After installing my own 4.77 gear set (with Marcucci's help), I have a theory about how it might be possible to reduce the risk of breakage by reducing backlash. The OEM specs for backlash between the ring and pinion gears are .002" - .0043". It seems to me that gears with a large backlash may see much more "shock" than those with a smaller backlash.

Basically, the backlash is the free play between the 2 gears. On a clutch dump, the clutch will be allowed to lockup to a greater extent before that free play (slack) is taken up if the backlash is large. It seems to me that this would increase the instantaneous force on the gear teeth. If there is less backlash, the slack will be taken up sooner in the clutch engagement. I figure this would be like the difference of dropping a hammer from 1" instead of 2".

Furthermore, I think the backlash may be able to be reduced BELOW the minimum spec once the ring and pinion are broken in. I don't know this for sure, but it seems logical. Has anyone even checked their backlash after a new gear set is broken in? Thoughts?

 

I was thinking the same exact thing. Except I had said that natural fatigue in the bolts that hold down the bearing caps could also cause excess backlash. An option is to install some ARP studs instead of the OEM bolts. ARP studs are rated at over 100,000psi. I'm sure the OEM bolts are nowhere near that.

 

Would you happen to have part numbers or pricing for the correct ARP bolts?

 

Although, I wonder if stronger (more rigid) bolts would put more stress on the brearing caps...

 

I don't have any part numbers, and I doubt they make any that aroe for this purpose. But all you would need to do is get one of the bolts from Honda and send it to them to have it sized. Then they will give you the correct part number so you can order it. Or just ask them what measurements they need. Then take it to a machinist to have it measured for those dimensions. Then just give ARP a call.

As for the bearing caps, just have them cryo treated or use the Comptech ones, or have the OEM ones reproduced in forged billet by any machine shop. Just have them make them more stout than stock. But I'm sure any machine shop can make these for under $400 which is what Comptech charges.

 

Here is a photo of Krazik

 

Big ben, I am going to get more nightmare tonite with those pics

gernby, is it right that reducing backlash will make the diff noisier?

 

Yes, (I think). If there is more contact between the gears, there will usually be more whine.

 

I haven't ever heard that, but I'm no expert. I installed my 4.77s twice, since I was considering installing them for other local members. I set my backlash pretty tight the second time, and I guess I might have more noise now...

 

I'm only basing my answer on the noise I hear from those timing gears that you can install on a V8. They have constant tight contact, so they whine like a supercharger almost.

But I really don't know, just guessing.