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Here is an idea, how about I test assemble all the parts on the crank and use a feeler gauge to see if I can get it all compressed correctly. I have some oversize bearing press guides that I can use to fit over the crank and press the damper hub on as it is cooling and then stack the reset of the items.
I think you have the wrong hub installed .
I have a new Hub and ATI damper kit for a 928 and my hub measures 40.00 mm.
NOTE your spacer you have is used to push the pulleys out enough to line them up with the accessories.
your hub 33.90mm + spacer 6.49 mm = about 40.00 mm.
My guess whomever installed this part before you got it,
pressed it on fully so it was clamping the crank drive gear and washers.
NOTE since its a press fit, no one was the wiser.
NOTE as the pulley stack was never clamping the damper .
I would guess the hub at some point got a lil bit loose and the washers started to make noise thus could be the reason for the car being sold.
That said measuring a GTS crank damper would be prudent.
Maybe Greg has one handy to measure.
NOTE procuring a properly sized hub would be a course of action I would take.
NOTE you need new hardware for that damper assembly
From your post no need to assemble everything just measure the parts,
get the washers pressed against the crank gear then measure from the large OD step to the face of the thrust washer that will tell you everything
Stan and Greg thanks for your help on this path to discovery in figuring out what is going on. Clearly there is a problem with the stack height. Just for confirmation I heated up the hub and installed it as snug as I could against the thrust washer and the crank cog. Clearly there is a gap to the step. See photo below.
And here I have slid on the shim for aligning the accessory belts but as you can see that shim does does not make contact with the hub and so the crank bolt cannot apply any compression.
I think this is the cause of the noice, buy why it did not happen prior is unclear to me. Maybe it just needed more time.
My question now is what to do to solve the problem. The hub seems made specific for 928's so it's clear why it's not thick enough. If there are differences in cranks or hub adapters please educate me. It would seem getting a correct hub, or adding a 3mm-4mm shim would be an option. The shim option is the least expensive but I worry about getting the alignment correct on the tip of the step. I wouldn't think the shim would go behind the hub.
Advice appreciated.
@Mrmerlin saw your note on new hardware, yes, agreed new hardware will be on the shopping list.
I suspect that Greg has new hub adapters that are the correct size, no shims, no extra washers, just pure excellence.
And they come with new hardware.
So all you need to do is reuse your ATI damper.
Please reread my post #32 on my speculation of why this noise was not happening till after you took the hub off and put it back on.
That crankshaft is different than what I'm used to seeing.
And would require a different damper than I'm familiar with.
Perhaps a GTS thing that I'm not aware of.
I'll have to take a look at the front of a GTS engine to know more.
But here is the "snout" of the crankshaft on the engine I'm currently assembling.
Clearly way different than your crankshaft.
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
Not sure what the VIN is on this one, but it is a 92', so likely some parts would be different given it's the first run of the 5.4 liter engine.
The crank could conceivably be different than the US 93 and up GTS's?
I talked with Stan earlier this evening and then went and measured two stock balancers: ~41mm deep. The only GTS balancer (and crank) I have are installed. So, no measurements available.
This is a picture of the nose of my '94's crank from when I did the belt last decade. (@GregBBRD you have seen this crank with your own eyeballs back in 1998.)
I checked pictures of couple of other GTSs and the early '93 and '95 looks like this too.
Here's the snout of an early '87 I pulled apart last week.
Clearly the nose of the cranks are different. The "big" part of the crank on the GTS is longer and the skinny part is shorter.
It *does* look to me like the "two-piece" adapter would work on a 5.0 crank and NOT on a 5.4 crank since the spacer ID is skinny. However, a proper one-piece adapter would work on either.
It also suggests that on 5.0 cranks the balancer is always only "1/2-way on" while on the GTSs it's "mostly or completely on."
Never noticed this have I...
So, TIL (Today I learned.)
But the proper fix is clear: @Michael Benno get thee a proper-sized one-piece adapter. Be done with this odyssey and don't pass it on to your future self or the next owner.
Wow so they have different cuts on the crank,
best to take some detailed measurements and compare them.
What year and model is that crank your measuring from Greg?
Mike whats the engine code on your engine?
Could this crank be for a marine engine?
or a Japanese engine?
That said after seeing the fit check, this hub was never right from the start.
NOTE the damper that came off should have been measured and the parts checked before swapping them.
I wonder what a GTS damper thickness is and if it changed over the years.
By the looks of things the 40.00 mm hub should work on MBs crank
Wow so they have different cuts on the crank,
best to take some detailed measurements and compare them.
What year and model is that crank your measuring from Greg?
Mike whats the engine code on your engine?
Could this crank be for a marine engine?
or a Japanese engine?
That said after seeing the fit check, this hub was never right from the start.
NOTE the damper that came off should have been measured and the parts checked before swapping them.
I wonder what a GTS damper thickness is and if it changed over the years.
By the looks of things the 40.00 mm hub should work on MBs crank
That crank is a custom stroker crank, but is probably modeled from a 5.0 crankshaft.
I think a 40mm hub is going to be cutting it pretty close.
(My current hubs are smaller than 40mm, BTW.)
But, '90/'91 crank looks just like the '87 above. So, dimensionally, I'm going to go out on a limb and say that the overall crank lengths are the same but the cuts are different on '92 to '95 cranks (where early US '93 is really ROW '92.)
Looking at my two pictures, the 5.4 does look, overall, shorter. But, it's an optical delusion...
Here, from more-or-less the same camera angle a '95 and a '91
This is absolutely fascinating! As a scan through images above, the crank in my car looks more like the 93/94 cranks shown by worf928. Specifically the shorter stepped section.
Here are the details on this 1992 GTS - Japan market LHD
VIN WP0ZZZ92ZNS800428 (build date 04/03/1992)
Engine Serial Number: M28/50 81N 50806 (305th production)
FYI, I created this diagram to help illustrate the measurements I took on my specific crank. It would seem that a damper hub with a <40mm thickness (4mm thicker than the one in car) would be more than sufficient, maybe a little less than 40 would be better. Thoughts on this? Looks like I am in the market for a new hub, @GregB if you have some.
Last edited by Michael Benno; 02-04-2022 at 12:32 AM.
This is absolutely fascinating! As a scan through images above, the crank in my car looks more like the 93/94 cranks shown by worf928. Specifically the shorter stepped section.
Here are the details on this 1992 GTS - Japan market LHD
Occam's Razor suggests that your Japan-market '92's crank is exactly like the US early-'93's in my first post.
Originally Posted by Michael Benno
It would seem that a damper hub with a <40mm thickness (4mm thicker than the one in car) would be more than sufficient, maybe a little less than 40 would be better. Thoughts on this?
I don't see why you wouldn't want an adapter that is the same "depth" of ~41mm like the stock balancer. In my head, it seems to me that the 'stack' comprising the crank gear, its washers, the hub/balancer, a/c and main pulley needs to be the same "length" as stock. A hub that is "thinner" than ~41mm will move the belt pulleys closer to the block and thus, potentially, result in the belts not running square.
One MM either way is probably not going to matter. But, how "short" can the stack be before the belts aren't square? Well, the answer is... the thickness of the air pump tension/adjuster bracket that bolts to the block.
Why?
Well, when folks delete the air pump and remove the bracket that's captured in between the A/C compressor bracket and the boss on the block, if the A/C bracket isn't spaced by 4MM (using the thick washer from the air pump bracket) the A/C belt will walk off the A/C compressor pretty quickly.
So, while I doubt 1mm matters, I'll bet 2mm does matter. 4mm is right out. And thou shall not count to 3mm me thinks.
I couldn't help but notice the groves in post #20 and I wanted to see what my 93 looks like.The photo of mine is from the first TB/WP I did 13 years ago. It's a late 93 US spec. As you can see, the snout has a slight ridge. I'm wondering if your pulley was machining away at the crank and caused those grooves.
02-03-2022, 06:03 PM
