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4WD SRB Racer

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1300GT
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4WD SRB Racer

Post by 1300GT » Thu Oct 02, 2014 6:50 am

This is something I've wanted to make for a long time now. As the pictures show it's early days yet and I've got a long way to go.

I haven't decided on a front gearbox but I have a couple of options available. Unfortunately no MIP front gearbox.

So far the specs are,
-Adjustable front track from stock SRB to 12mm wider and then out to 24mm wider than stock.
-The rear track can be widened 16mm.
-Kyosho Circuit 1000 semi trailing arms on the rear.
-SRB front suspension.
-SRB rear gearbox.
-Wheelbase stretched by an inch.
-The chassis is made from 1/8 of an inch thick G10.
-Kyosho Stinger MK1 ladder chain and Kyosho Blizzard sprockets.

I'll update as I can and we'll see what happens. :)

Any questions, feel free to ask.
Attachments
4WD SRB Racer.jpg
4WD SRB Racer 1.jpg
4WD SRB Racer 2.jpg
4WD SRB Racer 3.jpg
Chris.

Toys.............they are!

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Jirka
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Re: 4WD SRB Racer

Post by Jirka » Thu Oct 02, 2014 7:03 am

:shock: I do not have questions but what a cool project 8) ! I hope You find suitable front gear box soon. Longitudinal trailing arms front and rear with 4wd drive in 1:10 scale. Is that ever made before?

Jirka

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Re: 4WD SRB Racer

Post by tiger1 » Thu Oct 02, 2014 7:52 am

exciting :)

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RC104ever
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Re: 4WD SRB Racer

Post by RC104ever » Thu Oct 02, 2014 11:03 am

Why not get an aluminum chassis? I think I bought mine off ebay, works great. I also have the RCchannel independent rear suspension setup, works great.
- Chris
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Re: 4WD SRB Racer

Post by terry.sc » Thu Oct 02, 2014 12:42 pm

Jirka wrote::shock: I do not have questions but what a cool project 8) ! I hope You find suitable front gear box soon. Longitudinal trailing arms front and rear with 4wd drive in 1:10 scale. Is that ever made before?

Jirka
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viewtopic.php?f=33&t=3172
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Re: 4WD SRB Racer

Post by shodog » Thu Oct 02, 2014 3:08 pm

good luck on your project. I look forward to seeing the end result

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Re: 4WD SRB Racer

Post by tamiyadan » Thu Oct 02, 2014 3:20 pm

a kyosho progress or Gallop front gear box would work there as well, it is very self contained, similar to the mip design.
or you could mill something out of plastic or metal, or 3d print something,, spool the front gear box to make it simpler.
could then use one way bearings on the rims so they free wheel forward on the front axles.

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Re: 4WD SRB Racer

Post by DennisM » Thu Oct 02, 2014 3:57 pm

Great project 8)
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Re: 4WD SRB Racer

Post by 1300GT » Fri Oct 03, 2014 6:09 pm

Thanks for the comments everyone. Much appreciated. :)
RC104ever wrote:Why not get an aluminum chassis? I think I bought mine off ebay, works great. I also have the RCchannel independent rear suspension setup, works great.
Chris, I have a large sheet of G10 sitting around and wanted to use some of it. And I needed a chassis that is longer than stock and wider in the front than stock. I could have used aluminium but I prefer the look of the G10 and being 1/8 of an inch thick it doesn't flex too much.

The RCchannel rear suspension kit is nice but I wanted semi trailing arms for this buggy and I had a spare pair of Scorpion rear arms.
tamiyadan wrote:a kyosho progress or Gallop front gear box would work there as well, it is very self contained, similar to the mip design.
or you could mill something out of plastic or metal, or 3d print something,, spool the front gear box to make it simpler.
could then use one way bearings on the rims so they free wheel forward on the front axles.
Dan, thanks for the input. I plan on making it full time 4WD for now but the RWD front wheel assist would be interesting to try out one day.
Last edited by 1300GT on Fri Aug 07, 2015 3:17 pm, edited 1 time in total.
Chris.

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Re: 4WD SRB Racer

Post by tamiyadan » Fri Oct 03, 2014 6:58 pm

you have a few ways you could attempt it, mount the front or rear chain sprocket on a one way bearing like tamiya did on the CC or TA chassis; locate the one way in the front rims or setup the front drive gearbox with 2 one ways and separated outdrives you would need a larger hollow tube with the bearings inside and a split shaft to carry power to the front tires.
years ago, i hacked 2 gearboxes on a SRB chassis and ran 2 motor front and rear, the front steering radius was basically non-existent, it was stupid and heavy as well.

if you can match sprocket ratios you could grab many parts from the kyosho optima to speed things along. parts from the Kyosho/Cox/robbe S-10 Chevy would be adaptable as well, that electric truck and the datsun gas version used front one ways mounted in the rims as well.

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Re: 4WD SRB Racer

Post by SMOKE-DOG » Wed Oct 08, 2014 12:54 am

Looks sweet. Love these kind of projects. Are you going to keep all the parts vintage or will you also use some modern parts?

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Re: 4WD SRB Racer

Post by 1300GT » Wed Oct 08, 2014 4:09 pm

SMOKE-DOG wrote:Looks sweet. Love these kind of projects. Are you going to keep all the parts vintage or will you also use some modern parts?
Thanks SD. It's going to be a mix of vintage and modern parts plus some custom home made stuff.

Ideally it would be mostly vintage, but as it's going to be run I don't mind using some rere parts.
tamiyadan wrote:you have a few ways you could attempt it, mount the front or rear chain sprocket on a one way bearing like tamiya did on the CC or TA chassis; locate the one way in the front rims or setup the front drive gearbox with 2 one ways and separated outdrives you would need a larger hollow tube with the bearings inside and a split shaft to carry power to the front tires.
years ago, i hacked 2 gearboxes on a SRB chassis and ran 2 motor front and rear, the front steering radius was basically non-existent, it was stupid and heavy as well.

if you can match sprocket ratios you could grab many parts from the kyosho optima to speed things along. parts from the Kyosho/Cox/robbe S-10 Chevy would be adaptable as well, that electric truck and the datsun gas version used front one ways mounted in the rims as well.
Dan, I've been checking out one way bearings now. I like the idea of the one ways in the front rims. Seems easy enough to do with the sizes available.
Chris.

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Re: 4WD SRB Racer

Post by tamiyadan » Wed Oct 08, 2014 4:12 pm

a couple of cars had the one ways in the front wheels back in 82-85ish kyosho was the one that sticks out the most.

biggest drawback with the one ways in the front rims is dirt will get in gum them up and then they start to slip or not engage.

but they work and are the simpliest way to not have to deal with a front diff and a oneway in limited space. thus you can reduce the front end to a shaft with a spocket in it for the drive line
and not worry about the push from the spooled front end because the one way will act like a diff under power and a RWD under braking.

check out the kyosho progress for reaserch
http://www.oople.com/rc/manuals/progres ... al000.html

it was kyosho's first 4wd and 4ws car and used front one ways in the rims with a spooled front end.
the front gearbox is very easy to construct and might be a good template for you

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Re: 4WD SRB Racer

Post by 1300GT » Wed Oct 08, 2014 5:00 pm

I had a look at the manual Dan. If I use a single shaft and sprocket the front wheels will be rotating in reverse against the rear wheels on my buggy. I need a gearbox with a top shaft and final drive gear/diff for the front end. Thanks for the link though.

I'm going to have a go at making a front gearbox that uses an SRB top shaft and final drive gear. That'll keep both gearboxes driven equally with a 2:1 internal ratio.
Chris.

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Re: 4WD SRB Racer

Post by GoMachV » Wed Oct 08, 2014 5:08 pm

Even tho the idler is just an idler, when you drive off it for the front you need the front to have the same ratio as the rear idler to lower gear, not top shaft to lower gear. It will make more sense when you draw it out :mrgreen:
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