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Building the S960 "Tips & Tricks" Part 4 (FINAL) (12/10/2005)

By:: Glenn M. Cauley
Linked to:: Serpent 960 1/8 scale 4WD

Part 4 is the final instalment in my series of articles “Building the S960 – Tips & Tricks.” In this article I focus on the gearbox, clutch, and final assembly of the car – followed by some general observations and kudos to Serpent for a very fine product.

I will try to save some time and page space by referring to some of my previous articles where applicable, so that you are not forced to read through pages… and pages… and pages of article.

For those of you who are new to this series of articles, I recommend that you read through the other parts of the article to gain some understanding of the tips & tricks I mention:

Part 1: http://www.mytsn.com/publ/publ.asp?pid=11388
Part 2: http://www.mytsn.com/publ/publ.asp?pid=11411
Part 3: http://www.mytsn.com/publ/publ.asp?pid=11441

There is also a short, related article about the switch mounting plate that I created for my S960 at: http://www.mytsn.com/publ/publ.asp?pid=11447

Sage Advice

I know I am ‘flogging a dead horse’ here again, but this is still good advice:

Take your time and carefully prepare all parts for assembly. The car will go together better and operate more smoothly. PATIENCE is the key here. Sure you can "slap it together" quickly and the result will most likely be very good, or you can take your time and the result will be exceptional!

Items to Have On-hand

Here are some items to have on-hand, or have access to (note that some of these are already listed in previous parts of the article). These tools, chemicals, and materials are in addition to the typical items used during normal assembly.

• Mototool (Dremel™ or other)
• Drillpress
• Small and medium sanding drums (for mototool)
• Cutoff disk (for mototool)
• Drillbits: 2.0, 3.0, 3.25mm
• Hobby knife with sharp blade (e.g., #11 blade)
• Small jewellers files (round and flat)
• Black marker with wide chisel tip
• Digital calipers
• 3mm reamer and T-handle (Starrett™ brand is good)
• Haemostats (straight or curved tip)
• Thin CA glue
• Mugen Super Grease (B0308)
• ‘Sensor-safe’ silicon gasket material (I prefer Permatex® Ultra Copper®)
• Motor spray
• Metal polish
• Scotch-Brite™ scour pads (coarse or medium)
• Shop towels (paper towels)
• Cotton swabs
• Fuel tubing
• Safety glasses & gloves

Following the Previous Tips

Follow the various tips and procedures in Part 1 when assembling the S960.

GRAPHITE PART PREPARATION
Prepare and seal the edges of the left-side chassis stiffener.

THREADLOCK
Where indicated in the instruction manual, be sure to apply an appropriate amount of the threadlock. Apply threadlock sparingly.

Use only “removable strength” threadlock such as Loctite 242® “blue-grade.” DO NOT use permanent threadlock such as Loctite 262® “red-grade.”

Prepping the Engine

Before you install your engine, you should prepare it by following a few basic steps.

CLEAN ALL ENGINE PARTS
This goes without saying. Clean all parts very well before you install the engine. Disassemble the engine if you need to. Flush parts clean with motor cleaner or methyl hydrate (a.k.a. ‘denatured alcohol’). Lubricate parts as required during re-assembly.

CLEAN THE AIR CLEANER
Again, this is a ‘no brainer.’ Clean the air cleaner assembly carefully and completely, and use a new filter element if necessary. Remember to OIL THE FILTER ELEMENT!

USE NEW EXHAUST GASKETS
When installing the engine, use a new exhaust gasket where the header attaches to the engine exhaust port, and also replace the coupling gasket between the header and the pipe (if using a 1-pc pipe).

USE NEW FUEL TUBING
It would be a shame to have a brand new car with air/fuel leaks because you wanted to save on fuel tubing. Spend the extra few dollars and use new fuel tubing.

SEALING THE CARB AND ENGINE
Here’s a tricky, time-consuming task. Use ‘sensor-safe’ silicon gasket material (I prefer Permatex® Ultra Copper®) to seal the engine and carburetor. This helps to eliminate any air leaks.

The tricky part when sealing the carb and engine is to not allow any of the gasket material to get inside (where it could block fuel flow). Apply the gasket material carefully and sparingly; I recommend using a very small flat-blade screwdriver.

Here are the parts that I seal on the carb and engine:

• both sides of the two gaskets of the main fuel inlet (main needle assembly)
• between rubber bellow and carb body
• between rubber bellow and slide collar (at end of slide)
• at base of carb where it enters into crankcase (near O-ring)
• engine backplate (thin edge where the backplate meets the crankcase)

Centax-2 Clutch

Here are a few things that I did to set up the Centax-2 clutch in my S960. Remember that there are many different ways to adjust a clutch by using different and modified parts (especially flyweights and clutch shoes). What works well in one instance may not work well in others. It is all a matter of compromise (just like everything in these cars).

FLYWHEEL CONE
I installed a 0.5mm thick shim on the crankshaft behind the flywheel cone. This helped to reduce the amount of shims I would have to add on the other side of the clutch (for clutch gap and endplay).

A simple trick for the flywheel cone is to file a small bevel on the lower edge (closest to the engine). This helps to prevent the sharp base edge of the cone from ‘biting into’ the shim, which might cause the shim to warp or dish slightly.

FLYWEIGHTS
In speaking with some Serpent drivers, they recommended that I try the following trick for the flyweights.

Using a yellow clutch shoe, turn it upside down and cut 3 equal-size pivoting flyweights. Use a sanding drum to remove the stepped edge on the inside of each flyweight. Then drill two 3mm holes in each flyweight to lighten them. (I drill the holes slightly undersize, then use a 3mm reamer to finish.) Remove all flashing with a sharp hobby knife.

This results in a clutch that will have better low-end response. The drawback is that it will not put as much pressure on the clutch shoe, but this shouldn’t be a problem. I hope.

CLUTCH SHOE
The yellow clutch shoe included with the S960 kit is still my preferred clutch shoe.
I polished the back of the metal backing plate to a mirror finish (where it contacts the flyweights). This really helps to smoothen out the clutch action.

STEEL PINION GEARS
Call me silly (and I can hear the chorus of “You’re silly” coming from around the world) but I prefer to use steel pinion gears instead of the stock alum gears. Sure they add more rotating mass to the clutchbell, but steel gears are a whole lot tougher than alum gears (hard coating or not).

I feel much safer knowing that my big honkin’ powerful SX21KHM motor is putting the power down through steel gears rather than alum gears.

THRUSTBEARING CARE
I opted for Serpent’s ceramic thrustbearing for the Centax-2 clutch.

I recommend Mugen Super Grease (B0308) for lubricating the thrustbearing. It is very thick, lasts a long time, and has very good lubricating properties.

I have heard rumours of Serpent cars ‘rejecting’ Mugen products, but that is probably just an urban myth. :o)

A BIT OF LIGHT READING
If you want more information about the Centax2 clutch, please check out my article “Building and Setting Up the Centax-2 and Centax-3 Clutches”:

http://www.mytsn.com/publ/publ.asp?pid=10534

Gearbox

POLISH ONE ‘SHIFT POINT’ SCREW
Polish the head of (only) ONE M3x12 ‘shift point’ screw so it has a bright mirror finish. Leave the other screw unpolished so the head is black.

Now when are adjusting the shift point in your transmission, you will be able to easily tell the two screws apart, so you will not adjust the same screw twice.

2nd GEAR MODS
I used a 3.25mm drillbit to drill out the small oval holes in the 2nd gear alum drum. Instead of angling the holes, I drilled them straight into the drum. I moved the bit around to make the holes oval instead of round.

I used a cutting wheel in a mototool to cut away the ‘wall’ of the gear, to better expose the holes in the alum drum. These two things will make it much easier to see and adjust the screws inside the gearbox.

When I installed the gearbox and spun the 2nd gear, I noticed that the three screws at the back of the gear came very close to hitting the right-side chassis stiffener. So I used a sanding drum in a mototool to shorten each screw by 0.5mm it protruded from the back of the gear gear. When you sand the screws, you will also remove a bit of plastic from the gear… that is okay.

When grinding parts on the 2nd gear, be careful not to remove too much material or cut into the gear teeth.

Engine Monoblock

The engine monoblock is one of the first option parts I ordered for this car. It is a work of art, and is very structurally stiff. And the machining is top notch!

When doing a pre-install mock-up, I found the fit a bit tight, especially on the back mount where the monoblock is close to the left rear bulkhead, and also at the front of the monoblock near the brake pad assembly. I used a sanding drum in a mototool to remove a small amount of material from those areas as shown.

When the engine was mounted and the gear mesh was set, I found that the side belt was rubbing on the end of the monoblock. A few minutes with a sanding drum and a file solved that issue.

Cosmetic Touches - Screws

Anyone who knows me will tell you that it is not good enough for me to have a well-functioning car… it MUST be unique, well laid-out, and last but not least, have nice cosmetic touches. I figure, why have a car that looks like everyone else’s, right?

When I was looking over the completed car, it struck me that the black-finish alloy screws I used throughout the car (M3 flat-head Allen drive) looked odd underneath the chassis (against the polished chassis plate). So out came the black-finish alloy screws, and in went stainless steel versions.

So there you have it… silver screws on bottom (against silver chassis), black screws on top (against black carbon and composite plastic). My fastener supplier thinks I’m a bit excessive, but enjoys my business!

Simply Exhausting

MOUNTING POST
When I installed the exhaust pipe, I found that the forward end of the pipe was too low. I drilled an additional 2mm hole in the alum mounting post to bring the exhaust wire up higher. After doing this, I had to shorten the M4 flat-head screw (which attaches the post to the radioplate) to a length of 7mm.

THREADLOCK
Remember to apply threadlock to EVERYTHING when assembling the exhaust mounting parts:

• M3 setscrew in bottom of mounting post (secures exhaust wire in mounting post)
• M4 screw in top of mounting post (holds mounting post to radioplate)
• M5 setscrew in end of exhaust pipe (secures pipe to exhaust wire)

Zip Ties No More!

Previously when I installed fuel tubing onto fittings (pressure lines, fuel line to carb) I would secure each end with a small zip tie (cable tie). This secured the tubing well, but it was very tedious to remove the tubing since I would have to cut off the zip tie to remove the turing from its fitting. Then I would have to use a new zip tie when I reinstalled the tubing. There was always a risk when cutting off the zip tie, since I had to carefully avoid cutting the fuel tubing.

Now I use small pieces of fuel tubing, cut to 2~3mm lengths, as ‘rubber bands’ to secure the ends of fuel tubing on their respective fittings. They are easy to install, and best of all they are completely reusable!

1. Cut the fuel tubing band to a length of 2~3mm.
2. Put the band over the end of a pair of thin needle-nose pliers (or haemostats as shown here).
3. Stretch open the band, and push over the end of the fuel tubing you want to secure. Do this for both ends.
4. Push the fuel tubing onto its fitting, then push the band over the end to secure it.

List of Parts Used

Here is the list of the parts that I finally installed on my S960:

SERPENT OPTIONALS
• 1014 Torx screws CSH M4 (for engine monoblock)
• 1391 Bearing set ceramic S960 (19)
• 1666 Transponder holder carbon star
• 2879 Pipeset M21 inline 3C 9901 polished
• 6123A Bodyposts short alu (2)
• 9606 Brake disk ventilated (2)
• 808251 Aluminum middle block
• 902129 Titanium steering turnbuckles
• 902139 Servo saver spring 2.2 black
• 902156 Radioplate alu bracket
• 902253 Aluminum middle shaft coated
• 902280 Front CVD axle set
• 902341 Engine monoblock M21
• 902370 Wheelaxles rear QC/fixed set
• 902444 2sp gear 44T (2nd) LC
• 902450 2sp gear 50T (1st) LC
• 903162 Rear plate alu grey
• 909254 Pulley 18T alu H-anodized (middle inner)
• 909575 Centax pinion gear – steel 15T
• 909579 Centax pinion gear – steel 19T

OTHER PARTS
• 60224 KO Propo Electrical Switch
• DYN2541 Dynamite machined alu servo arm
• S9402 Futaba high-speed metal-gear servo (2x)
• Spektrum DSM (for Airtronics M8)
• Flathead M4 screws, Allen socket, alloy steel
• Flathead M4 screws, Allen socket, stainless steel

Kudos to Serpent

There are a few things that I would like to compliment Serpent on for their new S960.

FRONT STEERING BLOCKS
I had a very pleasant surprise when I installed the front wheels. The steering ball-joint doesn’t hit the tire! This was an issue with previous cars, and was solved by bevelling the inside edge of the front tires on a tire truer.

But Serpent came through on this new car to solve this issue… the arm of the steering block is well away from the wheel. And the steering block looks like it is 10x beefier than earlier cars.

ADJUSTABLE REAR ANTI-ROLL BAR
Finally, the coveted adjustable rear anti-roll bar is back as a standard included item! And ball-bearing supported to boot!

CENTAX-2 TENSION SPRING
The latest instalment of the Centax-2 clutch includes a newly-designed tension spring. This spring has 1 less coil, and the coils are spaced further apart. This prevents the coils from touching each other when the spring compresses and the clutch engages, preventing clutch slippage.

CLEAN LAYOUT
I was very happy with the layout options for the electronics. Using the upright throttle servo option, I found that there was plenty of space to put the excess wiring, and I did not have to route wiring all the way across the car to a receiver on the other side.

EASY ACCESS TO PARTS THROUGH RADIOPLATE & CHASSIS CUTOUTS
The strategically-placed cutouts in the radioplate and chassis plate allow me to easily access all sorts of parts: middle block, steering linkage, servo saver, etc.

Completed Masterpiece… my Serpent S960

IMPORTANT NOTE!

When you are using hand tools and power tools (e.g., drillpress or mototool), you MUST exercise extreme caution, and use proper protective eyewear and gloves. NO loose clothing around power tools, either! It only takes a momentary lapse in concentration to receive an injury or damage a part.