Engine: V8 alum. timing gear and crank flywheel bolts

[M-Webb]

I didn't want to hijack the post on the oil pan seal and get it too far off topic, so responding here with a new post to discuss the issues brought up about my alum. timing gear and the flywheel bolts.

Here is the thread on the oil pan that started it, with the photos for reference:

https://forum.studebakerdriversclub.com/forum/your-studebaker-forum/tech-talk/2066982-need-help-with-oil-pan-installation

That cam gear is probably at the very least 4-5 years old and most likely more about 8-10 years old as that was when this motor was first started to be put together by the original builder who supplied everything for it. I did not order it myself or put this motor together. So I don't know exactly when it was purchased, installed or where it came from at the time when we first started on this whole thing. But I have personally had the motor now for a couple years trying to work bugs out of it and I'm pretty sure the gear was put together with the motor originally close to 10 years ago at this point. So maybe is a good one, before the later possible problem ones?

Here are some more photos of the gear and the teeth. After the motor was originally put together, it was test run for about 5-10min just to see if it ran. So there are some wear marks on the gear from that as you can see here. It looks like they are fairly even across the teeth, so maybe that is a good sign, hopefully. Not seeing any chips or damage on it yet anyway. After I received the motor, other issues were found that eventually lead me to where I am now with it, basically the whole thing almost completely stripped back down and being rebuilt again, hopefully properly this time.








Same with the flywheel bolts, same deal, same timing. Those bolts are press fit in the crank, are not loose, will not come out by hand. Comparing them to other bolts I have, looks to me like they are the same as these grade 8 bolts, and are the fine threads. Looks like the bolts do have a bit of smooth shank that must be what is tight to the crank as the threads on the bolts are good, nuts thread on as needed. This would have been done by a machine shop, so assume were cut on a mill probably and looks like it, not just ground off by hand, so heat should not have been an issue. I've test fit the flywheel on there for length, didn't see any issues. Flywheel is for a manual shift trans, not auto. So unless there is some issue with this, I think it seems good?

[PackardV8]

As you suspected, the flywheel bolts are not OEM, but should be adequate to the task.

jack vines

[M-Webb]

Thanks Jack, hope so. Last thing I'd want is to finally actually get this motor rebuilt right just to have the flywheel go flying off at some point! Speaking of, is that how it got its name by any chance, lol. Maybe they did actually fly off back in the old days as the name implies!!

[StudeRich]

In picture 5, can you confirm that both the farther silver one, and the nearer Gold one are Both Fine thread ?
The gold one sure looks course in the Pic to me, camera angle ?

Usually, to get a standard non-factory Hex Head Crank bolt to fit, you have to do some grinding on one side.

AGAIN it seems that for such a short run time, a LOT of wear seems to happen in this engine, I would not expect ANY wear to show on that Cam Gear if the entire block and Oil were clean and none of the parts were actually used and run.

There was never a hardness issue with these gears, only tooth angle on quite recent ones 2023 forward.
You will never SEE any flaws, it takes precision gear checking equipment, we are talking over $100K to measure that.

Hundreds of these Gears were sold and run thousands of miles before a bad batch got sold, and a few with fit to the crank gear issues surfaced.

[M-Webb]

Yes, the more gold one is course thread. I just put that one there for comparison to the others ones which are fine thread so you can visibly see the difference.

On the gear, I would think steel on alum. is going to leave at least some witness marks on the alum no matter how perfect it is, especially since the cam has to resist against the valve springs. It is very light markings, hard to see in person. The camera picks it up with a bit more contrast. Plus that is as pulled from the motor, not cleaned or wiped down at all.

The whole history of the motor is a bit of a series of 10 years worth of a long string disappointments, which are still being added up quite frankly, as example these 2 issues. I'm just trying to clean up this mess as best I can without really knowing in detail all what really went on with it. Hence why it is now pretty much broken down to close to the final last bits and pieces, not much left to check.

[bezhawk]

Make sure if you use regular grade 8 bolts, that the flywheel or flex plate is on the shoulder of the bolt and the shear is not on the threads. It would be better to tap the crank and use ARP rolled thread fasteners. They make a 12 point bolt just for flywheels.

[M-Webb]

None of the shoulder is visible on them at this point, so the flywheel will be sitting on threads. These are grade 8 bolts, so maybe more hardened than the Studebaker bolts, so maybe OK once everything is torqued down as needed? The flywheel fits very snug on the bolts as is. It is hard to get on/off, no real slop or play in it. Just trying to find a positive here. Seriously, please don't tell me that even the flywheel bolts need to be fixed on this motor. Do the correct bolts fit in by hand or do they need to be pressed in too? And what if the holes in the crank are now slightly bigger than what they should have been if left stock and now there will be more play in that if use the correct bolts? To be honest, I'm sick of finding new things on this motor that have to be fixed and new things to have to buy day after day all because so called professionals that worked on this before were trusted to do things right, but screwed up even the most simple things like this, with this just being added to the long list of it that never seems to have an end. Not blaming you guys for telling me, I do sincerely appreciate it. Just venting of course. Extremely frustrating. This kind of thing is why people just put SBC's and now LS's in everything. I literally could have put 3-4 pretty nice high hp crate motors in this truck in the time and $'s I've wasted on this motor at this point, and that is not an exaggeration. And I'm not talking $3500 low budget crate motors either.

[PackardV8]

The same guy who can't do the simple stuff on a Stude can fork up a SBC or an LS.

jack vines

[M-Webb]

Well, that's true enough. That is why I said I could have burned through 3-4 generic GM crate motors in the 10 years time I've been dealing with this motor. Just replace it every couple years once it turns to crap, buy a whole new one, have it delivered to my house and yank out the old one and put in a new one in a weekend.

[JoeHall]

Here’s what the bolts look like, the ones for automatic are about 1/4” shorter. But both are designed for the flywheel or flex plate ride on the shank, not the threads. You can probably find some local, like the ones you have, but with shank about 1/4” longer. Looks like he shaved the hex heads slightly. They are not a press fit, but snug, and can install or remove them with your fingers.

[M-Webb]

Thanks, seems right. My concern now is if I press these wrong bolts back out, the holes are now enlarged and the correct bolts will be even looser than they are suppose to be, hence maybe end up with a worse problem and potentially a junk crank. Then I'm now looking at buying a new 289 crank if I can even find one. So basically close to a worse case issue on this motor at this point.

Do those correct bolts have a slightly thinner shank than a generic 3/8"-24 bolt has? Why would a standard bolt need to be pressed in, but those are loose fit? I assume those are 3/8"-24 as well? Or are they not? The ones I have are definitely in tight, as you can see in the photo, the crank is sitting on top of them and the weight of it is not budging them in the slightest. Maybe they are not in as tight as it might seem, but they are not finger loose, that is for certain.

I guess I can maybe try to gently tap one out and see if it comes out without too much effort. If so, then maybe not a problem to just get new correct bolts and move on.

[M-Webb]

I actually have a complete 259 motor with the same flywheel on it that I can use the bolts and nuts off of if needed. So I have that covered. Just a question on what kind of fit am I going to left with on this 289 crank now if I can tap, or worse need to press those bolts back out.

[JoeHall]

Another important thing to check is the rear main seal journal surface. First note exactly where the seal rides, then insure that area is clean all the way around, and not scarred or pitted. If so, you can maybe polish it sufficiently with 320 grit emery cloth. Google how to hand polish crank journals, and use same procedure. Many, if not most machine shops will not even look at that journal, even though the may grind the rod and main journals, it's as if they don't even know what it's for. It's OK if that journal has surface problems elsewhere, as long as they are not too close to where the seal lip rides, maybe at least 1/16" on either side. Many folks don't bother with this, then wonder why the rear main seal leaks later.

[M-Webb]

I have thought about that and have looked at it pretty closely. That is one of the things I stressed to all 3 shops that have "helped" me on this motor. I told them that one of the main reasons I was building this motor was to try to have one that leaked as little as much as reasonably possible, given that the 259 that came out of it had leaked from day 1 and was leaking like the Exxon Valdez by the time I pulled it out.

The rear seal as in it now does seem to have been 'glued' in pretty well and tightly, both 1/2's. And the condition of it looks nice and correct, no issues. I guess I could maybe just put it out and redo it too. But I think it seems pretty good to be honest, one of the few things maybe done right on the motor. It is at least glued in, or at least seems to be without really yanking on it. And the crank journal where it sits does seem good as well. But I'll double check that again on final assembly and maybe give it a little extra micro polish if can.

[JoeHall]

If those bolts were pressed in, only reason I can see why is if he did not grind enough of the hex head away. If that's true, I'd think they may all be cocked slightly inboard, and not line up with the flywheel holes, but you said you already mounted the flywheel, so maybe not. In any case, if you find the holes wallowed out, you could put the same bolts back in. No way you'd ever need to replace the crank because of those holes, there're other ways to skin that cat. As I mentioned, the originals fit snug in the flange, but only need fingers to install or remove them.

[M-Webb]

Yeah, that makes sense. Given how hard it is to come by 289 cranks at this point, I'm a bit leery to be messing with it too much to be honest. At some point I just need to stop finding problems, or at least not critical ones, and just hope for the best and move back forward with putting this motor back together. I was really hoping I was beyond at least the worst possible problems, but maybe not. As a reminder, I'm not looking at racing this motor or towing a huge much of heavy loads. So maybe it is less critical, can live with it the way it is, not make the solution to the problem worse than the problem itself.

There is some extra gap where they trimmed the heads on the bolts, so I'm pretty sure they fit plumb at least. And yes, the flywheel does go on like they would if they are plumb and likely would not if they weren't given how tight they are.

[M-Webb]

I'm getting .3705" for the dia. of the shank on one of those spare 3/8"-24 grade 8 bolts I have. Can anyone measure the shank on one of the Studebaker bolts and see if at least they should be the same? If not, I'll take the flywheel off my 259 and do it at some point.

I'm just trying to figure out how/why a standard grade 8 looking bolt would fit tighter than the correct Studebaker bolt, assuming they are both 3/8"-24. The threads need to be the same, so not sure how the Studebaker bolt could have a shank of a smaller size. And that is partly because the holes in my flywheel barely fit the threads on the bolts in it now, it is a very snug fit. So a shank much bigger than the threads themselves is not likely going to fit. So a tighter hole in the crank would not work to fit the threads through it to work. But maybe the Studebaker bolts are just slightly thinner enough to finger fit and the standard bolts do not?

[JoeHall]

My dial calipers say .370 " - .371". If yours are frozen ("pressed") in place, it's likely due to the hex heads having slight interference, perhaps the other guy did that on purpose, but if that's true, the bolts are all slightly cocked inboard, and may be the reason the flywheel "barely fits" onto the bolts now. If you look at the OEM bolts, the flat spot on the head nearly kisses the shank, but slips all the way home with only finger tip pressure.

Now is a critical point in your engine R&R, try to be patient and consider each small task as a job unto itself, and what doesn't get done today can be done tomorrow. It's important to remember that any shortcuts you take at this point can come back and bite you later.

[StudeRich]

I consider you quite lucky to have those correct Standard Trans. Crank Bolts available, the OEM Originals are getting harder to find with time.
I know it is a pain to disrupt the Main Cap sealing that has been done, but it is not that difficult with the Pan already off.

Some people say they don't prefer the Permatex RTV Silicone gasket maker Black that I use, over the old fashioned, Brown original Permatex, because they think it is harder to remove for future work, but I never experienced that problem and it works well for me on the Rear Main Seal/Pan Gasket combo and removes completely if needed.
I bond the ends of the 2 main seal half's together with silicone.

Due to the inexperience with Studebaker's of the last "Builder", it could be a good thing to see if they properly installed the tiny filler block Corks on each side of the Main Cap into the block, inserted the Tabs on the ends of the Pan side gaskets over them with proper sealant.
It's just another chance to verify and or correct the situation with fresh gaskets, AGAIN !

First though, the Main Seal small neoprene side seals (part of the lower half), go on the main cap and after torquing, get the excess ends trimmed off with a Exacto (Xacto?) knife.

So you may need to consult the Manual on that one, there is a double layer of small parts under the ends of the rear arch Cork pan gasket.


Doing this wrong, is what causes so many to have oil leaks at the rear of the pan.
Your engine, your time and money, just say'in !

[M-Webb]

That rear seal seems possibly good from what I can tell. But yes, you are probably right given everything else at this point and how easy and inexpensive it will be to redo that at the moment. Might as well do it, doing pretty much everything else at this point.

[M-Webb]

So yes, you guys were right, just some more garbage work on this motor, add it to the long list.



I got those 2 out with some reasonably gentle taps with a hammer. Bolts don't even have a smooth shank, are fully threaded, greenish stuff looks like epoxy maybe, which explains why they were stuck on. The other 4 didn't want to budget. I don't want to hammer on the crank any harder than already did, and I don't have a press or clamp of any sort that I think would work to push these out. So I'm going to go see if a another local machine shop, that is not the crappy one from before, can get the others out in some potential damage free way. And maybe just do a quick health and balance check on the crank while at it.

Good news is I did get 2 of them out and the holes don't look like they have been damaged or enlarged in any way. So if I can get the rest out, I can just put the correct bolts in and use those.

[StudeRich]

They probably have something like Blue or Green Locktite on them.
Yep, they are all thread, JUST STUPID !

[Topper2011]

Maybe go to Oreilly's and rent a tie rod separator for free? Not the pickle fork one though. https://www.oreillyauto.com/store-se...and-suspension

[JoeHall]

I'd just use a brass drift to tap those weird bolts out. As for correct replacement bolts, with your old motor, you do know you must remove the oil pan, oil pump and rear main bearing cap to remove them, correct? If it were me, in interest of saving labor and messing up the shop, I'd just buy new ones, if available.

It's also very important to clean all that crud off the face of the flange, and the mating surface on the flywheel. Don't go into the metal, something like 320 sandpaper to remove the rusty crud, then a scotch pad with solvent to clean the rest of the way. Also, if that pilot bearing is in question, I'd replace it at this point. Also, check the ID, as is appears a bit small, IIRC it should have about .750" ID, a few thousands more than the transmission snout that fits into it.

[Mark Klinger]

Russ Ware at Studebakerparts.com has those crank to flywheel bolts in stock.