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2025 21.5 Pre-Pro SE buggy
Posted: Sun Oct 06, 2024 6:57 pm
by Charlie don't surf
I've had this buggy that has lots of factory driver or factory supported parts that's essentially what factory guys were doing with the JRX Pro before the SE was released, so maybe 1989/1990 ish. Anyway the 21.5 heritage class is growing like fire because of the re re 40 car, so I thought I'd run it with something different.
Here's the start. Updates as possible!
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Sun Oct 06, 2024 9:38 pm
by Charlie don't surf
Geometry looks good, B6.4 rears fit with 6mm wide 12mm hex blocks. JConcepts RC10 fronts line up well. Car was setup for 7 cell, so the chassis works well for shorty packs moved forward.
Still need to get into the trans and see what's in there, there is a slipper...may be a Powerclutch.
Dug into the body stash and found one of Brandon G's original 2009 ish reproductions...our current paint scheme looks good on it. But...found this Protoform xx-cr Ripper X which looks pretty damn cool and looks like it will fit too.
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Mon Oct 07, 2024 1:46 am
by Lavigna
Very nice platform to start from. You may want to protect those uber rare shocks from damage somehow.
That is a very elusive body as well. Should be a capable racer.
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Mon Oct 07, 2024 7:21 am
by Charlie don't surf
Tore into the trans. Built well, diff is solid. Outdrive bearings were rubber shielded and as stiff as bushings, so I replaced them with some silky ones from another trans. I never realized how tight the Losi tolerances were. Good god that was a pain in the ass to change!
Trans is much smoother, still not stealth smooth...prob can't get that out of it anyway. Changed out the topshaft to a hydra one I had kicking around and threw on a B4 slipper setup
Anyone have any tricks to make this trans ultra free?
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Mon Oct 07, 2024 8:01 am
by RC10th
Ceramic bearings...
Eliminate the slipper....
Is the tightness caused by the mesh or other friction? It's a pain trying to find the source but I've found that even a snug fitting bearing pocket in a transmission case was enough to seriously slow down a bearing.
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Mon Oct 07, 2024 8:25 am
by Charlie don't surf
RC10th wrote: ↑Mon Oct 07, 2024 8:01 am
Ceramic bearings...
Eliminate the slipper....
Is the tightness caused by the mesh or other friction? It's a pain trying to find the source but I've found that even a snug fitting bearing pocket in a transmission case was enough to seriously slow down a bearing.
With the silly putty traction surface we're on at my home track I'm afraid the shock to the driveline would toast these gears. Ceramics are a possibility...assuming I can figure the bearing sizes out lol. Seems more like gear interface friction to me. It's not bad, just not 21.5 smooth
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Mon Oct 07, 2024 2:25 pm
by JosephS
Charlie don't surf wrote: ↑Mon Oct 07, 2024 7:21 am
Changed out the topshaft to a hydra one I had kicking around and threw on a B4 slipper setup
How does that work?
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Mon Oct 07, 2024 2:42 pm
by Charlie don't surf
JosephS wrote: ↑Mon Oct 07, 2024 2:25 pm
Charlie don't surf wrote: ↑Mon Oct 07, 2024 7:21 am
Changed out the topshaft to a hydra one I had kicking around and threw on a B4 slipper setup
How does that work?
The Hydra shaft "cut" and spacing is the same as the B4-B6
Slipper hubs. I'll shoot pics this eve
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Mon Oct 07, 2024 4:54 pm
by RogueIV
I just noticed that it has a JR2 chassis instead of the Pro SE one.
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Mon Oct 07, 2024 7:33 pm
by Charlie don't surf
RogueIV wrote: ↑Mon Oct 07, 2024 4:54 pm
I just noticed that it has a JR2 chassis instead of the Pro SE one.
Charlie don't surf wrote: ↑Mon Oct 07, 2024 2:42 pm
Sorry, I guess I didn't mention that in the first post. A lot of racers were doing this with the JR2 chassis for some time before the Pro SE was a thing
JosephS wrote: ↑Mon Oct 07, 2024 2:25 pm
Charlie don't surf wrote: ↑Mon Oct 07, 2024 7:21 am
Changed out the topshaft to a hydra one I had kicking around and threw on a B4 slipper setup
How does that work?
The Hydra shaft "cut" and spacing is the same as the B4-B6
Slipper hubs. I'll shoot pics this eve
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Mon Oct 07, 2024 8:38 pm
by RC10th
If you must run a slipper I was impressed with the magnesium slipper plates, they couldn't weigh more than a couple grams.
I'm sure you can make it free, it just takes time....
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Mon Oct 07, 2024 8:58 pm
by Charlie don't surf
RC10th wrote: ↑Mon Oct 07, 2024 8:38 pm
If you must run a slipper I was impressed with the magnesium slipper plates, they couldn't weigh more than a couple grams.
I'm sure you can make it free, it just takes time....
Not a bad idea. I may try the old toothpaste packed slave case trick.
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Tue Oct 08, 2024 8:30 am
by RogueIV
Charlie don't surf wrote: ↑Mon Oct 07, 2024 8:58 pm
RC10th wrote: ↑Mon Oct 07, 2024 8:38 pm
If you must run a slipper I was impressed with the magnesium slipper plates, they couldn't weigh more than a couple grams.
I'm sure you can make it free, it just takes time....
Not a bad idea. I may try the old toothpaste packed slave case trick.
Wait, what's this trick?
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Tue Oct 08, 2024 8:51 am
by Charlie don't surf
RogueIV wrote: ↑Tue Oct 08, 2024 8:30 am
Charlie don't surf wrote: ↑Mon Oct 07, 2024 8:58 pm
RC10th wrote: ↑Mon Oct 07, 2024 8:38 pm
If you must run a slipper I was impressed with the magnesium slipper plates, they couldn't weigh more than a couple grams.
I'm sure you can make it free, it just takes time....
Not a bad idea. I may try the old toothpaste packed slave case trick.
Wait, what's this trick?
We used to pack a case *not the one we were racing* with toothpaste and bushings, junk balls and rings and just run the gears in with a dremel on high attached to the top shaft to burnished the gears in and create a soft "wear" to free up any binding in the gears.
Also. That trans is stealth free and quiet now. The gear on the Hydra shaft wasn't as smooth as the one on the power clutch top shaft, swapped the topshaft gears, changed the diff bearings and it's silky and quiet. Now it is ripe for ceramics once I find the sizes needed
Re: 2025 21.5 Pre-Pro SE buggy
Posted: Tue Oct 08, 2024 8:55 am
by Frankentruck
Interesting. I've heard of using toothpaste as a polishing compound because it's mildly abrasive. Baking soda toothpaste might be a good choice too, for a little extra grit. Or GoJo with pumice (which is not a toothpaste
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