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Discussion Starter #1
I obviously need to get new rear shocks for my bike to raise the ass end up and preform better, wondering if I should just do a monoshock conversion for practically the same price as new shocks. Haven't seen a whole lot of info for this conversion on the SOHC frame I want to gather some of your thoughts/experiences, pros/cons on a conversion.

From what I can see is the CBR600F2 swing arms will bolt up with the obvious modifications to the frame for the monoshock to work.


Any info would help.
 

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I obviously need to get new rear shocks for my bike to raise the ass end up and preform better, wondering if I should just do a monoshock conversion for practically the same price as new shocks. Haven't seen a whole lot of info for this conversion on the SOHC frame I want to gather some of your thoughts/experiences, pros/cons on a conversion.

From what I can see is the CBR600F2 swing arms will bolt up with the obvious modifications to the frame for the monoshock to work.


Any info would help.
Ok slow your roll there chief....while on paper it looks like the same cost you aren't thinking it clearly. There is no monoshock "conversion kit" specifically for a cb750 which means if it costs say $250 for a cbr600F2 rear swing-arm setup with wheel and shock you still need to change the spring, the dog bones, tire, brakes, swing-arm bushings, sprockets, etc... so that costs money as well. Also You have to sit down and engineer the geometry of the setup which means evaluating the angle of the shock, the reinforcements to the chassis, the ride height, the sag, etc....and then you have to weld it all in. There are no pre"set" measurements for a rear conversion so it is a lot of measuring, cutting, welding, and advanced fab work. Of course you could just stab it in and set it up to "look right" but if you don't build a death trap it would be out of sheer luck.

For shocks, you can just call dave quinn at dave quin motorcycles, answer a few questions, spend $200, and have a set of budget but good shocks setup for your weight, ride height, sag, riding style, and then just bolt them on in less than an hour.
 

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Last year every hack in the world was doing mono shock set ups.
late to the show
 

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Discussion Starter #4
Well I'm trying to bring it back...

Understand there is no kit for the setup just just wondering if anyone has any experience with it.

Thanks Geeto I'll look into all the stuff you mentioned see if it makes sense or not. Also thanks for the contact!
 

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I'll do you one better:

Dave Quinn Motorcycles
[h=2]Twin shocks from $194 a pair and NEVER an extra charge for custom build twin shocks! [/h]

all the race guys in NY used him for budget shocks for their vintage race shocks. Hagons have their limitations but in a street use you won't notice those limitations. I own marzocchi, Boge, and ohlins as well and the only thing slightly better on a budget are the boge because they are rebuild-able (hagons are not), used sets cost me $40, and the seals to rebuild one are cheap (rebuild kits don't exist anymore so it is a lot of matching up seals individually). Hagons are the better shock in terms of damping but like I said, not rebuild-able.
 

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BTW, the stock swingarm is not strong enough to be a mono-shock, although I have seen people convert that way. That is just asking for lateral flex in my opinion so....just in case you were thinking of saving money by welding a mono-shock mount to the stock swingarm.
 

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Grab a copy of Tony Foale's Motorcycle Handling and Chassis Design. After you study and digest all 500 pages worth of info, you'll be in a better place to decide whether or not you want to tackle something like that. There is a lot more involved than just making everything fit.
 

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I've also heard that it's easily downloadable in PDF for free from certain corners of the internet's seedy underbelly.
 
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Yup, easily downloaded.
amazing book.
 

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Motor Cycle Chassis Design: Practice and Theory: Amazon.co.uk: A. Foale, Vic Willoughby: Books

It seems to be available as a later reprint as well under a slightly different name
That's the 1984 edition. The 2002 edition is available from Amazon in the US for about $80:

http://www.amazon.com/Motorcycle-Handling-Chassis-Design-Foale/dp/8493328618/ref=sr_1_1?ie=UTF8&qid=1400707460&sr=8-1&keywords=Motorcycle+Handling+and+Chassis+Design

- - - Updated - - -

I've also heard that it's easily downloadable in PDF for free from certain corners of the internet's seedy underbelly.
Don't steal from Tony
 

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Just another point regarding monoshocking a dual shock frame. Almost every one of those I have seen has the wheelbase stretched out too far because a monoshock swingarm is too long from the pivot to the axle. Almost all engines in bikes that are monoshocked are shorter than earlier models so the swingarm pivot is accordingly farther forward. To monoshock a CB750 SOHC with a CBR600F2 swingarm would need to have the swing arm pivot point moved as close to the rear of the engine as possible and/or shorten the swingarm to put the rear axle back in a reasonable location. Shortening the swingarm will change the shock leverage ratios and you would probably need to change the spring and damping. I think an easier solution is to use the direct acting shock type of monoshock like the early Yamaha or Vincent (ok it was twin shocks, but could have been a single if they had wanted to) used.
 

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Just another point regarding monoshocking a dual shock frame. Almost every one of those I have seen has the wheelbase stretched out too far because a monoshock swingarm is too long from the pivot to the axle. Almost all engines in bikes that are monoshocked are shorter than earlier models so the swingarm pivot is accordingly farther forward. To monoshock a CB750 SOHC with a CBR600F2 swingarm would need to have the swing arm pivot point moved as close to the rear of the engine as possible and/or shorten the swingarm to put the rear axle back in a reasonable location. Shortening the swingarm will change the shock leverage ratios and you would probably need to change the spring and damping. I think an easier solution is to use the direct acting shock type of monoshock like the early Yamaha or Vincent (ok it was twin shocks, but could have been a single if they had wanted to) used.
If you shorten the swing arm in the process, that kind of defeats the purpose of going to a mono shock rear suspension in the first place imho.
To make a vintage CB750 monoshock frame, I think you are looking at a built from scratch frame build and that sounds like a project for somebody who likes building motorcycles more then actually riding them.
 

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Why anyone refers to Tony Foale as a "chassis expert" is very strange: his weird lookling hub-centre steering bike-things that hardly any rider bought, BMW twins with the forks "on backwards" and tiddler race bikes. He was never in the league of great chassis engineers like Bakker or Egli, or even single-handed efforts like Norman Hossack: www Home

To fit a good mono shock system to an old bike is far more involved than just bolting on late-model eBay flotsam. Even when completed you just have a good rear end on a crappy old heavy flexy frame. Most old bikes are better with a proper box-section or braced stock swingarm and good shocks like Works, Hagon or Ohlins. Cheap eBay shocks just go up and down, and little else.
 

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Why anyone refers to Tony Foale as a "chassis expert" is very strange: his weird lookling hub-centre steering bike-things that hardly any rider bought, BMW twins with the forks "on backwards" and tiddler race bikes. He was never in the league of great chassis engineers like Bakker or Egli, or even single-handed efforts like Norman Hossack: www Home
What (another) numbskull this guy was....

If you've read his book on motorcycle handling/chassis design, you wouldn't say that.

I downloaded a particular section that I was interested in about countersteering, balance and steering and the discussion had my head spinning.
Gyroscopic procession, forces around the steering axis, camber thrust, roll, yaw rates, etc.
Finally was able to comprehend most of it and take away some practical points for riding.
 
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