Z750 Twin Forum

I apologise for mixing the two topics, but I was not certain if I could have more than one !

So this is duplicated from the Glemseck thread.

Once the shock unit was in hand - immediately alternative methods became obvious. :

So the obvious is to mount the shock the other way up using the bottom yoke platform as the rigid attachment to the H-D style springer hoop and a simple bracket at the top end. That way the springer / shock becomes a rigid unit and can only move in a vertical and parallel motion.

We will need a shorter top mounting extension  [ which is a stock item ] and relevant length spring and we're GTG.

The plastic tub is optional !!!

Hi TJ,

maybe I've got you wrong, but the lower platform isn't able to support the shock absorber when it's upper end is fixed to the upper plattform.
Even if lower platform and damper body are close to each other and are in "fixed" position, there is need for the spring to move up and down.

Here two drawings (same, but second one with additional remark): ------------------------------

If you want to get some more inspiration have a look at Hazan Motorworks.com.

Here is the Link to his latest work
http://hazanmotorworks.com/?portfolio=supercharged-ktm

Cheers, Michael

Michael - I appreciate your continued involvement. 

However, my mock up is a bit misleading ! I do not have a spring of the correct length.

The body is fixed at the bottom via a very strong mounting on the body [ designed for Oilhead front ] and the spring I will use is about 50% shorter than the red one in the picture and is attached in the normal way with a spring collar.

See the attached pic for the original BMW Oilhead shock - this is the base unit i will use. 

We will remove the lower metal yoke [ Black ] and this will be replaced by the mounting direct to the springer hoop. The fitting is substantial [ 4 screws and a dowel ] into the bottom of the shock body. The top loop mount will be 90 degrees from the normal mounting to eliminate any back and forward pivoting. The correct spring will be mounted in the same way as the BMW. 

I will draw up a small sketch when I have the correct parts. However, I do prefer the idea of using the shock main body as the fixing as in the first ideas. ....... Still at P.O.C. !!!

I hope to have the correct components in the next week and will show you the correct set up for your comments.

many thanx for the link - Hazan's bike is awesome !
TJ

I have the option to use the "Pin" top mount [ left shock ] without the rubber mounts to allow a solid fixing to eliminate any possible pivoting.

Hi TJ,

I give it a next try It is only a detail that is shown.
That would allow the damper body to be fixed with upper and lower yoke.
Spring is only below lower yoke.
BTW: There may be a second spring - just for decoration - around the upper part of the damper body

I rely on you to find the right solution to ensure travel and gap to front tire.

Good luck,
Michael

Thank you Michael. That was a solution I looked at, but we cannot get enough travel - minimum 4 1/2". My pal at RAM is going to look at the possibility to produce a special length body

Here is a schematic sketch - no detail and simply mechanical - no cosmetic detail.

The shock is mounted completely rigid top and bottom, and the bottom connection of the Banana is also fixed rigid. This allows the Banana to travel only in a parallel plane to the Bantam fork leg. We have around 2" of clearance above the tyre to the Banana - this distance does not alter.

The bottom attachment of the shock will be covered with a decorative plate to disguise it !!

The forks are now completely dismantled ready to be rebuilt.

Hi TJ,

I love to see your sketch and I like your hand writing

Solution looks good and will work as far as I understand by now.
Using same travel both sides is perfect.
Will you keep the spring adjuster at the RAM shoX ?
I may think about different spring strenghts and the RAM is for sure stronger than the Bantam springs.
Any ideas to avoid sticking of the teleskopic fork or is that something you don't worry about or just give it a try ?

Sorry to be a pain, but I need to verify, that there is no connection planned between lower yoke and RAM shoX ?
Can't see anything like that in your sketch and that is fine

Cheers, Michael

First off Michael - apologies for not presenting a rough P.O.C. sketch earlier ! I am in awe of your command of technical English !

Yes exactly so Michael - I just showed the lower yoke, but cut off in the sketch, but it is not connected in any way. Fortunately it is shaped and the spring clears easily.

Re: spring rates - the honest answer is that I HAVE NO IDEA at the moment !

New shock variant ordered 4.00pm yesterday - arrived 8.30 this morning ! Good to have mates. It arrived with additional collar and the correct length spring. Rates yet to be determined, but at least this will serve for the setup.

The bottom mounting platform is also shown clearly. 

Yes, I will keep all the RAMSHOX adjustment. The Bantam has NO DAMPENING !! Just the springs. In reality I could leave the Bantam springs out and just use them for the sliding component. 

The Bantam does have very good phosphur bronze bushes for the sliding motion. Normally there is only a small amount of grease added to stop the springs from rusting ! I will replace this with  a good quality oil. The bushes are very cheap [ £15 for 4 .... 2 per leg ], I could even add another or even 4 per leg.

I am happy with the solution we have arrived at - and as ever I thank you [ and Carsten ] for your input.

Haha,

looking forward to your next live-CAM pics, TJ.

Cheers, Michael

Michael - you have invented a new phrase ..... "Live-Cam" !!  :biggrin:

In the days when it was my business to design and manufacture new auto products, I did of course use correct technical drawings. LONG before computers and Cad-Cam !! 

But I found that a rough POC sketch often instantly showed what was in my mind.

My sketches were famous around the industry for being drawn on all sorts of media - serviettes, old boxes, receipts ........... even Carroll Shelby kept one of mine when we were liaising over his Caddy Northstar powered Cobra [ 1990 ] ! 

One of the best compliments I ever received from Shelby was being introduced to his [ Shelby American ] chief designer as - "TJ, that good ole' British Hot Rodder."

The Bantam forks are now completely stripped thanx to my pal Brian. BOTH springs were broken and very difficult to remove.

Surprisingly the bushes and the hard chrome on the stanchions are OK. That simplifies the means to shorten the forks. We simply shorten the springs ! 

As there is NO oil / hydraulics to worry about, nothing else is affected. By simply opening up the spindle [ wheel axle ] hole by 1mm the Honda axle is perfect. It needs to be shortened and re-threaded - but otherwise - simple.