eddietheripper

Hey everyone long time no talk. Looking for some input on a issue I am having. I have a 1985 iroc. Came with the 305 h.o. l69. I put in a zz5 gm crate a few years ago. No issues. I then bought a 1996 firebird with a lt1 t56 as a donor car for a trans swap. I did the swap, and due to the pull style clutch I had to use the flywheel off the lt1 on my ZZ5. I put the 5 speed back in the firebird and sold it. So now at 2300ish rpm I have a vibration that goes away at around 2500. I installed a new McLeod clutch as well. I unbolted the trans mount, jacked it up a bit and ran the engine again. The vibration was gone and with my hands on the engine itself felt nothing.

question is this. Are both engines balanced the same? The flywheel should be compatible? I am stumped. Also, I realise the factory setup had 2 rubber isolators on the trans mount. Now that I am using the sphon t56 swap crossmember, it is directly bolted to the body. Is this vibration just something I will have to deal with due to this design?

any input is greatly appreciated. Have a good one

skinny z

Greetings from the Edmonton area...
If my information is correct, in 85 the SBC had a 2 piece rear main seal and a flexplate (and I believe) flywheel that would be neutrally balanced. Once the 1 piece rear main seal was adopted in 86, flexplates (and flywheels ) were fitted with a counter-weight due to the new design. Certainly the LT1 and ZZ5 are a 1 piece RMS. If you've crossed over between the two designs, you're going to have trouble. I can't say for certain how your mix and match has panned out but this may something to consider.

NoEmissions84TA

iTrader: (1)

So then he should be able to pull the flywheel and have it neutral balanced then, correct?

skinny z

That's a question I can't answer. If indeed that is the issue (and it would seem to me that if that is the problem the vibration would be considerably worse) it would make sense to have it corrected that way.
But, I'll relate a story from personal experience. After a transmission rebuild, I had a noticeable vibration. All investigating led to a transmission problem as the vibration went away when the flexplate was decoupled from the engine. I blamed my trans builder. Long story short, I came across a procedure in the GM manual called "Flexplate/flywheel vibration test". Hmm. It stated that when a vibration occurs (after a re and re), re-clock the convertor to flexplate by 120 degrees. If vibration persists, rotate another 120. The vibration disappeared. Turns out the stack up of unbalances made an acceptable situation worse. My mistake was not marking the relationship between the two components and caused a world of grief in the process.

Aviator857

So its had the vibration since the t56 swap or did it develop over time, if over time it may be getting loose. Does the vibration show up in with the clutch in at those RPM's or just while driving?

I would look to see of someone sells a flywheel for the T56+ZZ5 combo. Or if you still have the T5 flywheel a machine shop may be able to compare the balance. Did the donor vehicle end up with the t5 flywheel? if so did you drive it and did it have a vibration? Did you drive the donor while it had the T56?

naf

iTrader: (7)

the LT1 T56 clutch and flywheel should be a bolt on to the ZZ5 with no re-balancing.

stock LT1 clutch/pressure plate assemblies are notorious for balance issues, there was even a factory TSB about it. A search on some other forums will show several threads on the issues.

I recently took the stock style clutch/pressure plate assembly off of mine and a shop found it woefully out of balance. Mine would start at around 2500. They found my flywheel in perfect balance. They spun it attached to a one-piece rear main crank with the appropriate bob weights. The assembly cannot be spun by itself without taking into account the last counterweight that was moved from the crank to the flywheel when the motor changed from two-piece to one-piece rms. Any reputable shop should know this.

A new RAM clutch/pp I received showed no balance holes drilled. Talked to tech support at RAM and they could not guarantee that it was neutral balanced. I sent it back. They are local and I regret that I did not take it by them to try to get them to confirm the balance.

Purchased a LUK clutch/pp from RA. It had balance holes drilled in it. Installed it and no more vibration.

If you still have vibration I'd take your McLeod clutch/pp and your flywheel to a local shop to check.

Stock style clutch/pp's for the T56 appear to all be made by the same vendor. The RAM clutch I spent ~$400 on was identical in every visible way to the $130 AZ clutch/pp I had originally installed.

eddietheripper

Sorry I didnt reply to these. My stupid email was sending my notifications to my junk folder.

So far I found a mcleod flywheel, 460350( ouch expensive )
and installed the appropriate weight onto it in the kit you can buy 560222. So that is bolted on. Right now, I am waiting for parts for my T56 from hawks in south Carolina. I took it apart to see if there was any issues during winter and the cluster gear came off by hand. Mainshaft is worn. Also a lot of the crappy plastic shift pads are worn right out. So I ordered the stage 2 kit with the steel fork.

so that's what's up so far. Hope the vibration will be gone after all this time and money. Shipping stuff to edmonton from the states is ridiculous. I've already told off ups twice for their scamming brokerage fees. Will update when shes runnin

skinny z

Tell me about it. I'm pretty sure these couriers just have a "wheel of fortune" in the back somewhere that they spin to determine their fees. At one time a long while back they'd even return to collect the taxes that weren't included in the original invoicing. Surprise! At least now a place like Summit pre-calculates shipping, taxes and fees before you pay.

Now if I could only do something about the 75 cent CDN dollar.

eddietheripper

skinny z

I wouldn't hold my breath on that one. There are plenty of other equally inept candidates ready to take his place.
Off topic question: Do you know Charlie from AMS Racing Engines? 1986Z28Owner

GeneralDisorder

iTrader: (1)

Can confirm - ran across this exact scenario except I received the car already in this condition. Took me a LONG time to figure out the converter/flexplate needed to be re-clocked. Like months. Lesson learned.

I have to wonder how they dealt with this at the factory. They ran them and then if they got a vibration they re-clocked it? That seems unlikely for a production environment. But things were different in those days. They had someone manually selecting what main bearings to install in the block too so maybe it's not so far fetched.

GD

Galaxie500XL

iTrader: (1)

I have this very flywheel setup still in the box, awaiting for warmer weather, and for me to recover from the heart attack I had last month. As a result, my freshly rebuilt T56 is sitting in my storage area, waiting to be installed behind my '88 L98 IROC.

PLEASE let me know if it worked well for you. The flywheel was VERY expensive IMHO, and I'd feel much better before unboxing it to know it works well.

Abubaca

iTrader: (3)

five7kid

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