Fleet Tacoma Bucking/Shuddering/Bouncing

Just returned from a 6k miles cross country trip and got the porpoising effect on some sections of segmented, concrete on I-80 and other roads in the East. Mostly on older sections, but also on a new section in Iowa. I estimate it happened on a total of 200 miles out of about 5k of interstate highways, so will probably just slow down and live with it in the future. It has not happened driving roads near where I live so no way to easily test any modifications.

I have an FWC fleet on a 2008 Tacoma with 76k miles, V6, 4x4, TRD off road and E rated Cooper AT3 running 45 psi rear, 40 front, two additional leafs in rear springs, everything else original including the shocks.

Porpoising happens on all sorts of vehicles. Google for "highway porpoising" and you will find all sizes and brands of trucks, RVs, trailers etc. reporting this problem.

I think that fixing the problem is trial and error and there are so many components that could be added or replaced that a lot of money can get thrown at it and still not solve the issue. When my shocks give out I will replace with adjustable ones and monkey with those to see if it helps.
 
I noticed the porpoise action when I first got my tacoma (2005 4dr lwb) driving on the freeway. I solved the problem for the most part by moving out of the truck lanes and staying in the auto lanes. I still find this happening when on truck routes usually on interstate hwys and in cities.
Two questions for WxMan, what tire pressure are you running and are you riding on your timbrens? If you run high tire pressure you'll definately bounce a lot more and if your running on the timbrens they will enhance the motion.
I replaced the factory bumpstops on the rear with timbrens and they can/do rebound quite harshly. If you compress them slowly they rebound slowly, hit them hard at speed and they act like a pogo stick. When I moved up from OME shocks to Icons' the rebound was handled by the Icons and I do not notice it anymore.
Just my 2 cents
Cheers!
 
Bill,
I told Icon that I was carry extra weight, but do not recall what that number was and they valved the shock accordingly.
In hindsight I should have gone in for the adjustable model, not that it's needed but I always wonder what "if".
Model #IVD-57805P

Cheers!
 
Its 100% suspension configuration

With the Fleet I have OME BP51, Dakar Heavy pack with AAL and Bags at 80PSI

Even on the worst bridges with huge whoops, it settles perfectly after each section into the next. The money you spend on shocks directly affects your ability to negotiate suspension usage
 
Well maybe 90%... If one drives the old, segmented cement highways of the industrial states, Pennsylvania being the worst, It does not matter what vehicle you are in... a certain resonance builds and the only thing that stops it is varying the speed to break the pattern. They are in the arduous process of tearing all of these up and replacing them with non segmented road.
 
BillTheHiker said:
....When my shocks give out I will replace with adjustable ones and monkey with those to see if it helps.
Click to expand...
Bill it's a safe bet that your shocks are already shot. You may want to replace them with upgraded ones.
 
I have a 2011 tacoma the we used with a 93 Pastime, but have a fleet on the way.

The problem starts at the length of the wheelbase.
It's the perfect storm for the hoping.
So to fix it, you need to get the correct suspension for the weight you are carrying, then get the appropriate shocks to keep that suspension from cycling after the initial bump of the road joint
 
I posted in this thread back in December 2016 noting similar porpoising problems (2016 Tacoma with 2016 Fleet). The camper is on the truck May-September, so truck needs to be drivable without the camper.

At the time I was running Firestone air bags, Cooper AT3 e-rated tires, OEM struts/coils in front and Bilstein 51 shocks in the rear. Finding the right tire pressure (45 front, 55 rear highway) and airbag pressure (approx. 45 left and 25 right) for my truck/camper combo and driving style helped a lot, but didn't entirely solve the problem. Plus, when driving on rough potholed and rocky FS/BLM roads I just felt I needed more suspension.

At the suggestion of Martyn at AT Overland in Prescott, I upgraded to Rancho adjustable shocks/struts (RS 999319/RS999777) back in May because the adjustable Boss shocks are no longer available in the US.

So far, so good. Much better performance on washboard, rocks and potholes. I also think it's better on segmented paved roads but I've been mainly on unpaved or decent paved roads since the change. I will find out for sure when I drive from Montana to Florida in a couple of weeks. So far I haven't changed the factory setting (5) or fooled around with different settings. I'll update this post following my drive home and once I've driven around with the camper off.
 
Thanks for all the recent replies to this topic. The general consensus appears to be adjustable shocks to damp out the rebound and play around with the shock setting to achieve an optimal ride.

What do folks think about the OME BP51 vs Icon shocks?
 
I went with the OME BP51. They have both adjustable compression and rebound damping which helps dial in the right settings for our particular applications.
 
That does seem like a lot - with the same setup I have never gone over 30 psi, and typically just have the minimum of 10 psi.
 
With our pastime I think I was around 45-50psi
I need to re evaluate my suspension, because I think I am carrying too much weight on the bags, and not enough on the springs
 
badtoytrd said:
Damn, 80 PSI seems like a lot. Is that with the flatbed or your stock bed?
Click to expand...
both stocker. I prefer a stiffer setup on the road. also a level vehicle.

I also have about 300 lbs more than the rest of you hanging behind my axle with the bumper, swingout, tire etc
 
I'll add my two cents since I'm driving a Taco. I have a gen1 Tacoma ('98) with an extended cab and Eagle. Similar issues and similar resolution as most other posters. I think there is an element of truth about the bucking being inheritent to the Tacoma, probably because the size of the wheel base can be in harmony with vibrations on certain pavements. I'm also running firestone airbags in the rear and adjustable Rancho shocks on all 4 corners. It requires some tuning (experimentation) to minimize the bucking and bouncing on certain pavements. The adjustable shocks enable me to pull into a rest stop and change the setting if I'm having a problem (but I have to lay on the ground to do it).

Regarding the tuning, here's my recent experience... you have several different variable than can be adjusted (tire pressure, shock settings, airbag pressure) and sometimes you have to consider all three. For my first year of ownership of the camper I had no major bucking issues. Then I got new Bridgestone Dueler tires. (my old ones were also Duelers) Costco said that the manufacturer recommended 45 psi, so I went along with it (this was about 10 pounds higher than my old tires). That totally changed my formerly acceptable driving experience. WAMMO! I had some very difficult road bucking in certain sections of the slow lane on I-5 in the central valley and other areas with high truck traffic. I'm still adjusting the settings, but lower tire pressure (35 psi), slightly stiffer front shock settings, and slightly lower air bag pressures seemed to smooth things out.

Also wanted to add that I was always told that the airbags are simply to help re-level the load. If it rides level than that's all the air you need in the air bags. For me, I can get by with as little as 10 or 15 pounds in the air bags and it rides level or even slightly elevated, however I was trying high pressures at the recommendation of another FWC'er. I'm not trying to start a discussion on the proper air bag pressures. I'm just saying that you need to adjust the variables that you have and see if you can tune out the bucking issues.
 
Somehow I don't see moving from 5100's to Rancho's as being an "upgrade." I've used Rnachos and had good luck with them in some applications (front of '79 & '91 Suburbans) and no luck at all in others - like under Toyota pick-ups & my current 4rnnr. Likely those 5100's had the 255/70 valving in them and IME that's bit soft for anything with a load in the bed. Going to the 275/78 valving made a world of difference.
 
The adjustable Rancho shocks for the rear, is on my to do list.
I think that is the way to go for me, since my camper is off and on very often.
 
If you are doing Rancho adjustable shocks on the rear, I think you would be short-changing yourself if you didn't also do the front shocks with adjustables. For me, the adjustability of the front shocks is a big reason that I can tune out some (or all) of the bucking. I'm not sure if I could attain the same results otherwise. I guess you could always try the rear first and then add the front ones afterwards if needed. On my gen1 taco the front shocks are part of a complete suspension strut, so they are a pita to change out.
 
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