RC10Talk - The Net's Largest Vintage R/C Community

Hi,
I want to rebuild and run my old Schumacher CAT from 1986, as left for the last 30 years on a shelf.
This was one of the first kit imported in France, with short wheel base, I later convert it to an XL/XLS hybrid with long chassis, widened front and rear end with spacers but original one way (no front diff).
It is in a good state apart the front ball joint to one way bearing parts that have exploded (ref T031/T515) and some rust here and there.
I am still hesitating between restoring it to its original SWB or to a LWB with a front diff from new parts, any thoughts ?

The original parts to start with :

I’d go SWB if only for the rarity of the version and it’s originality, a nice project to have

I agree but I guess it depends on what you have planned for the car. If you want to compete, LWB is best. If it's going on the shelf, SWB is very rare and very cool imho.
FWIW, I also have my original SWB parts in a box and someday I'll use re-re parts to restore it - but only for display, I'll not run the car again.
I still have an original XLS that sits on the shelf and a re-re "Masami" with c/f plates and hex screw upgrades for a runner car.
The CAT is a legendary RC car and I'm very happy that I didn't sell my originals.

Thanks guys,
I want it to be a runner, so I think I'll go for the XLS because I already have most of the parts. For the SWB I do not have the short belt, front joints, bodyshell, bottom shell, top chassis plate, grey front bumper and they are very hard to find.
Any tip for gently removing the light rust spots from diff/integrator balls and washers ? Or is it better to replace them ?

bismuth wrote: ↑Mon Sep 21, 2020 2:15 pm Thanks guys,
I want it to be a runner, so I think I'll go for the XLS because I already have most of the parts. For the SWB I do not have the short belt, front joints, bodyshell, bottom shell, top chassis plate, grey front bumper and they are very hard to find.
Any tip for gently removing the light rust spots from diff/integrator balls and washers ? Or is it better to replace them ?

FYI, OldRC (aka Sabulatech) has the complete CAT SWB bodyshell set. Price is reasonable (22 bucks) and quality is very good. I've picked one up back in January.

https://store.sabulatech.com/b018-Cat-SWB-Body-Tray-and-Belt-Cover-Set_p_106.html
A haven't tried it myself but I've heard that Coke will remove surface rust.

Thanks Doug,

Good to know for the SWB shell.
The hardest to find missing parts for me doing a SWB are the T515 font one way joint and the short belt.

bismuth wrote: ↑Wed Sep 23, 2020 1:10 pm Thanks Doug,

Good to know for the SWB shell.
The hardest to find missing parts for me doing a SWB are the T515 font one way joint and the short belt.

A short belt is available here: https://www.ebay.co.uk/itm/Vintage-Schumacher-CAT-Short-Wheelbase-SWB-main-long-drive-belt-T128-New/254546827890?hash=item3b442c5a72:g:10sAAMXQWuRQ-tyL

winner_evo wrote: ↑Wed Sep 23, 2020 2:31 pm A short belt is available here: https://www.ebay.co.uk/itm/Vintage-Schumacher-CAT-Short-Wheelbase-SWB-main-long-drive-belt-T128-New/254546827890?hash=item3b442c5a72:g:10sAAMXQWuRQ-tyL

Great ! Thank you.
So a SWB could almost be done, the last missing part of the puzzle would be the T031 or is it T029 ? The original manual is unclear showing the part annoted "TO29" under "hub moulding" on first pages and annoted it "T031" later.

A little time today to dissect the Cat guts !
Good news rust is really minimal and balls and washers are in very good shape and reusable. But I did a sad discovery... Its integrator is .. disintegrated ! I had completly forget that 30 years ago I transformed this integrator into a normal rear differential. I cut the external pulleys in two, screwed the external part to to center pulley with four screws and use the center part for diff. I also blocked the layshaft diff with a pin across a hole I drilled in the pulleys.



Until I dismounted the transmission I was totally amnesic about having done such a surgery 30 years ago !
I was still hesitating between a SWB or a XLS rebuild, thinking that 95% original parts was cool for a SWB, but now that I have to rebuild by buying a lot of rereleased transmission parts I'm even more confused...

I also noticed the sideplates and rear outer trans housing have only one hole, and this cannot be transformed in a XLS that need a second lower hole.



Still going in circles...

bismuth wrote: ↑Tue Sep 29, 2020 6:54 am ...

I was still hesitating between a SWB or a XLS rebuild, thinking that 95% original parts was cool for a SWB, but now that I have to rebuild by buying a lot of rereleased transmission parts I'm even more confused...
...

FWIW. if you're concerned about authenticity, I've found no difference between vintage CAT plastics and the re-re ones. It appears that Schumacher has used the original molds although I have not researched so I cannot confirm that.
I don't believe rebuilding your SWB trans using re-re parts will make the car less cool, less desirable or diminish its value. Just my opinion of course.

bismuth wrote: ↑Tue Sep 29, 2020 6:54 am
I also noticed the sideplates and rear outer trans housing have only one hole, and this cannot be transformed in a XLS that need a second lower hole.



Still going in circles...

An option would be to rebuild as an XL that also only had upper hole. They are still quite competitive against XLS's. That said, I would keep it as a SWB for stumpy coolness.

Hi Bismuth, Great to see another SWB - would be great to build it back up as it was originally.

As others have said the transmission parts for the re-release appear identical to the originals. That said, if you want to keep it original, I probably have some original integrator parts in a box - I'll have a look in a day or two and let you know.

Hi,

This "spot the difference" game between Original SWB and CAT XLS is really fun.

I ordered and received rereleased replacement parts to restore the integrator : 51T Rear Side Pulleys (part# U7204) and Thrust Race (part# U7216) naively thinking they will fit.
I tried to mount the integrator with, but it does not fit well, some parts are different between the original CAT SWB and the CAT XLS rere. :
- the new thrust race is thicker than the original ball bearing (9/64 vs 7/64),
- the integarator axle head is not the same either, the original one (part# TO84 T520) has a thicker head and no recess like the rere one (part# U7142).
And the resulting spacing is not leaving enough room for full univ joint movement.

I tried to install the integrator the new way (as in CAT XLS manual) but Eccentrics housing have changed too, the original ones (TO81 T517) are narrower than the rere ones (part# U7187) and joint head cannot pass through, installation was much more fun back in the days when integrator's balls were bouncing around when assembling the whole parts at once.

Giving up with the integrator I tried to mount front XLS diff, but it doesn't fit at all in my original front housings (TO55 T520) where the flanges are nearer to the center that the XLS ones (part# U7206).

I also noticed front pulley teeth count is not the same, orginal SWB one (part# T034) has 50 vs 51 for XLS one (part# U7203). So the orginal SWB is underdriving its front wheels.

I was still hesitating between SWB or XLS, and motivated by your comments and the parts I have in stock, I decided to rebuild two CATs, the SWB as a shelf queen / gentle runner with only original parts, stock flat head screws, etc... and a XLS as a runner with a mix of orig/rere/hopup parts.

Groomi wrote: ↑Sun Oct 04, 2020 10:46 am Hi Bismuth, Great to see another SWB - would be great to build it back up as it was originally.

As others have said the transmission parts for the re-release appear identical to the originals. That said, if you want to keep it original, I probably have some original integrator parts in a box - I'll have a look in a day or two and let you know.

That's very nice from you Groomi, the only parts I cannot find to restore the SWB are the front univ joint parts enclosing the one way clutches.

If I do not find them, maybe as last resort I can repare the cracked ones I have.

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?