97TAMONEYPIT

Hi all (and Injuneer),
I spun the crank hub on my LT1 according to my mechanic due to the power steering pump seizing up intermittently. Initially he said that it didn't;t look like there was very much snout wear on the crank, but that to technically fix it 1000% right, I was supposed to replace the crank at a huge amount (at least to me), and since that's what I had less than 1000 miles ago due to a snapped crankshaft, I wasn;t itching to do it all over again if not needed. So he recommended a keyed hub from Pioneer, which I bought. HE called to day to let me know the car was ready, however he said there was a little more snout wear than initially thought, so there was a little more play than he would have liked. However, he warned that the stress is basically on the key more than the interference part now due to the extra snout wear, and that how long it worked/lasted would basically be how long the key held. We had spoken about pinning the hub to the crank before, however he said with the design of the aftermarket hub, this would not be very feasible. He stated he felt there would be a limited amount of time before issue arose, sounding much like a new crank conversation again. So, I guess my question, is has anyone else replace their hub using the part # 872049 Pioneer keyed crank hub on a 97 LT1, and any opinion on how long this "fix" may last...1997 LT1 with some work done, but nothing crazy like NOS, turbo, or supercharger. Thanks in advance

gaedbo

Sounds kinda scary to me. When your mechanic mentions there is more play than he would have liked and how long the install lasts is up to a key in a keyway. What is holding the key in so it can't come out ? With the more play, does that mean it is possibly not running true (eccentric), which would drive me crazy. If it was me, from what I read, I would be afraid to WOT that car.

I hope someone can offer you a more positive response from their own experience.

Chimera96

OP

since you are not doing this work yourself you can only rely on the verbal representation of your crank from this mechanic. A good mechanic would have said "your crank is down .00xx" so the interference fit of a hub will be to loose.."

If the new hub was able to be installed just by pushing it on by hand...than yeah that is lose. If he did use a install tool to press it on and with a key you should be fine.

Speedy sleeve, knurl the inside of the hub would have been ways to bridge any gap if there was one to be concerned. Even using .xxx sizing material wrapped on crank

Injuneer

My input was actually in post #6 of your earlier thread..... thought this looked familiar.

https://www.camaroz28.com/forums/gen...eering-885408/

97TAMONEYPIT

Thanks guys. Basically, my mechanic hates my car. I have no reason to think he's lying to me, but wouldn't be surprised if he was....emphasizing a potential problem in hopes of convincing me to sell the car, which is where I'm at, so he doesn't have to see it again. He simply said the snout was more worn than expected, but since this car has been a headache to both of us, he wants to avoid any warranty at all. Car seems to run smooth, for the mile i just drove it, no shudder or wobble at least up to 45 mph. Even though I just blew the money on the pioneer keyed crank, I'm considering an ati damper/hub with a pin kit, bit really just kinda ready to sell the car. He did not state any wear amount in numbers, so hard to say, other than he felt the key would be bearing the force of acceleration/deceleration to where it could wear out or break. Lastly, the guy I used was supposed to be experienced in these as far as what I knew, but now I'm told there just not a lot of guys messing with lt1's anymore, if I wanted a second opinion, Anyone know anyone east side of phoenix,Tempe, Mesa Arizona area as experienced engine builder?

gaedbo

I have quite a bit of experience with keys and keyway fits on bearings, sprockets, gears, pulleys etc. for over 40 years of machine building. If the fit is not what it should be, you can bet the install is not going to last. Once movement starts, it will only get worse.

This really sucks that this has happened to you ! Seems like you didn't end up with the most skilled mechanic, and now he wants out.

Injuneer

Need measurements, but doesn't sound like you will be able to get them unless you do it yourself.

Another answer would be a double key, splitting the load on the key in half. When the high HP (1,000+) S/C LT1's started breaking ATI hubs, they needed a solution. Buddy of mine reinforced the outside of the ATI hub with a steel ring. Then his shop cut a second keyway (180-deg opposite) in the ATI hub. Then somehow managed to cut a second keyway in the crank, WITHOUT removing the engine from the car, or the crank from the engine.

But you still need virtually zero clearance between the snout and the hub. The damper is not going to protect the crank like it is supposed to if the hub is able to wobble, and won't be long before you have an even bigger problem with the snout.

Chimera96

measuring the crank snout then the ID of the new hub would have told you, and the mechanic, wtf the the interference , or not, fit would be.

From Op's post he just says mechanic says fitment is lose and the key is really the only thing holding the hub on.

so from this side of the internet we can't advise how this will turn out. You may be fine or find yourself with another "spinning" hub.

You could try just removing belt then remove the crank bolt and try to pull off damper/hub by hand...if it comes off you have a problem.

Ask the mechanic if he used a tool (not a hammer) to install it or was able to push it on by hand. The later would be a problem

Injuneer

I wonder if it would be possible to build up the hub hole by chrome plating it? Chromium is hard, and with a bit of cobalt in the mix, becomes even harder. Just an off-the-wall thought.

97TAMONEYPIT

So, I spoke with mechanic, and he said the hub started by hand, needed to be tapped with a hammer to seat it, like NOT suggested above, and needed to use a tool/puller to pull back off. So, not totally just sitting there, but not great either. Then he stated he loc-tited the crap out of the bolt to keep it from backing out due to any vibration, and stated that he would be money that it was good for at least 10 hours of drive time, but nothing past that, and no warranty at all. Pretty upsetting to say the least, wish I could go back and make some different choices, but guess I just gotta cry in my cheerio's at this point. Picked the car up and it seems fine, but feel like I have a time bomb waiting under the hood, so I hate even looking at the thing right now. So, since I can't re-measure myself, and opinions based on the above info on durablilty of the repair? I don't think this guy wants to work on the car anymore, and I think with the way he fixed it, he seemed to suggest not trying to take back off. I was going to try and find a different mechanic to re-replace hub and pin, but at this point I don't know what to do anymore.

Chimera96

he used a hammer to put in on....and then loc tite the bolt...you don't want to ever have him touch the car again.

sounds like there is still some "interference" fit if he has to use a puller to remove it but not as much as normal

Fred's note about getting the hub chromed sounds like that would work vs replacing the crank. basically you need just .001-2 max increase in inner ID so a "coating of chrome" would do that. Powder coating also but I suspect that is not as strong as chrome

You could also take the hub off and have a machine shop knurl the inside some. I did this on a pilot bearing into a after market crank that had the pilot bearing hole "slightly" larger than stock (read I could push the bearing in by hand). The machine shop charged me $20 and it then fit "tight" as it should

Since you don't do this work yourself you are at the mercy of whoever does your work at whatever cost they charge.

Removing the hub is not rocket science. A 3 spoke star puller available at just about any auto part store (sometimes as a loaner) or a cheapo at Harbor Freight will work easily to remove it.You may need to buy the 3 bolts that are the thread size of your hub if the puller does not have the size you need with it

Installing it can be done with a home made tool using a piece of all thread rod the same thread size as the bolt that holds it on, large washers and a thrust bearing and a nut that fits the all thread rod you can buy at a hardware store work to install it. You can Google "home made LT1 damper hub install" or something to that affect to see a how to. There are likely several threads on this forum showing how. The GM dealer would have the factory Kent Moore tool specific to installing and removing the damper hub. Those are exploding wallet $ but occasionally come up on ebay

NEVER EVER USE A HAMMER TO POUND ON A HUB ON CRANKSHAFT

IDK if the mechanic is more telling you to F off and never bring the car back by saying it has a 10 hour life span and no warranty...maybe the key will hold it fine as is. If your PS or AC lock up again that could snap the key and cause the hub to spin...that is a very rare occurrence but apparently happened to you causing what seems to be some OD reduction in the crank snout

You now will likely need a breaker bar to remove that loc-tite crank bolt. At least you have a 6 speed so you can put it in gear to keep the engine from rotating

97TAMONEYPIT

THANKs again for the help. I will look into it, just not sure who would do that around here. My mechanic was "supposed" to specialize in these cars, but the owner/mechanic is the owner now, and his guys are not what he was. He did put my hub on personally, but I think your assessment is correct in not wanting to see me or the car again. Tough to spend $6K with a guy getting a car fixed up, put less than 1000 miles on motor due to constant issues (not really his fault there, bad sensors etc), then this happened. He was up front about nothing making him happier than never seeing my car again. I worked retail 10+ years so I just don't have it in me to go ballistic on someone after time I put in, situation really just sucks. So I can either sell the car asap (don't really feel too good about that) or try to find someone else around here to help. Any suggestions on what to google to find someone to chrome plate the hub? I'm sure I can find a machine shop, but do I have to remove and take to them, or will they actually turn wrenches on a car? Typically machine shop, I'm sure everyone is different. Any suggestion on how to find is appreciated. Thanks

Injuneer

If it's got a "slight" interference fit, and he actually added a key, I would just drive it. I doubt it's going to be a problem, just make sure your PS pump and A/C compressor are in tip-top shape. I don't recall too many people having problems with those components locking up and causing problems like this in the 20+ years I've been helping LT1 owners on sites like this.

Chimera96

You may be fine just driving it the way it is.....from this side of the internet I didn't put the hub on so don't know how the fit is. It took a puller to get it off so there is certainly some interference fit now

you have to take the hub off to have it chromed or the inside knurled and I think the later would work and cost less than sending to a chrome shop. Machine shops typically don't R&R a part they are machining. You bring them just the part.

without measuring the crank and ID of the hub we don't know WTF if there is a real problem or not. IDK what the interference fit is supposed to be on a press on hub

drive it..maybe it won't move at all. 10 hrs and see if the center bolt is lose

97TAMONEYPIT

Thanks all. To anyone rebuilding an LT1, I know its been covered on here many times, just wish I had seen it sooner, but put some kind of KEYED HUB or damper on the crank while its apart. I wish I had known. Thanks again all above for everything! I think I may keep it a minute and see how it goes, I appreciate the support.