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Flywheel thickness? the machine shop may have messed up my flywheel...

scouthead

scouthead

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Is there a min thickness on a flywheel, as on brake drums and rotors? I don't see anything in my service manual. It's out of my 1988 K5 with TBI 350 and sm465 trans.

Back story:

6-7 years ago I had the flywheel resurfaced when I rebuilt my motor- have about 50 thousand miles of towing and off-roading on that clutch now- it's all used up. I took the flywheel back to the same place that resurfaced it last time, and I got a call a few days later - a kid telling me that the "hot spots were probably too deep to resurface my flywheel" and that he would have to take more than 100 thousandths off of it to get it cleaned up... And that it would be too thin, and then warp, and ruin my new clutch. He wanted me to buy a new one instead of resurfacing.
Ok...
I told him it didn't look that bad to me, and that my motor had been balanced with that flywheel. I also told him I would would appreciate them trying to cut it. He grumbled and said it prob wouldn't work but they would try.

A few days later I went to pick up the flywheel. When they brought it out- the they had resurfaced the flywheel where the friction surfaces are, and they claimed they only cut 50 thousandths off of it...ok great.
-but somehow they gouged and grooved the outer inch of the face. That would be the mounting surface for the clutch assembly... I did not feel the new clutch would line up or stayed bolted down correctly with the new wavy and uneven surface, and I complained to the owner. He said it must have come in to his shop like that! I said no way, and the showed him a picture of what it looked like before. He held a ruler against it, and I could get my fingernail under it where they gouged the face. He said he was very sorry and they would re cut it. -said he didn't understand how that could happen on their lathe. I asked him if it was going to be too thin to reuse the flywheel after they removed even MORE material, and he said "oh I'm sure it will be fine"

So, now after putting all the pieces together, I'm pretty sure the kid tried to resurface my flywheel- screwed it up, and then called me to say I should buy a new one -hoping I wouldn't question it.

Now, I'm worried that there really will be too much material missing from this thing to reuse it. There is likely an 1/8 inch or more material cut off from how it was origionally. It's a thick flywheel, but that is a LOT of metal when it's usually only taken off a few thousandths at a time!
It's a serious pain in my ass to get at the clutch- I want at least another 40-50 thousand miles before having to do this again. So, I'm on my way over to pick it up again- and before I install it I want to put a caliper on it and compare to something.
?????
 
I dont know if there is a minimum thickness,but there most likely is,and a limit as to how much material can be removed...

I only turned a few flywheels when I worked in a parts store with a machine shop,both for my own trucks--we had a surface grinder ,not a lathe,and it was a tricky thing to set up--I let the other guy who did most of the work in that part of the shop resurface them,and I did other jobs he disliked ,like u-joints and pressing out kingpins,drilling out busted exhaust manifold studs,etc..

One thing that removing material from the flywheel will affect is clutch pedal height,and it'll need shims to get the fluwheel back in the proper relation to the rest of the clutch parts and engine,bellhousing,etc..

If it were me,I'd probably ask the store owner to get me a new flywheel,if not for free,at a healthy discount,like his cost,just to be safe and avoid having to tear it all down again if it didn't pan out..
 
You can remove a TON of material from a flywheel as long as it's not a hydraulic clutch. If it is a hydraulic clutch you cannot remove much material before you can no longer release the clutch disc when depressing the clutch pedal.
 
4X4HIGH said:
You can remove a TON of material from a flywheel as long as it's not a hydraulic clutch. If it is a hydraulic clutch you cannot remove much material before you can no longer release the clutch disc when depressing the clutch pedal.
Click to expand...

Dang. It is a hydraulic clutch.
 
Ok- just picked it up- owner said he had to put a new cutter in the lathe- surface looks good. I asked how much had been cut off- he said 50 thousandths. That's the same as what he told me last week before they had to fix their grooving/ gouging. I asked if that was total material removed, or the last round of cutting- he said total, and that they only had to take 10 thousandths off to fix the grooving they did. I'm guessing he doesn't actually know how much was removed?
So- I guess I have no idea how thick it still is, or how thin it has become...

To be fair I called the machine a "lathe" but I really have no idea what the specific machine is they used- could be a grinder- I don't know. Never done it myself.
 
Hmmm. I hadn't thought about haven't problems with it functioning do to changed geometry- was mostly worried about how long it would last before warping/ cracking.

It is indeed a hydraulic clutch. It always worked, but pedal was super heavy- I always wondered if something was wrong- it was like driving a dump truck. I had pop eyes' arms for a left leg when I drove it more frequently- I wonder if something wasn't adjusted correctly, or if they removed too much material the first time I had it surfaced? Maybe it's been out of whack for 6 years? It's Been thru several master cylinders and slaves over the years- don't think the heavy pedal or short throw on pedal had anything to do with the hydraulics.

Also seemed like all of the engaging and disengaging was happening in the first Half inch of pedal movement- very stiff- then a few inches of over travel until something inside the clutch bottomed out and stopped the slave from expanding anymore. The heavy effort Made me want to try a master with smaller bore, or slave with a larger bore. Never got around to it.

...so the pedal dropping a bit closer to the floor wouldn't really upset me- but if something else is going to be out of adjustment, and prevent it from working- that would be bad. Can't remember if the pivot stud on the hydraulic bell housing is adjustable? Bring the throw out bearing arm in closer to the flywheel? I'm going to go scrub all that stuff down now and then come back later tonight to scrounge more info on this...
 
diesel4me said:
This may help..http://talk.newagtalk.com/forums/thread-view.asp?tid=273496&DisplayType=flat



http://www.transmissionpartsusa.com/Chevrolet_GMC_RWD_Flywheel_shims_p/609-00sc85789.htm

I think Dorman has flywheel shims now..
Click to expand...

Thanks for the read- I hadn't considered the clearance for the shouldered bolts that hold the clutch to the face of flywheel- they most definitely did not cut the holes deeper for me. I grabbed one and threaded it in- the bolt's shoulder bottoms on the threads about 1/8 to 3/16 of an inch before the clutch would be tight on the flywheel. I will either have to take it back in again, or, drill some of the threads out myself. And the I might still have misalignment probs with throw out bearings and forks and pivot points and slave cylinders, and , and, and....

-or just get a new flywheel-
Putting that bolt in gave me a visual for just how much material is missing now. Dang.

So if I end up with a new flywheel- what can I use the old one for besides spraying it yellow and shooting at it ?
I put the tools away- headed for the bourbon now.
 
Throw it through the front window of the place that bodgered it all up for you...
 
I would now be demanding the shop to replace your flywheel with a new one. Unless this is an externally balanced engine (400 SBC or a stroker engine that was externally balanced) the flywheel will be zero balanced and you really wouldn't have any issues because of your engine being balanced, now if your engine is externally balanced then the replacement flywheel and the bad one need to go back to whoever balanced your engine and have them match balance the replacement flywheel.
 
The worst part here is Id be leery of having a new flywheel balanced with all that materials missing off of it now. How did they balance it? Did they add weight/slugs or drill out spots?



Also yes, run away if they cut your flywheel on a lathe.
 
I've seen some flywheels ruined when an "auto machine shop" used a brake lathe to turn them--a surface grinder is the right tool for the job--a big engine lathe might work OK too,but brake lathes are notorious for being "sloppy" after many hours of use,and they usually ruin more flywheels than they save..

Lathes leave "threads" and a rougher finish than a surface grinder ,unless the machine is good and the operator is experienced,and watches it like a hawk during the entire process--too many just set the machine up and walk away,and it ends up mucking it up..

Also few employees of parts stores REALLY know how to run a brake lathe--even with the many rotors and drums I turned over the years,I'd still goof up and flip the wrong lever once in a while,when I had a drum chucked in the lathe,and the cutting bit would start traveling "out" like you'd need it to do when cutting a rotor,and end up cutting a deep gouge in the drum!..:doah:..

It's not a job where you can set up the drum or rotor and trust the machine not to goof it up,if you run off to answer the phone,or wait on someone..which is often what happens in a parts store..

My boss insisted you could "set it and forget it",and would get pissed if I stood there and watched it the whole time--but he's still got a bad reputation for ruining more drums and rotors than he "saves"..he'd also just use a cone and a cup with a spring,to "self center" the drums he'd turn,which never really worked well..made eggs out of round drums !..:doah:
 
4X4HIGH said:
I would now be demanding the shop to replace your flywheel with a new one. Unless this is an externally balanced engine (400 SBC or a stroker engine that was externally balanced) the flywheel will be zero balanced and you really wouldn't have any issues because of your engine being balanced, now if your engine is externally balanced then the replacement flywheel and the bad one need to go back to whoever balanced your engine and have them match balance the replacement flywheel.
Click to expand...

I was trying to build a new engine to swap into the place of the one that was knocking in my blazer at the time- was hoping I could pull one out and stuff the new one in in the same weekend...
The balancing job changed that- my blazer is an 1988 model with sm465- my spare engine was out of an 1989 suburban with 700r4 automatic... Ended up having to tear into the blazer earlier than I wanted, just to pull out the flywheel. The block, crank, and rods were out of the '89 burb, brand new balancer, the flywheel out of my blazer, and had machine shop dude order pistons for me- he had all parts in hand...

From what I remember, I was told it was supposedly an internally balanced design, but really needed to be checked with both flywheel and balancer in place... I think he also told me that the manual trans version of my motor was "internally and externally balanced" And he told me that GM was sloppy as hell with what they let go out the door... He had a new electronic, super fantastic, mostly awesome,but also partly magic balancing machine- said it was very expensive and it was the 2nd one installed on the west coast... Some tv show came out and did a short segment about it... Wish I could remember more, but i was having all my machine work done in trade for graphics for a trade show he was going to. I was in a hurry to finish his graphics and I wasn't there when the new machine got fired up... I should have watched. I still have the spin sheet somewhere- dunno how it stacks up compared to other balance jobs, but, I was impressed with difference between "as stock" and the finished balanced assembly.
I think they added (welded) material back into one of the crank counterweights, removed some from another counterweight, removed material from balancer, and I honestly cannot remember what they did to my flywheel... Although- memories are starting to come back now- the machine shop that did all my engine work surface ground my flywheel before balancing- I think the place that just ****ed up did a flywheel for my fj55 a couple years ago- not this flywheel.

I guess I will start by calling machine shop dude on Monday and see what he recommends. And I will go buy some black widow poison - blazer has been sitting in the same place for almost 3 weeks... There's a bunch of nasty little buggers living under there now.
 
You engine balance guy is correct, when the 1 piece rear main engine came out the front of the engine is internal balanced meaning a neutral balanced harmonice balancer and externally balanced on the rear meaning a flywheel with a small extra weight on it.
 
So... I just started putting things back together, and have found that the jerks at jerk auto parts not only ruined my flywheel, but they sold me a rear main seal that's either used, or someone tried to install it, and returned it. Has black grease on it- and seal is warped. I had a fel pro rear main seal kit on my shelf to scavenge another rear main seal from- so at least I have one installed.. but the nasty seal is just another gripe to take with me to clown auto parts.

Pissed.

I've purchased a new flywheel from Luk had it match balanced to the old one. I Measured the two of them...
New one: 1.2195 inches thick
Old one that got killed on a brake lathe: 1.028 inches thick

And they he said "I cut blah blah THOUSANDTHS off of it" !!!!
-DONT TAKE YOUR CAR PARTS TO TARDS- That's what Ive learned from this I guess.


Tonight I replaced the pilot bushing (the one in my clutch kit was a crappy looking needle bearing- I had to go buy another bronze one), and I replaced the rear main seal...
I Bolted the new flywheel on, unboxed the clutch and wtf? A Plastic throughout bearing came with my clutch kit? Grrrrrrrr I don't want it. If for some reason the clutch was getting worked hard in hot weather- how long will that nylon body hold up for?

I'm sorry- I'm fine with a standard duty clutch from luk, but needle bearing pilot, and a plastic bodied throw out bearing are either going to get me stranded somewhere, or have me back under my truck too soon. And I won't sleep well before or during 4wheeling trips. No thanks.

Any recommendations for good throw out bearings? I have 2 in hand now, so making sure I have the right length shouldn't be an issue... The Old one I just pulled out wasn't sealed but lasted a while... New one that came with my kit might be a sealed bearing- but it's on a plastic body, and the inside diameter is too big- it has a lot of play when I put it on the input bearing retainer- up, Down, and side to side kind of play. And the bearing itself shifts side to side in the plastic body about an 1/8 inch as well.

I think I like the idea of a sealed throw out bearing if those are avail... And I would like it to be made of metal, and fit my input bearing retainer correctly.
 
Did you check out Rockauto? Even if you don't buy there, often they have plenty of part numbers and pictures. These are the Delco part numbers Rockauto lists CT24KVAL, 15613306, 19245400. Their listings for an '86 K5 manual throwout bearing show plenty of cheaper alternatives. SKF N4068 description reads sealed, and shows a red seal on the "back", and the Delco piece appears to have the same seal, just different color. M-PACT N1716SA looks sealed as well, but doesn't say if it is or not.

Never heard of a plastic throwout bearing, guess it's time to stock up on metal ones. Thanks for the heads up on the sealed vs. non-sealed, don't think I would have realized that.
 
My friend just replaced a clutch on a customer's 2006 Dodge Challenger RTS last week...clutch was smoked so bad,it wouldn't even move the car,even with up pushing while he attempted to drive it in..

Turned out Dodge only sells the clutch "complete",including the flywheel--he didn't find any listings at parts stores for it ..
It had dual discs too!--and the flywheel appears to be a one shot deal,that cant be turned due to its design and its so thin to start with too..cost over 800 bucks for the clutch kit..

The "throwout bearing" is a hydraulic slave type,with NO bleeder !--instructions say "pedal must be depressed up to 200 times to "self bleed" the system !..no bleeder on the clutch master either !--the bearing is plastic looking too,and the two discs are only about 10" in diameter...all I could think was what a POS setup for a car with a 400+ HP Hemi in it...

My friend said it royally sucked trying to get the transmission back in--we all know how hard it can be sometimes to get ONE clutch disc spline to line up!--try doing it with TWO in a row!..that 6 speed isn't exactly light either...

I don't know about you guys,but I prefer the good old clutch setups we had up until the 80's..seems like ever since then they have made them rather sucky,with the throwout bearings also doubling as a slave cylinder and the disc sizes shrinking...its no wonder hardly anyone buys a manual trans vehicle any more,and so few are being made,period..
 
Flywheels are one of those things that have to be done right. In my old corvette I was doing a clutch replacement and got a used flywheel (with some drag launches most likely) with the new clutch from a forum member. Naturally I went to get it resurfaced. The shop looked it over and let me know that they'd probably have to take 20 thousandths off of it to get a good surface. They got it looking good, but recommended using a 0.20-0.025 flywheel spacer. I did and never had any problems. It's a plus when someone knows what they're doing.

With the new clutches, people are demanding increasingly long clutch life, combined with smooth, easy engagement on high horsepower cars. Just try finding a clutch in the 80's that would hold the 450-700 horsepower that seems to be the norm in muscle cars today that would have been in anyway tolerable for a street driver. The only thing I don't like is the expense, a combination throwout bearing/slave cylinder for the Corvette is almost 200 dollars, and you feel obligated to change it because removing the transmission is such a pain. It does sound cheap to have plastic parts and no way to bleed the system though. Must be a Chrysler thing, I've never seen that on any other car.
 
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