Rebuilding my JRX Pro-SE

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HS-YZ250
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Re: Rebuilding my JRX Pro-SE

Post by HS-YZ250 »

So I have a XXX buggy I overpaid for that I'm in the process of collecting parts and, in research, I saw there were a number of rare aluminum parts made for it. While finding those for a reasonable amount seems futile at this point, I got the idea to see if there were any for the TLR 22. Turns out there were and so now my Pro SE has aluminum uprights.
20231210_011425.jpg
There are some problems, though. The aluminum parts were made for the TLR 22 2.0 while I designed my caster block adapters around the 4.0 parts. The compatibility tab on the A-Main site says the 4.0 bag of parts should be for all 22's up to 4.0, though you can see there are differences.
20231210_120225.jpg
The most impactful difference is the aluminum upright is set further out. I compensated by moving the front axle spacers to the inside to bring the wheel in more, and it's pretty close to the width of the rear tires.

Another issue was the height of the steering arm. The one I had chosen from the 4.0 bag let me get rid of most of the bump steer, but the aluminum piece has different geometry, so I had to remove the shims of the inboard steering ball stud to cut out the bump steer. I might need to tweak it more.

A last problem I found was the small limit stop in the aluminum uprights don't contact the adapter, so you can turn the inside wheel far enough the steering link may toggle and lock up, so when I have time I'll re-spin the adapter to account for this.

An interesting observation about the aluminum upright is that the kingpin hole is threaded, though the kit they came in had a solid pin that was TiNi coated (which I haven't put in, yet). I gather it may be the same as the 22-4 aluminum upright.

Another observation is the upper and lower pivots on this upright are equally sizes and don't allow for as many spacers below the caster block for ride height adjustment, which isn't a concern for me.
Losi LXT (JRX-T Conversion)
Losi JRX Pro SE
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HS-YZ250
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Re: Rebuilding my JRX Pro-SE

Post by HS-YZ250 »

Finally got my 3Dprinters up and running and also found time to get back to working on an RC project. I took some time to alter my upright design to accommodate the Aluminum 22 2.0 spindles. Apologies the pictures didn't come out the greatest.

I had to offset the upper camber link back to clear the spindle. I would probably need to offset this more for plastic parts, but I presume if others were to do this conversion they'd either go for the aluminum parts, or the 22 4.0 and 5.0 parts.
20240429_221643.jpg
This brought the front wheel in so the outside more closely aligns with the rear wheel. I presume what's been lost over the 4.0 parts is there is more wheel scrub, with the king pin closer to the outer arm pivot. I'll be interested to see if I can feel a difference in handling.
20240429_221443.jpg
20240429_221330.jpg
The bump steer looks pretty good, still, thankfully. If there's any more than there was with the 4.0 parts, it's slight enough I think I can shim it out.
20240429_221316.jpg
I need to make some changes to provide a good stop for the upright, so I've got a couple more iterations to do.

If there's one complaint I have about the aluminum uprights is that they allow the bearings to move a little, which introduces a bit of slop in the steering. But they look great and don't have the weak trail adjustment inserts the 4.0 plastic parts have.

If I get it ironed out, I might go back with the first design and verify it with 22 5.0 parts, and then see about putting them somewhere where people can get them.

Also I got a set of 22T 2.0 aluminum uprights for when I refresh my LXT like I've done, here, with the Pro SE.
Losi LXT (JRX-T Conversion)
Losi JRX Pro SE
Kyosho Rocky
Parts-Car-to-Runner Kyosho Rocky
Yokomo YZ10 WCS '95 Pavidis
RJ Speed Spec10 "Chew Toy Mk1"
Redcat Lightning STK "Chew Toy Mk 2"
Kyosho Lazer ZX, ZX-R, ZX-RR

HS-YZ250
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Re: Rebuilding my JRX Pro-SE

Post by HS-YZ250 »

As I'm iterating to finalize the design, I'm starting to think about how to configure this in a way/ways others are most likely to use.

V1 was designed around the TLR 22 4.0/LXT geometry because my Pro SE has the Jammin Jay Steering Enhancement Kit which came with the larger LXT uprights. I presume most people with a jrx 2/Pro/Pro SE are going to want to match the smaller Pro SE upright pivot points, so I included both upper pivot locations when I laid out the first sketch for reference later. You can see in this image how different the two are. Also, what's sketched are current TLR metric ball studs and not classic Losi 4-40 thread studs, so that's another issue.

Losi Upright V1 - For TLR 22 4.0/LXT Geometry
Losi Upright v1.png

Then, when I got new ideas about Aluminum TLR 22 2.0 uprights, I had to step the kingpin in a good bit to compensate for V2

Losi Upright V2 - For TLR 22 2.0/LXT Geometry
Losi Upright v2.png
Making V1 and V2 both available seems obvious, but I'm wondering about the Buggy/LXT and Modern/Vintage hardware options. If I account for all options, it'll be a handful of variations and that could get confusing. I've not tried it yet, but I'm also a little concerned about parts fit if I clearance for the stock Losi buggy geometry. I guess I need to try modelling them, or at least sketching the vintage ball joints. I also wonder if I should redesign the upper ball stud so that it takes a thinner spacer so there's some range of adjustability of the roll center. Ugh! Choices.
Losi LXT (JRX-T Conversion)
Losi JRX Pro SE
Kyosho Rocky
Parts-Car-to-Runner Kyosho Rocky
Yokomo YZ10 WCS '95 Pavidis
RJ Speed Spec10 "Chew Toy Mk1"
Redcat Lightning STK "Chew Toy Mk 2"
Kyosho Lazer ZX, ZX-R, ZX-RR

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