Eliminating bounce, improving ride on leaf spring trailer...

[Johnnyred]

I have a tandem-axle leaf spring trailer that came under my 2021 Ranger RT198P. While it has more than enough load capacity and ample quality construction, it bounces a lot over some bumps, road transitions. It bounces much more than on the other boat/trailer combos I have owned.

Who has successfully modified their tandem, leaf spring trailers to eliminate bounce, improve ride? What did you modify: change spring rate, add shocks, add sumosprings, change suspension completely, etc?

Did you do the work yourself or did you have a pro do it for you?

[MikeF]

What does the rig/trailer actually weigh?

What tire are you running?

What air pressure are you running?

[Johnnyred]

The load weight is prolly 2525lbs. The trailer weighs 895lbs. That makes package weight 3420lbs ish.

I have Karrier ST215/75R14 Radial Trailer Tire - Load Range C on. Their rated for maximum load 1870lbs at 50psi and 81mph.

I have run the max psi 50, I have run 45 and 42. Don't see a meaningful difference in bounce, ride quality at any of these inflation numbers. Even at the lower inflation number the tire rating would still not limit the trailer GVWR or max load rating.

[MikeF]

My suggestion was going to be to decrease the tire pressure a bit, but you already have a handle on that, knowing your loads and testing different pressures already.

What are the trailer weight ratings on the trailer sticker or the tongue coupler or both?

Maybe the trailer has spring sets that are for a heavier load than your current rig.

[CatFan]

I think I’d try adding some tongue weight temporarily and see if it helps. Get some kind of water container(s) and put 15 or 20 gallons of water as far forward as you can on the boat. If it helps, you might be able to move the boat forward a little to make a permanent change. Cheap, easy test.

[Johnnyred]

trailer_sticker.jpgtrailer_suspension.jpg

Mike, trailer sticker pictured here. I also included a picture of the suspension. The mono-leaf springs are rated for 1750lbs apiece x 4. All-in including the weight of the trailer, hull, outboard, TM, full tank gas, my gear, etc I am 3425lbs ish.

CatFan, unfortunately there is no room to move the winch post farther forward as it is restricted by cross members.

ETrailer shared that they thought I might benefit from lower weight rated springs but thought finding them would require having them made locally to get all the specs right.

[MikeF]

Maybe ask a local spring shop if a multi leaf spring pack would bounce less vs a mono spring.

A multi leaf pack may provide a more progressive spring loading on bumps resulting in less of a jolt or thump on wheel contact.

Don't know if we have any spring guys on BBC to ask.

I don't have any personal experience with a mono spring setup.

[fishnfireman]

Maybe ask a local spring shop if a multi leaf spring pack would bounce less vs a mono spring.

A multi leaf pack may provide a more progressive spring loading on bumps resulting in less of a jolt or thump on wheel contact.

Don't know if we have any spring guys on BBC to ask.

I don't have any personal experience with a mono spring setup.

IMO -- That is correct. Based on what the op is experiencing and what I experienced with an OLD shop made horse trailer that had single leaf suspension.

[Johnnyred]

MikeF and fishnfireman, this is EXACTLY my suspicion that the mono leaf is much less progressive in spring rate than a multi leaf spring might be. The mono does have some progression in spring rate at least it is made with a progressive thickness... thicker in the middle thinner at the ends.

Think I am going to look into this. If I can find a good local guy and their advice mirrors our suspicion, then I would prolly switch out the equalizer to an EZ Flex or similar at the same time. Or add shocks if it is not too expensive and does not change the ride height. Or all 3... hell it is only money!

B.O.A.T. = Break Out Another Thousand!

[DewRonInc]

You could get torsion axels and it would help also, torsion is as close to air ride as you can get

[Johnnyred]

new_trailer_suspension.jpg

Update: Major changes to my tandem-axle trailer made all the difference. Wow, I now have the smooth-riding trailer that I expected to get from Ranger from the start. The hard bounce is gone! It is like having a new trailer!

After asking tons of questions to Dexter, EMCO and eTrailer, I ordered and installed 1250lb, 3-leaf springs to replace the 1750lb, mono-leaf springs that were on the trailer from the factory. Since every bolt except the one attaching the equalizer to it's hanger had to be removed to install the springs anyway, I ordered and installed a wet bolt kit at the same time.

An engineer at EMCO shared that the friction between the leaves of a multi-leaf spring help to control the rebound and movement of the spring as it compresses. He said that mono-leaf springs, which they also make, will be more bouncy because of this lack of friction.

The old springs were DEFINITELY overrated for the actual load. I went to a CAT scale and my package weight was 3240lbs and 2840lbs sprung weight (subtracting the tongue weight). The install took my trailer spring capacity from 7000lbs down to 5000lbs. While that is still way above the actual load on the springs, I can now see and feel the springs compressing over road bumps.

I also changed tires from the 215-width Kenda/Loadstar tires to 205-width Provider tires. A local guy who has built trailers for 40 years thought my tires were the problem when I went to see him about my trailer bounce. While I thought to myself he is trying to sell me tires, I was BLOWN AWAY by how much better the Provider tires rode when he put them on and promised to take them off no charge if I did not like them after a long test ride.

With the wet bolts, brass bushings, beefier shackle straps, and higher-quality bolts and nuts, my trailer is now as quiet as a church mouse!

I HIGHLY recommend to anyone having trailer bounce more than normal or ride quality issues with their trailers that they look at their spring ratings and get CAT scale weights of their actual loads.

[MikeF]

Good to hear you solved the bouncing problem.

The wet bolt kits are definitely the way to go if you tow a lot of miles per year.

[fishnfireman]

Thanks for the update.

[leonreno]

Definitely was under loaded, that was the issue, surprised they put that boat on a 6600lb trailer. Glad it worked out.

[Williep99]

Very nice on the process and updates. Heck, I see most guys driving 80 with their trailer bouncing all over and I always wonder if they even look on their mirrors.

[leonreno]

Luckily my 6600 lb rated trailer has around 5000lbs on it so I really never see it bounce. Probably more of these under loaded boat trailers than we think, I would suppose many dual axle boat trailers with bass boats are not loaded properly.

[Ranger391v]

Congrat's man!!!! On both the success and the long hard road of figuring all this out! Having been one who just this year had to figure everything out on his own about torsion axles and all the parts needed to replace everything, I can sympathize. I almost ripped all that mess out and went back to multi-leaf spring suspension myself ..... if I had not found 2 axles. Guess I'll reapproach all this in 10yrs when it wears out again. SMH.

[Johnnyred]

Thx guys. Leonreno, I think you hit the nail on the head. Many boats out there riding on trailers with springs not rated for their loads.

[21XDC]

I can only imagine how much better it would be by adding the Roadmaster or Monroe trailer shocks. Made to bold right on as a retro fit.

[Johnnyred]

Yep shocks would no doubt take it to the next level. May still do that who knows...