"MINOR" engineering flaw in Revo suspension

[Sandho]

***This is only MY opinion on something I've found***

I've broken darn near every piece on a Revo already and I've come to the conclusion that the suspension has a MINOR engineering flaw in the area of suspension travel, down travel to be exact. I don't try and break parts but I also don't try NOT to break parts either.

The stock shock ends are getting torn out (as if you didn't know) due to the limited down travel (or extension) that the shocks allow. I personally don't think the aluminum ends are the answer to the problem. I tried them and I broke more shock shafts then I've ever broken plastic ends.
Pay close attention to when they rip, it's usually when you land upside down and the force of the ground is hyper-extending the suspension (down travel) causing too much force on single components instead of spreading the force over all of the parts.
Limit straps could stop this but I haven't found a solid enough place to mount them. The body mount is really the only effective place to mount to but there is far too much flex to completely solve the problem.

Take this how you will .........
My solution (or attempt to solve) is thin rubber strips (1/16" thick 1/4"W x 2"L) placed between the rear skid plate and the A-arms right below the arm pins. Look close at your Revo and you'll see the recess in the skid plate and you'll also see that the skid plate acts as the bump stop to limit the down travel. These rubber strips slow the arms down right before they stop. The skid plate will need some minor relief trimming so the arms can still move freely.
One more area I'm still working on is the push rods. Do a little test and you'll see how the shock ends are getting torn out.
With the Revo suspended, remove the screw that holds the push rod to the rocker arm and watch how much further the tire drops after the push rod is removed. Way Too Much!
I'm still working on this one to get it perfected but so far I have moved the lower rod end to the Inner-most hole and installed ONE of the rod spacers from the P-2 kit to extend the rod. This will allow the shock to be fully extended at the same point the A-arms hit their travel limit.
The shock compression will be another area I look at latter. The next time I service my shocks I will modify or possibly even remove the little blue bump stop to gain a small amount of shock compression.

To summarize what's happening...
When the suspension is fully compressed (bottoms out) all of the components are at their LEAST vulnerable position for breakage. The shock's bump stops are working and the rockers are applying straight even force on the shock ends ..... Everything is in line and working good .....
BUT .... When the suspension is hyper-extended from landing upside down or even barrel rolling, the suspension is in the MOST vulnerable position for breakage. The shocks are fully extended and the A-arms want to extend even more, pulling so hard on the shock ends it wants to wrap the shafts around the rocker post.
The end result becomes shock ends torn apart or even rocker post being bent. Look closely at the bent posts they'll bend down toward the A-arms from being pulled on so hard. Some more things are; the rockers can even break (I've had that too) or you could possibly even break the bulkhead (I haven't had that one yet but I'm trying).

Most of you will probably be thinking I need to learn how to drive ..... I think I drive fine.
The truth is I love to push my Revo to the limits and beyond. I have three of them .... I can afford to destroy one. Heck I'm still considering jumping my house someday. Driving around in circles and bouncing over some bumps is only fun for so long ... then I get bored and want to practice some anger management if you know what I mean.
I'm not lucky, there aren’t any good dirt tracks around here to race at so I have to resort to a small, limited track I built in my neighbor’s empty lot and bashing around anywhere else I can find. I still think the concrete skate park was the most fun and most expensive time yet. :spit:


An effective set-up that's been working for me so far is.....
*RPM Arms
*P-1 rockers
*Aluminum rocker posts
*GTR coated shocks & TiN coated shafts with stock plastic ends
*70w shock oil -- #1 piston in fronts, #2 in the rear
*Green front springs / Tan in the rear
*Modified P-1 push rod (inner most mount hole) --- the standard steel ones, they're cheaper to replace.
*Rubber strips in the rear suspension to cushion down travel.



Happy Bashing ....... and remember ...... It's not fun until something gets broken

 

[Tweak]

I picked up my first ever issue of a nitro racing mag at the LHS today and glancing at it on the way home. After picking through some editorials, I came across the pics of the Revo and even my wife commented about the suspension, It looks like there are two small plastic bars supporting most of the weight. I'm sure when they flex they allow the other parts a lot more wear. Thanks for the post SandHo, I am sure it will be very helpfull.

 

[jetmechG550]

How the hell can you have broken almost every part of the Revo? I've had mine basically since it came out. I race it and have hardly broken anything. The only shock ends I had problems with, were in the very beginning and it was the rears only. Conclusion as was from most everyone else it was the heat from the exhaust. I picked up the RD Racing ends before my replacements showed up and have been running them ever since, without problem. If your jumping and landing on the lid it doesn't seem like any truck would take that abuse for very long. There's a difference between bashing and abuse. It must be nice to have enough cash to have three Revo's and just beat the ever livin' crap out of em.

 

[Plaidfish]

Sandho, have you tried putting fuel tubing in the shock body under the Piston head? that will act as limiting straps or at least slow down the falling weight of the suspension so as not to hyper extend the shock.....I've used that trick on a few RCs to limit droop and it rocks.....

 

[outlaw]

The bulk of my problems with the REVO are caused by the exhaust's position. The problem I've had with only the rear shock ends is due to the the heat from the exhaust like jetmechG550 mentioned. On one occassion at the track, I had a not so hot landing on the rear of the truck, which pushed the exhaust further down the connecting rod until it was touching the rockers. By the time I pulled it off the track, the rockers had melted from the heat and friction (but were still usable).

I've had my REVO since they first came out last year and the components I've broken too often have usually been parts of the rear suspension (rockers, rod ends). Another part I've broken one too many times are the front axle carriers (at the pivot balls). Aside from that, the truck has been pretty solid for me at the track; I don't really bash mine.

Maybe someone will develop a heat shield for the exhaust.

 

[dfn_doe]

I'm curious how landing upside down is causing the shock to extend? No matter if the truck lands right side up or upside down the suspension should compress, one way it'll be the weight of the body compressing it(sprung weight) and the other it'll be the weight of the wheel and tire(unsprung weight). Am I missing something?

 

[mr_bob]

i think hes talking about when it rebounds there nothing stopping if from hyper extending

 

[Sandho]

If you land upside down it is rare you land flat on the roof ... usually it hits a tire first. When this happens it pushes on the suspension as if it were hyper extending.
All I'm saying is the A-arms allow the suspension to drop MORE than the shocks can extend. In a bad landing something is bound to give and that usually ends up being the shock ends.

If this happens on an off-road rig a limit strap is installed to eliminate any shock damage that could occur. On a Revo there isn't any good place to put a limit strap so I improvised by altering other parts of the suspension.