Which springs to lower front of 1973 CB350K?

[CuppaJoe]

Greetings everyone,

LONG time reader here, first time poster (now that I have a project).

I just got off the phone with Dime City and asked them about lowering my CB350's front. I have their 11" clevis/eyes shocks on the rear (2" drop) and need to even out the forks, now.

DCC was great on the phone, and they mentioned I should call Progressive and see what they have.

After chatting with Progressive, they informed me they didn't have anything specific for the CB350.

Couple Qs for you lads and ladies...

1) Does Progressive really not have anything for this bike?

2) If not, has anyone used a spring model that works with the 350?

If I can't get anything aftermarket, I will be going the spring shortening/spacer/extra spring route with the stock internals. That being said, I'd prefer to not get too hacky with this.

I've read about sliding the forks through the triple tree, but what's to stop the forks from sliding further up during riding? Outside of the pinch clamp+bolt, I don't see how the forks would stay in place after slipping them up. I'm very open to being told otherwise on this, though - if it's a safe route to go.

All the best and thank you!

Cheers

CuppaJoe in Virginia, USA

 

[nrcb125]

I've read about sliding the forks through the triple tree, but what's to stop the forks from sliding further up during riding? Outside of the pinch clamp+bolt, I don't see how the forks would stay in place after slipping them up. I'm very open to being told otherwise on this, though - if it's a safe route to go.

What's holding the forks in place in the triple clamp right now? If it's got a pinch clamp and bolt top and bottom, there's nothing else holding the forks in place. Scary right? But there's nothing to worry about.

There's no issue with sliding the forks up other than you might have to consider where to put the handlebars and making sure you torque anything you loosen back to the proper spec.

I think, and someone please correct me if I'm wrong, shortening the stock internals will affect the travel of the forks also affecting handling.

Out of curiosity why did you lower the rear?

 

[CuppaJoe]

Thanks for the reply, nrcb!

Shocks: I've added 11" clevis-to-eyes DCC shocks to the rear to aid in accommodating the 5 foot 4 height of the rider who will be piloting this bike. I now am in need of lowering the front, to match the rear drop.

Forks in place: One of the things I'm seeing that is keeping the stock fork set-up in place are the upper fork covers (with reflectors, turn signals) with rubber grommets at the top and bottom. In order to slide the forks up, I'd have to remove the covers (it seems), and then it seems the forks would have the ability to slide more during use, since the covers aren't there acting as shims/jams between the triple tree and mid-fork.

Just spitballing here, coming up with the best route to go

As an additional note, I'm a big researcher and respect the wealth of knowledge on this forum as well as across the web. I'm doing as much reading as possible in addition to my questions here, and appreciate any and all help from you fellas. I know I'm a newbie here, so just wanted to get that out there

 

[nrcb125]

Thanks for the reply, nrcb!

Shocks: I've added 11" clevis-to-eyes DCC shocks to the rear to aid in accommodating the 5 foot 4 height of the rider who will be piloting this bike. I now am in need of lowering the front, to match the rear drop.

Heh, I'm also vertically challenged at 5'6" I try not to lower a bike if I can get at least one foot on the ground. But here's a great website to check the ergos on your bike (and future bikes as well): http://cycle-ergo.com/

Forks in place: One of the things I'm seeing that is keeping the stock fork set-up in place are the upper fork covers (with reflectors, turn signals) with rubber grommets at the top and bottom. In order to slide the forks up, I'd have to remove the covers (it seems), and then it seems the forks would have the ability to slide more during use, since the covers aren't there acting as shims/jams between the triple tree and mid-fork.

Just spitballing here, coming up with the best route to go

Those covers shouldn't be bearing any of the load at all. They're just to hold on the headlight, turn signals, reflectors, etc. The forks should act the same regardless of the covers.

As an additional note, I'm a big researcher and respect the wealth of knowledge on this forum as well as across the web. I'm doing as much reading as possible in addition to my questions here, and appreciate any and all help from you fellas. I know I'm a newbie here, so just wanted to get that out there

Good to hear! Research is key, although sometimes if no one's tried an idea before you might have to be the first!

 

[CuppaJoe]

Cheers, bud! Thanks for the positive reply. I'll begin tackling the forks this weekend, as they're the last piece of the project I haven't gotten to.

Currently, I'm wrapping up the paint and shaved seat. Will post pics

 

[nrcb125]

Cheers, bud! Thanks for the positive reply. I'll begin tackling the forks this weekend, as they're the last piece of the project I haven't gotten to.

Currently, I'm wrapping up the paint and shaved seat. Will post pics

I did a little bit more research and it looks like the CB350Ks had two different fork setups. The K0 had the springs on the outside of the fork just like my old CB125S forks. The K4 has internal forks just like most other modern(ish) bike. Only the internal springs will play nice with lowering the forks.

I've attached some pictures I found on cmsnl (http://www.cmsnl.com/honda-cb350_model132/)that should help to clear things up.

K0 (no good for lowering):

K4 (should be good!):

 

[CuppaJoe]

Excellent diagrams, nrcb. Thanks very much for those!

I'm working on a K4, with the internal spring set-up. Good news.

Wondering - do you know of a thread, article, or vid with basic steps on slipping the forks up? I imagine the caps on top of the forks at the triple tree need to be wrenched off, then the pinch bolts loosened? Seems pretty straight forward, but alas, I'm a newbie.

 

[TheCoffeeGuy]

As i recall you don't take any caps off, just loosen the pinch bolts and slide them up through. Make n El jig to ensure that both slide up EXACTLY the same amount

 

[xb33bsa]

yeah just loosen the clamp bolts fully and you can pry them open gently just a bit and get them close to the same heigth with a ruler,within a 1/32" is fine but it is easy to get them real close and you could get them EXCACTLY ;D with a micrometer but that is not neccesary
sometimes there is rust between the clamps on the stanchion tubes and it makes it a bitch to slide them up, you should clean that off if so

 

[xb33bsa]

just remember you lower it too far and the fender goes crashing into the lower triple clamp when you bottom out the forks on that big chukhole you didnt see,then the fender bends down and locks up the front tire and you go over the bars
you really shouldn't be messing with this type of stuff unless you have all those bases coverd
also ;lowering the bike 2" makes it dangerously low for any type of cornering without hitting metal hard which will lift the rear tire off the ground sending you into a spin and off for a tumble

 

[CuppaJoe]

Guys, thank you all for the quality feedback.

Great point on the fender and lower triple tree, xb33! I will only go one inch then in the front when slipping the forks

Will do this over the coming weekend and report back with results!

(Also excited to get the seat, paint, and everything else done. Lots of little things I'll be scratching off the list)

 

[xb33bsa]

good luck,have fun GO RIDING

 

[CuppaJoe]

Cheers to that! I have a completely free weekend from tonight through Sunday evening, and will be enjoying a solid stint in the garage for the duration. Fitting in a ride on my 750, both days

 

[CuppaJoe]

Gents, the paint job is done, new air filters are in, rear tail light always being on is fixed, new brake switch is in, seat is shaved (covering this week), and every nut and bolt is wire-brushed and back in the bike.

I've attempted to slide the forks by loosening the bolts pinching the triple clamp to the forks. Nothing budges, but I somewhat anticipated that due to 40 years of age. I imagine they're stuck from a little rust, or something.

I imagine lining up a dull-end bar on top of the clamps and tapping with a hammer shall be in order to help them slip?