Optima Mid LWB belt is too tight?

[ecloptima]

Hi,

I am building an Optima Mid LWB. It is an SWB to LWB conversion.
I apparently have an Optima Mid Custom Special graphite chassis and an LWB belt.
I checked that the belt has 127 teeth and is apparently the correct length (one groove is approximately 5 mm and that times 127 equals 635 mm).
I measured the chassis is 327 mm in total length and as another post here said it is also "app 238mm between the rear and the front gearbox mounting holes".

However when I screw the rear gearbox into the chassis and at what feels like the maximum tightness of the belt the front gear box cannot reach it's screw holes by approximately 5 mm.
If I actually screw the front gearbox in place the chassis bends. I don't think that is supposed to happen...

Could it be possible that the belt has somehow shrunk in storage or something?
But to me the measurements seem correct so what is going on?

Hope you can help me out... Maybe I just need to buy a new belt.

[DennisM]

http://images.cloud.worthpoint.com/wpimages/images/images1/1/0810/03/1_7eb371b4ed966dd7ed4b793731788557.jpg

If Your chassis looks like this, You might have a Bullet LWB Stretch chassis.
This is longer than the original LWB chassis.

[Coelacanth]

http://images.cloud.worthpoint.com/wpimages/images/images1/1/0810/03/1_7eb371b4ed966dd7ed4b793731788557.jpg

If Your chassis looks like this, You might have a Bullet LWB Stretch chassis.
This is longer than the original LWB chassis.

That link doesn't seem to work, Dennis--requires one to login.

[ecloptima]

http://images.cloud.worthpoint.com/wpimages/images/images1/1/0810/03/1_7eb371b4ed966dd7ed4b793731788557.jpg

If Your chassis looks like this, You might have a Bullet LWB Stretch chassis.
This is longer than the original LWB chassis.

That link doesn't seem to work, Dennis--requires one to login.

For me the link works after I login to this forum. Strange.
Anyway my chassis does not look like that. It is not as wide as that one.

My chassis looks like this one:
http://thumbs3.ebaystatic.com/d/l225/m/mqaQSbOo22JI3g5znrynekQ.jpg

[DennisM]

The original belt from Kyosho says 254XL for the LWB and 240XL for the SWB.
Okay - it´s not a Bullet chassis.
Perhaps You´re using lazer diffs?(don´t know if they fit at all)


Marc -
When I use the link, it gives me a small picture.
No log-on required here?

[EvolutionRevolution]

The original belt from Kyosho says 254XL for the LWB and 240XL for the SWB.
Okay - it´s not a Bullet chassis.
Perhaps You´re using lazer diffs?(don´t know if they fit at all)

Lazer diffs fit, but have different belt pitch (3 mm).

You're not using Lazer gearboxes on a Optima chassis, are you? The screw holes match, i think.

[ecloptima]

The original belt from Kyosho says 254XL for the LWB and 240XL for the SWB.

The car's original belt says "MBL Synchrostar 240XLF014" and the LWB belt is labelled as "OTW-7 (254XL014)" in the plastic bag.

Perhaps You´re using lazer diffs?(don´t know if they fit at all)

Lazer diffs fit, but have different belt pitch (3 mm).

They are ball diffs and came with the car (when it was SWB) and they fit the SWB body and belt.
They have the yellow "rings" while Lazer diffs seem to be competely black.

Anyway, the front and rear diffs both have 17 teeth for the belt.

I realized that maybe my chassis indeed is a bullet length as I miss about 5 mm in gearbox distance.
That would mean 10 mm more in belt length which means I should have 129 teeth. Incidentally that happens to the belt size for the bullet chassis.

Does anyone know the length or the distance between front and rear gearbox mounts of the bullet chassis?
Now that I re-checked the measure it is roughly 243 mm. I measured between the center's of the closest screw holes.

[DennisM]

Roughly 238mm between the nearest gearbox mounting holes on the original Kyosho LWB Mid chassis.
I think You should look for a belt for the Bullet chassis.

[DennisM]

Type in "Bullet belt" on Ebay and You´ll find at least one (Fireboy125)

[ecloptima]

Type in "Bullet belt" on Ebay and You´ll find at least one (Fireboy125)

Thanks, yeah I was looking at that earlier too.

I'll first see how the other parts would fit with this bullet chassis like body and belt covers. If they don't fit nicely then I'll rather acquire or even make a proper length LWB chassis from carbon fibre.

Update: I figured the body mount holes will be easy to cut to proper positions so I ordered the belt for bullet chassis. Let's see how it fits.

[DennisM]

And now - the pictures!

We want pictures, we want pictures, we ........

[ecloptima]

Yes, later! Unfortunately I don't have a PC with a card reader here so I cannot post photos before I get back home
Also I'll open a new thread for this Optima Mid project.