Real bulletproof 5th scale suspension on a Savage
 

Hi fellas,

thought I'd share my thoughts and findings on this topic.

After getting tired of the Savage suspension (it just doesn't hold up with the added weight of a brushless setup IMHO) I searched for some beefy 5th scale components that I could use on a Savage (and maybe on my twin truggy later on).

My first idea was to use Losi 5ive-T parts, but as it turned out, they are waaaayyy too big and heavy, so I had to scrap that idea.

Then saw a complete 'backend' of a Redcat Rampage XB-E 5th scale Buggy on ebay for cheap and thought "give it a try".
Well, it seems like I was really lucky :)
First, I think it can be made to fit on a Savage and second, there are a lot of options to choose from because Redcat and other brands make a whole line of 5th scale cars with similar suspension components. You can even get FLM ball-drive CVDs and 7075rc alloy steering knuckles and carriers for them, very nice.

When you look at those parts, you can see that they have "buggy-stlye" geometry/layout (and not 1950's russian truck geometry like on the Savage) and are very beefy because they are made for much heavier cars. Hingepins on the diff side are 6mm, on wheel side 5mm, bearings are 10x18x5 for the buggy arms with 10mm axles. For axles there are two options, one with a thread at the end for FG-style 18mm squares, one without thread but pinhole which could be used with 17mm or 24mm hexes. Dogbones are 12mm ball diameter with 6mm shaft and also bigger diameter pin than 8th scale components.

There are two different A-arms and knuckles available, from Rampage Buggy and Rampage Monster Truck. The Monster-Truck ones are even beefier and it's said the V3 MT arms are made of a better plastic (PA66) than the ones before.



As it seems, there are only two bigger problems to make them fit on a Savage:

First is to attach the 12mm ballend dogbones to the Savage's (CEN in my case) diff outputs.

So far I've come up with different ideas to accomplish that:
1. Drill out the Savage diff outputs to 12mm and also widen the slot. Probably not the best idea because HPI drivetrain components tend to be soft and wear down fast, with the cup being thinner after drilling it out that will be even worse.
2. Use a Redcat (or some other largescale) diff output. Largescale diff outputs seem to use 8mm shafts, so it needs to be turned down to 6mm diameter. Problem with that is, that the Redcat diff outputs are 21mm outside diameter, one would have to dremel the hole in the bulkheads, I am not sure yet if there is enough material left when doing so.
3. Use CEN GST-E Heavy duty diff outdrives with the CEN 8mm outputs and diffs. Eliminates the 6mm shafts and also there are no pins inside the diffs anymore that could break. Problem with that is, that then CEN 8mm output diffs use larger bearings and thus cannot be used with Savage diffhousings, one would have to change the whole diffhousing/bulkhead setup to CEN. Apart from that, the CEN heavy duty 8mm diff output is made for 12.5mm ballends so there will be some slack, probably not good.
4. Use FLMs extended 11mm ballend dogbones and stock Savage cups on the diffside and stock Redcat cups/axles on the wheel side. Drawback would be that you don't have CVDs then and the slack on the axle cup because FLM dogbones are 11mm bals and Redcat cups are 12mm.
5. Use FLMs extended 11mm ballend dogbones and stock savage parts on both sides (with 8x18 bearings instead of 10x18). Drawback would be the 8mm axle weakpoint then. On the plus side, the bearings will be stronger.


Second is the length of the dogbones and cups compared to the a-arms. When the dogbone is properly spaced in the cup, the arms need to be a little more to the outside than stock savage arms.

1. Try to find a shorter outdrive cup or dogbone/CVD so that everything lines up nicely.
2. Make new hingepin braces with holes spaced a few millimeters more apart.





Hop Up Parts:
http://7075rc.flyingcart.com/
http://www.rampageshop.com/aluminum-hop-ups.html
http://www.fastlanemachine.net/produ...?cat=Redcat+XB



Pictures of the Redcat Rampage XB-E buggy parts compared to Savage parts, FLM extended Savage arms/bones, CEN heavy duty parts and ThunderTiger ST-1/MT4G3 parts (click on pics to get highres version)

http://i54.photobucket.com/albums/g1...psb4c5f060.jpghttp://i54.photobucket.com/albums/g1...psefd6abd5.jpg






Pictures of Redcat Rampage MT V3 parts (hex is 22 or 23mm unfortunately so the stock ones are not of much use):

http://cs-shop.de/bilder/produkte/gr...PEC-4-_b17.jpg
http://cs-shop.de/bilder/produkte/gr...SPEC-4-_b6.jpg
http://system.netsuite.com/core/medi...2154f79b53a7f7

Put the parts together for a first rough testfit. Looks good.
The lower shock mounting position on the Rampage buggy arms is almost the same as on a stock Savage A-Arm.

http://i54.photobucket.com/albums/g1...ps7e981372.jpg


If I see this correct on the photos, the shock mounting position on the Rampage MT Amrs is a little
more outwards, should be better for Innovative-RC or LST shocks.
http://ecx.images-amazon.com/images/I/41QR3A0wvSL.jpg

Have checked if the Redcat diff outputs can be turned down to 6mm shafts so that I would be able
to use the Redcat dogbones (or FLM balldrives). Well, unfortunately the pinhhole in the shaft is
at the wrong position and too big. Drilling a new one is not possible because it would interfere
with the old one. Not nice. Other ideas would be using a wheel axle and turn it down to 6mm, problem
with that is, that most (if not all) wheel axles are hollow so that won't work either. Another idea
would be to make some custom diff output shafts like the ones from RC-Monster but with 6mm diameter
inside the diff and 8mm outside, so that a diff input cup could be attached. Downside is, that this
will make everything wider, so one would have to mount the arms more outwards, also not easy.

For people who want to use Savage axles, I think there is a way to get it to work using stock Savage
axles and diff outputs with FLM extended 11mm dogbones. To fit the Savage axles in the Redcat hubs,
replace the 10x18 axle bearings (for the buggy, MT bearings are different size) with 8x18 bearings
(or use a spacer sleeve). To get the length correct, make custom hingepin braces with holes more to
the outside.

Since I don't want to use Savage axles anymore, the only easy (but not cheap) option I see would be:
Have some custom dogbones made that are a tad shorter than the Redcat ones and with 12mm ballend on
the axle side (for Redcat axle cups) and 11mm ballend on the oder side (for Savage diff output cups).


Got some 10mm axles and 24mm hexes from a Reely Carbonfighter 3 (also sold under "Smartech" label),
and test-fitted them. Looks like this would be a good option for people with Baja or XL size chassis
and 24mm wheels, it gives about one inch of extension per side.

http://i54.photobucket.com/albums/g1...ps7125cee5.jpghttp://i54.photobucket.com/albums/g1...ps20a98737.jpghttp://i54.photobucket.com/albums/g1...ps2775877d.jpg
http://i54.photobucket.com/albums/g1...psacceabc6.jpghttp://i54.photobucket.com/albums/g1...psdc445ab4.jpghttp://i54.photobucket.com/albums/g1...ps9c1b084d.jpghttp://i54.photobucket.com/albums/g1...psa8209525.jpg

Nice writeup, with pics too!!!

I tried to mod a savvy to use lst and cen parts. Never really finished, then sold all of my savvy stuff, just got tired of the many faults.

I have really though about going to a cen e gst, not sure how they hold up. Must be better than the savvy, and better than a lst. I have had good success with the lst though, best so far that I have tried.