Oversized Clutch Springs?

[Jimmbuzz]

Hey all,

I've had to swap a new motor into my 82 GS750T, and after the first startup, I noticed the clutch would not disengage. I tried letting it warm up and shifting into first or second and it would immediately die. I tried adjusting the cable on both ends, but found no success.

So I ordered some oem clutch springs, as I thought they could be old and tired. They arrived and they all measured about 40mm. I went to put them in and tried to torque the bolts in a crisscross pattern to 8lb, but then they bottomed out, and one snapped/exploded. Feeling puzzled I measured the springs I took out and they were all closer to 45mm. I still have the motor that I had to replace and I checked its springs and they were all <40mm...

Anyone have any idea whats going on? I compared all the other bits and they seem to be identical and have matching part numbers.

 

[rphillips]

You've got me feeling puzzled, those springs engage the clutch, not disengage. Bottomed out or not, correct torque should never snap nor explode a bolt. If springs are bottomed, clutch lever can't be pulled & clutch can't be released...Just my opinion...Hope I'm not reading this wrong.

 

[Rich82GS750TZ]

Clutch spring fee length limit is 38.5. That said, the 38 year old springs I took out 2 years ago measured w/in spec. And exactly the same as the new OEM springs I put in. I think the new springs feel stronger, but it’s the kind of thing you get used to pretty quick so hard to say if they actually made a difference. I replaced all the drive plates at the same time so, who knows? Clutch Spring bolt torque spec is 8-9.5 lb-ft. IMO, that’s too small a number for a 1/2” lb-ft torque wrench to handle with any amount of accuracy. Best to use a 3/8” in-lb wrench. 8 x12 = 96 in-lb.

Z supplement manual for your bike.

 

[Jimmbuzz]

You've got me feeling puzzled, those springs engage the clutch, not disengage. Bottomed out or not, correct torque should never snap nor explode a bolt. If springs are bottomed, clutch lever can't be pulled & clutch can't be released...Just my opinion...Hope I'm not reading this wrong.

My thoughts too. What's up with the bigger than stock springs that I took out? Could they be from a larger bike?

 

[Jimmbuzz]

Clutch spring fee length limit is 38.5. That said, the 38 year old springs I took out 2 years ago measured w/in spec. And exactly the same as the new OEM springs I put in. I think the new springs feel stronger, but it’s the kind of thing you get used to pretty quick so hard to say if they actually made a difference. I replaced all the drive plates at the same time so, who knows? Clutch Spring bolt torque spec is 8-9.5 lb-ft. IMO, that’s too small a number for a 1/2” lb-ft torque wrench to handle with any amount of accuracy. Best to use a 3/8” in-lb wrench. 8 x12 = 96 in-lb.

Z supplement manual for your bike.

Thanks, but I have an inch pound torque wrench. The bolt exploded before I got anywhere close. I'm just confused why there were longer than oem springs when everything else seems the same.

 

[bwringer]

Not sure what's happening here, but a few things I've seen in GS clutches:

- Stronger than stock aftermarket springs. These make the clutch pull WAY too hard if you use all 6; I've also seen people use three aftermarket and three OEM.

- Stripped 6mm threads with 1/4"-20 bolts from lawn mowers jammed in... yeah.

- Barnett "extra plate" clutch kits (slightly thinner plates so you can stuff in one extra) were popular for while in the '80s and '90s. They are completely unnecessary, even with very serious modifications (the stock clutch will handle fairly substantial power increases just fine) and render the bike nearly un-rideable because they have so much more drag. Pre-internet, you just had to get your advice from dudes in mullets and acid-washed jeans, and thus airboxes were discarded, exhausts gutted, clutches rendered useless, etc... quite a few ruinous myths were passed around as gospel, and the remnants trouble us still.

- I've seen much confusion and confuzzlement between the 8-valve and 16-valve GS750 engines. Perhaps this could help explain something of your current predicament? Not sure of the clutch differences between these models, but a LOT of aftermarket parts did not make a distinction, and many owners and shops never clued in. The same applies to the GS1100 models; you have to be very careful to make sure you're getting the right stuff, since there are two completely different engines with the same displacement.

 

[alke46]

Not sure what's happening here, but a few things I've seen in GS clutches:

- Stronger than stock aftermarket springs. These make the clutch pull WAY too hard if you use all 6; I've also seen people use three aftermarket and three OEM.

- Stripped 6mm threads with 1/4"-20 bolts from lawn mowers jammed in... yeah.

- Barnett "extra plate" clutch kits (slightly thinner plates so you can stuff in one extra) were popular for while in the '80s and '90s. They are completely unnecessary, even with very serious modifications (the stock clutch will handle fairly substantial power increases just fine) and render the bike nearly un-rideable because they have so much more drag. Pre-internet, you just had to get your advice from dudes in mullets and acid-washed jeans, and thus airboxes were discarded, exhausts gutted, clutches rendered useless, etc... quite a few ruinous myths were passed around as gospel, and the remnants trouble us still.

- I've seen much confusion and confuzzlement between the 8-valve and 16-valve GS750 engines. Perhaps this could help explain something of your current predicament? Not sure of the clutch differences between these models, but a LOT of aftermarket parts did not make a distinction, and many owners and shops never clued in. The same applies to the GS1100 models; you have to be very careful to make sure you're getting the right stuff, since there are two completely different engines with the same displacement.

This reminded me of the new to me 80 850 I bought in late 81. The PO had taken a center punch to make small indentations around the perimeter of the head so the two mating surfaces would seal better. Hey, at least he didn't use RTV Ah, PO's, you just gotta luv em eh?

 

[Jimmbuzz]

Not sure what's happening here, but a few things I've seen in GS clutches:

- Stronger than stock aftermarket springs. These make the clutch pull WAY too hard if you use all 6; I've also seen people use three aftermarket and three OEM.

- Stripped 6mm threads with 1/4"-20 bolts from lawn mowers jammed in... yeah.

- Barnett "extra plate" clutch kits (slightly thinner plates so you can stuff in one extra) were popular for while in the '80s and '90s. They are completely unnecessary, even with very serious modifications (the stock clutch will handle fairly substantial power increases just fine) and render the bike nearly un-rideable because they have so much more drag. Pre-internet, you just had to get your advice from dudes in mullets and acid-washed jeans, and thus airboxes were discarded, exhausts gutted, clutches rendered useless, etc... quite a few ruinous myths were passed around as gospel, and the remnants trouble us still.

- I've seen much confusion and confuzzlement between the 8-valve and 16-valve GS750 engines. Perhaps this could help explain something of your current predicament? Not sure of the clutch differences between these models, but a LOT of aftermarket parts did not make a distinction, and many owners and shops never clued in. The same applies to the GS1100 models; you have to be very careful to make sure you're getting the right stuff, since there are two completely different engines with the same displacement.

My assumption is a previous owner of the donor bike added the longer springs but I'm unsure to as why... Bike was also a 750T so same engine... They have the same number of plates and stacked all together they have the same thickness. The baskets, hubs, and pressure plates seem the same between them. I might just take the clutch assembly from the bad engine and put it in this new one.

 

[bwringer]

My assumption is a previous owner of the donor bike added the longer springs but I'm unsure to as why... Bike was also a 750T so same engine... They have the same number of plates and stacked all together they have the same thickness. The baskets, hubs, and pressure plates seem the same between them. I might just take the clutch assembly from the bad engine and put it in this new one.

Hmmm... yeah, I sorta left out "unfathomable PO assery" as a separate line item on my list earlier. I guess this is ever-present. And I also wasn't clear whether this clutch had ever actually worked before or not.

Your plan sounds like a good one.

Maybe someone just dumped in some random longer springs for reasons we'll never know, and then wandered off and forgot all about it. Sometimes it's best not to think about this stuff too much.