Help, no backlash on my Intermediate gear

[RetroSC]

Ok, here's the rundown. My 67S came with a 68S motor, so during my rebuild I picked up a 67S sandcast case and the proper intermediate shaft/gear. I'm using the crank from the 68 case and when I fit these together I get absolutely no backlash. Everything turns ok, but there's no play in those gears. Both intermediate shafts have "0" gears and this setup worked fine in the old mag case.

So the question is, how do you adjust backlash? The only way I see it is a different size gear...slightly smaller. Where does one find such an item and how do I know what size to get? The other question is, why did this configuration work in the mag case and not in the aluminum one, is the spacing between the shaft and crank bores slightly different?

Help...... Bill

[RetroSC]

Ok, I've done some searches and have a better understanding of a few items. First, I have a 0 intermediate gear, a 0 crank gear, and a 0 case-size stamp. With that configuration, the only possible issue I can come up with would be too much backlash from say a worn intermediate gear. In which case you'd simply replace the worn gear with a new 0 size gear, right?!

So should I just bolt this thing up and not worry about it. Is it somehow possible that all my matching 0 sizes could result in too tight a fit? I mean, they don't make em any smaller than the 0 spec, so what could I do anyway? A 1 size gear would only make things tighter the way I understand it. Not that my understanding of things has gotten me very far in life, so I'd like some reassurance that I'm not crazy.

[Determined]

I just replaced my aluminum "0" gear on my 3.2 engine rebuild, it too is matched up with the appropriate components. I noticed that it turns freely but seems to have minimal backlash. The gear was a direct part number replacement, I don't believe there is anything to worry about. I hope others jump into this topic as well. Oh, replacing the gear was challenging alone, I recommend a very large gear puller and don't get too frustrated.

Best Regards,

Alex

[Eagledriver]

I put a new gear on my layshaft last year and ran into the same thing. I decided that as long as it wasn't binding up it would be ok. The aluminum gear will wear fairly quickly and loosen up the gap. Also as the engine heats up the case will expand making the shafts get furthur apart, loosening the gap. I know the aluminum gear will also get bigger with heat but the steel gear on the crankshaft won't expand as much.

-Andy

[NevenM]

Bill

If you have the engine rebuilding book or a tech spec book it will give you all the measurements involved, The 2 critical ones are the centre to centre distance of the bearings (0 or 1 on the case) and
the diameter of the timing gear. These can be measured by any competent machine shop (or yourself if you have the tools). I'd check these measurements against the markings on the items you have before you proceed, Id worry about no backlash damaging the aluminiium gear

HTH
Neven

[RetroSC]

Thanks for the replies. I think everything looks ok, spun freely against the crank and JW seemed to think it would be fine, so I bolted everything up last night..... guess we'll see.b