GT750J Plastic Clock Housings

[oldjapanesebikes]

I (and others of course) have been looking at options for repairing the 1972 series J clock housings which are plastic. The common problem is the side of the housing cracks, often up into the lens as per the photo below:



The rest of the instrument is fine - but the housing is unique to that year, and from the research folks like Allan have done, also unique to Suzuki for that model, that year. So I've been looking at replacement options. Originally I had thought of faithfully duplicating the original design, but then realised that would possibly faithfully duplicate the original problem of setting up stresses in the material by having an interference or snap fit plastic lens in a plastic housing. So I'm now thinking of a one piece injection moulded design done in clear plastic, and then gauge restorers would have to paint the outside of the shell to suit. The tach and speedo housings are the same, with the obvious exception of the reset knob, which would have to be drilled by hand. At this point I am not considering duplicating the water temperature housings as they generally are not in bad shape, clean up well and seldom crack the way the tach and speedo housings do.

This is a printed 3D model I've had made from the CAD/CAM drawing I now have. It is in an opaque plastic as the model was to double check fit, shape and finishes.



With the inside ring installed.



And mounted on the clock base plate. The slightly curved lens shape is preserved.



Before trying to have a few made to further test out plastic choices and methods of finish, I'm interested in gauging what level of interest there may be from other GT750J owners/restorers- is there any ? Unit cost would be around $100 each plus shipping. PM me here, or email me at ian (at) oldjapanesebikes (dot) com

Thanks !

[TLRam1]

Fantastic work Ian but I have no J Model.

[oldjapanesebikes]

So it appears that no one out there needs one of these ? Seems odd, as almost every set of J clocks I look at seems to have at least the start of a small crack in them. Or has every J owner managed to stash away a decent spare set or two ?

[Suzsmokeyallan]

Ian, judging from the response you've gotten or more so a lack thereof, it appears most people in situations such as this, don't want anything they will have to pay a pretty penny for.
I can risk a bet on this too, if you did go ahead and invested time and money to make some cases and put them onto J internals and then listed them on ebay, they will still find something else to bit*h about.
Don't mind they will look great and be as good as new, they would rather stare at their cracked old gauge housings and reassure themselves somehow that the price of the restored ones doesn't justify the money.

[oldjapanesebikes]

Making progress. These were shot in clear for convenience, but the plan is to do it in two parts - a clear lens (in polycarbonate) and a gloss black polycarbonate housing. These are a first pass - in the upper left you can see a test piece mounted on the metal base and inner sleeve. In the foreground are the blanks shot for the housing and in the upper right the lens. In the lower right is an original part I've used as a base comparison.

Might have a finished product by January

[tz375]

That is awesome work Ian. I cannot imagine the investment you have made there.

[ArticusMax]

Excellent work Ian.

[oldjapanesebikes]

More progress today - these show the assembled lens and housings, with the housings shot in the black plastic. Original housing on the left and the reproduction is on the right in both photos.



Here with the reproduction installed on the metal base and inner liner.



A few more steps to go before production, but I'm pleased with the current status.

[Suzsmokeyallan]

That Sir, is excellent looking work, I cant wait to see the final production result once its all completed.

[diamondj]

That is amazing work Ian! You're almost making me wish I had a GT750 to have a reason to buy a pair of these. So is this something you are having done or doing yourself? I've always thought it would be neat to have the skills to set-up and run an injection mold machine at a home shop level.

Jim

[oldjapanesebikes]

Thanks folks - appreciated.

So is this something you are having done or doing yourself?

Jim - these are being engineered by a company I've hired here in Alberta and are based on the 3D models I had built earlier (photos at the top of the thread). Next step is the addition of the texture on the sides in the next couple of weeks which is the next milestone on the project time line.

[oldjapanesebikes]

Another milestone yesterday - the copied parts with the texture added - original on the left, and copy on the right. The two small nubs you see on the right are locator pins for the CNC fixture so ignore them. Also - the one on the right doesn't have 40+ years of hard life and sun damage.

Making progress !

[oldjapanesebikes]

Getting pretty close now - these are fresh off the production line at the place doing the design and injection moulding for me. If you look at the photo closely, you can see on a few that that I've had the hole for the trip meter reset knob pre-drilled just to make life easier.



The drilled hole is offset at an angle so the reset tube (recycled from the old shell) sits correctly.



Just a few small things still to be sorted.

[Bloop2]

That is awesome and a lot of gauges!!! Way to go Ian!

[oldjapanesebikes]

Finally open for business - I'll also but a note over in the for sale/wanted section, but I now have the shells in my possession and I think they turned out OK (which is Canadian for 'they look amazing' ). I've put together a couple of web pages about them - just click here.