GS750 with 34mm Forks

[Azul the Cat]

I cross threaded a bolt into my upper triple tree clamps, and rather than try to get it our, I thought I would get a "new" one off a 78 GS750 for my 77 GS750. No issues getting the old part off, but come to find my forks are 34mm, and not 35mm like they should be. The upper triple tree looks very similar to the new one I got, and the offsets are the same. Now I'm wondering do I shim the forks the 1mm, or try to find another triple tree. When I checked the fork tube list, I don't see a lot of suzuki bikes with 34mm forks. I thought it might be a GS550 fork ar first, but those had 35mm forks as well. This is what I have right now. Silver is the old part, and black is the new one with 35mm holes.

Any ideas, on what bike I pull a 34mm clamp from, or anywhere to find shims?

 

[RichDesmond]

I cross threaded a bolt into my upper triple tree clamps, and rather than try to get it our, I thought I would get a "new" one off a 78 GS750 for my 77 GS750. No issues getting the old part off, but come to find my forks are 34mm, and not 35mm like they should be. The upper triple tree looks very similar to the new one I got, and the offsets are the same. Now I'm wondering do I shim the forks the 1mm, or try to find another triple tree. When I checked the fork tube list, I don't see a lot of suzuki bikes with 34mm forks. I thought it might be a GS550 fork ar first, but those had 35mm forks as well. This is what I have right now. Silver is the old part, and black is the new one with 35mm holes.

Any ideas, on what bike I pull a 34mm clamp from, or anywhere to find shims?

View attachment 61172

I have a friend who once bought a set of 41mm clipons for a bike that turned out to have 40mm forks. Discovery of said problem happened a couple of days before race weekend, no time to exchange. Luckily my friend was not opposed to turning full beer cans into empty ones, and the resulting shim stock worked quite well.

 

[Azul the Cat]

It's not stupid if it works, right?

 

[RichDesmond]

It's not stupid if it works, right?

That’s what I...er, my friend said.

 

[Guest]

fix the old triple clamp?

 

[Big T]

I think it's a measuring issue
Just pull a fork tube and slide it into the new triple clamp

 

[Azul the Cat]

I think it's a measuring issue
Just pull a fork tube and slide it into the new triple clamp

I double checked everything with my digital calipers. The forks and the old triple clamp are definitely 34mm, and the new one is 35mm. This makes me wonder what bike the front end that's on there now came from then. The forks only have brake caliper mounting on one side like the 77 should have, and there isn't any mounting location for a second brake disk on the front wheel like some had.

 

[bull958]

Is it possible that because it has never been tightened that it is measuring 1mm over?

 

[Azul the Cat]

I just went to double check my measurements, and of course the battery on the calipers dies. Looking at the analog scale it does look like I have might have 35mm forks. They measured ALMOST 35mm, maybe 34.75mm. I went to check the diameter of the new triple clamp tightened all the way down, and it measures 36mm, or more like 35.75mm. Still doesn't help me solve my issue though, and the mystery continues since Suzuki doesn't have a lot of bikes with 36mm forks either. At least the new part has a Suzuki logo in the underside, while the old one does not. This is what it looks like with the clamp tightened all the way, and there is still a 1mm gap.

 

[Guest]

I believe you are over thinking it, install a fork tube and tighten it down that will answer all your questions

 

[RichDesmond]

I believe you are over thinking it, install a fork tube and tighten it down that will answer all your questions

He did that, see post above yours.

 

[RichDesmond]

I just went to double check my measurements, and of course the battery on the calipers dies. Looking at the analog scale it does look like I have might have 35mm forks. They measured ALMOST 35mm, maybe 34.75mm. I went to check the diameter of the new triple clamp tightened all the way down, and it measures 36mm, or more like 35.75mm. Still doesn't help me solve my issue though, and the mystery continues since Suzuki doesn't have a lot of bikes with 36mm forks either. At least the new part has a Suzuki logo in the underside, while the old one does not. This is what it looks like with the clamp tightened all the way, and there is still a 1mm gap.View attachment 61177

it's probably a clamp for 37mm forks. A measurement with the bolt loosened would help. There weren't, as far as I know, any Suzuki street bikes with 36mm forks.
Shimming 1mm is a bit dodgy, I (I mean my friend) wouldn't do 2mm.

 

[Azul the Cat]

it's probably a clamp for 37mm forks. A measurement with the bolt loosened would help. There weren't, as far as I know, any Suzuki street bikes with 36mm forks.
Shimming 1mm is a bit dodgy, I (I mean my friend) wouldn't do 2mm.

I think this may be the answer. Tightened all the way down, the clamp measures 36mm, so it makes sense it would go on 37mm forks.

 

[Azul the Cat]

Here it is loosened. They are almost 37mm with no tension on the bolt.View attachment 61180

 

[salty_monk]

The early single brake 78 1000C had 37mm forks. I thought the 78 750 did too..

You have a 37mm triple clamp. You need one from a 550 or 650G

 

[RichDesmond]

The early single brake 78 1000C had 37mm forks. I thought the 78 750 did too..

You have a 37mm triple clamp. You need one from a 550 or 650G

I'm pretty sure all the 2 valve 750s had 35mm forks.

 

[salty_monk]

Perhaps the new part is just wrongly labelled... wouldn't be a first with NOS stuff