Help: anyone with LT4 extreme duty chain!
 

Do those of you who have used the LT4 chain setup have any issues with it? I'm having a big one and I want to know if this has happened with others:


@ 75k mi I did a heads/cam upgrade and I added the LT4 extreme duty timing set (#12370835), along with new opti and waterpump to the car.
Car has 90 k mi now.

I have road raced (well instructional) 3 times in the last 10 months. Total 4 days, approx. 16 20 min sessions. I'm careful not to let the rpm build too high and usually never to over 5000-5500, but I did hit a rev limiter (6300) once. Also did rev it up on the main straight (like drag racing) to 6000 a few times during this. Did some drag racing too.

Ok: The cam sprocket is destroyed!!!! The gear is completely chunked and gone where it meshes to the driven gear (on engine, goes to water pump). Water pump bearings are also kind of tight but still turn but tighter than new or 75k used pump.

I have over 30K miles on my Extreme Duty Timing set with no problems.
My set includes all new gears for the cam, crank, water pump drive, along with the chain.

Mods:
Crane cam
AFR heads
Roller Rockers

Tom Piper

:eek: DAYUM!!! I'd like to hear the outcome to this. I just installed mine last month so I can't exactly help you. I will note though that I bought mine based on a strong recommendation from Jim Mason who is a forum member, but his ID escapes me right now. Anyway, he races his car quite often and he uses the extreme duty chain. Good luck to you... I hope someone can offer some insight on this :bigears

I have heard of problems if you do not install the supplied water pump driven gear. I have installed several of these gear and chain sets and have not had any problems with any of them.

I have the old LT1 parts so I know he used the supplied gears. Unless he substituted, but there would be no reason to do that.

Thanks for your replies!

I use it. I have a couple thousand road course miles on it. No issues.

Jim,

This is the extreme duty set, 12370835, not the LT4 stock set up?
Do you know other fellow road course guys that use it too? Do any use the stock LT4 set up?

When did you buy your extreme duty set?

Thanks for your replies, guys, the info. is helpful.

Ok folks--

Metallurgist just looked at the gear and he points out that the wear is even on both sides of each tooth. Also, the mating gear is not destroyed like this.

It is looking to me like GM did not properly heat treat this gear.

Also, this cam gear and driven gear are unique to the timing set whereas the crank gear and timing chain are mass-produced. Makes you wonder.

Sounds to me like you don't have the correct water pump gear for the ED timing set.
It is required to change the water pump gear when installing the ED timing set.

Tom Piper

Tom,

I have the original LT1 water pump gear and the other parts of the ED set were on the car. Seems odd that an installer would deliberately substitute the gear / or give me back an LT1 gear already on hand to fool me.

The gear I was speaking of which is not as hard as the LT1 gear is the cam sprocket of the ED set. I checked 3 stock LT1 gears: water pump, cam, and crank. All significantly harder than the ED cam gear.

I have the extreme duty setup. NoGo on this forum uses the ED setup. Not sure about other guys. The events I go to are 95% other car brands and about 5% Corvettes...the majority of which are Z06s. Seems most Corvette folks don't like playing on road racing circuits.

I know of two guys using the stock setup without any issue.

I bought my ED setup from Superior Chevrolet.

As I remember, the chain came in with the two accompanying gears. I had also ordered another water pump shaft. However, the new water pump shaft had the smaller standard LT1 gear already installed. Since I did not have a press handy to remove the LT1 gear on the new one and install the new beefier gear, I simply reused the LT4 original shaft which already had the beefier gear since it really had no wear on the shaft at the point of the seal.

If this chain went onto an original LT4 setup, then you should have no problems. If you used a regular LT1 setup, then your gear was already smaller than the new crank gear with the chain.

One must remove the LT1 cam gear from the original water pump drive shaft and replace with the new larger gear included with the cam. The original LT4 shaft gear is the correct size to begin with. Evidently, the mechanic figured the old pump shaft gear would be just fine. Wrong......

Perhaps he was not sure how to remove the old gear and replace with the larger one.

You should contact Cloyes engineering department. They are extremely helpful and also they make the extreme set up for GM. If there is a metalurgical problem I am sure they would want to know about it.

I believe I had the same problem with mine, The gear was way worn and the teeth were filed down razor sharp. I just went with a stock LT4 set up.

:iagree:
I have heard of a couple of people who left the OEM WP gear and it trashed everything just as you described. I have the LT4 HD with no problems but I have an electric WP as well so there is no WP drive gear because I removed it, or actualy never installed it.

Do tell details! For my part, I will talk to parts guy today and ask for physical description of the 2 gears. I have one water pump gear from 2 years ago (the head/cam job) and I presume this is the original LT1 gear. It meshes well with the LT1 cam sprocket. Hard to tell with trashed one.

Details: Was the water pump gear trashed? Mine is not. How long did it take to show up as an issue? Mine arguably performed flawlessly during about 40 drag passes and a chassis dyno (which had good #'s as results). Also 15,000 mi. What trashed it was 4 road course events in 10 months.

Thanks for the feed back, keep it coming.

Everyone,

Just to wrap this up: I did check the water pump gear. The one that is still on the car IS the extreme duty water pump gear. I know because it has 3 holes at 120 deg. (not counting the center one). The other gear that I have has 6 holes (not counting center) and that is correct for the LT1. Plus the 6 hole gear is worn. If mechanic did not replace, he would have given me the brand new, unused ED gear when I asked for all parts back. Parts guy at Superior Chevy confirms that the 3 hole is the ED gear, 6 hole is the LT1 gear.

So mechanic did everything correctly.

As far as I am concerned, this was bad gear. I would not buy another if my life depended on it and I would not recommend the ED set to anyone.

Thanks for your help on this, it would be hard to figure this without knowing how the products are used by customers.

Andy

Andy aren't you being a bit harsh...parts are parts...most are perfect some are defective...Cloyes is one of the best products around...one sample doesn't make the world crash.

^ Um....one bad sample....Mine was bad....