Porpoising Bluebirds
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06-04-2008, 09:53
Post: #1
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Porpoising Bluebirds
David and Brad:
I have been following your posts on this subject and found your results very interesting. I worked in a huge truck chassis/spring shop in my youth. Of course in those days rauckers were macho and never complained about anything ! Hear that Greg?? One thing I did learn about pickup trucks was that good shocks ere very important. We sreviced trucks that went to the oil fields and front suspensions were always being repaired. he Monroe rep had special shocks built for these units. My own experience is as follows: factory shocks on just about any vehicle are usually cheap junk. In 2001 I had a new Chev Duramax duallie crew cab. We had a 11.5 Alepnlite slide in on the back. It handld horribly. I dropped the rear shocks and you could compress them with one hand. Extension could be done by a child. Naively I took it to the deAler thinking they were faulty. Shop foreman brough out a new shock. We pumped it a bunch and it was the same. Installed 4 Rancho 9000's and it became a new truck!! Last year I took off he Sachs shocks that were factory on our 02 Bounder with a Freightliner. The shocks looked small enough to be from a Nissan pickup. Installed new Koni FSD's and I could drive without white knuckle fever. My point of all this jibberish is: Have you considered installing different shocks? I dont know what BB uses on the LXI's but maybe they are not enough shock. I know that Henderson had some real brutes at Q. Of cousre they were pricey. Once a vehicle starts porpoising the dynamics just keep it going. Sems to me that som real shocks would solve the problem. I now that BB uses Konis on some units but the FSD's are fairly new to the market. Alternatively have you tried going to Henderson,s? I find them overpriced but they are experts. my 2 pesos worth Bruce 1988 FC35 |
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06-04-2008, 09:56
Post: #2
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Porpoising Bluebirds
Bruce, I think mine are big Koni's, but I can't tell you the model or capacity. Strangely enough, the problem seems to be the suspension was overbuilt with the anti-sway bar rather than underbuilt.
BradBarton00LXiDFW bbartonwx@...
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06-04-2008, 11:05
Post: #3
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Porpoising Bluebirds
David,
Let's use the verb "galloping" instead of porpoising. My spellchecker likes it a lot better. And you're right about the combination ofweight transfer, road gallop and that ISRI air-loaded seat. If you don't have your seatbelt on, you're catching air under your derriere. BradBarton00LXiDFW bbartonwx@... Now you can invite friends from Facebook and other groups to join you on Windows Live⢠Messenger. Add them now! |
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06-04-2008, 11:52
Post: #4
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Porpoising Bluebirds
Hi Bruce, Thanks for the input and a sincere thank you for bringing up my favorite topic. I'm running Koni FSD's on the drive and on the tag, and Koni adjustables on the steer. Yes, Brad and I have tried everything regarding the LXi's porpoising and I appreciate your input too. I think that "porpoising" is the wrong term in this case. The LXi, in it's stock form, doesn't porpoise. Ninety percent of the time, it's very composed and very compliant, and this is why 99.99% of the owners are quite happy and do nothing to change it's behavior. What it does do is transfer weight violently from the front to back, and then from the back to front when hitting a fairly large perturbance in the highway (picture Hwy 10 thru Louisiana). As Brad will surely agree, most LXi owners will cringe a little upon sighting an oil spot on the highway ahead, a sure sign that most vehicles experience some sort of suspension "event" upon traversal. Not so in the LXi. If both front tires hit the dip simultaneously, then the event is probably no more severe than any other 50K lb vehicle. However, if the dip is asymmetrical, meaning one front tire hits it first, which is usually the case, well... you had better have your seatbelt on cause the bus's front tires will hit hard, barely registering any suspension travel, and instead toss the bus's weight rearward only to load the rear suspension just when the rear tires are hitting the bump. At this point, and thanks to the SRI air seat, the driver is catapulted toward the ceiling. The weight transfer, to-and- fro, can be so severe you'd think that a front tire or airbag is about to blow. I tried everything to compose the bus, tag axle air pressure, tire air pressures, Koni FSD's, full stiff front Koni's, heavy cargo weight distribution, finely tuning ride height, countless calls to the "experts". Everything improved the problem, but nothing solved it. Not until I removed the front sway bar. Then nirvana. The anti-sway bar on slide equipped LXi's is monstrous: 2.125" in diameter and possessing over 4000 lb/in in spring rate. It's capable of creating a 64000 ft-lb moment, or torque, at full deflection. It virtually eliminates independent wheel motion at the steer axle, and when it winds up - look out! If your an LXi owner, it's gotta go: toss it in the garbage! As I've learned, the LXi really is capable of a very good ride. It's got good weight distribution, high tech hour glass shaped air bags, 315/80/22.5 tires, great Koni FSD shocks, and the Ridewell suspension typically provides very good independent wheel motion with good roll center and huge, long life, rubber suspension bushing providing lots of compliance. All the ingredients are there, but every LXi driver that you talk with will tell you that their buses ride rough. I've had one owner tell me that after purchasing the bus brand new, he traded it 3 weeks later for an H series prevost because the ride was so rough. I could have saved him some money... BTW, how's that Monaco? David Brady '02 LXi, NC brad barton wrote:
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06-04-2008, 12:56
Post: #5
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Porpoising Bluebirds
Hi David:
It appears that my suggestion is worthless. I tried. I hope you guys get that problem totally solved. Ther is a fellow who hnags ou on RV.net and is also the President of the Yahoo Cat forum. Handle is Wolfe 10 or wolf 10. He is very knowledgeble and owns a Foretravel. I do remeber that he worked with Roadmaster sway bars. BTW: Do you use the urethane bushings? The 99 LXI that I drove was probably the best handling large vehicle I have ever driven. My new Monaco: We are loving it but there is a huge larning curve. Lts of electroncs that are new to me. Today I was telling my wife I will have to install the Pressure pro system when I discoverd the Alladin computer has a basic TP feature. All the wiring, both coach and chassis are multiplexed. Everything is interconnected. You cannot open the drivers door until the engine is off or the park brake is applied. This is a 4 slide unit. The drivers chair automatically moves forward when you bring in that slide. This is no BB but the build quaity seems excellent.Lots of hardwoods, excellent drawer construction, hige Jenn Air residential fridge, 37 inch LCD and another 27 inch in the bedroom ( Sharp Aquos), energy management system, 2800 Magnum tru sine, electric hose And power reels, lots of leather, one piece windshield, semi monocoque, 10 air bags and 8 shocks. Where it is lacking as compared to a Bird is the 12 volt system. only 6 6volt wet batteries for the coach. The BB's I looked at had 4 or more 4D glass mats. BB also uses a huge alternator. I think mine is 200 amps. But I do notice a lot of small things that are not up to snuff. I guess I shouldnt compare it to my Bird. If it had Sporlan valves I would feelat home!!! I am confident we will get lots of enjoyment from this baby. We are currently at the J in Beloit on our way to Canada. Bruce 1988 FC |
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06-04-2008, 13:27
Post: #6
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Porpoising Bluebirds
Thank you. 'porpoising' is a greek hazing task where you have to
bring a large date to the beer bust. Greg --- In WanderlodgeForum@yahoogroups.com, brad barton <bbartonwx@...> wrote: > > David, > > Let's use the verb "galloping" instead of porpoising. My spellchecker likes it a lot better. > And you're right about the combination of weight transfer, road gallop and that ISRI air-loaded seat. If you don't have your seatbelt on, you're catching air under your derriere. > Brad Barton 00LXiDFW bbartonwx@... > _________________________________________________________________ > Now you can invite friends from Facebook and other groups to join you on Windows Live⢠Messenger. Add now. > https://www.invite2messenger.net/im/?sou...AddNow_Now > |
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06-04-2008, 14:22
Post: #7
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Porpoising Bluebirds
Bruce, Now your making me jealous, there's nothing like new. Four slides has gotta blow your mind. I've been in a few and the space is impressive. It sounds good and it looks good too; I checked out the Monaco website. I'm interested to see what kind of factory service they have. Certainly CCW is doing wonderful things with Wanderlodge factory service, but prior to them we bird owners definitely suffered in that category. A friend with a Prevost tells me about the free parts shipping and the automatic line of credit... About the '99 LXi, I'd expect the non-slide LXi's not to have the galloping problem. The non-slide BB's have a 1.75" anti- sway bar. While still too stiff in my opinion, it's a whole lot lighter than the 2.125" diameter bar on the slide equipped LXi's. The difference in stiffness is a factor of two: 4000lb/in versus 2000lb/in spring rate. David '02 LXi, NC birdshill123 wrote:
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