Clutch plates - OEM or upgrade recommendations?

[sam000lee]

The clutch on my '77 GS750 started slipping last summer. I replaced all 6 springs with OEM suzuki parts and it was still slipping. The friction plates were either right at spec or slightly under so I replaced them with a combination of used plates I pulled out of a couple of unused GS550 engines I've had lying around. At least one of those engines had been sitting for 20+ years with an unknown history. The GS550 has the same plate part #, just a few less plates than the 750 uses. Either way, the plates I installed were within spec but I'm still getting LOTS of slipping when the engine is cold and some slipping when I hit the throttle after it's warmed up.

Soo, at around $20/ea (x8) for the friction plates and $10/ea (x7) for the drive plates (or whatever they're called), it's about $250 to replace them all. I have no problem paying for OEM but was wondering what other options I had that would either be slightly cheaper or a slight upgrade. I ride medium - hard, but by no means totally wail on the throttle and am using shell rotella oil. I've also been planning on a few other upgrades this year, possibly including a delkavic 4-1, which I know isn't significant enough of a change to actually affect the clutch set up but it would be nice to at least be able to say I have an upgraded clutch to match

Bike has ~35k

Thanks in advance

 

[Gorminrider]

To me, that sounds like something else is going on but I can't think of much except the number and order of the plates. I've used old plates before and never had an issue-so you where I'm coming from. Don't buy new stuff until you really are sure... so many bikes seem to use the same setup and size. Once I asked a mechanic how long clutches last -he said "forever..or nearly so if you're normal"


sooo, If you're absolutely sure you have it right,try adding one.

If you bolt the carrier together without the plates you should get an idea of what width is required.
Also get your nose in there and see if/how the push mechanism is working. By loosening the clutch's "bolt-together bolts" you can make the clutch slip or grip which is informative....even useful with plates that will not come unstuck. Running atiny ways around the backyard like this can cure things.

 

[Nessism]

The OEM parts are best available. No such thing as "upgrade" when it comes to aftermarket parts and the clutch.

 

[gs11ezrydr]

The OEM parts are best available. No such thing as "upgrade" when it comes to aftermarket parts and the clutch.

OEM are probably the best for the money,for longevity,Even though they are way overpriced...But a company called FBG makes what I think is the closest to original and last depending on use, and are several bucks cheaper..A lot of Drag Racers use them.

 

[grcamna2]

OEM are probably the best for the money,for longevity,Even though they are way overpriced...But a company called FBG makes what I think is the closest to original and last depending on use, and are several bucks cheaper..A lot of Drag Racers use them.

I'd like to check those FBG friction plates out:do you know if they're made as good as OEM,Japan?

also OP might check to see if his clutch actuator is still in good order/not worn-out and the clutch cable moves freely.

 

[Redman]

Humm... replaced springs and clutch plates, and still having clutch slip....

Using motorcycle oil? Or high detergent automotive oil...? high effeciency automotive oil??

Have you inspected the slots in the clutch basket? Is it notched?

 

[salty_monk]

The friction material can go kinda hard or get polluted... I'd try a set of EBC springs if I didn't want to spend a bunch of money. Scuff the steels too.

 

[sam000lee]

Update:

Took the clutch apart again to triple check number of plates like somebody suggested. All good there although I did end up breaking one of the clutch basket retaining bolts. A little rusty from working on things last year and I forgot that they have a low torque spec, doh! Had a spare that I threw in after wiggling the stub out.

Anyway, after I bolted it up the kickstarter wouldn't turn the engine over indicating the clutch was engaged. On the left side, I took off the clutch pushrod pushing mechanism, cleaned and greased the bearings and could immediately see the issue on re-assembly:

There's a gap between the mating surfaces that indicating that when everything was bolted up, the pushrod was engaged. I've never adjusted the nominal position of the pushrod actuator so am not really sure how it comes out of adjustment but that sorted it right out. Still thinking about getting new plates because there's a bit of a hesitation as I engage first from a stop but it's totally rideable now.

Thanks all

 

[Gorminrider]

Oh good! Great success if you find the prolem without buying parts you don't need..and yes indeed. The clutch actuator at the end of the cable is a maintenance item, and it can go awry if not right.
It can be tricky even putting that sprocket casing back on the bike where the cable end gets hung up or falls loose from the slotty thing as you slip it into place... Perhaps someone cranked it tight so the cable end wouldn't flop about and then forgot to readjust it when tightened on?

 

[headsbikesmopars]

Sand blasting the steel plates will improve the friction and holding properties of the clutch and is cheap and easy enough to do. Works every time for me. Most auto oil has 'friction modifiers' in them and will cause the clutch to slip. I use only motorcycle specific oil , Amsoil 10 W 40 , there are others. 10 years now and no clutch issues. Just FYI . Keep us informed .

 

[bwringer]

I'll agree that OEM is consistently the best, and OEM friction plates and springs are all you need.

And yep, I've also encountered old plates that looked good and measured in spec that were hardened, glazed, or contaminated and just wouldn't grip very well.

Unless they're badly blued, warped, damaged, etc. the steel plates can easily be re-used. As above, scuffing or sandblasting can help make sure everything has the best grip.

Some folks have installed three aftermarket springs and three new OEM springs for somewhat firmer grip at the expense of a harder clutch pull and less feel. This is usually not needed.