SG Coyote improvements

[1300GT]

I first saw an ad for the SG Coyote in January 1986 and thought it looked interesting. I then promptly forgot about it until 1988 when I read about John Schweitzer's modified two speed Coyote in Dirt and Track number four. I was thoroughly impressed and vowed that one day I would own one. Fast forward to 2014, I bought two NIB two wheel drive Coyotes from ebay at a really good price. Both were combined into a 4WD, a few small things were done and it was left on the shelf waiting until I could start modifying it. Moving on again to 2021, I bought a Sieg lathe and began to realise the dream.

This thread will be used to document the mods I make to improve the Coyote. The goal is to keep as much SG in this buggy as possible, improve performance and reliability, whilst retaining the stock looks.....mostly.

First mod is to eliminate fore and aft rocking of the steering posts. The stock setup shown in this picture allows the steering bellcranks to exert force on the posts which can potentially change steering geometry. The small crappy looking post with two grooves is the stock item. It's mate is screwed to the chassis rail with the black mount. On the left is one of two new posts that I made. Note the M3 thread at the top of it.

Here's the new post mounted using a stock mount at the bottom and a modified mount at top that allows the 4mm shaft to pass through it. The two lower holes were drilled into the chassis to accommodate the mount.

The other chassis rail is modified in the same manner. An M3 nyloc nut is used to retain the bellcranks and can be adjusted for any slop in the system.

I'll update this thread when I can. Thanks for looking.

[Dadio]

That's nice and tidy , uses original mounting parts as well

[1300GT]

Thanks Gav, the post is rock solid now.

All Coyotes are afflicted with the dreaded giant single wheel bearing disease, which allows massive amounts of wheel wobble and more as the bearing wears.

Here's my solution. Machine double bearing holders from Acetal with a total width of 6.95mm. Instead of one 5x16x5mm bearing, the holders use two 5x10x3mm bearings spaced .95mm apart. The holder is stepped to allow it to be mounted into the steering knuckle in place of the single bearing.

I first saw this mod on PRP's Coyote.https://www.rc10talk.com/viewtopic.php?f=33&t=20503
He bored out four kit wheel bushings and fitted two smaller flanged bearings in each. It looked like a great idea and after some measuring I realised that two non-flanged bearings could fit utilising the entire available axle width.

[BattleTrak]

I am loving this thread so far! As awesome as the Coyote chassis is.. there are many areas that need improvement. I addressed a few problems in my build and looking forward to see what you do! Also consider making some extras so I can buy them! .

[Dadio]

Again very neatly executed , I should put some modified hubs on my Shapeways shop really .
Of course the big question is "whatcha gonna do about dem shocks?"

[1300GT]

I am loving this thread so far! As awesome as the Coyote chassis is.. there are many areas that need improvement. I addressed a few problems in my build and looking forward to see what you do! Also consider making some extras so I can buy them! .

Thanks Brad. I"ll see about making extras. although it looks like the problem could be solved by Dadio.

Again very neatly executed , I should put some modified hubs on my Shapeways shop really .
Of course the big question is "whatcha gonna do about dem shocks?"

Thanks. That's be nifty if you added modified hubs to your Shapeways empire. As for the shocks, I've already got some for the Coyote. They're not the stock ones though. The originals are terrible and the mounting system is one of the worst designs ever.

[1300GT]

Stock Coyotes are limited to a 48 tooth .8 module spur gear which doesn't stand up to the ravages of time and use. More than one person has mentioned that their spur was on the verge of crumbling to dust.

With a couple of passes on the lathe this spur gear adaptor intended for Tamiya's TT-02 series of cars now sits at home in my Coyote.

It's from Eagle Racing (part Number TT02-24U-LBL) and is listed as "American gear adapter for Tamiya TT02." Kimbrough spurs fit directly on without any need for a spacer inside the gear. This opens up the range of ratios now available. Currently fitted is a Kimbrough 72 tooth 48dp spur.
Note the plastic motor mount, this item will be replaced.

[Dadio]

I've done a similar thing with the spur but I found a 48 tooth .8 mod modern gear that just needed the centre boss to be slightly thinner , even had the pin drive but your solution gives you much more flexibility , what do you have planned for the motor mount then ? I already have the motor mount CAD model and could stick it on Shapeways if you want ? Mine was bent as a banana

[1300GT]

I'll machine a new motor mount out of 6mm alloy plate. Good for heat dissipation.
I did think about bending one up in a similar fashion to a TAG Pro 10 mount but in the end decided on a machined one as it won't need any M3 nyloc nuts to secure it to the chassis rails.

Haven't you got the 3D motor mount in your Shapeways shop already? I thought I saw it in there with all the other goodies.

[Dadio]

Probably there I loose track the alloy milled part will seat the prop shaft bearing better than a folded one as well as heat dissipation , you could mill fancy heat sink fins into it too

[1300GT]

One of the worst things about the Coyote is the need to disassemble half the car to change a spur gear, this includes opening up the rear diff housing to access a single grub screw to slide the diff pinion off it's shaft allowing you to then get to the spur. This is my solution to the problem.

In this picture the stock 5mm shaft is the top one with the drive cup and shaft machined as one. I made the 5mm shaft on the bottom which utilises a separate modified Coyote drive cup.

Here's everything assembled in the chassis with the exception of the main drive shaft. The stock drive shaft is a 4mm steel unit. The front and rear drive cups were bored out to accept a 5mm aluminium drive shaft which I've yet to make. This was done so the rear drive cup could slide rearwards on it's shaft as you will see shortly.

To change the spur first remove the pinion and motor, then undo the grub screw in the drive cup followed by removing all four motor mount screws. The motor mount, shim and drive cup now all slide rearwards on their shaft butting up against the spur gear. At this point the main drive shaft would be free to move away from the drive cup and slide backwards allowing it to disengage from the front drive cup and be removed from the chassis.

Once the drive shaft is removed, the drive cup, shim and motor mount can now slide forwards off their shaft and be removed from the chassis exposing the two screws holding the spur to it's hub.

Change the spur then reverse the order for installation.

[dinglem]

Cool thread - always interested in Coyote mods!

We did the alloy motor mount mod with heatsink ribs/air flow grooves and it works well.

[1300GT]

Thanks Martin! I'm the same. Every time a new picture or thread of a Coyote/Pro 10 turns up I investigate it thoroughly looking for mods or any optional parts.

The next thing I'll make is the main drive shaft. After that it's onto the motor mount.

I keep going back to your thread, I think it's those wheels!

[1300GT]

Coyotes come with a piece of lexan as a means to keep dirt and other things from flying up inside the chassis. Being lexan it offers no rigidity to the chassis structure. I made a new underguard from 1.5mm carbon fibre sheet which adds some torsional stiffness to the chassis as well as tying the bottom of the bulkheads together. While I was at it a new bumper was made from Kydex based on a TAG Pro 10 bumper. There's nothing really wrong with the stock item apart from the fact it looks terrible (to me at least).

[BattleTrak]

That front bumper looks great! And cool idea on making the spur easier to change. It is hard to imagine what it would be like to race one of these with all the oddities like those guys did! You should use a front diff case in the rear too for extra bearing support on the spur shaft..makes it easier to setup and shim the rear diff too.