M103 Trailer Shock

[Valence]

M103 Trailer Shock Absorbers and mount

I just purchased these pair of shocks off of a Mobile Kitchen Trailer to put on my M105A2. I was wondering if anyone else has done similar. Did you keep the oil (hydraulic) shocks or did you go with a different type?
The stock shock appears to be 13" from center of bolt to center of bolt when fully compressed, and 20" when fully extended; all on a ~5/8" bolt.

As you can see, the part of the shock bracket that goes around the axle has a notch out for the brake line.

I think this will do a lot to make that M105 less BOUNCY (especially when empty). I'm probably a little too excited about them!



For reference, an unrelated picture (that I had handy) of the backside of my M105 that doesn't have shocks - you can see the hard brake line the axle-clamp brackets are notched for:

 

[juanprado]

My suggestion if you are going to do this much work is ditch the old school hydraulic shock and invest in modern gas charged.

Also, those shocks in the pics are definitely bad as they are leaking fluid......

 

[Valence]

Would the gas make it ride rougher?

Through a simple, not in-depth search I found this video, and it seems to suggest adding gas shocks would make it ride rougher (I have no knowledge/experience in this area). I don't want the trailer to be even bouncier...

https://www.youtube.com/watch?v=o70v71Rxsyg

 

[Gunner USN]

Another way to reduce the bounce in an empty trailer, let some air out of the tires.

 

[Recovry4x4]

I've never noticed a particular problem with and of the M105s I've owned but then again, ride comfort of the trailer was low on the list. What application will the trailer be used for? Removing a leaf and adding shocks would smooth it out. By the by, shocks really aren't shocks. The spring absorbs shock, the shock dampens the recoil.

 

[Valence]

I use my M105A2 for anything from parade/display duty (empty) to hauling fire wood, or junk/debris to the dump (like a torn down shed).

I would say, obviously, these heavy trailers were designed to perform best when carrying a full load (it did great with the fire wood, didn't bounce or throw any wood around), but my uses will not often be that heavy or full.

A year ago I had a spare end rack on the trailer side pockets and, through my ignorance of not having it tied down, the empty trailer bounced the rack partly out and drug it for about 2 miles. But that's another story for the Safety forum.

Anyway, in short, my goal is to smooth the ride out some.

 

[juanprado]

The article below at the end gives a lot of good info on the shock evolution.

http://www.bilstein.de/en-uk/technology/basic-know-how/

My .002 is from selling parts for many years in a previous life . I do not believe any major manufacture even still makes hydraulic. They will leak and blow out much faster than a gas charged product.

I routinely change all the shocks on my m101's that I keep or flip. I feel they do ride better with newer gas charged shocks.

 

[Valence]

The article below at the end gives a lot of good info on the shock evolution.

http://www.bilstein.de/en-uk/technology/basic-know-how/

My .002 is from selling parts for many years in a previous life . I do not believe any major manufacture even still makes hydraulic. They will leak and blow out much faster than a gas charged product.

I routinely change all the shocks on my m101's that I keep or flip. I feel they do ride better with newer gas charged shocks.

Thanks for that link and education on shock absorbers. I'm continually re-learning things that I forget (like the foaming of older style hydraulic shocks). However, I'm glad to learn that my original intent of replacing the shocks with gas shocks was the correct one.

Do you happen to have suggestions on how I can go about picking the correct shock, besides just the fitment of max/min length?

Again, I appreciate the help!

 

[two.fiveM35]

I routinely change all the shocks on my m101's that I keep or flip. I feel they do ride better with newer gas charged shocks.

Can you provide us with a part number for the shock that you us on the M101? Thanks

 

[juanprado]

Yes Sir! See below 2fiveM35 :
http://www.steelsoldiers.com/showthread.php?97814-Shocks-M101A1-A2-A3-is-there-no-part-available

There are only 2 major shock brands Monroe and Gabriel besides the more high performance specialties like kyb, Blisten etc.

I am not saying they are better but I sold Monroe most of my parts' selling years and they are the private label for NAPA.

For your m103 shocks, call the tech line of your favorite brand and give them the stud mount width, compressed length and extended length. They can spit out a part number. In my days we had things made out of paper called catalogs with illustrated technical guides but today's alleged counterman are clueless. The modern shocks have one piece bushings already pressed into the shock and those will work fine. The military shocks have 4 cone shaped bushings but again that is old school and no one uses that design anymore.

 

[Valence]

What is the proper location to measure the shock for compressed/extended lengths?

As I indicated in my first post, when measuring the stock shock from center of the mounting loop to center of the opposite mounting loop, it is 13" when fully compressed, and 20" when fully extended; all on a ~5/8" bolt.
If I just measure just the body of the shock it is 11" fully compressed and 18" when extended.

Pages 83-87 of Monroe's 2015 Shocks & Struts catalog show measuring conventions on various types of struts and shocks, but it is still unclear to me as to the proper place to measure on a shock with a loop mount on both ends. Figure SS1 on page 86 seems the closest, but only one end is a loop mount but it does show measuring from the loop center.
http://www.monroe.com/assets/downloads/english/MonroeMountingLengthSpecifications.pdf
(also attached here for later reference)
View attachment Monroe_MountingLengthSheet.pdf

This website indicates measuring from center of loop to center of loop. Can anyone confirm the veracity of this convention?
http://www.shockwarehouse.com/news/how-to-measure-shocks.cfm

 

[Valence]

So I poured through the above referenced Monroe 2015 Shocks & Struts catalog, and here's my findings:

My gut says that the correct measurement method is from center of mount to center of mount. The stock oil shock was 13" collapsed and about 20" extended; mounted on a 5/8" bolt.

The following are Monroe shocks that fit that criteria:
Note: All the below shocks had the "Body End Code" and "Rod End Code" of "L1" (5/8" loop mount), but has been excluded for readability.

No.	Part Number	Comp. Length	Extended Length	Travel Length	Parts Pack(s)	Additional Description
1.	32293	11.97"	19.66"	7.69"	None	Matic Plus Shock (Passenger Car)
2.	34905	12.63"	19.75"	7.13"	None	Gas-Magnum Shock
3.	37073	13"	20.75"	7.75"	None	OESpecturm Light Truck Shock Absorber
4.	37078	12.63"	20"	7.38"	None	OESpectrum Light Truck Shock Absorber
5.	58567	12.5"	20.38"	7.88"	60 P573	Load Adjusting
6.	911530	13"	20.75"	7.75"	None	Reflex Monotube Shock
7.	MA727	12.75"	20.38"	7.63"	(2) P00573	Max-Air Shocks
8.	MA792	13"	21.25"	8.25"	None	Max-Air Shocks
9.	MA812	12.75"	20.75"	8"	None	Max-Air Shocks

The above table give a nice spread for customization of the trailer depending on usage. Reading further into each shock type is the following description of each on Monroe's website:

Monro-Matic Plus Shock:

• Passenger Car Shock Absorbers
• AN ECONOMICAL REPLACEMENT ALTERNATIVE
• Monro-Matic Plus shocks and struts provide an ideal balance of comfort and control for any driving condition.

Gas-Magnum Light Truck Shocks:

• Light Truck Shock Absorbers
• FIRM CONTROL WITHOUT A HARSH RIDE
• Gas-Magnum light truck shocks are designed for mid- to full-size, light-duty work trucks and vans

Monroe OESpectrum®: Truck Shock Absorbers

• TWIN TECHNOLOGY™ TUNED FOR EXCEPTIONAL CONTROL
• The Monroe® OESpectrum® shock absorbers feature our latest, global, original equipment valving technologies for domestic and foreign nameplate applications. Monroe OESpectrum units provide an unprecedented level of handling precision and control while filtering out ride harshness. This unique blend of control and comfort is made possible through Tenneco’s Twin Technology™ Active Control System, an exclusive internal damping control technology.
• Tenneco’s Twin Technology™ consists of the latest Impact Control Valve (ICV), delivers exceptional control by regulating the flow of fluid which helps control vehicle roll and isolate road impact, and a patented Low Speed Tunability (LST) piston design that isolates impact-related noise, vibration, and harshness experienced with rough, bumpy road conditions. Our best ride ever, guaranteed!

Load Adjusting:

• Monroe load adjusting shock absorbers adjust rapidly to changing road and weight conditions, delivering enhanced control with uncompromised ride comfort. They offer superior comfort for normal driving and deliver extra control when operating conditions get more demanding. These units also include a heavy gauge calibrated spring for extra control and comfort. A new pair of Monroe load adjusting shock absorbers can assist in maintaining ride height when up to 1,100 lbs* of additional weight is loaded. These units are ideal for light trucks that carry varying loads or tow trailers.

Monroe Reflex: Monotube Shock Absorbers

• HELP REDUCE VEHICLE ROLL AND DIVE
• Ideal for larger light trucks, SUVs and other vehicles with a high center of gravity
• Enhanced stability by reducing body roll rate in evasive maneuvers or tight turns.
• Reflex Monotube for OE-equipped vehicles.
• Reflex shocks are application-engineered to each vehicle model.
• Monroe Reflex® monotube shocks are specifically engineered to provide better handling, control and performance for light trucks and SUV's. These shocks feature a high-pressure gas charge that separates the unit internal oil and nitrogen to provide additional spring rate, helping to maximize damping efficiency and control. To further enhance ride control characteristics, Monroe® Reflex® monotube shocks include a hydraulic lockout to cushion the impact as the vehicle suspension is fully extended.

Max-Air Shock Absorbers: Air Adjustable Shocks

• Ideal for vehicles that occasionally haul heavy loads or tow trailers
• Large-volume air chamber inflates up to 150 psi with vehicle loaded, and deflates for normal driving
• A pair can maintain ride height when up to 1,100 lbs. of additional weight is loaded.
• Can be adapted for most vehicles equipped with automatic leveling systems.
• The Max-Air® shock absorber is ideal for vehicles that haul heavy loads or tow trailers. Designed to maintain level vehicle height, they can be inflated or deflated as needed...from 20 psi to 150 psi with the vehicle loaded.

My application (General Cargo Trailer) evaluation: (I mainly want to reduce the bouncy trailer)
- (#'s 7, 8, & 9) The air shocks are interesting because if the trailer is having clearance issues off roading you can increase the ride height but is way more complication and certainly not needed for my desires.
- (#6) The Monotube shock is intriguing because the trailer does fit the bill high center of gravity, but I fear it would just make the trailer ride rougher for it.
- (#5) Load adjusting sounds like it'd just make the suspension stiffer, and that's certainly not wanted, and there's no need to maintain ride height.
- (#3&4) Only seems to differ between each other by a small amount of compression/extension lengths. On Monroe's website #4 has a 5/8" piston rod while #3 only has a 1/2" piston rod. However, #3 has a better travel length.
- (#1) "Passenger Car" just sounds like they wouldn't hold up well enough or provide enough shock absorption.
- (#2) There's an inconsistency between 2 and 3&4. When looking up the part numbers on Monroe's website, the 1-line brief description on 3&4 said "Light Truck", but the detailed description is just "truck' and the detailed description on #2 is "Light Truck". However, #2 seems to indicate that is has a larger reservoir.


I think any of 2, 3, or 4 would work just fine. They each have their pluses:

• (#2) Possibly Larger reservoir, 5/8" piston (1/8" thicker than #3) ($31.56 on Amazon)
• (#3) Longest travel length (1" more than #2, 3/8" more than #4) ($35.96 on Amazon)
• (#4) 5/8" piston (1/8" thicker than #3, travels 1/4" more than #2) ($29.00 on Amazon)

Conclusion?
It appears that #4 is the winner. Heavier duty piston while still maintaining the full travel lengths needed to match the stock oil shock, and is the cheapest (at this time).

What do you think?

-----
For reference, if the shocks should be measured from end of tube to end of tube (not the mounting holes), with a compressed length of 11" and an extended length of about 18"; mounted on a 5/8" bolt, only the following Monroe Part numbers fit:
(P/N, Compressed Length, Extended Length, Travel Length, Additional Comments)
32207, 11.25", 17.875", 6.625" - Monro-Matic Plus Shock
555004, 11.25", 17.875", 6.625" - Gas-Magnum RV Shock

 

[juanprado]

I would recommend the gas magnum. They are a bigger bore than the "stock" type monroe matic. The reflex are nice but you will not get any noticeable difference in a trailer application. More $ and better suited for a SUV or truck where there design will give you a better ride.

Air shocks will cause you problems. The air lines or boots will fail some time down the road. It is just a question of when.

You can take the gas magnum part number and try to cross to Napa or O Reilly. They usually carry the same shock private label, different color, with lifetime warranty than the yellow "monroe" branded. You will pay more $ for the paint and label.

 

[Valence]

I would recommend the gas magnum. They are a bigger bore than the "stock" type monroe matic. The reflex are nice but you will not get any noticeable difference in a trailer application. More $ and better suited for a SUV or truck where there design will give you a better ride.

Air shocks will cause you problems. The air lines or boots will fail some time down the road. It is just a question of when.

You can take the gas magnum part number and try to cross to Napa or O Reilly. They usually carry the same shock private label, different color, with lifetime warranty than the yellow "monroe" branded. You will pay more $ for the paint and label.

Excellent feedback juanprado, thank you very much! I'll go with #2 then, the Gas Magnum. It is 1/4" shorter in full extension than the stock oil shocks, but that should be okay (I hope). I'll call local O'Reilly's here and see what they sell equivalent to it.

 

[Valence]

Just got off the phone with O'Reilly's, and it's about $5.00 cheaper to go the Amazon route for the Gas-Magnum (#2) - and Monroe was the primary shock they carried, the other brands were a little more higher priced and he said they'd be a bit stiffer. (I think he said that an equivalent KYB shock would be $46.99).

 

[John Galt]

I have put Monroe Load Adjusting coil overs and Ranch RS5000 shocks on 101 trailers, and much prefer the Rancho shocks for the less bouncy ride (and ease of installation).

The shock mounts on the 101s are 3/4" so I am surprised that the 103 has 5/8" mount. That should open up a lot of options for you. I would stick with an oil shock.

Below is a pdf with all the Rancho options. Just need to find one with dual L1 mounts in the length you need. I buy mine from Amazon.

http://www.lunghd.com/Downloads_and_Links/2005_productshock_spec.pdf

 

[juanprado]

The whole industry has changed and is gas charged for a reason. Monroe and Rancho are owned by the same parent company, Tenneco. Monroe is 100% gas, and most of Rancho. I am surprised they still make and sell the same hydraulic 5000 they made 25 years ago. Shock technology has come a long way from 50-80's old school oil. I don't know of anyone else making hydraulic shocks, let alone installing them OE.
Hydraulic oil shocks will leak and go bad. Just a question of when and then they make a mess when leaking.

 

[Valence]

I sand blasted the shock mounts (a long with a few other projects!), but one of the lower ones I destroyed the thread trying to get the old oil shock off. So the fabricator at The Iron Works in Woods Cross, UT currently has it and I'm waiting an estimate to fix it. It will probably cost me more than I paid for all the parts. Maybe I should just post a Want Ad and see what a replacement would cost so I could compare lol.

I should have used the impact from the beginning.



See this post in my other thread for more info about the powder coat I've used before and plan to use next.
http://www.steelsoldiers.com/showth...M66-Gun-Ring&p=1835359&viewfull=1#post1835359

 

[Valence]

I sand blasted the shock mounts (a long with a few other projects!), but one of the lower ones I destroyed the thread trying to get the old oil shock off. So the fabricator at The Iron Works in Woods Cross, UT currently has it and I'm waiting an estimate to fix it. It will probably cost me more than I paid for all the parts. Maybe I should just post a Want Ad and see what a replacement would cost so I could compare lol.

I should have used the impact from the beginning.

I spoke with Scott at The Iron Works this morning. The repair cost for that driver's side, lower shock mount is pretty high (as expected) so I'm going to post a want ad to see if I can't just buy another for less.

 

[Valence]

Tonight I found out that months ago when I measured the shock mount I had done so incorrectly. I had measured the mount before I removed the shocks, so yeah, 5/8" is the thread size, while the shoulder that the shock rests on is actually 0.76", or basically a tight 3/4"!

Whoops.

So the part numbers in my post #12 in the thread? WRONG!

For accuracy, I've recreated the table with the correct diameter bushing.
This shock equates into an "L3" Loop mount style for a matching Monroe shock.
Reminder: The stock oil shock was 13" collapsed and about 20" extended.

(Of course, in my other trailer thread, juanprado already - correctly - answered this question with a viable option of P/N 32283, LOL - so much for all my "clever" work)

The following seem to be the decent matches.
Note: All the below shocks had the "Body End Code" and "Rod End Code" of "L3" (3/4" inside diameter loop mount), but has been excluded for readability.

No.	Part Number	Comp. Length	Extended Length	Travel Length		Additional Description
1.	32247	13.63"	21.63"	8"		Monro-Matic Plus®: Passenger Car Shock Absorbers
2.	32283	13.13"	21"	7.88"		Monro-Matic Plus®: Passenger Car Shock Absorbers
3.	32294	12.88"	20.38"	7.5"		Monro-Matic Plus®: Passenger Car Shock Absorbers
4.	32295	12.5"	19.63"	7.13"		Monro-Matic Plus®: Passenger Car Shock Absorbers
5.	34828	13.13"	21"	7.88"		Gas-Magnum® Light Truck Shocks: Light Truck Shock Absorbers
6.	37032	13.88"	21.5"	7.63"		Monroe® OESpectrum®: Truck Shock Absorbers
7.	37113	13.25"	20.38"	7.13"		Monroe® OESpectrum®: Truck Shock Absorbers
8.	37114	12.88"	19.5"	6.63"		Monroe® OESpectrum®: Truck Shock Absorbers
9.	65101	12.69"	19.67"	6.98"		Monroe® Gas-Magnum 65
10.	65113	13.31"	20.94"	7.63"		Monroe® Gas-Magnum 65
11.	65177	13.06"	20.5"	7.44"		Monroe® Gas-Magnum 65
12.	65405	13.13"	20.07"	6.02"		Monroe® Gas-Magnum 65
13.	65434	13.58"	20.86"	7.28"		Monroe® Gas-Magnum 65
14.	66413	12.17"	19.13"	6.95"		Monroe® Gas-Magnum 60
15.	66435	13.3"	20.3"	7"		Monroe® Gas-Magnum 60
16.	66618	13.38"	21.5"	8.13"		Monroe® Gas-Magnum 60
17.	66828	13.13"	21.13"	8"		Monroe® Gas-Magnum 60