sothpaw2

Anybody know what these respective waterpump gears (the driven gear which resides on a shaft pressed into the block) visually look like? The ones I have seen don't have part numbers--makes a double check hard.

Do the '95/'96 LT1 waterpump gears have 3 holes equally spaced (not counting the center one) and are they lighter in color, goldish?

My '93 LT1 gear is a little lighter in color (goldish) then the LT4 stock gear I received or the LT4 extreme duty gear. The '93 gear has 6 holes eq. spaced compared to 3 for the LT4 gears (either variety).

While I'm at it, does anyone know if the LT4 waterpump gear is exactly the same as the LT4 extreme duty (cloyes) gear? Was the 1996 LT4 production set provided by Cloyes?

Thanks guys

tjwong

I spoke with Cloyes a week or two ago about this very subject. The actual gear pitch is identical in all the gears. Also in the early LT1 engines there were no holes in the gear at all. Later GM came back and had Cloyes add holes, I beleive the first rendition had 6 holes. Later GM came back and had it changed to what it is now, which is three holes. As far as hardness ratings go, Cloyes said that the hardening process was the same for all the gears, the only difference was the holes. GMs assessment was that the holes were required to aid in additional splash lubrication for the gear and its mating ring gear on the cam sprocket. Cloyes assessment is that as long as there are holes (at least three) it is OK to use the gear. And, if you are replacing the timing set they recommend that the driven gear be replaced in all instances. If you are using a LT4 extreme set, use the supplied gear. Check this post out as Sothpaw2 had some major problems with the drive gear:

http://forums.corvetteforum.com/show...ater+pump+gear

tjwong

According to GMPD they are the same. I just purchased a couple new shaft assemblies for a couple LT1 engines I am working on. The shaft assembly is one part number to cover all the LT1/LT4 engines. This assembly comes with the shaft, gear and bearing assembled. The gear has a gold tint to it, and it is a differenct color than the ED gear. Also it has 6 holes in the gear as well. Cloyes take is that as long as there are holes you can use the gear, the ED gear has 3 holes, but you already know that one.

sothpaw2

I ordered 1996 LT4 parts from GM and the waterpump gear they delivered (part of the shaft assy of course) has 3 holes, looks like the ED gear.

So you think the LT1 gears have 6 holes all the way thru 1996? And maybe the LT4 w.p gear = w.p. ED gear (= 3 hole design)?

tjwong

Strange I ordered the shafts for a LT4 and I got gears with 6 holes The dealer told me it was the same part number for 92 through 96 LTx engines. Cloyes says that they manufacture them all, and that there is no hardness difference between the gears and that the only difference was the number of holes from the different designs.

sothpaw2

I doubt that the hardness is all the same--If it is it would explain a lot.

My '93 w.p. gear, 6 hole, measured Rockwell A 71 (RC 41) as did the cam gear it mated too. This compared to Rockwell A 64 (RC 28) for the LT4 cam gears (ED & stock LT4).

I should (with luck) have measurements of the LT4 (3 hole gear, still on its shaft) gear and the Cloyes gears (not the ED set but the Cloyes in-house set) today. Will post FYI.

Strick

Here's a picture of my 92 water pump driven gear assembly. I don't know if it helps you or not.

sothpaw2

Thanks Strick.

Yeah, My '93 Gear looks just like that. I was wondering if they changed the LT1 gear to a 3 hole for '95-'96 LT1. Parts guy gave me 1 part number just now and says it is good for '92-'96. It's the 6 hole design you show.

Also: My ED gear is different than the LT4 gear (which is different from the 93 gear). The ED & LT4 look same except the LT4 is not flat, has chamfer cut on the teeth.

So, I think there are only 3 gears and I have them all.

sothpaw2

Hardness wise, the new ED cam gear came up same as before.
The water pump gear supplied with the set is much harder.

The cam sprocket tooth from the standard chevy gear set (no waterpump drive gear on the cam spocket) also came up very hard, like the water pump gear.

These are in the same range as the LT1 parts. The only parts that measued soft are the ED cam sprockets.

REDC4CORVETTE

Bottom line is change the gear with the one that came with the new unit .
The gears are cut different and will make noise if mis matched.
Just use your hands and spin the gears against each other and I will guarentee if you use the old one it will make noise and wear out very quickly.
Been their done that!

sothpaw2

Yeah--what I was really after with this thread was to determine what the gears look like so i could positively rule out that the wrong gear was used with the ED cam gear when I had it assembled 15 k mi ago. I have ruled it out--correct gear was used.