theoUK

Strange question, I know.
but something just seems a little odd to me...
Pulled the balancer off the other day for some new gaskets/seals.
I notice looking at it that the timing mark is not in line with the key way groove. Are they supposed to be in a straight line with each other (i.e along a line drawn from the very centre out to the edge)

If so, i suppose the outer metal ring could have moved round a few degrees, although god knows how...?
The angle between them is only a few degrees, less than 10 I'd say, but significant none the less.
If it has slipped, then setting the timing could be interesting...
I realise i can work it out by rotating the engine to TDC and seeing where the line comes, but I just wanted a bit of feedback in the meantime
What do people think??? :skep:

ldyoung

I recently had mine off and noticed the same thing. I'd guess this is normal. :cheers:

wcsinx

:confused: Is there any reason that it should be in line with the keyway? Whether or not it lines up with the tab is what should concern you.

theoUK

No, but then there's equally no reason why it shouldn't! :lol:
I just wondered if the keyway on the crank nose was "conveniently" set at tdc, quite often you see this on hubs and shafts - where alignment marks and keyways line up. And not knowing much about these balancers, the thought crossed my mind that it could have slipped round, being as it's more than one part - and a few degrees out on the timing may not have noticed.

You're quite right, of course the alignment with the tab is the important thing - in fact I have the sump off now, so it'll be very easy to verify that the mark is correct at tdc, since i'll be able to see the piston.
Only I pulled it off late last night, and couldnt be bothered to get back into cranking it round to find tdc etc etc... :) So i just wanted to know in the meantime.
Anyway as ldyoung has said above, it seems they're done this way anyway.
Thanks ldyoung!


:cheers:

JB

I could be wrong, but I've been shopping around balancers for my BB lately, and every single chevy balancer I've seen has the 0 mark lined up dead on with the key. They can definitely slip--the one I just took off my car the outer ring had slipped around more than 90degrees.

JB


[Modified by JB, 11:20 AM 8/15/2003]

theoUK

Aha! That makes things a bit more interesting... :lol:
A different view....

Well it just seems logical that they'd machine the keyway in the crank to coincide with a reference point of some sort,
I'll get the final word on this soon - Since i have the sump off, when i next venture back under there, Ill check out what the marking/keyway are doing as the piston is at tdc - I don't think you can beat actually looking at the piston as about the most fool proof, dead-cert, way of finding tdc!
I'll let you all know - this is obviously quite important as far as timing with a light goes!

Any ideas for stopping them slipping? Can they be pulled apart and glued (or similar) very easily?

JB

Bluevetteman rebuilt his own, but the process seems pretty involved--for one thing, to do it right, you really need a press.

JB

theoUK

Press is no problem - might look into it... But not before offering it up and just seeing if it really is off TDC. If it appears to be a lengthy job I may just put my own mark on it as a temporary fix - the car has to be back together for next weekend, as i have a 300 mile drive coming up!
Did bluevetteman post any details? (I'll have a search on the forum in the mean time)

Thanks for the info - I'll keep you posted.
:cheers:

bigvette1

Just finished putting together the 454 in my car. When the #1 is at true TDC, the balancer groove for the keyway and the index mark for TDC on the balancer ring were all in alignment. Yes, over the years the rummber can break down and inner ring slip some from the outer. Does not change the TDC timing of the engine only what you see for timing.

JB

Here's the thread where he describes how he did it: http://forums.corvetteforum.com/zerothread?id=603782

My understanding is that it's a bad idea to do much driving with a slipped balancer, because it may come apart and tear things up (including your bearings), and because if the rubber and metal have separated enough for it to slip, then it's not doing the job of dampening harmonic resonance in the crank, and that's also hard on your bearings.

JB

WashingtonRacer

He is absolutly right, For whats it's worth, just get a new one for 60 bucks or so from Summit, Or drop the 250 or so and get a Fluidamper.

Larry B.

I could not find an eight inch BB replacement anywhere except corvette houses and they wre pretty expensive and looked different. That was the reason I did mine.

Pete79L82

Small blocks do not have the keyway and timing mark in alignment. On 68 and earlier small blocks the timing mark is 2° before keyway centerline. On 69 and later small blocks the timing mark is 10° before keyway centerline.

DO NOT ever try to press the outer hub off and on a balancer unless you want to become freinds with the ambulance crew.

theoUK

OK cool...
Thanks JB for diggin the link up for me -

Pete those could be the magic words!
Looks like mine is close to 10 degrees before the keyway (ie 10 degs anti clockwise from it as you look from the front)

I've only checked that roughly, not with a protractor or anything.
The rubber looks in fine condition, so hopefully it's a false alarm. I'll check it properly before it goes back on the motor, and do the check in the engine before i bolt the sump up.
Fingers crossed... (Spent too much money on it this month, can't be hassled with more expense and waiting for shipping :smash: )

theoUK

By the way, whats the prob with pressing the hub out? (Not that Im expecting to) Is it the springiness in the rubber that makes it dodgy :confused:



[Modified by theoUK, 3:22 PM 8/16/2003]

Pete79L82

When balancers are assembled the rubber is put in with a vulcanizing method, not just pressed in. The method bonds the rubber to the metal of the hub and outer ring.

If you have ever seen a balancer come apart at high RPM (I have) it is not a pretty sight. For the cost of replacement balancers, it is not the place to try to skimp on money.

Pete

lars

theoUK -
The timing mark is NOT in line with the keyway groove. Also, you cannot disassemble the balancer as the rubber is bonded/vulcanized into the assembly.

It is not uncommon for SBC balancers to slip the outer ring. When it happens, you just need to replace the balancer. You can easily check for this condition by doing a TDC check and verifying the location of the timing mark. I have a paper on how to do this - e-mail me if you want a copy:
lars.grimsrud@lmco.com

theoUK

Pete - I understand now: I thought you were referring to the actual pressing on/off process being the dangerous part, that's what confused me. Rather you meant the chances of a rebuilt one deciding to cut loose at 90 miles an hour!

Lars - thanks for the confirmation.. I fully intend to do a TDC check with it anyway, even though I'm fairly sure now, thanks to yourself and pete, that it's normal. I posted the original question just to see what the general consensus was, in the space of time before I get round to working on the car again next week.
Thanks for the offer of your paper, I appreciate that - but no worries I'll be fine to check it myself :cheers:
All the same, is it hosted on the corvettefaq site, as many of your papers are? I'll have a look just out of interest...
Cheers
Theo
:thumbs: