duragg Posted July 31, 2012 Author Share Posted July 31, 2012 I am a pilot also: "crashing and burning" are not good analogies... I did find another shop to do 7000rpm balance. Got to get ready for the big Zcon show here in September. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted July 31, 2012 Share Posted July 31, 2012 The tripod axles always shake when in full droop because of the angles. Speaking of planes.......Czech Mate is back with some huge innovations for reno this year. Quote Link to comment Share on other sites More sharing options...
duragg Posted July 31, 2012 Author Share Posted July 31, 2012 Love Czechmate. My favorite. Nice artwork on the wings... Quote Link to comment Share on other sites More sharing options...
jt1 Posted August 1, 2012 Share Posted August 1, 2012 duragg, back in your first post you said it does it in neutral? Without the driveline engaged? jt Quote Link to comment Share on other sites More sharing options...
duragg Posted August 1, 2012 Author Share Posted August 1, 2012 Correct on below. If ripping down the freeway with the harsh buzz / vibration and you you push in clutch and select neutral there is no change. Of course the only thing that really disengages is the clutch / flywheel and engine. When I had the R180 in this issue was not present and all the components were otherwise the same. Unfortunately I've not had a chance for further investigation quite yet. duragg, back in your first post you said it does it in neutral? Without the driveline engaged? jt Quote Link to comment Share on other sites More sharing options...
jt1 Posted August 1, 2012 Share Posted August 1, 2012 OK, I was thinking in neutral on the jackstands. My bet is on the driveshaft angles. Try the laser pointer thing, it works real well in my experience. This sounds crazy, but I've pulled a plug wire off and run a car on stands to try and tell if the vibration was engine/driveshaft frequency or wheel frequency. Works best in whatever gear is direct. jt Quote Link to comment Share on other sites More sharing options...
duragg Posted August 2, 2012 Author Share Posted August 2, 2012 But driveshaft angles different now than with R180? Quote Link to comment Share on other sites More sharing options...
jt1 Posted August 2, 2012 Share Posted August 2, 2012 Well....maybe. I guess you changed mustache bars, and all the mounts were moved around some, and the different front mounts. It's really just a process of elimination. I've spent a bunch of time chasing vibrations, and it can be quite frustrating. Sometimes you have two vibrations going on, and they hit a harmonic at some point. Are the pinion bearings tight, and the rear bolts on the diff tight? Mark had one of the rear bolts work loose, and it was making a real fuss. We thought the diff was going out. jt Quote Link to comment Share on other sites More sharing options...
duragg Posted August 2, 2012 Author Share Posted August 2, 2012 Agreed. Yes the pinion bearing feels tight and the LSD spins freely and quietly. The only thing that is loose and obvious are the snap-in side shafts whose OD splines wiggle in the ID splines of the spider gears as shown in the video. Hopefully this weekend I can dig in some more. I'd like to wipe out this problem before moving on with the new suspension. Quote Link to comment Share on other sites More sharing options...
jt1 Posted August 3, 2012 Share Posted August 3, 2012 I guess if I was working on it, I would pull both halfshafts and the diff flanges, then run the car on the stands and see if the vibration was still present. If so, I would look at the driveshaft ujoint angles. If not, I'd go to the diff flanges. Since you've tried different halfshafts, that would seem to be eliminated. Have you checked the companion flanges to be sure they are tight and true? jt Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 4, 2012 Share Posted August 4, 2012 The question is did they mean 'balanced to 3200' or 'balanced at 3200'? Many times balancing is done at a surrogate speed, with settings on the machine far lower than actual speed. For turbine wheels that run on 24,000 rpms, the speed we use is in the 1,800~2,400 rpms. The Aluminum one we had done was balanced for use to 10,000 rpms--what actual speed was I don't know (I would assume around 900~1200 rpms with similar load cel setup) -- we haven't had a problem. 3200 seems like a very low number, generally you balance for terminal speed. A 4 speed car (or a 5 speed run in 4th) will easily hit anywhere between 5500~6500 in stock form. A modified driveshaft IMO should be balanced for the redline of the engine, as in 4th chances are good you WILL see that driveshaft speed. Good balance at high speed will reap benefits at lower speeds. Not saying this is the issue, but in general just asking if everybody is balancing for that low speed? Now if they spun it to 3200 and balanced well...then it's better specification than ours! In which case you're golden! Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted August 4, 2012 Share Posted August 4, 2012 There is a complete R200 setup with axles driveshaft, mounts and mustache bar on ebay this morning for $229. Somebody should ****** it. (it isn't mine). Quote Link to comment Share on other sites More sharing options...
duragg Posted August 4, 2012 Author Share Posted August 4, 2012 The DS builder said it balanced beautifully and his machine has 3200rpm capability. I didn't know to dive much deeper. (The TPE331 powered Mu2 I am flying this weekend is a 41,230rpm shaft btw... yow.) I know the prop balance guys always say "vibration is vibration" it will always be there no matter what Rpm, out of balance is out of balance. And this was the same DS on the R180 that ran smooth, so I am back to looking at my R200 this weekend. Not trying to be a snitch, but there is also an R200 I might try to ****** up in northern AZ this weekend. The old crank is being a ***** and parting out the *****. Quote Link to comment Share on other sites More sharing options...
rags Posted August 4, 2012 Share Posted August 4, 2012 I know it would seem weird that the problem would be before the diff since you only did a diff change to have the situation come up, but are you by any chance using a BW trans? The rattling noise heard in the second video sounds exactly like my BW trans do when they lose their tailshaft bearing. I've gone through 3 of these now and figuring out the vibration was coming from the trans and not the diff/axles the first time was very difficult. A stethoscope on the trans while in gear and on the lift will tell you the condition of the trans. If the tailshaft bearing is worn badly, you will also be able to see the front driveshaft u-joint slightly wobble around while spinning. The wobble will not be steady but you will be able to see it. Not saying this is your problem, just giving you some insight from my experience. Joe Quote Link to comment Share on other sites More sharing options...
madkaw Posted August 4, 2012 Share Posted August 4, 2012 You ve gone thru 3 bearings ? I'm running the bw trans and always wondered if it could be an issue. So you can hear the problem turning the shaft by hand or does it have to spin faster? Did you ever put a dial guage on to measure run out on the shaft or just went by ear Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted August 5, 2012 Share Posted August 5, 2012 (edited) Boy, the profanity filter is really touchy. My message said to either (g r a it or (s n a t c h) it. That is pretty funny. Edit: I must have a virus; I don't know how that smiley face got there. Edited August 5, 2012 by RebekahsZ Quote Link to comment Share on other sites More sharing options...
rags Posted August 5, 2012 Share Posted August 5, 2012 I don't bother changing the bearing, I change the trans. When it gets really bad, you can pull the driveshaft and move the output shaft of the trans side to side. A good trans will have some play but the bad ones the play gets very excessive. I have opened up a few of them and for some reason, it appears that the countershaft is located too far away from the primary shaft causing a significant amount of play. I don't claim to be a transmission engineer and there is probably a reason for how and where the countershaft was placed but it just does not seem right to me when comparing the play with any other model trans. Oh yeah, I forgot to mention, when this trans starts acting up, it is getting replaced with a Z32 trans Joe Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted August 5, 2012 Share Posted August 5, 2012 MU-2 is a sweet plane and has a deceptively low landing speed for the wingspan and it's great speed. It's also pretty cool that you don't need to wait for a pushback. One of the coolest civil planes ever. Quote Link to comment Share on other sites More sharing options...
duragg Posted August 6, 2012 Author Share Posted August 6, 2012 Yes thanks we do love the Mu2. Maligned and a bit unusual, but as long as a firm grip is kept on the reins will respond wonderfully. Flew our short body to Page, az, and then test flew a long body. Final approach speed was around 101kts in each case. Never used reverse thrust to back up the plane. It exposes the $25k / copy prop blades to rocks and increases the chance of FODding the 1st stage compressor on an engine valued at $250k / copy. *somebody* caused this video to happen: And now we resume the regularly scheduled program: Having a Biattch of a time finding replacement snap-in side axles. I don't want to pull the rear end apart without some spares ready to go. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted August 6, 2012 Share Posted August 6, 2012 Just realized that someone had photoshopped the swept wings onto Czechmate..........a very good troll got me. Quote Link to comment Share on other sites More sharing options...
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