Replacing shocks when upgrading leaf springs

[John Welte]

Hi all, I plan to replace the four leaf spring type with Alcan five leaf type springs.  The weak point in the four leaf spring type is that three inch section to the eye that's a single piece.  Our trailer is hull number 1290, one of the last built in 2022.  I thought it might be good to replace the shocks at the same time.  I have about 12,000 miles on the trailer.  My question is what model number and brand is best?

John

[Geronimo John]

22 hours ago, John Welte said:

The weak point in the four leaf spring type is that three inch section to the eye that's a single piece. 

If you had said "OEM Leaf Spring" I would of course agree 100%.  Its only got about 11 pounds of metal and most of us agree it is undersized/undersprung for OTT OE2 fleet wide use.

The Dexter 2400 pound rated PB4   PR4   is a bunch more beefy spring than the OEM ones.  It weighs about a pound less than the Alcan's.  So to cast dispersion on ALL four leaf springs is a streach at best.  It is also an exact fit without any of the user's reported challenges that have posted about the Alcan's.

GJ

Edited Saturday at 12:59 PM by Geronimo John
typo

[rich.dev]

37 minutes ago, Geronimo John said:

The Dexter 2400 pound rated PB4 is a bunch more beefy spring than the OEM ones

GJ, is PB4 a typo, isn't it PR4?

[rich.dev]

1 hour ago, John Welte said:

My question is what model number and brand is best?

I believe this bulldog shock is a direct replacement for the Monroe 555001  https://www.4statetrucks.com/bulldog-hd-shock-absorber-replaces-555001-19-050000007

 

[jd1923]

I've been wondering... Some have reported that when upgrading to the Alcan spring it has increased ride height up to an inch and that there is more travel in the leaf spring. Should a replacement shock allow for the greater travel?

The Monroe 555001 is the OEM spring. Monroe also has the 555025 model, which is the same overall yet slightly longer with greater stroke. I copied these specs from the 4statetrucks website, as Bulldog has aftermarket replacements for both models:

Shock Specs	555001	555025
Compressed (in)	7.95	8.66
Extended (in)	11.97	13.35
Stroke (in)	4.02	4.69

Perhaps those who have installed Alcan springs can chime in?

@Mountainman198 @MAX Burner @ScubaRx and @rideadeuce
Did the shocks installed appear the correct length or would it allow for +3/4" in compressed length and +3/4"stroke be a better fit? Sure, the OEM length fit, but would +3/4" in stroke allow the slightly taller springs to perform without constraint? When I get the chance to make this upgrade, I would take before and after measurements on one side prior to ordering (let her sit on jacks stands a couple days to get the right part). I'm figuring 3/4" longer should be better. This has been a discussion on other TT forum websites. Stronger spring rate in the shock would also be preferred although Monroe does not list these specs.

Either way I would choose Bulldog over the Monroe OEM brand. Bulldog describes their products as a "High Quality Aftermarket Replacement Part (Not OEM)." This is the ~+3/4" longer version:  Bulldog HD RV Shock Absorber Replaces 555025 For Trailer Leaf Spring Retro Kit - 4 State Trucks

[Mike and Carol]

In May before the rally, Oliver service replaced my springs, shocks, bearings and brakes.  Jason did not mention any issues fitting the ALCAN springs I brought.  I’m sure they used the stock Monroe shocks.  I don’t notice my trailer sitting any higher, although I’m not sure I’d be able to discern a .5-.75” difference.  After our summer trip through Colorado and Utah we didn’t notice any significant difference in the ride either.  This should be a good setup as we start our second 100,000 miles.  Mike

[Mountainman198]

Seemed to have plenty of available up/down travel with the stock monroes after installing the Alcan springs. I plan to look long and hard at the Bulldog shocks when the monroes wear out

[John Welte]

3 hours ago, Mountainman198 said:

Seemed to have plenty of available up/down travel with the stock monroes after installing the Alcan springs. I plan to look long and hard at the Bulldog shocks when the monroes wear out

I get the impression that the Bulldog shocks are better made.  They don't seem very expensive.  Is your Monroe shock the 555001.  I can look at what the equivalent number is on the Bulldog.  Thanks

John 

[Mountainman198]

6 hours ago, John Welte said:

I get the impression that the Bulldog shocks are better made.  They don't seem very expensive.  Is your Monroe shock the 555001.  I can look at what the equivalent number is on the Bulldog.  Thanks

John 

Yes, stock shock for my trailer is the 555001. Appreciate the lookup of the equivalent Bulldog. 

[Geronimo John]

20 hours ago, rich.dev said:

GJ, is PB4 a typo, isn't it PR4?

You are correct.  PR4  Thanks for the catch.  

GJ

[Jim and Chris Neuman]

Can anyone tell here are the Bulldog shocks are made?

[John Welte]

5 hours ago, Mountainman198 said:

Yes, stock shock for my trailer is the 555001. Appreciate the lookup of the equivalent Bulldog. 

Here is what I found out.

[rideandfly]

We installed Bulldogs this year.

 

Edited Sunday at 12:33 PM by rideandfly

[MAX Burner]

We echo @Mike and Carol's comments above.  As reported in another thread, we replaced our 12-month old Monroe shocks after we replaced the axles & leaf springs last May.  I was surprised that 3 of the 4 Monroes were toast after only 8k miles - but we were not in a  position to acquire a set of Bulldogs (in Hohenwald at the time) so we replaced them with OEM Monroes.

We've logged just north of 6k miles since May and we function-checked the OEMs at the 5k-mile point - all good.  We also checked axle U-bolt nut torques at the same time - all within specs.

I'm thinking with the max travel of the axle set being approximately 4-1/4" (2-1/8" up and 2-1/8" down) that the longer stroked Bulldog (4.69") option would be fine given the slightly higher lift with the Alcans.  Also, I believe that any higher rated leaf spring will tend to dampen the OTT load at a lower frequency and shorter stroke when under tow as compared to the OEM 4-pack 1,750# springs.  This may allow the shock absorbers to last longer, IMO.

Regarding towing the Casablanca with upgraded running gear:  Like Mike mentioned, no appreciable difference observed in towing during this last 6k+ miles - other than a general overall "solid" feel and less "porpoising" at slower speeds over rougher roads.  We reduced the electrical trailer brake gain from 6.0 down to 4.5 due largely to the 12" drums' greater braking action.  The OTT always pulled like a champ, anyway - its, quantitatively, a more "confident" towing experience and a "peace of mind" in the overall running gear with the upgrade.

Bulldogs are definitely on our radar screen for a swap-out probably when the 10k-mile point is reached on the existing Monroes, FYI.

Cheers, All!

Edited Monday at 11:49 AM by MAX Burner