Cheap rear alloy arms for Optima/Turbo Optima

[Coelacanth]

I finally found a great off-brand upgrade for the stock Javelin/Optima/Turbo Optima rear arms. This "mod" is so cheap it's laughable, and will upgrade your rear control arms, dog-bones, and give you a slightly wider stance all at once.

First, you begin with a set of these; this seller has plenty at this starting bid, with free shipping to boot, or you can do a BIN for just over $10:

http://cgi.ebay.ca/GPM-DF2056-Alloy-Rear-Lower-Arm-1pr-BU-DF02-/380339221100?pt=Radio_Control_Parts_Accessories&hash=item588dfbf26c

These arms are about 4.5 - 5 mm longer (pin-to-pin) than the stock arms; about 71mm vs. 66.5mm. So, you have 2 options.

1) Simply drill new 3mm holes about 5mm in from the existing holes, then cut down the ends a bit; or even better...

2) Buy slightly longer Kyosho Lazer ZX-5 swing shafts, which are commonly available in either 65.5mm or 68mm lengths (stock dogbones are 62.5mm)! I figure you could choose either one as the difference either way is about 1 to 1.5mm only. You can find them real cheap from this seller:

http://cgi.ebay.ca/Kyosho-Lazer-ZX-5-RS-Rear-Universal-Swing-Shafts-65-5mm-/220772021273?pt=Radio_Control_Parts_Accessories&hash=item336709b419

[Coelacanth]

Here's the recipe:

-The inboard ends of the arms are EXACTLY the same length as the stock arms; no modding required, just slap 'em on.

-The outboard (hub/carrier) ends are wider apart than the stock arms; simply add a few 1.5mm spacers on either side of the hubs when inserting the included suspension pins & e-clips, and it's a done deal.

-You'll still be able to mount your rear shocks with your choice of 3 mounting holes on the arms.

A few minor mods may be required:

-You'll need to drill a 3mm hole in the backs of the arms and install 4.8mm ball studs if you wish to mount a rear stabilizer set;

-You may need to replace your camber links with slightly longer ones, but you're going to be upgrading to titanium turnbuckles anyway, right?

[Coelacanth]

Test-install to confirm fitment.

[besty22]

Great work, Do you know if there's a matching front set?
I really like the Blue too.

[Coelacanth]

Great work, Do you know if there's a matching front set?
I really like the Blue too.

Not yet--but I'm still looking.

[EvolutionRevolution]

Yes: http://www.asiatees.com/model.php?Tamiya-DF-02-Upgrades-Parts-Hop-Ups&brand=Tamiya&model=DF-02

(Asiatees is essentially GPM's factory shop front)

[Coelacanth]

There are matching front arms, but I cannot confirm the fitment on an Optima yet...hopefully soon.

[highwayracer]

Great find!!! Ive been looking for a modern aluminum arm for the optima for some time now. Looking at your pictures, you might not have to purchase new universals.

You may be able to use a different rear hub carrier...like from the ultima, triumph, rs4 or if you're using a standard planatary diff, move the diff out drives about 3mm towards the wheels.

[Coelacanth]

Great find!!! Ive been looking for a modern aluminum arm for the optima. Looking at your pictures, you not have to purchase new universals.

You may be able to use a different rear hub carrier...like from the ultima, triumph, rs4 or if you're using a standard planatary diff, move the out drives about 3mm.

True, outdrives that are 5mm or so longer would be another way to resolve that. Do you happen to know of any? I can say that the existing outdrives cannot be moved out very much, maybe only a mm or two--because the shafts sticking out from the diffs don't go out that far. Moving out the outdrives would also open up the bearing to more dust getting in, I imagine.

[highwayracer]

I seem to remember kyosho making a longer outdrive for their boats. I think it may have been used on the jet stream. It's similar to the ones on the link below:

http://cgi.ebay.com/2pc-Universal-Joint-Cup-B-RC-Truck-Car-Buggy-Boat-02016-/150583392851?pt=Radio_Control_Vehicles&hash=item230f783a53

[Mr. ED]

why not use axle carriers with less offset; like the Ultima or even Lazer ones?

EDIT: the front arms fit but they they put the front wheel further forward which interferes with your shocks and puts the dogbones in a straight agle, and screws up steering geometry. Plus you need front c-carriers of the lazer style or DF-02 or it will be way too wide. (pictures at asia tees show the rear arm even where it says 'front')

I have a set for the DF02 from eagle racing and the plastic ones from tamiya: all the same geometry

[Coelacanth]

I seem to remember kyosho making a longer outdrive for their boats. I think it may have been used on the jet stream. It's similar to the ones on the link below:

http://cgi.ebay.com/2pc-Universal-Joint-Cup-B-RC-Truck-Car-Buggy-Boat-02016-/150583392851?pt=Radio_Control_Vehicles&hash=item230f783a53

I searched for longer outdrives with no success thus far. Plenty of outdrives in nice lengths: 17.5, 18, 19, 20mm...but almost all of them were 13mm diameter. That wouldn't fit the holes in the rear gearbox sideplates (the stock outdrives are 10mm diameter). I sourced some possibilities but no confirmation on sizes yet...

Thanks for the help, Mr. ED. Carriers with less offset is another possibility...how much less offset are we talking about? It would be interesting to compare between an Optima carrier & Ultima/Lazer carrier.

[besty22]

Hi all,

I bought and fitted the arms and swing shafts as per first post. All good except the outdrives are a bit short.
Has anyone found longer ones yet? I am really keen to get this to work.
Cheers
Chris

[Coelacanth]

Hi all,

I bought and fitted the arms and swing shafts as per first post. All good except the outdrives are a bit short.
Has anyone found longer ones yet? I am really keen to get this to work.
Cheers
Chris

Chris, did you get the 65.5mm or 68mm swing shafts? And about how much longer outdrive distance do you require? I haven't sourced longer outdrives yet but I've seen some that might work, one is a Losi part.

You can also mount the outdrives a bit further out on the diff shafts, maybe 2 or 3 mm outboard...I know it's not much but it might make a difference.

Lastly, the Lazer ZX-5 alloy rear hubs (mentioned by Mr. ED above) have much less offset than the stock Optima hubs, which will give you more options as well. They only cost $12 a pair, and are a stronger part due to the alloy construction. I'll need to do some measurements to be more specific though. Let me do some test-fits tonight with those blue alloy arms & stock Optima hubs and Lazer swing-shafts, I have both the 65.5 and 68mm ones.

[Coelacanth]

Chris, I did some test-fits, putting the blue alloy control arms & stock Optima hubs on one side of my Zebra Optima, then slapped on the wheel to get a visual on the camber & up/down control arm action. When I used the 68mm Lazer swing-shafts, they were a perfect fit. The 65.5mm shafts were a bit short but still workable, even without longer outdrives, unless you want totally vertical or weird camber. If you adjust your shock travel to get the control arms more or less parallel to the swing-shaft 'bones, I found the 65.5mm shafts might just work. Further, you could insert some shims--maybe up to half a millimeter or even as much as a millimeter--onto the swing-shafts before inserting them into the rear hubs, which would force them that much closer to the outdrives--but you might then have issues inserting cross-pins into the wheel side of the shafts/axles.

That said, it would appear the 68mm swing-shafts might be the perfect units for this mod.