[SOLVED] TRF511 - Excessive Vibration from Rear Wheels

[djmcnz]

Hi again guys,

Looking to see if anybody has some insight on my problem.

My 511 has recently developed excessive vibration in the rear wheels under power. The best way to explain it is to say it's like the wheels are horribly unbalanced - or the outputs are running in elliptical rather than circular cycles.

The effect is significant, even under weighted load, to the point that it severely affects rear traction. 5 seconds a lap over a 35 second lap to not point too fine a point on it... and on a dead flat astro test surface the rear end hops like a bunny.

It's not that I'm inexperienced, this particular chassis has seen about 150 packs without a problem in the past...

So, first thing I did was check the wheels and swap them out even though they looked and felt fine (no cracked rims either).

Second was to disassemble, check, clean and reinstall the diff. There appeared to be no problems with it.

Finally I've swapped the outdrives (which were reasonably new) with brand new ones and made sure it was all seated properly.

None of this has fixed the problem. So I assumed the uni-shafts were bent (!) but have visually inspected these and also dipped them in gunk and ran them over a blotter sheet to check - they seem true.

Anything else obvious to check? The chassis squares up and the rear-end all seems tight and true... I'm at a bit of a loss here and this is killing me...

Separate question - do those of you using the Tamiya alu front steering assembly Hop-Up notice that the lay-back mounting posts can't be tightened to a "no-slop" config? At max tightness I still get ~0.5mm of play - is this typical?

Thanks!