i pulled out my annoying gear drive and went to install new double roller and the bottom gear will just slide all the way on??? i even went to local parts store and bought one from them and it does the same??? only thing left to try is replace the keyways but they look good to me. any help????

sometimes they do that. it's just the way the tolerances stacked up in your case.
as long as it doesn't flop around, it will be fine.

sometimes they do that. it's just the way the tolerances stacked up in your case.
as long as it doesn't flop around, it will be fine.


what do you mean flop around? the keyway keeps it from moving side to side. and i assume the balancer holds it in place then?

496,
The keyway does not really keep it from moving, it just locates it correctly. The press fit and the clamping force from the damper and crank bolt is what keeps it from moving.
I would measure the crankshaft and see if it is worn, or has been machined smaller for some reason. How easy did the gear drive bottom gear come off ? If the gear drive gear was tight, then either the sprockets you are buying are made wrong (pretty unlikely) or the crank is worn. It will probably not be much of a problem in a street engine, but I would measure it just to be sure.

496,
The keyway does not really keep it from moving, it just locates it correctly. The press fit and the clamping force from the damper and crank bolt is what keeps it from moving.
I would measure the crankshaft and see if it is worn, or has been machined smaller for some reason. How easy did the gear drive bottom gear come off ? If the gear drive gear was tight, then either the sprockets you are buying are made wrong (pretty unlikely) or the crank is worn. It will probably not be much of a problem in a street engine, but I would measure it just to be sure.


The gear drive sprocket, I had to use a gear puller for it. The gear drive is a (C.A.T brand) and if i remember right i had a hard time putting it on.

this is a street engine making about 400 h.p

i think the crank is deffinitly worn, ive had this engine since it was built 10 years ago. it originally had a double roller on it, then when i put aluminum heads on a put a gear drive on it ( ive regreted it ever since) will I be ok just running it?

496,
If the gear drive needed a puller to get the gear off, I would think that the crank was ok. You should be able to feel an obvious step where the crank gets larger where the gear goes on. What brand of chain set are you buying ?

496,
If the gear drive needed a puller to get the gear off, I would think that the crank was ok. You should be able to feel an obvious step where the crank gets larger where the gear goes on. What brand of chain set are you buying ?

Comp cams.

here are some measurements

crank---1.238

old gear---1.240

new gear--1.243

im sure the old gear when it was pressed on took some meat off the crank. theres a lip and metal shaving from it. the old timing set was a C.A.T brand and i think it was machined a little small and thats why I am having the problem.

question---can i run the new timing chain this way? will the chain/balancer and bolt keep it in place?? or should i put it back the old way and live with the gear drive?

should i run it??

It should be just fine. Chevy's typically have a press fit gear and balancer, but all Pontiacs had slip fit gears and balancer from the factory. As long as it's not wallowed out it should make life a little easier. How about the balancer? Will it just slide on?

No way I would run it.

You must have an interference fit in the area between the lower gear and the crank, if not, the lower gear will eventually shear the keyway. There's no way the balancer is going to keep it under control. The fit ususally sees
about .0015"/.002" press.

Harry P. Hunter

Just guessing you could have the ID of the crank gear knurled. Should be able to get this done at most machine shops.

I think they can put a sleeve in a balancer. THis is for worn balancers I believe, but they could hone it for your crank, assuming the snout is still round. I wouldn't knurl it as this could induce stress risers which is bad on a crank snout.

Actually, Loctite has a product out that repairs worn out press fit applications, but I can't seem to remember the name.. I have some at home, I'll post it tonight...

Actually, Loctite has a product out that repairs worn out press fit applications, but I can't seem to remember the name.. I have some at home, I'll post it tonight...

i picked some up at Advance. i put some on and let it sit overnight and it wont budge. also put a little more on in the degree keyways so it could work itself between the crank and gear.

this is just a 355 that has been beat on with nitrous and served its time. it makes around 400 hp. after this year i will be building a new shortblock anyways, so this is just a band-aid untill then. thanks for all the replys and advice.

Sorry, I forgot to look when I got home...Glad you found it :thumbsup:

I would not hesitate to use a LocTited sprocket. As long as you clean both surfaces well, the LocTite will hold. LocTite has changed the colors and descriptions often in the last 30 years, so I would check their website for recommendations. Be sure to cover both surfaces with LocTite before you assemble them. You won't need a lot: a couple of drops on each part should do. You won't know how well it works until you try to take it apart, and then you will need to heat the pieces with a torch.

I also suggest you peen the top (and maybe the bottom too, if it needs it ) of the woodruff key slightly to assure a good snug fit in the sprocket keyway, if it has any looseness.

LocTite products have always performed well for me. A lot of my stuff is held together with their two part epoxy.

When you can't wait for the standard cure time of the thread seal products, heating with a Burnzomatic torch to 140-160 degrees will hasten hardening. The heat and the CO2 both work to make it set up.