Clutch plate specs 82 cb450sc Nighthawk

[Maine Nighthawk]

I am rebuilding the clutch and ordered a set of friction plates and drive plates said to fit my model and year. After clicking "buy", I noticed the drive plates were 2mm thick. The service manual specs call for 2.7mm new with a service range down to 2.3mm.

I measured the existing plates, and they were all 2mm (except for the one thicker plate that matches to the one thicker friction plate).

Also, the free spring spec is 42mm, and the ones I removed were 37mm.

I find it hard to believe they are that far out of spec due to wear - the bike has less than 20k on the clock.

So, I'm in a quandary as to whether I should keep my order with the 2mm drive plates or cancel and order oem plates?

I could not fond any technical info on the oem parts to know what thickness they are.

So, I'm a bit confused and seeking the wisdom of the group.

Thoughts?

[Bob H]

...order oem plates?

I don't have your model, but when I recently did my NH 750 clutch I ordered OEM from Partzilla.

Based on the uncertainties you face, I would absolutely go with OEM parts (if available)

I had twice the miles and mine "just" had started slipping after putting in proper jets in the carbs.
Why are you doing a clutch? What are the symptoms?
Shouldn't need it with that low miles and horsepower of a 450.
But I have heard that clutch plates can get glazed due to their age...

[Maine Nighthawk]

Thanks. Yeah, I'm leaning toward OEM, just hate to relinquish the 20% restocking fee for the parts purchased.

I just got the bike a few months ago and have done the carbs, sprockets and chains, and when I went to move it, I could not get the clutch to engage. I tried adjusting the cable, but no dice,so I decided to go ahead and rebuild the clutch while I had it in the basement and spring is a month or so away.

[Bob H]

and when I went to move it, I could not get the clutch to engage. I tried adjusting the cable, but no dice...

Honestly if that was my bike I would just take the clutch cover off and see what was going on.
I would manually move the lever that the cable attaches to (with large channel lock pliers) and get a feel for the current situation.

I would take the clutch cover off and see why it isn't engaging.  If that bike had 5x more miles it would still "engage" even if it was slipping.

Who knows, the clutch plates may NOT BE THE PROBLEM. My money is on something else.

What is the history of the bike? Was it like that when you acquired it - or did it work when you got it?
If you recently got the bike and the clutch was like that, someone else may have screwed with something and not got the cover - lever etc. back together properly.

Do you have a manual? if not that is the first part I would get.

[Maine Nighthawk]

Yes, I have both Clymer and service manual. Perhaps I will put it back together and test as you suggested.

It was engaging ok last time I had occasion to use it a couple of months ago.

I am still mystified by the existing plates and springs being well out of spec...

[Bob H]

If it was engaging OK last time you used it - what changed?
20k miles is nothing for a Honda motorcycle.
And it's not a lot of horsepower going to the clutch on a 450. Honestly it could last the lifetime of the bike.

...I am still mystified by the existing plates and springs being well out of spec...

If it was engaging OK during the early chapter of your brief ownership of this bike, then the plates and springs did not suddenly change. I wouldn't get hung up on that. Something else changed.

Haven't done your model clutch, but if anything was taken apart (cover removed due to crash damage? etc.) they can be tricky to get back together just right.

[Maine Nighthawk]

Yeah, thanks. I guess I'll just have to reassemble and re-diagnose. I'll let you know what, if anything, I find.

[Maine Nighthawk]

Finally got around to putting it all together with the new plates and all is well!