Nyper build thread

[Nikolai]

I had bought a lightweight 6” brake rotor a few years ago for kart racing. The ID on the rotor was not larger enough for the Wahl hub and I didn’t want to turn down the hub that much so I bought the Wahl Bros 6” rotor as well. It’s heavier but it’s also thicker (3/16 thick) so I think it will be less prone to warping. Almost all of the 6” diameter lightweight rotors for Jr Sprint or Kart Racing are only 1/8” thick.

The Wahl hub started life at .48 lbs.

On Wahls website they have a lightweight hub but it’s only available for 1” keyed shafts so I copied their design and modified this one.

Hub went from .48 lbs down to .29 lbs

Only thing I don’t like about the rotor is they use 8mm bolts which are heavy. Im going to order some solid rivets to install, lighter than bolts and a cleaner look.

 

[Nikolai]

Killing some time until clutch comes back.

Installed chain & gears so I could cut tensioner bolt down to necessary length.

Cut down from 65mm to 40mm

Drilled out 90% length and dished head. Went from 35.96 grams to 19.13 grams.

 

[kennyspec]

Cool to see this thread alive again!

 

[Nikolai]

Thanks.

- Ice Age rails showed up so I can get the skid finished up. I need to narrow up the front suspension arm mounts(cut off the ends and turn down bushings) and turn down the rear axle to fit my narrower tunnel.

- It took a few days of scouring the internet but I was finally able to source some 5/16 diameter solid rivets in 2117T4 from Jay-Cee Sales & Rivets for the brake rotor. 99% of the rivets this diameter are 1100F aluminum but Jay-Cee had them in the aircraft grade aluminum. They’re a brazier head so I had to order a 5/16 brazier head set tool. These will be super light for securing the rotor to hub and plenty strong.

- Ordered a new coolant fill bottle and cap for a 95 Arctic Cat, they have 1” inlet and outlet in a 90 degree configuration, are plastic and small, they also have the overflow barb going the correct direction for my application(overflow bottle will be in front of motor). This will make for a very clean and minimalist cooling system. Probably took me 2 weeks of searching google images to find a coolant fill neck that was exactly what I wanted. Polaris had one that is similar but the inlet/outlet were only 7/8 when I measured at the dealer and I want to stay 1” so my heat shrink clamps are all the same size.

- Ordered some M10 x 1.25 x 15mm steel bungs from Bung King. Was going to make them but for $3 a bung it wasn’t worth my time. These will be for securing the chaincase. I want to weld bungs to the frame tubing as welded bungs ease in installation and are stronger (IMO) then using a bolt & nut. This also depends on how much the bungs weigh though. The chaincase mounting tabs/bungs need to be under 1 lb to meet target weight. I have 1 lb allotted for chaincase side and 1 lb allotted for clutch side which is going to be pushing it. I really need the chaincase side to come in around .75 lbs so I have 1.25 lbs for clutch side since it’s going to be .090 plate.

- I got the chaincase about ported and polished as much as possible to shed some grams.

- Bought a clean set of used black spindles that should be here shortly. Still need to purchase 36” lower a-arms and tie rods.

- Steering u-joint finally came off backorder after a couple months so that should be here shortly. Shipped from The Chassis Shop a couple days ago.

That was a lot of rambling. Some tedious things that I’m glad to have sorted out.

 

[Nikolai]

A question for my fellow TYers. The upper and lower gears both have steel spacers behind them. Is there any reason these spacers could not be aluminum? I know the metals expand at different rates when heated but I don’t know if chaincases get hot enough for that to be an issue and what issue it would even cause?

If I were to make them out of aluminum I would use 7075-T6.

 

[kinger]

I would not hesitate to use 7075 aluminum in that application.

 

[Nikolai]

Thanks, I ordered a 5” piece of 1.5” 7075 round bar from Speedy Metals. I will replace both steel spacers with aluminum.

 

[Nikolai]

Got lucky and picked up a brand new take off Polaris Series 6 155 x 2.6 track local to me. I remembered these being about 44 lbs but I weighed this one and it was 47.3 lbs. I’m thinking Polaris maybe has added some material back into them to assist in durability. I am glad to see that they stopped clipping the cross bars and started putting the clips on the paddles.

Coolant fill showed up, going to work perfect.

Steering u-joint showed up as well. This will end up being modified a bit and I will do a detailed post on the steering when I get around to it after the drivetrain is done.

 

[Nikolai]

Not much to update. Spindles showed up, they’re heavier than they look, I was little surprised at the weight.

My counterbore bits finally showed up. Going to counterbore everything I can to reduce fastener length. Started with the speedo gear to give them a try. Didn’t leave much meat around the outside but it’s not structural in anyway so I don’t think it will be an issue. 32.65 grams down to 19.81 grams. Going to order a short Ti bolt for it when I order my chaincase bolts.

Going to counterbore the brake caliper bolts and starter bolts next. Also started swapping my Ice Age rails over while I wait on the clutch.

 

[Nikolai]

Bought a used set of 36” tie rods off eBay. Also ordered new 36” lower a-arms from the dealer. That’s the last of the front suspension parts I needed

Started putting the rear suspension back together and found both cast adjusters cracked. Searched the forum and found that’s a common issue so I ordered the Grip N Rip billet adjusters, should be here next week and then I can wrap up the suspension.

My piece of 7075 showed up today so I made the spacers that go behind the gears. Pretty substantial weight difference.

62.82 grams for steel spacers

25.14 grams for aluminum

 

[Nikolai]

Need some ideas for the steering bushing.

Original plan was to use the hardened steel sleeve from the Nytro and bolt it to the framing with an M12 bolt. I really don’t want to use an M12 x 60 bolt if I don’t have because of weight, that’s a heavy bolt. Did some reading on TIG welding hardened steel and that has mixed results so I think welding it is out of the question.

So then I made one out of steel bar stock to weld to the frame. Even though the steering arm doesn’t see high speeds like a wheel bearing I’m concerned about needle bearings against a non-hardened sleeve. I don’t know if they would really wear into the steel and how long it would take, maybe this isn’t an issue? So here’s where I’m currently at, the bolt would be removed after welding.

So now I’m not sure what to do. I wanted smooth steering and thought needle bearings would be the best, but against a non hardened sleeve I’m not sure now.

I’ve also thought about bolting an aluminum sleeve to the frame and making a bushing out of UHMW or oil lite bronze and eliminating the steel sleeve and needle bearings.

Anyone have any better ideas?

 

[kennyspec]

You probably won’t like this idea but on my build I welded a bolt in one of those spherical bushings at the spindle end of a Nytro a arm. Then welded the outside of the bushing to the steering shaft. Has worked great so far. Just don’t get it too hot welding it and melt it. I don’t think the bearings will ever wear out the mild steel shaft.

 

[Nikolai]

That’s a good idea. If possible I would like to keep the steering geometry unchanged but I’m not set on it.

These would be my priories in order.

1. Retaining factory geometry
2. Ease of steering
3. Weight
4. Maintenance (don’t mind occasionally replacing a plastic or bronze bushing if I go that route)

Edited: Have done some more reading. Sounds like oil lite bronze would wear out the aluminum. Although this is very low speed application. Now thinking maybe an aluminum shaft and bushing made from UHMW. Have had good luck with UHMW on my side x side.

 

[Nikolai]

Came up with a plan for steering I think. Waiting for an oilite bushing to get here.

Tie rods showed up. Bought a used set of 36” tie rods of eBay for $56 shipped. Way better than over $200 from the dealer. The rod ends new are stupid expensive.

Immediately swapped out the huge AC jam nuts for Yamaha jam nuts from old Nytro parts, both are M10 x 1.25. Also swapped out the outer stud lock nut for a Yamaha metal lock nut to save weight and use the same 14mm wrench size.

Just simply swapping out the 6 AC nuts with 6 Yamaha nuts I already had saved 28.59 grams. Not bad for free.

I’m just going picture heavy on this stuff because I don’t really have much else to do until clutch or steering parts get here.

 

[Nikolai]

Finished the rear suspension finally. Not super impressed with the Ice Age rails. The rails themselves are a thing of beauty, but the parts sent with them were frustrating. The front bump stops they send had to be trimmed to clear the limit strap shaft. I got their “trimmed to fit idler blocks” but the bolt pattern wasn’t right so I had to trim the slots on my idler blocks. This actually turned out fine because their block setup was heavier.

Grip N Rip billet adjusters.

43.5 lbs as pictured. Kinda on the fat side but at least it will be a good suspension. Should be tough with the Ice Age rails and it has good shocks. Not many skid options these days. Either $3k for a KMod that’s nearly the same weight or $5k+ for a Nextech carbon fiber which there’s no way I’m doing that.

There are ways to save weight on it, a lot of the bolts could be shorter and used with lighter K-nuts but I have zero desire to mess with it right now. Once the sled is on the snow and everything else that can be done is done I might build 4130 arms for it but that’s a long way out at this rate. If I weigh the sled and it’s 401 lbs then I will build chromo arms to get under 400.