Re: Rear vibration 65-70mph+ Reply #25 – July 06, 2014, 11:54:08 am Allison 3000 and 4000 series transmission:4th gear 1:15th gear .75 OD6th gear .65 OD Quote Selected
Re: Rear vibration 65-70mph+ Reply #26 – July 06, 2014, 04:51:43 pm Krush,Is this vibration something you can feel at the driver's seat or do you have to have someone else go back to the bed area to notice it? Quote Selected
Re: Rear vibration 65-70mph+ Reply #27 – July 06, 2014, 06:16:42 pm Quote from: rsihnhold – July 06, 2014, 04:51:43 pmKrush,Is this vibration something you can feel at the driver's seat or do you have to have someone else go back to the bed area to notice it?I feel it up at the driver seat (I travel alone, so I haven't been to the back underway yet). It just starts to be noticeable at 65. 70-75 it vibrates the floor slightly and I can feel it in my foot. It isn't "shake the mirrors" bad like some people with this same problem have had on other coaches. Quote Selected
Re: Rear vibration 65-70mph+ Reply #28 – July 07, 2014, 11:02:16 pm Tires in the air and spin it up. Check the DS (remove it) and check the joints and find someone that can verify DS balance. Slow down and enjoy the ride until you get things figured out. pc Quote Selected
Re: Rear vibration 65-70mph+ Reply #29 – July 20, 2014, 05:29:35 am No progress on my problem/solution, but I did come across this: http://www.allisonelearn.com/lms/scorm_host/scorm_modules/1.0/en/tt-adv-3k4kevol01.0wbt/documents/01-wt-98.pdfIt's regarding the upgraded retarder that came out in 1998. One thing that interested me:* P3 Carrier P/N 29530458 must be used on MY 1998 uprated MD 3066 models due to that models HP and torque ratings. P3 Carrier P/N 29530458 can be identified by a circular raised rib on the rear face of the carrier (page 3)Page 7 has an explosion of back end of the transmission. There are two identical bearings on the p3 carrier. #13 &27 (race) and 58/51. From what I see, #60 looks to be the retaining nut that people talk about not being torqued enough by allison at original construction. Looks like to get to it all that is required is remove driveshaft, then yoke, then seal.As for replacing the bearings, it looks like #58 can be replaced fairly easily. #13 requires removing the retarder (if I read drawing correctly).Edit: here is what it all looks like put together. The 2nd picture show each planetary set separated. p3 has the bearing on it: Allison MD3060 Planet Set Close Ratio | eBay Quote Selected
Re: Rear vibration 65-70mph+ Reply #30 – July 20, 2014, 08:19:36 am Good information there. So, it looks like the M70 X 2 retainer nut is the historically undertorqued part that can cause the bearing(s) to go out? I have a Q for you. Does your retarder have what looks like a harmonic balancer on the output shaft? It's my understanding that some 3060 have this balancer and some don't, with the P3 problem usually showing up on units with the balancer. It's checked by gently prying up and noting excess play in the taper bearing. Since it's most likely the output end bearing would be the damaged item, it seems like it would be possible to replace bearing and seal in place though I wonder how one would lock shaft so the retaining nut could be torqued. Quote Selected
Re: Rear vibration 65-70mph+ Reply #31 – July 20, 2014, 11:27:10 am Are you positive that's your problem?? pc Quote Selected
Re: Rear vibration 65-70mph+ Reply #32 – July 20, 2014, 12:15:17 pm Seperate from the diagnosis of your vibration issue I noted the 300 degree temp max in the test for the retarder itself without a degradation in effectiveness."Retarder capacity is reduced" past that not damaged. Quote Selected
Re: Rear vibration 65-70mph+ Reply #33 – July 20, 2014, 09:53:31 pm Quote from: Chuck Pearson – July 20, 2014, 08:19:36 amGood information there. So, it looks like the M70 X 2 retainer nut is the historically undertorqued part that can cause the bearing(s) to go out? I have a Q for you. Does your retarder have what looks like a harmonic balancer on the output shaft? It's my understanding that some 3060 have this balancer and some don't, with the P3 problem usually showing up on units with the balancer. It's checked by gently prying up and noting excess play in the taper bearing. Since it's most likely the output end bearing would be the damaged item, it seems like it would be possible to replace bearing and seal in place though I wonder how one would lock shaft so the retaining nut could be torqued. Everything I've heard regarding "problems" has been second hand, word of mouth, etc etc. Some of it may be true, some not, some may be wrong. That's ok, I'm used to this as it's what I do for a living, lol. I haven't called up Foretravel or Allison yet because I've just been slammed with travel and work. However, I will talk to them.In my earlier posts, I mentioned that I crawled under the coach and push/pried/pulled/banged on everything possible and didn't notice anything terrible. There may have been a TINY bit of up/down play on the balancer/yoke, but it only showed when using a pry-bar. My transmission does have the big balancer around the output yoke.My vibrations start at 65mph and are not horrible. They don't shake mirrors or glass. But, I don't like it.I may NOT have a failed part at all! To me, the "problem" is that the rear end gearing of 5.13 is too low and spinning the driveshaft too fast. There's little to no vibe below 60mph. See my quick number calc earlier in the thread to show what a different set of gears would do for drive shaft RPM.I'm going on a short 500mile round trip over the next week. I'm just goign to stay around 60mph max. Once I get back and some time, I'll do some investigating. First, check yoke/balancer for runnout. Next, remove driveshaft and go up to 70mph on tranny. etc etc.I looked up the part numbers for the bearing/race/nut/lock. $10-20 each for genuine allison on ebay. Quote Selected
Re: Rear vibration 65-70mph+ Reply #34 – July 20, 2014, 10:45:40 pm The balancer in my coach has a slight amount of play in it when prying up with a bar. I would rather it have none but in conversation with Foretravel mechanic was told that a small amount is normal. I'd guess it at about .025". No vibration at any forward speed that I can detect. Vibrates a bit at idle in gear. Hearsay that if driveshaft is removed for towing that it needs to be replaced in original orientation. I've wondered why this should be necessary, is it possible that driveshaft is somehow balanced/indexed to trans, diff? There's enough rotating mass there for an out of balance to show up as vibration. Seems like the axial thrust lines of trans wouldn't do it unless there is a major mechanical issue. Quote Selected
Re: Rear vibration 65-70mph+ Reply #35 – July 20, 2014, 11:03:20 pm Our engines/transmission are not bolted directly to the frame but have mounts. They usually fail slowly and may transmit vibration to the rest of the coach at certain speeds when they do. Good to do a check here before going too far looking at a transmission shaft problem.The generator is a good example. While the mounts may look in good shape from above, when you pull the generator out on it's slide and look under, the damage is readily apparent. Our generator vibration was all mount related as the rubber mount was absolutely shot underneath. Pierce Quote Selected
Re: Rear vibration 65-70mph+ Reply #36 – July 21, 2014, 08:24:13 am Chuck, the reason for putting the drive shaft back in the same position is the joints must be "timed", in other words, the cross must both be in the same position or they will be fighting each other. So same position or 180 degrees out. Quote Selected
Re: Rear vibration 65-70mph+ Reply #37 – July 21, 2014, 10:05:09 am Quote from: Gayland Baasch – July 21, 2014, 08:24:13 amChuck, the reason for putting the drive shaft back in the same position is the joints must be "timed", in other words, the cross must both be in the same position or they will be fighting each other. So same position or 180 degrees out.And how many tow truck drivers would pay attention? Another big reason to pull both axles to tow and leave the driveshaft alone.Pierce Quote Selected
Re: Rear vibration 65-70mph+ Reply #38 – July 21, 2014, 10:38:50 pm When purchased, my coach had 4 year old Toyo tires and it had a bad vibration in the front (feel thru steering wheel) and rear (feel thru seat bottom) starting at 55 mph. I thought it might have been balance and maybe drive shaft. Took the coach to my trusted chassis shop and what do you know, all six tires were badly out of balance (none had any weight on the wheels!) and 5 of the six had to be trued. Now all of the vibration is gone. So have a good shop check the run out and shave/true the tires if necessary. You would be surprised how many tires are out of spec and/or the run out spec is so large that it creates vibration issues. Quote Selected
Re: Rear vibration 65-70mph+ Reply #39 – July 21, 2014, 11:22:12 pm I had a similiar problem on the 95 240 and found some idiot had put golf balls inside. At slow speed the front end wobbled like crazy.Once removed all was better.JohnH Quote Selected
Re: Rear vibration 65-70mph+ Reply #40 – July 23, 2014, 12:14:23 am We just hit 300 degrees hot on a Colorado down mountain run. Did manually back off retarder a little several times, but the coach went down the hill slow & safe without brakes the whole way. The higher tranny temp did increase the coolant temp as the heat exchanger did its job. Downshifting to increase RPM to keep coolant flowing through radiator is a good idea. Quote Selected
Re: Rear vibration 65-70mph+ Reply #41 – July 23, 2014, 12:17:18 pm Barry,What road were you on in CO? I am getting ready to go through CO next week on my way to OR. I am concerned about taking 70 vs 80. Did you Trany temp reached 300?Thank you,AL Quote Selected
Re: Rear vibration 65-70mph+ Reply #42 – July 23, 2014, 01:07:05 pm Quote from: Barry & Cindy – July 23, 2014, 12:14:23 amWe just hit 300 degrees hot on a Colorado down mountain run. Did manually back off retarder a little several times, but the coach went down the hill slow & safe without brakes the whole way. The higher tranny temp did increase the coolant temp as the heat exchanger did its job. Downshifting to increase RPM to keep coolant flowing through radiator is a good idea.My limited understanding is it takes one hour over 300 degrees to start to damage normal old style ATF.Transynd is probably more heat resistant? Quote Selected
Re: Rear vibration 65-70mph+ Reply #43 – July 23, 2014, 04:26:25 pm Al, We were eastbound on US 160 between Alamosa & Walsenburg. We did fine. 300 is acceptable for our engine-tranny on major down hills.I-70 has westbound climb up out of Denver and other parts have hills. Don't know about I-80, but it looks a little less windy on a map. Others will know more.The old rule was petroleum lubricants can break-down above 250. Synthetics are MUCH higher and that is why transmissions, especially with retarder need to be using synthetic. And Allison Transynd is supposed to be the recommended synthetic, as it is made for Allison. There are other synthetics that say they are same or better, but why not use Transynd for that expensive part. Quote Selected
Re: Rear vibration 65-70mph+ Reply #44 – July 23, 2014, 05:14:42 pm My Trany is on Transynd & most temp it showed was 230 while running it at 70-75 for a while on 95+ TX hot day trip.I have been on 80 and it is easy enough. I want to take 70 west and I have been on some parts of 70 ... up to Vail area. I just don't want to struggle so much going so many up hill roads but 70 be fun i think. I will make up my mind when i leave Caste Rock, CO next Thursday go N or Go W ... Quote Selected
Re: Rear vibration 65-70mph+ Reply #45 – August 28, 2014, 03:44:14 pm I can 2nd an earlier recommendation for Stewart & Stevenson in Longview to deal with the vibration issue. We had what I think was the exact same problem on our 97 U295 about 8yrs ago. As I recall, at any speed over about 50mph we would get a violent shuddering at the rear of the coach. It was notceable up front but really bad at the rear. It was an internal bearing/dampener issue in the transmission. I would have to look up the paperwork to remember exactly what it was called. Anyway, it was about a $2500 fix. That included a full conversion to Transynd. No problems whatsoever since then. Quote Selected
Re: Rear vibration 65-70mph+ Reply #46 – August 28, 2014, 04:01:35 pm Dale,Might be a good idea for a customer of Stewart & Stevenson to call them and nail down the cause of the problem.What transmission, year, model, possible relationship to retarder, possible preventative check, what parts have to be replaced, Allison bulletin, etc.? Nice to be able to avoid a $2500 fix down the road.Good for members to avoid wives' tales and get the information from the horse's mouth. Pierce Quote Selected
Re: Rear vibration 65-70mph+ Reply #47 – August 28, 2014, 05:12:45 pm Quote from: bdale – August 28, 2014, 03:44:14 pmI can 2nd an earlier recommendation for Stewart & Stevenson in Longview to deal with the vibration issue. We had what I think was the exact same problem on our 97 U295 about 8yrs ago. As I recall, at any speed over about 50mph we would get a violent shuddering at the rear of the coach. It was notceable up front but really bad at the rear. It was an internal bearing/dampener issue in the transmission. I would have to look up the paperwork to remember exactly what it was called. Anyway, it was about a $2500 fix. I'm going to bet P3 bearing based on a number of 96-98 U270/295 36' coaches reporting this issue (if you search the forum for P3 bearing you'll get a number of hits and threads with good descriptions of the issue). Quote Selected
Re: Rear vibration 65-70mph+ Reply #48 – August 28, 2014, 05:19:41 pm I spoke with my father to see what he remembered about this repair because he was the one that actually dealt with it. His recollection was that there was a batch of Allison transmissions with a design defect that, for a while, were repaired for free by either Allison or Foretravel. Ours failed after the coverage period expired so we got no help. I'm no expert on the construction of the transmission so hopefully this makes sense....the defect was internal at the input shaft. As Michelle stated, it was called a P3 Bearing or P3 Carrier and required some degree of tear-down to be repaired on our unit. Some only required adjustment or tightening but ours was too far gone and had damaged internal bearings. We didn't drive it long after the symptoms started showing up so if you think you're getting this type of vibration you should get it checked ASAP. Foretravel or Allison may be able to tell you if your particular unit is one of the unlucky ones with the defect. Quote Selected
Re: Rear vibration 65-70mph+ Reply #49 – August 28, 2014, 05:24:41 pm Thanks to Michelle (and Berry Beam for the great work), here it is: U295 Driveline vibration issues and the Allison service letter: http://www.allisonelearn.com/LMS/scorm_host/scorm_modules/1.0/en/TT-ADV-3K4KEVOL01.0WBT/Documents/04-WT-05.pdfAllison Mechanic's Tips for 3000/4000 models: http://www.utxchange.com/pdfs/MechanicsTips/MT4015EN.pdfProspective buyers might see it this has been done on the coach they are considering. Pierce Quote Selected
Topic: Rear vibration 65-70mph+