Rear shock and spring specs.

[Owen N]

I am not sure of the form topics layouts, so I hope I am posting in the right place.
As part of my frame rebuild project, I want to relocate the rear shock to the side,
above the rear drive shaft.
I have devised a linkage, but I haven't got a bike to measure up yet.

1) what is the average leverage ratio on the shock versus rear wheel travel?
Most bikes seem to be slightly under 1:2 ie 1.8 or so.
2) is this a floating piston shock? can it be laid down on its side and still work?
I would like to reuse the shock because of the air spring.
3) the shock and spring seems quite small and slim for such a heavy bike.
(starting at around 530 lbs on the rear wheel, and going up with extra load.)
Does it need to be firmed up a bit, or is the air spring adequate for this?
Is the damping OK?
4) what are the overall dimensions-end eye centers, largest diameter,
bottom yoke width, top and bottom mounting bore sizes.
5) how is it mounted? shafts/bolts, needle roller bearings in the rocker?

I did a layout and shock calculation at 1:2, wheel travel 4.4 inches, shock travel 2.2 inches,
 and came up with a 10 inch spring
that has to compress 2.7 inches, and is 3.5 inches in diameter. The existing
spring seems to be smaller and shorter than this.
spring rate was 1056 lb/in.

It would be good if the existing unit would slot right in, and a lot less expensive.

[MAN OF BLUES]

 

Well, it seems like you want a better mouse trap... might as well get busy measuring the parts you have, instead of asking us to do your work for you.

[Rick Hall]

Air spring is adequate, if it holds air. They tend to leak over time.

Damping is also adequate for a '70's era shock. I *think* it's much like the stock forks, that only rebound is adjustable. Compression is fixed by some sort of internal passage. Maybe it's the other way around (damping vs rebound)

Top shock mount is "I don't remember", think it's a simple steel heim joint in the shock with a bolt to the frame. Bottom mount is ears and a bolt that fits into a needle bearing 'dog bone'.

With mechanical advantage (and high skool geometry calcula-ma-cations) of the rear suspension "UNI-Track", the shock doesn't travel that much. Perhaps 2 inches at most.

Rick

[Owen N]

I haven't got the bike yet- I thought I would do a little design work while saving up.

I think it is quite normal for cheaper bike shocks to just adjust the rebound.
Compression damping is generally very light.

These type of bikes generally feel a bit wallowy over bumps at speed. The only way to fix that is to
go for higher spring rates and upgraded shocks all round.

Mind you, if you really want to ride fast in the twisty bits, you would get a proper sports tourer, with
radial tires and all the good suspension, and put up with the low screen.

Trundling along at the legal road speed of 100 kph (62.5 mph) suits me.

For the shock, I am guessing at 56mm stroke, and 310mm between eyes. some similar kawasakis (gpz, etc)
are around those figures. The GTR14 is different, at 350mm/74mm.

I have scaled the rest of the dimensions off a photo. Please excuse the metric measurements - divide by 25.4 if you want inches.
I did the last spring in inches to use the usa Koni catalog.

Bike shocks seem to be a lot skinnier than the Konis.
The outside diameter of this shock is around 80mm,and if the spring fits under the bellows it is 58mm, or 2.25 inches overall
diameter. That is the inside diameter of the Koni spring.
If the shock is happy running inclined/laid flat, I will reuse it.

I will post drawings on my Blog as I complete them.
https://owenprojectsblog.wordpress.com/

[T Cro ®]

Well, it seems like you want a better mouse trap... might as well get busy measuring the parts you have, instead of asking us to do your work for you.

I'm not looking to be rude here but I'm with MOB here... Get the bike and then we speak.... Your wanting to do a hell of a lot of re-engineering to accomplish what? Your still left with an extremely portly and tall 30 year old sport-touring bike that was built from dated parts bin parts to start with.... Don't get me wrong as I loved my old girl dearly and spent a hell of a lot of money updating her but to reinvent the wheel on her? No thanks!

[Owen N]

I think the shock thing was all I really needed. - I can go with the assumed values for now.
It is not really about making the bike
itself a lot better, but to turn it into a general-purpose testbed/chassis for other engines, and still do a good job of being
a light(ish) touring bike-compared with the Voyager, for example.

Time will see if I actually get to the stage of building and fitting another engine.

I strongly suspect that the front calipers need biffing, too. A set off an earlier GPZ would probably fit on there.
Has anyone successfully gotten rid of the squishy feel?
Anything double-sided 4-piston non-radial could be made to fit, I think. I will need to check that the master cylinder bore is correct
for the calipers.

[gPink]

Might as well swap the whole front end.

[T Cro ®]

... It is not really about making the bike itself a lot better, but to turn it into a general-purpose testbed/chassis for other engines, and still do a good job of being a light(ish) touring bike-compared with the Voyager, for example....

Balderdash... That's an even taller order! The engine itself is a stressed member of the frame and does not lend itself well at all to being cobbled on... Only engine ever successfully transplanted into the Concours frame was the ZRX1200 and it requires so much work to preform that it was only done a couple of times...

Get rid of the squishy? Sure, stainless steel lines help a lot and 4 to 6 piston calipers are the bomb... Done many times over with the right fabbing of adapter brackets. Not sure if anyone is still making or selling these; perhaps Murph at www.murphskits.com

[2fast]

I still have sets of brackets for early model Concours to upgrade from stock to 4 pot Nissan's and 320mm rotors.

[txfatboy]

You're enthusiasm is commendable...., but unless you just have nothing but time and money to burn, and just want to have a project to tinker with, you will most likely be met with a lot of "been there, done that" comments. There is most likely Nothing you can do to the Concours that hasn't been done before. There are tried and true, PROVEN ways to improve every aspect of the bike. It will never be a c-14 or FJ, but you can shape and mold the old girl into something pretty freekin' nice.  This is my personal bike. It started out as a 1991 Concours and now Just looks like one. It won't win many road races, or drag races, but it is far better a bike for ME now, than it was when it left the factory. The wheels are now 17 inch front and rear, the forks (pictured) are inverted zx9 forks. It now has a complete ZRX front end with  full racetech springs and revalve and rubber isolated tubular handle bars, not to mention much better brakes with full stainless brake hoses. The rear shock is a hybrid ZX9/ZZR1200 combination that gives separate rebound and compression AND remote spring preload adjustments, and the shock is fully rebuildable and can be revalved. The engine has been upgraded and makes more power and gets better gas mileage. SOOOO many different ways to go with this very versatile platform.

Oh, as far as the external rear shocks go, you will need the rear subframe from a ZRX 1100 or 1200. This has the upper shock mounts that are already properly braced. The points where the subframe is welded to the main frame are identical  on the Concourse and the ZRX. You will have to beef up the boxed section of the swing arm on the right side because the metal is thin and was not intended to support the load of a shock and spring. It will also require the use of the ZRX seat and tail section/lights and if you want to you will have to figure out how to adapt the saddle bag mounts to the ZRX subframe. I know all this because I had started working on building a shaft drive ZRX. I bought the subframe section to verify the attachment points. It is possible, but still a lot of work.

[Owen N]

Balderdash... That's an even taller order! The engine itself is a stressed member of the frame and does not lend itself well at all to ...

Get rid of the squishy? Sure, stainless steel lines help a lot and 4 to 6 piston calipers are the bomb... Done many times over with the right fabbing of adapter brackets. Not sure if anyone is still making or selling these; perhaps Murph at www.murphskits.com

Owen:
Re-adaper brackets- I will get back to you on that. The later model disks seem to be big enough.

I have a frame scheme that will do the job. It involves replacing large chunks of the original frame, and putting a bolted pin-joint under the rear of the tank. This relies on the engine to act as the diagonal member, and also provide bending  and twisting stiffness.

The top arch of the front sub-frame is set quite high, and there is another removable bracing tray underneath.
This holds the battery and electrics. Any replacement engine needs to be hard-mounted, also.

The bottom tray is bolted to the GTR engine head.
If I stick a v-motor in there, the battery will need to be moved again.

The fuel tank will be moved under the seat. I may need secondary tanks to get the volume up around the 24 liter mark.
I have a plan for a welded polypropylene tank, mounted on foam strip and sheet edge pieces, welded to the frame.
The GTR fuel cap fitting should go straight on. (aircraft-style).
The fuel pump/pickup unit is from a Gixxer.

The "tank" top becomes the airbox, like the Buells, and seals against the top arch tray.
Wiring and cable runs are to be put in before adding the top frame arch and front forks.
I may make the top tray floor removable if possible, to improve access.

There needs to be main wiring plugs at the front of the tray, so that the instrument/lights section can just be plugged in.

Much of the mid/rear subframe will be modified and beefed up a bit.
Fitting the swingarm brace may be a bit tight, as the shock will be in the way up top,
and the centerstand is rather close in underneath. I may need to spread the centerstand out a bit, and tuck it a little closer to the
exhaust pipes. The center suspension mount at the rear can be removed. Maybe I can support the centerstand at the outside,
like the swingarm.
It is all a fair bit of work, which will probably take me a couple of months.
I have a good workspace available, and plenty of tools.- grinders, welders, etc. I haven't had oxy-acetylene for a while.
I need to lease the tanks, but the monthly fee is quite small.
I am planning to braze-weld the joints, and use 3/4 and inch square furniture tubing. I shouldn't need any bends.
Curved bits can be fabricated from steel sheet.

See the blog. Larger scale detail drawings will be posted as they are finished.

[Owen N]

You're enthusiasm is commendable...., but unless you just have nothing but time and money to burn, and just want to have a project to tinker with, you will most likely be met with a lot of "been there, done that" comments. There is most likely Nothing you can do to the Concours that hasn't been done before. There are tried and true, PROVEN ways to improve every aspect of the bike. It will never be a c-14 or FJ, but you can shape and mold the old girl into something pretty freekin' nice.  This is my personal bike. It started out as a 1991 Concours and now Just looks like one. It won't win many road races, or drag races, but it is far better a bike for ME now, than it was when it left the factory. The wheels are now 17 inch front and rear, the forks (pictured) are inverted zx9 forks. It now has a complete ZRX front end with  full racetech springs and revalve and rubber isolated tubular handle bars, not to mention much better brakes with full stainless brake hoses. The rear shock is a hybrid ZX9/ZZR1200 combination that gives separate rebound and compression AND remote spring preload adjustments, and the shock is fully rebuildable and can be revalved. The engine has been upgraded and makes more power and gets better gas mileage. SOOOO many different ways to go with this very versatile platform.

Oh, as far as the external rear shocks go, you will need the rear subframe from a ZRX 1100 or 1200. This has the upper shock mounts that are already properly braced. The points where the subframe is welded to the main frame are identical  on the Concourse and the ZRX. You will have to beef up the boxed section of the swing arm on the right side because the metal is thin and was not intended to support the load of a shock and spring. It will also require the use of the ZRX seat and tail section/lights and if you want to you will have to figure out how to adapt the saddle bag mounts to the ZRX subframe. I know all this because I had started working on building a shaft drive ZRX. I bought the subframe section to verify the attachment points. It is possible, but still a lot of work.

It definitely will not be coming apart until I have collected the parts I want. That may take a year or more. In the meantime, I will have all the measurements I need. I am planning in reusing most of the front fork parts, but may need tubes an inch or more longer. I can work that out when I get the bike. Frame fabrication is not a problem. I have enough tools, info, and experience to do that.    I am not looking for sportsbike-like suspension performance, so that will help keep costs down.

[T Cro ®]

Keep us abreast of your progress.....   

[Owen N]

revisions:

1) Abandon Suzuki rear drive-only 36 mm saving.

2) Correction- put engine in the correct place fore-and-aft. This is 44 mm closer to the front wheel than standard,
mainly due to steeper rake.
(check fender clearance).

3) settle on 3/4 inch x 1mm (39 thou) square furniture tube for all frame structure.

Use extra tube to triangulate all loads. Plate in high stress points with 1.5mm sheet (59 thou).

Center section braced by fuel(gas) center tank box-cross brace bottom, front, back, top corners.
4) Some areas can use plating-in instead of triangulation- 0.5mm and 1mm where appropriate( 19 and 39 thou).

-Use glued and screwed 3mm polypropylene sheet where possible to reduce vibration "ringing".
Self-tappers, TEK self-drilling screws?

Check surface prep for painting?. It can be done, but adhesion is not that high.


Bond thin aluminium sheet to polypropylene with silicone sealer for heat reflection
around engine.

5) Braze-weld all joints.(more reliable than gas seam-welding, and less shrinkage).

6) Main bolted joints 10mm bolts (0.4 inch) lugs 4mm (0.16 inch).

7) Generate engine drawings from photos (going well - mounting points should be within 0.4 inches).

front structure of swingarm brace from profiled and brazed sheet, to get a curved shape.

Further details to follow.

More accurate dimensions can be added closer to build time.
These are good for overall design and material purchase.

[Rick Hall]

You really should have you meds adjusted and go riding; your spending far too much time in front of the PC....

That could be said about a lot of people here Though done before, by various manufacturers, I admire his gumption.

I know someone that made stick coils for the C10, stick coils! WTF is wrong with the stock ignition?

SPOOFAK anyone?

Know another dude that sold screws for the C10. That's all he sold, screws, five different lengths. In any color you wanted providing it was stainless. Then he wanted other stuff... Hella headlight upgrade, horn and lighting harnesses, fuse block, ...

Rick

[MAN OF BLUES]

Hehehehe
Well, I hear some folks actually build planes out of foam and fiberglass, and want to actually fly them....
Heheheheheheh

How's that plane coming along Rick???
I'm just pulling your leg, I know it will be uber cool.....

But I doubt if they drew up the plans from scratch, by scaling a photograph.....
I'm with the "check your meds" opinion... heheheheheheh

Anyway, people will build just about anything these days.....
http://youtu.be/3u2MopQylio

[Rick Hall]

Hehehehe
Well, I hear some folks actually build planes out of foam and fiberglass, and want to actually fly them....
Heheheheheheh

I've heard that! On the interwebs, so it must be true

How's that plane coming along Rick???

The styrofoam and fiberglass one?
First engine start 'soon', first flight shortly thereafter. Approved to take passengers (after 40 hour test phase per FAA), after Oshkosh/Airventure @ end of July or mid Aug.

Rick

[Nosmo]

Hell, the first aeroplanes were made out of spruce sticks and Irish linen.   Worked fine.  I went through the last A&P school class that taught wooden spar splicing and fabric repair, rib-sticthing, doping, etc.  Good stuff.

[RFH87_Connie]

Things do get crazy around here sometimes.  Why just last night I built a 6" PVC 7-gallon pressure tank out of mostly spare parts just so we can hose ourselves off when we take the Jeep to OBX on the 4th.  Held 50 lbs of pressure overnight so I guess it will work.  Didn't someone around here make headers for the C-10?
This is sounding a little more than normal crazy though.

[T Cro ®]

Why just last night I built a 6" PVC 7-gallon pressure tank out of mostly spare parts just so we can hose ourselves off when we take the Jeep to OBX on the 4th.  Held 50 lbs of pressure overnight so I guess it will work.

Your going old school there... I recall bumpers made of pipe with caps welded on and turned into air as well as water reservoirs back when I was into the 4x4 scene in the early 80's...