Crankshaft Hub Bolt Loose? Torque spec?, Sigh... Options

[Superhawk996]

Definitely looking better and promising.

Would love to see that lapped down to 400 or finer.

The smoother the surface finish, the higher the torque that can be applied to the taper.

I wonder if the loctite would have cured more readily with clamp force applied to the key to ensure that no oxygen was able to get in under the key or on the sides to get the cure started? Assume you did use primer too? Their response to the question is highly annoying as if Amazon is the only place that could end up with counterfeit product and that seems unlikely to begin with. Who’s getting rich counterfitting such a specialized product?

Not like your average auto parts store or Walmart carries their more specialized Loctite products!

[rudedude]

You might want to make sure that the hub doesn’t bottom on the crank face before the taper is fully engaged. Could the crank have been to long and kept the first hub from fully engaging? Other people have had issues with counterfeit products from amazon sealing 911 cases.

[ClayPerrine]

This same thing happened to Betty's car 35 years ago in a little town called Copperas Cove, Texas. We were in town for an AX, and on her last, best run, the engine spit the fan into the shroud. She always said it was because of the lightened load on the engine gave her more HP to the wheels! (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/driving-girl.gif)

Turns out the bolt holding the hub onto the crank broke. So, with the help of a local auto parts shop owner, I got a wodruff key and a new washer and bolt, plus some locktite. I then took the hub off the fan, and put it back together. No crank polishing, no checking it, nothing. We had to drive home that day to be at work the next day. So It was a "field expedient" repair. One of the "repair" techniques I did was to use a brass hammer to drive the hub onto the crank before installing the bolt. That way I wasn't pulling against the bolt to install the hub.

The damn thing stayed on the engine for another 5 years before I had to remove it to replace the seal. And it was a bitch to get back off when I did.


Good luck in your fix!

[GregAmy]

Still ongoing. Using a dental pick I realized the very bottom part was solid (it's anaerobic, after all) and the key was supported so I put in the o-ring and crank seal for final install. Then as I was taking it out one last time for inspection (Shroedinger's o-ring) the key came out with it, along with some of the upper part of the 660.

Visual inspection showed that the bottom part of the 660 was still there and when I put the key back in it was well-supported, no movement. I slipped the hub on and there was no more side-to-side movement. So I packed the top of the space with "JBWeld Steel" and I'm going with that. It'll be reassembled today.

New spark plugs, fresh valve adjustment (love me them zero-lash chromoly pushrods) and I'll get the whole thing leisurely installed this week/end.

What did you use as an abrasive?

Loctive Clover 150 grit lapping compound, then a follow up with 280 grit lapping compound. Got plenty left if you need some...

Would love to see that lapped down to 400 or finer....Assume you did use primer too?

Thought about going higher than 280 but honestly I think this will be fine. I guess we'll see.

Did not use the primer as I couldn't get it within a reasonable timeframe.

You might want to make sure that the hub doesn’t bottom on the crank face before the taper is fully engaged.

It's not; you can see how far up the lapping compound was grinding on the taper and there's a lot of space left. And when I test-fit the hub with the bolt torqued down the or-ring wasn't over-compressed.

I do kinda wish that I had measured the distance from the end of the hub to the nose of the crankshaft; I'm curious how much farther in all this cleanup and grinding allowed...

[Superhawk996]

(IMG:style_emoticons/default/clap56.gif) Will be watching.

I think it’s all going to work out just fine.

[930cabman]

Still ongoing. Using a dental pick I realized the very bottom part was solid (it's anaerobic, after all) and the key was supported so I put in the o-ring and crank seal for final install. Then as I was taking it out one last time for inspection (Shroedinger's o-ring) the key came out with it, along with some of the upper part of the 660.

Visual inspection showed that the bottom part of the 660 was still there and when I put the key back in it was well-supported, no movement. I slipped the hub on and there was no more side-to-side movement. So I packed the top of the space with "JBWeld Steel" and I'm going with that. It'll be reassembled today.

New spark plugs, fresh valve adjustment (love me them zero-lash chromoly pushrods) and I'll get the whole thing leisurely installed this week/end.

What did you use as an abrasive?

Loctive Clover 150 grit lapping compound, then a follow up with 280 grit lapping compound. Got plenty left if you need some...

Would love to see that lapped down to 400 or finer....Assume you did use primer too?

Thought about going higher than 280 but honestly I think this will be fine. I guess we'll see.

Did not use the primer as I couldn't get it within a reasonable timeframe.

You might want to make sure that the hub doesn’t bottom on the crank face before the taper is fully engaged.

It's not; you can see how far up the lapping compound was grinding on the taper and there's a lot of space left. And when I test-fit the hub with the bolt torqued down the or-ring wasn't over-compressed.

I do kinda wish that I had measured the distance from the end of the hub to the nose of the crankshaft; I'm curious how much farther in all this cleanup and grinding allowed...

maybe put a bit of clay to get a measure from the back of the hub to the face of the crank? It's hard to imagine you took off too much material, but a double check might not be a bad idea.

[Superhawk996]

You might want to make sure that the hub doesn’t bottom on the crank face before the taper is fully engaged.

It's not; you can see how far up the lapping compound was grinding on the taper and there's a lot of space left. And when I test-fit the hub with the bolt torqued down the or-ring wasn't over-compressed.

I do kinda wish that I had measured the distance from the end of the hub to the nose of the crankshaft; I'm curious how much farther in all this cleanup and grinding allowed...

maybe put a bit of clay to get a measure from the back of the hub to the face of the crank? It's hard to imagine you took off too much material, but a double check might not be a bad idea.

NOTE: not an attack on anyone - no ill intent. I understand why folks would be concerned.

The distance the taper moves inward will be a fraction of few thousandths of an inch.

The distance moved inward is a function of how much material was removed (lets call that A) and the angle of the taper (lets call that angle Z).

The depth moved inward will be A x sine(Z).

Lets assume some numbers. Let's say .001" of material was removed off the surface of the taper by lapping. This would be quite a lot.

Let's assume the taper angle is 15 degrees (I honestly don't know what it is but it could be measured).

So removing .001" of material off the face of a 15 degree taper moves it inward .001" x sine(15) = .00026". You couldn't conceivably measure that with out CNC measuring devices.


Sleep easy tonight.

[GregAmy]

It's done, no more checks/changes. Hub, toothed gear, fan, and housing are on and torqued, valves getting adjusted tomorrow and back into the car it goes.

I'm sincerely hoping that I never have to post in this thread for as long as I own this car.

Go check your fan hub torque. - GA

[GregAmy]

Ok, really really last post here, I'm hoping: drivetrain installed, engine is running nice. Took it for a spin tonight and I'm pleased.

Interesting data point, the difference between the notch on the flywheel and the zero mark on the front pulley are 5 degrees apart, per my adjustable timing light; I don't know if it was like that before, as I always used the pully. I'll use the flywheel mark as my core reference. - GA

[GregAmy]

Ok, seems I can't quit you...

I was cleaning up the garage yesterday from the mess I made with this project. Came across the old pulley hub (with its slice of key still in the groove) and decided to add it to my "wall of shame" of failed parts I have (when you get into racing you tend to collect stuff like this).

On the shelf, I picked up the broken crankshaft from 2019(?) and was going to slide the hub on there but the crank still had a key in it; I tapped the key out and noted that the key was damaged, offset like the old offset keys we used to use on VW overhead cams for timing. And there were scuff marks on the downstream side of the crank nose where its pulley was chattering.

So that engine's pulley was loose, too. I don't know if that was related to the crankshaft failure, but this certainly caught my attention.

I put the race car on the lift and checked its crank bolt - that engine uses a Bus fan and shroud - and that bolt, too, was slightly loose, about 1/16 of a turn to get it to 23 ft-lbs. So I removed the bolt, loctite blue'd it, and reinstalled to 30 ft-lbs. And I know who built that engine and I know he would not have missed something like this.

One time is random; twice is coincidental; three times is a trend. I think we have a trend going on here. I certainly seem to...

Does anyone know the class of bolt that's being used here? The markings on it are not standard. If it's equivalent to a 10.9 then most charts are showing in the 40 ft-lbs range. The underside of the bolt has locks similar to a Schnorr washer, and I'm sure the engineer didn't want that taper to get hammered in too tight (it would be a bitch to get loose).

However, I noticed all three crank washers have a circular groove where those locks have dug in; if that groove is too deep then the locks may be making less grip contact. Are these supposed to be single-use bolts and washers?

Maybe I'm overthinking this thing, but I've now experienced three potential failures, just in my own garage. So I'm'a thinking that proper torque, Loctite Blue, and maybe new bolts and washers is in order here. And maybe a higher torque value.

Has anyone else checked theirs? What have you found? - GA

[Superhawk996]

I'm sure the engineer didn't want that taper to get hammered in too tight (it would be a bitch to get loose).

I think you’re missing the principle of how a taper works.

It MUST be tight fitting. It should be so tight that it requires a pulley puller, some heat, and a few brass hammer bangs to remove the hub after it has been installed.

[Superhawk996]

One of the "repair" techniques I did was to use a brass hammer to drive the hub onto the crank before installing the bolt. That way I wasn't pulling against the bolt to install the hub.

The damn thing stayed on the engine for another 5 years before I had to remove it to replace the seal. And it was a bitch to get back off when I did.

(IMG:style_emoticons/default/agree.gif) This

Though I generally don’t want to be hammering / impacting main bearings you get the point.

It should be a a bear to remove it after a proper install with well matched tapers.

(IMG:style_emoticons/default/smash.gif) (IMG:style_emoticons/default/welder.gif) (IMG:style_emoticons/default/smash.gif)

After the install, the bolt is doing very little to hold the joint together.

[technicalninja]

Ok, seems I can't quit you...

I was cleaning up the garage yesterday from the mess I made with this project. Came across the old pulley hub (with its slice of key still in the groove) and decided to add it to my "wall of shame" of failed parts I have (when you get into racing you tend to collect stuff like this).

On the shelf, I picked up the broken crankshaft from 2019(?) and was going to slide the hub on there but the crank still had a key in it; I tapped the key out and noted that the key was damaged, offset like the old offset keys we used to use on VW overhead cams for timing. And there were scuff marks on the downstream side of the crank nose where its pulley was chattering.

So that engine's pulley was loose, too. I don't know if that was related to the crankshaft failure, but this certainly caught my attention.

I put the race car on the lift and checked its crank bolt - that engine uses a Bus fan and shroud - and that bolt, too, was slightly loose, about 1/16 of a turn to get it to 23 ft-lbs. So I removed the bolt, loctite blue'd it, and reinstalled to 30 ft-lbs. And I know who built that engine and I know he would not have missed something like this.

One time is random; twice is coincidental; three times is a trend. I think we have a trend going on here. I certainly seem to...

Does anyone know the class of bolt that's being used here? The markings on it are not standard. If it's equivalent to a 10.9 then most charts are showing in the 40 ft-lbs range. The underside of the bolt has locks similar to a Schnorr washer, and I'm sure the engineer didn't want that taper to get hammered in too tight (it would be a bitch to get loose).

However, I noticed all three crank washers have a circular groove where those locks have dug in; if that groove is too deep then the locks may be making less grip contact. Are these supposed to be single-use bolts and washers?

Maybe I'm overthinking this thing, but I've now experienced three potential failures, just in my own garage. So I'm'a thinking that proper torque, Loctite Blue, and maybe new bolts and washers is in order here. And maybe a higher torque value.

Has anyone else checked theirs? What have you found? - GA

That key looks like a specially designed offset key, not a damaged stocker.
That's weird!
Normally special keys like that are used to offset cam timing and not offset the hub alone...

For the reason why all of your crank hardware appears to loosen over time.

This is a bit of a guess on my part but it's worth thinking about.

The Type 4 engine has no vibration damper on it.

In its stock form it probably works fine without a damper.

Each power stroke applies individual power "spikes" into the crank. As these spikes increase in intensity and cycle rate this hammering can induce resonance into the crank assembly.

Making the rotating mass heavier reduces this tendency. All of the dual mass flywheel that are in use today are stupid heavy.

Slowing the rotating mass down helps combat this as well but that's not "sports car".

Adding some type of elastomer in an external pully is how these issues have been delt with in the past by most manufactures.

A complete BS "power upgrade" for many cars is a solid crank hub and lightweight smaller diameter drive pully. Sometimes these were listed as a "power pully."

What you get with one of the puppies is accessories that don't work worth a shit at idle and excessive crankshaft resonance.
You end up with broken locating keys, torn up crankshafts, loose crank bolts, and crank driven oil pump explosions (this is very common!!!).

I REMOVE "power pullies" whenever I find one...
A stock balancer is vastly superior to one of these.
For street cars I try to use a "Fluid Damper" if it's available for that engine.
Fluid Damper is awesome at eliminating harmonics and resonance below 6500-7500 rpm.
For an engine constantly operating at or above those numbers I prefer a tunable elastomer balancer (you can get different O-rings for these) or a specific balancer for high rpm use. It will be listed as a "tuned" balancer and it should spec out an RPM range where it is effective.

The T4 has no harmonic balancer anyway.

Most performance oriented T4s are using much lighter pistons and rods and being spun to higher engine speeds.
It looks like most decently built T4 have at least 50% more power than stock and some double the stock power levels.

I agree with Jeff.

I'll be spending extra time on the crank snout and pully interface.
30lbs sounds good too.
New hardware (maybe upgraded) should be incorporated.
Medically clean threads and blue Loctite will be used.
Once a year inspections (maybe more often?) will be done.

My thoughts...
Maybe wrong?

And now SuperHawk will produce a white paper showing something else...

[technicalninja]

SH is right about the crank bolt not being the reason stuffs loosening up...

I got a core 2.0 from 914Sixer.
It was complete stock engine in pretty good shape.

During disassembly the crank bolt removed easily.

The crank hub not so much.

I pimp-juiced it and fitted a harmonic balancer puller.

Went tighter on that puller than I normally like too.

Long 1/2" breaker bar tight

Tapping on it with a hammer didn't do shit.

It stayed "torqued up" for a couple of days.

Impacting the flywheel bolts off (at the other end of the crank) popped that bitch right off.

The taper connection was TIGHT!

[Superhawk996]

The Type 4 engine has no vibration damper on it.

In its stock form it probably works fine without a damper.

The T4 has no harmonic balancer anyway.



And now SuperHawk will produce a white paper showing something else...

(IMG:style_emoticons/default/happy11.gif)

Horizontally opposed engine has nearly perfectly balanced 1st and 2nd order harmonics. Therefore doesn’t need or get a harmonic balancer.

And that my friend is why I love air cooled horizontally opposed engines. Simple, light, and smooth running vs inline 4, V6, and V8. I would die for a V12 but fortunately Tygaboy hasn’t fit one in a 914 . . . Yet.

[930cabman]

SH is right about the crank bolt not being the reason stuffs loosening up...

I got a core 2.0 from 914Sixer.
It was complete stock engine in pretty good shape.

During disassembly the crank bolt removed easily.

The crank hub not so much.

I pimp-juiced it and fitted a harmonic balancer puller.

Went tighter on that puller than I normally like too.

Long 1/2" breaker bar tight

Tapping on it with a hammer didn't do shit.

It stayed "torqued up" for a couple of days.

Impacting the flywheel bolts off (at the other end of the crank) popped that bitch right off.

The taper connection was TIGHT!

If fitting correctly a tapered connection should not come apart easily. Generally a bit of heat is required to open it up a bit.

If this connection does come loose when in service, is there a telltale noise or other symptom us novices could heed? I know this winter I will be checking mine.

[technicalninja]

OK Master...

Why are SO many high-performance balancers available for the Subaru 4 cylinders?

There's a bunch of different Fluid dampers for them as well.

I cannot remember a Subie with a solid balancer as stock equipment ever.
I've been repairing Subies since the early 80s.
Seen WAY TOO MANY.



I didn't say I was right...

I'm trying to help determine why one member (a freaking knowledgeable one!) has 3 of the same problem.

I'm in agreement with Jeff.

3 is NOT a fluke.

SH, what do you think is the reason for Jeff seeing as many of these as he has?

[930cabman]

I will put my $5. on they were never properly fit, checked for a high percentage of contact and torqued correctly.

[GregAmy]

...is there a telltale noise or other symptom us novices could heed? I know this winter I will be checking mine.

Yes, but I suggest by then it's too late.

Either end of last driving season (October?) or beginning of this year's (April?) I began to hear a knocking noise at idle, frequency changing with the RPM, a lot like a light rod knock. It was coming from the fan end of the engine. Car drove OK, and the noise went away off-idle. I ignored it.

I suspect this was the key and keyway getting beat to s**t. If I hadn't been such an idiot I would not have ignored it.

However, it was very soon after that, like maybe 2 hours' driving time, that the engine began to run like crap and thus post #1. So I may had staved off some damage by investigating the noise sooner but I probably would have had to rework the crank anyway.

I do admit to giving the fan/hub a light tap-tap with my small ball peen hammer prior to tightening it down, both cars.

GA

[Geezer914]

Greg, sorry to hear about the layoff. After reading all the posts, I think I am going to remove the fan hub bolt, loc tight it and re-torq it for peace of mind.