XL/XLS CAT or Original CAT SWB

[bismuth]

Wow, what a pain! Sorry for your troubles.
The eccentrics were revised to ease assembly - not a bad thing, that's for sure.
I'd reckon that the front diff was a bit of an afterthought. The original car came with a spool and one-ways so when they added the diff, the case halves required revision.
I think the main takeaway from your experience is that the revised (thicker) diff thrust race necessitated a revised diff bolt so they are a matched pair and need to be kept together. Mixing old and new here won't work.
Anyway, thanks for the update. Can you post photos of your projects?

The pain was part of the fun with a 34 years old car I guess !

I did a clean up of every parts, I was impressed by how some plastic parts came up despite their age. The epoxy chassis is like new, the top plate has still some rust marks. I sanded and polished a bit the motor and side plates, they look ok now. I also did a full clean and put new springs and brushes on the motor. I sanded the diff washers to flatten the old ones (grit 240/400/600) an break the mirror finish of new ones (grit 600), lubed with silicone grease the diffs and integrator are now smoother than ever.





For the XLS, I bought new belts from a belt specialist company, they nicely recut the long one at a 4mm width, but the cut is not very straight... I also ordered some new rere option parts from Schumacher, lexan undershell, alloy eccentrics and alloy front diff housing, a bit costly but a real upgrade and very nice machined parts. The front housing has two screws to set belt tension more easily like on the procat. I also cut a rear shock mount in a CF plate to replace the ugly one I hand made with a hacksaw years ago in PCB epoxy without removing the copper. I'm now waiting for 2mm stainless piano wire, new screws, ball bearings from China and some washers to remount the supension. Maybe a test run before Christmas !

I ordered new rere plates (with lower holes) for the XLS and will keep the original ones for the SWB.

On the SWB, no progress, I'm thinking on how to repare/rebuild the cracked parts I cannot find replacment for, maybe I'll go for 3D printing new ones, or having some machined in nylon as I fear they are too damaged to be fixed. Any tip/idea for the front one way joint solution is appreciated !



I planned to keep the original ball bearings for the SWB, but the soft plastic of the brown flange is totally dry and broke in dust in my fingers.

To be continued !

[bismuth]

A quick update on the XLS rebuild progress :

- foam added to top and bottom belt covers,
- custom handmade lipo shorty holder,
- wishbones and upperlink axles blocked with clips in front and bending+collar at rear,
- trial of shock springs more adapted to car weight with lipo,
- steering servo installed,



The goal is still to have a test run before christmas !

[bismuth]

Hi, first test run at the park today !
Fun to drive this CAT after a 34 years nap, so much nostalgia...



Test report :
- the car feels light and steering precise and responsive, maybe too much at speed, very pleasant and predictable drift,
- the rear is hopping, obvious near a modern car, maybe a better tuning of Kyosho Option house gold shocks may help,
- transmission break in was ok, belt tension, diffs and integrator all fine.
- custom Lipo holder validated, very convenient, hyper fast to change pack,
- brushed motor fast enough for the car and the driver for now, HW esc is smooth but brake not very powerfull,
- rear wing does not stay in place, wire support twist too easily,

Overall a real pleasure to drive but I have doubts on its ability to handle the big jumps of modern tracks, don't know if it is reasonable to try...

[XLR8]

Those are some great action shots, thanks for posting them.
FWIW, I don't believe my CAT's were ever the best jumpers. I'd always fiddle with shock oil and springs and never seem to get it perfect.
I also agree with you about the wind shovel mount, not the best for holding its position.