Lazer ZX / ZXR Rear Bet Tensioner

[Welshy40]

Well after finishing my carbon fibre tub project for the Lazer ZX / ZXR I decided to continue my design on the rear gearbox tensioner for the standard gearbox so every one can have one. My issue was that I snapped the rear belt if I used a brushless motor over 10.5 turns, so have made the below which resolves the issue and now there is no motor limit and also if the belt stretches over time you can tension it more. This item doesnt get in the way of the motor either. Picture is the item fitted to the Carbon Fibre plate to show you wht it looks like. Other is fitted to the gearbox. Your point of view is welcome.

[Jay Dub]

Why did you choose that side of the belt?

[GoMachV]

Why did you choose that side of the belt?

Isn't that the slack side under power?

[Welshy40]

Nope the best place to tension is under. The zxs has a tensioner under as well as my carbon fibre rear gearbox and works, so far ive never replaced a zxs belt and same with my proto cf gearbox. If on the top then youll get slack below as the direction causes it hence why the bottom is the best way. This also slots in perfectly out of the way in the gearbox

[cyber10b]

Well after finishing my carbon fibre tub project for the Lazer ZX / ZXR I decided to continue my design on the rear gearbox tensioner for the standard gearbox so every one can have one. My issue was that I snapped the rear belt if I used a brushless motor over 10.5 turns, so have made the below which resolves the issue and now there is no motor limit and also if the belt stretches over time you can tension it more. This item doesnt get in the way of the motor either. Picture is the item fitted to the Carbon Fibre plate to show you wht it looks like. Other is fitted to the gearbox. Your point of view is welcome.

[Welshy40]

Interesting, but do you have support as the gearbox can flex. Thats why i did a brace. I also have tension options as if the belt starts to stretch & jump i can tension more. Looks like your belts going to be tensioned too much.

[Jay Dub]

I think a combo of the two is not a bad idea. I like the adjustable lever type like Welshy's, but the simplicity of the other. I have used on many cars (and planned to on my lazer) a single, properly placed post with bearings. Then to properly tension, you change the size of the bearing. No flex, and 1/2mm finite adjustments. Works beautifully, you just have to disassemble the gearbox to adjust. -J

[Coelacanth]

Disassembling the gearbox is something you would hope to avoid. On some cars, getting at the gearbox is a righteous pain (*cough* Optima *ahem*). Something that would be externally adjustable would be the ideal design; i.e. with a lever, 2 screw attachment points with one oval hole, etc.

[Welshy40]

Pity LA112 is is no longer available as if it was my cf gearbox design would suit everyone

[Jay Dub]

Well, with the lever design as shown, a hole is cut in the case. I suppose one could cut a rectangular hole in the case, and pull the static tensioner out to change bearings. I reality, once the tension is set, one would not adjust it very often. -J