else see it?

 

It shouldn't be because the end of the crank has a hub that fits into that big hole in the center. That, plus the dowel pin make what you are seeing almost impossible.

 

Did you install a pilot bushing?

 

Looks like he installed one from his clutch kit.

 

yes i installed the new pilot bushing from the kit and noway the bolts moved with all the locktite used on them lol. The only thing i can come up with is to try the neutral balanced flywheel and see how it works out. doesnt make sense but nothing else has on this entire thing so.... Now the $10 ticket for VH speaks for itself and your a old fart like myself but those were the good ol' days. lol

 

Keep me posted..I’m about to do a T56 swap in my ‘88 L98, and have been concerned about the same possible issue...and yes, I can confirm being an old fart...I saw VH in 1982, and 1984.

 

if your motor is 1 piece rms the flywheel that comes from an 93-97 camaro works unless your going LS if it's an older 2 piece rms block like mine you need to buy an aftermarket flywheel from someone like centerforce or spec

 

It's a 1-piece rear main seal engine...however, the OEM flywheel is no longer available anywhere. I'm inclined to splurge for the McLeod steel flywheel--it has provision to add/subtract the appropriate weights, so if there is a problem, it's easily resolved.

 

OK...stupid question. I was just on McLeod's website, and read something interesting.


You said you bought new flywheel bolts--are you certain they were FLYWHEEL bolts, and not FLEXPLATE bolts?


According to the tech bulletin I was reading, the two bolts are very different--to quote:





"A common mistake is to use flexplate mounting bolts to attach a flywheel to the crankshaft. You must use a flywheel bolt! The main differences are the bolt head and the shoulder area. A flywheel requires a bolt head with a small radius at the shoulder location to allow proper contact at the flywheel mounting hole locations. The shoulder of the bolt must fit snugly at these hole locations. The shoulder of the bolt takes the torsional load on a flywheel bolt. The threads on a flexplate bolt will not handle these torsional loads when used to mount a flywheel. If attempting to use flexplate bolts you will find there is very little or no shoulder as a typical flexplate is quite thin (~.090 - .140" thick). A large diameter short head bolt is ideal for a flexplate as there is little clearance between the bolt head and the torque converter. A flywheel/clutch system has more available space and a taller bolt head is utilized."

 

In other words, I'm wondering if Rockauto sent you flexplate bolts, instead of flywheel bolts.


If you compare what you took off of the original engine to the new bolts you were sent, the difference should be obvious.


But, I'll admit, I could be barking up the wrong tree.

 

 

Ive been told the bolt thing and here is what I ordered. I say the "flywheel" bolt sure resembles a pressure plate bolt. Think im gonna need a therapist soon lol

 

http://arp-bolts.com/kits/ARPkit-det...p?RecordID=770

 

something is not right, the neutral balanced flywheel you should be using should have a small counterbalance on it...like the size of a quarter or half dollar...that counterbalance is huge, the counterbalance on a 1 piece RMS 305/350 is to compensate for the flange being round not odd shaped like a 2 piece RMS...its not that big and is uasally advertised as neutral or "0" balanced, you need to try a 0 balanced one if it is a 305....

 

I suspect if the flywheel bolt holes aren’t damaged, and you replace the bolts, your vibration problem may be solved. Without the extended shoulders, which take the load, your flywheel has been swinging back and forth against the bolts, and causing a vibration, because the diameter of the bolts don’t completely fit the holes in the flywheel.

 

I've seen balance plates that bolt to the crank shaft that are suppose to make up for the round end on the one piece RMS so that a true neutral balance fly wheel can be used.

That pilot bushing that came in the kit is probably filled with iron. I recommend getting a good bushing that is made from oil impregnated bronze. Your input shaft will thank you, and it will last much longer than the one with iron in it. I lost a good T5 because of one of those iron filled bushings.

I saw VH on their "1984" tour. I'm getting old too.

 

IIRC, when I rebuilt my T5, NAPA has the good pilot bushings..I think they cost around $5.00.

 

i have a spare flywheel i removed from my 86 i will have to take a look at it tonight, i also have some ARP flywheel bolts from it.

 

I too bought a new Luk clutch from Rockauto and it vibrated.
Got another one and it went away.

 

I got the one in my car from Autogear. Later I needed a custom size for another car, so I bought a piece of oil impregnated bronze and now I make my own.

 

Im pretty sure that the pilot bushing is bronze judging by the color, and the whole flywheel is like stupid nuts and the engineer that came up with must have worked at FORD some point in their messed up life..... now the flywheel bolt part is getting nuts as well... DORMAN offeres 3 different manual trans flywheel bolts of which none appear to have any type of "shoulders" on them, they are just threaded to the top like the ones installed. think i may go sit in my sad camaro and annoy the neighbors with some VH...

for the record I saw VH like '84' '85 '86 (dont quote me on those yrs) at the best jam of all!!! The TEXAS JAM AT THE COTTON BOWL!!! was helluva show from what i can remember lol

 

To solve this you are probably going to have to take the flexplate you removed to a shop that does engine balancing to have them determine the amount of imbalance you need for a flywheel.
I have an engine test stand. I normally use only an SFI flexplate on the back. I wanted to see if a flywheel made any difference on my 302 Chevy. I ordered a ProComp 168 tooth and it came with a bolt-on weight attached - and no documentation. The 302 is internally balanced, so the flywheel or flexplate needs to be neutral - zero imbalance. I was not sure whether to take the weight off or leave it in place. I left it and when I fired the engine, it jumped around on the stand like the OP describes in post #1 - shakes all over at 2000 rpm & up. I removed that weight and everything was smooth again. He has his problem diagnosed correctly.

Oh yeah, I also saw VH when I still was in my teens on their 1984 tour. Old farts are we now.

 

I did this swap years back although mine is a 350. As others have said the one piece (after 86 I believe) uses a flywheel or flex plate with a "weight" on it to compensate for the round rear flange. I believe ALL 305/350 use the same flywheel or at least the same type weighted wheel.
Yes, stock 400's were counterweighted in a similar manor and all "internal" balance cranks use "0" or neutral weight flywheels.
Even with the proper wheel there can be vibrations caused by the pressure plate. I went through a few different brands, Valajo Zoom, Ram and centerforce and all had "some" vibrations. To the point I figured my builder had done something wrong until I installed a McLeod RST and all the vibration went away.

If you can, reinstall the flex plate only and start the engine. See if its smooth. You should be able to do it even with the trans removed. You may need to brace the engine with a strap but it can be done. Then, if it runs smooth install only the manual flywheel. See if it is smooth. Then you will know for sure if it's the engine, flywheel balance or something else.

 

this is a stock replacement flywheel that i bought for my original t5 1986 over 10 years ago.

 

Yep, no balance weight, since it’s for an earlier 2-piece rear seal SBC.

 

no. that came off a 1 piece seal block

 

A 1pc rms engine is combo balance. Internal on the front and the loss of the D shaped balance pad on tge rear flange is in the flywheel or flexplate. Neutral flywheel/flexplates are for internally balanced setups. 1pc rms is not rear internally balanced. Oem number
14088646

 

that # is a lightweight 1 pc seal external balance.

the photos above is the exact same part that came on my 86 1 pc seal T5 original car.

 

I am not an expert on this so take with a grain of salt.
My 350 flexplate and then flywheel both had weights on them.
Catalogs show 350/305 & 4.3V6's all use the same PN.
All are 3.48 stroke. The only difference in 305/350 is the bore so very little difference in piston weight. I believe the 305/350 are balanced the same. Whether it is considered "external" balance or not I don't know. A 400 crank has more weight for balancing and is definitely external balanced.
But let's assume the part ordered is the correct one. (int or ext bal) The vibration the OP mentioned may or may not have anything to do with the flywheel. Good to eliminate variables if possible. Run the old FP, then new FW without the clutch and PP and see if vibration persists.
.02 worth.

 

Correct. 1 pc RMS.
Look at the outline for the smaller (than gen 1) and round flange.

 

He is correct... they offer 2 different flywheels for this set up. Its a crap shoot to guess when you look on the website. After tons of sorting through and researching and finding someone with the exact same problem and switching to a neutral balanced flywheel fixed the problem.... So Im waiting on my neutral balanced flywheel to come in so i can install it... I will keep you updated on this it should be interesting. lol

 

Yes and see that large raised portion on the right side from 2 o clock to 4? That's the heavy side. That is not a neutral fw. The N after casting nr means nodular.

 

Lots of good information in this thread...

 

As mentioned before, take the fly wheel and have it balanced. And also, I would only us ARP bolts. Rock auto is a good parts place, but something like clutches, fly wheels, flex plates, I think i would have went elsewhere. Just my

 

Just some reference pics. Top flywheel is GM 14088847 removed from my all original 92 Z28. Bottom is GM 14088671 from a T5 swapped L98. Top flywheel is much lighter.

 

So how do you truly know what flywheel to use? The info on various websites is far from being clear on this subject. Excellent pic Ty92Z.

 

Both are for 1pc rms, so I believe either would be correct. TPI cars got the lighter flywheel and the TBI cars got heavier piece. Performance wise I would think one would prefer the lighter flywheel. I have a flywheel from an 2wd 87 Chevy truck that came with a 1pc rms sbc and a 4 speed. I will dig it out tomorrow and see if/how it’s different.