LT1 Harmonic Ballancer & Hub Installation
Thread Starter
Instructor
Joined: Sep 2003
Posts: 118
Likes: 1
From: Plano TX
LT1 Harmonic Ballancer & Hub Installation
I've developed an oil leak @ the harmonic ballancer hub. I did a cam swap about 6 months ago & am dreading taking this thing off again, because I remember what hell it was to get the thing back on. I have heard that a groove will wear in the hub from the original seal & it's almost impossible to get the old hub to seal up, so I'm going to replace the hub and a new seal. About 3 months ago I saw a discussion on here where there were several good ideas regarding getting the hub back onto the crank shaft but can't seem to find anything now. I've considered buying a whole new set-up with a fluid ballaced ballancer, but learned today thet the Corvette LT1 is ballanced at the flywheel and the ballancer itself is nothing more than a serpentine pulley, so I'm not going to waste any $$ on a fluid ballancer (new hub from GM is $60). This also explains why there is no "key-way" between the crankshaft and ballancer hub, because if it slips, it's ballanced at the flywheel. Any suggestions that have worked in the past for anyone will be pleasantly welcomed...looking for ideas before I tear it back down this weekend.
Racer
Joined: Feb 2002
Posts: 390
Likes: 0
From: St. Louis MO
Re: LT1 Harmonic Ballancer & Hub Installation (greggo's 94LT1)
You're exactly correct in your analysis of why this leak develops. When I did my cam change I had exactly the same consideration - replace the hub or not? Mine had a bright ring around it but I couldn't feel any wear with my thumb nail so I re-used my hub. As far as re-installation....my engine was still in the car, so I used a series of bolts and a stack of washers to chase the hub back onto the crank. It was slow work and I wasn't quite sure when it was completely seated - eventually the bolt just totally refused to turn and I got the idea!! It was pressed completely back into place. I'm sure there will be some other more enlightening guidance from the other builders but the bolts and washers worked for me.
:seeya
:seeya
Racer
Joined: Jan 2002
Posts: 419
Likes: 0
From: Tampa FL
Re: LT1 Harmonic Ballancer & Hub Installation (greggo's 94LT1)
Went to the local bolt store in my area w/ the crank bolt and bought four different length bolts and an assortment of washers. Worked great. :)
Burning Brakes
Joined: Feb 2003
Posts: 1,144
Likes: 18
From: Panhandle FL
Re: LT1 Harmonic Ballancer & Hub Installation (greggo's 94LT1)
Not really sure about the balancer part. I just did my opti last weekend, there is a mark on the hub that has to be lined up with a mark on the balancer.It doesn't have a keyway because it's held on with 3 bolts. :chevy
Heel & Toe
Joined: Jan 2004
Posts: 22
Likes: 0
From: Tower City PA
Re: LT1 Harmonic Ballancer & Hub Installation (greggo's 94LT1)
yeah, working on that balancer is a pain. I bought a piece of all thread and several nuts to get mine on and off.
I'm not sure if this is the same for a '94 LT1, but my manual states to match mark the cast arrow on the hub to the front cover and not crank the engine to lose the crankshaft position.
If the position is lost however it can be brought back by bringing #1 cylinder to TDC and setting the cast arrow at 12 o'clock.
I'm not sure why GM would be concerned about getting it back where it belongs if it didn't have something to do with balance.
I'm not sure if this is the same for a '94 LT1, but my manual states to match mark the cast arrow on the hub to the front cover and not crank the engine to lose the crankshaft position.
If the position is lost however it can be brought back by bringing #1 cylinder to TDC and setting the cast arrow at 12 o'clock.
I'm not sure why GM would be concerned about getting it back where it belongs if it didn't have something to do with balance.
Thread Starter
Instructor
Joined: Sep 2003
Posts: 118
Likes: 1
From: Plano TX
Re: LT1 Harmonic Ballancer & Hub Installation (SPEED750)
Not really sure about the balancer part. I just did my opti last weekend, there is a mark on the hub that has to be lined up with a mark on the balancer.It doesn't have a keyway because it's held on with 3 bolts. :chevy
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Race Director
Joined: Feb 2003
Posts: 11,672
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From: Lake Wylie SC
Re: LT1 Harmonic Ballancer & Hub Installation (greggo's 94LT1)
I hate to burst your bubble, but the damper you remove from the hub is part of the balancing of the LT1. Just look at the front outer edge and you will see a series of holes about 3/16 to 1/4 inch in diameter. Some may have been filled with weight plugs. When replacing this damper, you must match the weights or risk a vibration. Both the flywheel and damper are used in balancing the LT1, especially in the 92 engines. This was a factory procedure to stop a vibration above 3000 rpms. The engines came assembled to Bowling Green and many had this vibration and GM engineers came up with an in-house procedure to balance out the vibration, hence, the holes and weights in the flywheel and damper. There is a sleeve you can put over the hub, but I'm with you about replacing the hub, but keep the old damper, especially if it has weights in the holes. This help?
Melting Slicks
Joined: Oct 1999
Posts: 2,501
Likes: 177
From: Houston, Texas FEAR THE BONES
2023 C5 of the Year Finalist - Modified
Re: LT1 Harmonic Ballancer & Hub Installation (Strick)
Even if you replace the front crank seal and the hub, the thing can still leak, as the crank snout can be scored. To ensure no leaks, install a Speedi Sleeve from NAPA over the crank snout. Actually, you really don't need to buy a new hub, as the crank snout is the area of concern for oil leaks. The sleeve costs about $5 -- cheap insurance for such a difficult and time-consuming repair. I have had no leaks since performing this repair (about 1 year ago).
Drifting
Joined: May 1999
Posts: 1,697
Likes: 1
From: Joliet IL
Re: LT1 Harmonic Ballancer & Hub Installation (greggo's 94LT1)
cool, thanks. BTW, good luck with the leak. I redid all the seals over a year ago. 2 weeks ago my water pump started leaking, and right after I fixed the water pump, I got a massive oil leak from the crank seal.
[Modified by maduraj, 3:29 PM 5/18/2004]
[Modified by maduraj, 3:29 PM 5/18/2004]
