Lazer2000/Alpha Toyota Celica Rally - Layshaft done!!!

[EvolutionRevolution]

So after noticing I couldn't get the transmission really smooth, no matter what I tried, due to drag around the rear belt, I compared the width of the Team Atlas ball diff with that of a normal Kyosho PureTen diff. Turns out the Atlas diff is 1 mm or so wider than the Kyosho diff.
Now this is fine in a PureTen, because the rear diff has some lateral play inside the bulkheads, but in a Lazer this play is absent, meaning the diff gets squeezed between the gearbox halves. Thus drag in the transmission. So I will be replacing the Atlas rear ball diff with a normal PureTen ball diff.

And since I received the ball bearings I had ordered, all the ball bearings exposed to the elements will be replaced by rubber sealed Avid units - much better for a basher off-road car.

[isobarik]

Bonus: Lazer Alpha/2000 front gearbox versus Optima Mid front gearbox:

frgbcomp3.jpg

Quite similar, and indeed you can use the Optima Mid's shock towers on the Lazer.

Now for a Lazer-related question: Are there any differences between the rear gearbox/motor plate of the Lazer ZX and ZX-R? I'd like to use Fibre-Lyte's ZX-R's Motor stabilizer plate (left gear box plate) and want to know whether it fits.

Nope they are the same its the MKII and the RR that uses an shorter one.

Regarding youre diff its 3mm balls and if using different size balls ..will make the diff wider ie 1/8 wich are 3,2 and narrower ie 3/32 wich are 2,4 .

mvh Isobarik

[Mr. ED]

Isn't 2.4 mm less than the thickness of the plastic center of the pulley?

[EvolutionRevolution]

Yes. But the Team Atlas diff used a special delrin pulley with smaller 2.4 mm balls compared to the regular PureTen diff. What I didn't expect is that the steel outdrives were also different in length - they looked exactly like the Kyosho outdrives on first sight, so I figured I could use a Kyosho pulley instead with no issues. Which wasn't the case.

Edit: Here's a picture of a Pureten diff (left) next to the Team Atlas diff with Kyosho diff pulley (right). You can see the difference:

Isobarik, you are mistaken. Each of my PureTen diffs has come with 1/8" balls, including the ones I bought new in package. Using 1/8" (= 3.175 mm) diff balls instead of 3 mm wouldn't cause a 1.2 mm difference in diff width in a properly set diff anyway...

Original Pureten diff ball (left) vs. 1/8" diff ball (top right) vs. Tamiya 3mm hard ball (bottom right):

diff-balls.jpg (28.78 KiB) Viewed 1553 times

diff-balls.jpg (28.78 KiB) Viewed 1553 times

Chassis at this point:

[EvolutionRevolution]

Now for a Lazer-related question: Are there any differences between the rear gearbox/motor plate of the Lazer ZX and ZX-R? I'd like to use Fibre-Lyte's ZX-R's Motor stabilizer plate (left gear box plate) and want to know whether it fits.

Nope they are the same its the MKII and the RR that uses an shorter one.

Okay, thanks. That saves me from making a custom part.

[EvolutionRevolution]

Some time ago I installed the ball bearings on the universals, and assembled the front uprights and c-hubs. I decided to keep the original uprights, as they are a better, more beefed up design than the regular plastic Lazer front uprights while being made from the same tough nylon:

Rear universals:

Front c-hubs with uprights and universals:

Then today I received the next step:

James Instone version shock towers and ZXR Mk. I motor stabiliser plate. They fix problems.

A comparison of the new and old shock towers:

The old shock towers are bendy, the new ones stiff. Most of the holes match. Those that don't match are not a problem.

The motor stabiliser plate bolts straight on, as does the front shock tower:

They also fix a major problem:

The belt problem:

The front gearbox is held on with two screws here, and check out that beautiful gap below the front gearbox:

Now check out what happens if I now press down on the front of the gearbox, closing the gap:

Looks like my hunch that the whole belt problem was caused by the rear half of the chassis bending was right. With the carbon motor stabiliser plate installed the belt is perfectly tight when the front gearbox is properly attached. I will still add a custom bottom and top deck to prevent the front half of the chassis from flexing.

The rear shock tower also attaches perfectly fine, but I had to drill out two holes on the shock tower to 3 mm to attach the rear body mounts for the body I'm gonna use:

So now my chassis stands at this:

[EvolutionRevolution]

Suspension arms and rear uprights came in:

Comparison with original fragile arms:

The Lazer ZX arms are pretty much the same, but with more attachment options for the shocks and swingbar attachment points.

Rear upright comparison:

rear-hubs.jpg (64.92 KiB) Viewed 1540 times

rear-hubs.jpg (64.92 KiB) Viewed 1540 times

These are very different.

I used some left-over hinge pins from a Kyosho Spider to assemble the arms:

Still have to decide whether I use the original inner hinge pin mount blocks or Pargu's alloy mounts. Using Pargu's mounts, only two fit right onto the car. One won't fit due to the different front gearbox and the other will require a custom part to be made so I can attach it to the chassis.

Custom slipper musings: So the alloy hex layshaft fits a 5.5 mm nut driver perfectly. From a quick Google search I gather that 5.5 mm hex standoffs with a 3mm hole exist in a variety of lengths. Now this is very interesting because the alloy hex layshaft has a very short threaded section that might lead to problems when trying to build a slipper based on it. With a 5.5 mm hex standoff coupled with a long steel 3 mm machine screw (and some threadlock), I could build a longer layshaft onto which a slipper can fit without too much trouble...

[Jay Dub]

I think you should check out the hex cross section of the Traxxas layshafts, and or the AE (MiniGT ?) layshafts as they are metric, and might be the right size. If so, use a Traxxas spur bushing and spurs, and slipper pads. -Jeff

[EvolutionRevolution]

Thanks. Do you have any particular Traxxas layshaft in mind? The MiniGT shaft appears to miss a threaded section.

[jwscab]

they are all similar/identical between the blue eagle/trx1/etc. The shaft is 5mm, so the hex is smaller, but you can use all the traxxas slipper parts. Once you click these links, browse through the recommended links and you can see the slipper clutch parts

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJJ89&P=7

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJK31&P=7

[Mr. ED]

One problem: the spur you need is gigantic: something like 100 teeth in Kyosho's M0.6 module would be ... wel even more teeth in 48dp.
I don't think there's anything big enough in the traxxas catalog.
But you could modify a lazer spur and use that with the original slipper pads on the traxxas slipper, I think

[Mr. ED]

PS: if you're fine witht heoriginal spur but are worried about spares: I saw a couple of them in the LHS

[EvolutionRevolution]

they are all similar/identical between the blue eagle/trx1/etc. The shaft is 5mm, so the hex is smaller, but you can use all the traxxas slipper parts. Once you click these links, browse through the recommended links and you can see the slipper clutch parts

http://www3.towerhobbies.com/cgi-bin/wt ... LXJJ89&P=7

http://www3.towerhobbies.com/cgi-bin/wt ... LXJK31&P=7

Okay, thanks. Unfortunately, those won't work, because the hex portion is located on the wrong place. With the Lazer Alpha, the hex portion slots into the pulleys.

[jwscab]

I see now, I went and looked at the first page. the whole upper shaft is a hex to drive the pulleys.

[Mr. ED]

time for new pulleys but I think the traxxas shaft may be too short also.
The kyosho transmisson case is pretty wide from moterplate to the other side.

the traxxas case is narrower in the top than at its base