Don't swap the Med for Heavy OEM Springs

Romer

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Christo and I were talking at Moab and he told me the ARB load specs for the Med and Heavy springs are the same, its just the heavies are longer. He said it mighty be a typo, but thats what the specs say. I was talking to him about changing the springs when I get a winch. I sent ARB an e-mail with the following question:

I currently have your medium lift springs on my 80 series Land Cruiser. I was going to switch to Heavies when I install a winch on my ARB. Looking at the two specifications, they seem to have the same load specs, but the Heavies are just longer. Can you confirm this. Why wouldn't a 1 inch spacer added to your medium springs give me the same performance?

This is their response:

You are exactly correct. The OME850 and OME851 have an identical spring rate, however the OME851 is 20mm taller than the OME850.

We offer 10mm polyurethane spacers than can be used on top of the coils for additional height. The Aussies refer to these as trim packers.

Our suspension book says use a maximum of 2 trim packers per coil. You could also use a 1" spacer to get the same result.


I know Nakman took this approach, but someone here (can't remember who) told me not to because of the load rating. Well, the load rating is the same. :D
 

e9999

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spring rate meaning absolute deflection length per unit weight, I guess?

but Christo's site says that both med and heavies give the same lift...

and how do the Js figure in this picture then?

(and btw, why can't I find any good tech info on the arbusa.com site... ?)
 

phatairman

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Long day at the office and not thinking correctly, so exactly why would this be bad? Castor correction would be 20 MM off?
 

phatairman

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So the medium spring (851) is exactly 20 MM taller than the heavy spring (850). Thus is the need for the spacers?

Brain starting to work..... :idea:

Fame suit on. :doh:
 

NorCalDoug

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phatairman said:
So the medium spring (851) is exactly 20 MM taller than the heavy spring (850). Thus is the need for the spacers?

Brain starting to work..... :idea:

Fame suit on. :doh:
no, that's backwards.
Heavy springs are 851
Medium springs are 850.

To "convert" med. to hvy add 1" spacers or 2 10mm trim packers.
 

Fochdog

 
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NorCalDoug said:
no, that's backwards.
Heavy springs are 851
Medium springs are 850.
NorCalDoug... you running medium fronts and heavy rears from your sig.

the other backwards... :D

Mediums are 851. Heavys are 850 and are 20mm taller then the 851.
 

phatairman

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NorCalDoug said:
no, that's backwards.
I got this from Slee's site -->

2.5" OME Lift
Heavy Load
Part #: ARB1001

Consist of:
2 x OME 850 Front Coil Springs
2 x OME 863 Rear Coil Springs


So the 850s are the heavy springs, no?
 

Romer

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850's are the heavies and they are just longer Christo gets the kudos here because he said he noticed it. I just followed up with ARB. Your right, the ARB site sucks, thats why I e-mailed them.

So I guess if your installing the springs for the first time and have a heavey load, go with the heavies. If you have med springs and add a heavey load, just add spacers.
 

e9999

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Romer said:
850's are the heavies and they are just longer Christo gets the kudos here because he said he noticed it. I just followed up with ARB. Your right, the ARB site sucks, thats why I e-mailed them.

So I guess if your installing the springs for the first time and have a heavey load, go with the heavies. If you have med springs and add a heavey load, just add spacers.
but wait, if the heavies are just longer with the same spring rate, would that not mean that they aren't any better for a heavier load, dynamics wise, and that they will just keep things higher (which may not be bad, but perhaps not enough)?
 

semlin

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interesting. i was either the guy or one of the guys who assumed packers/spacers would diminish performance compared to longer heavy springs. In my mind it is still true although the advantage may be smaller than i thought if the load rating is idnetical. to take an extreme example, surely a spring half as long with the same load rating would not perform as well dynamically as the longer spring. therefore the shorter medium spring will not perform quite as well as the heavy even with the same load. the difference may or may not be discernible.

here is a question. I believe people have found the ride on the heavies to be stiffer and harsher with insufficient weight. christo leans against the heavies unless you have a winch. this doesn't make sense if the load rating is the same. have people found the same thing using spacers with no winch/or arb?
 

e9999

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went and had a look at the australian ARB site. Just as lamea$$ as the USA one... sheesh... If you go under "catalogue" then USA then look left you'll see a small mention of vehicle specific info. There is a pdf file for the 80 but with very little info. However, this is what it says:

---------
Model Location Description Type Lift Quantity Part No.
80 Series Front Stock/Light Load (0-110lbs) Spring 2.0" 2 OME851
Shock 2 *N73/N70
80 Series Front Heavy Load (110-250lbs) Spring 2.0" 2 OME850
Shock 2 N73
------------

so it shows a difference in weight between the 851 and 850, but the same lift. I take that to mean that the heavy 850 will provide 2" of lift *after* it's been loaded with the 110-250 lbs...

They also mention the 850J but did not include the lift or length for those... sheesh...
 

MoJ

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e9999 said:
spring rate meaning absolute deflection length per unit weight, I guess?
Spring rate definition:

Amount of force required to compress the coil spring a given distance, generally 1-inch (US).

For every inch of spring compression, the spring pressure increases by the
specified rate, i.e. 1 inch = 300 pounds, 2" = 600 pounds for the 300 pound
rated spring.

This is assuming a constant rate spring. Of course spring rates can be variable (non-linear) as well, a characteristic created by the changes in the geometry of the coil such as coil pitch (angle of the coil turns) or barrel diameter.

So, it would be possible for two springs to have the same spring rate during the first 1-inch of compression/load but have different spring rate characteristics as the load is increased.

Not sure if OME just lists the rate for the initial 1-inch or an average across the spring as IIRC the OME are variable rate (which would give the ability to soften ride but still stand up to a load or reduce corner lean when pressed).
 
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Romer

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phatairman said:
Romer- so are the 850's longer or the 851's?
Sorry, I see I got it backwards in a follow on. The Heavies are longer than the mediums. I won't vouch for which is what part number. I thought the Heavies were 850's, but the e-mail from ARB shows them to be 851's. Other sites show them to be 850's. I think he got it backwards in his reply.

So lets just say the Heavies are longer than the Mediums
 

Romer

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I just sent the ARB guy the following message, I'll post his response:

Just want to make sure, the 850's are the heavies and are 20mm longer, right?

Also, is the listed spring rate for the initial 1-inch or an average across the spring as IIRC the OME are variable rate

Do you have any test data to show the Medium Springs with a 1" spacer vs. a Heavy Spring performance? Load is with an ARB Bumper Winch and Sliders.
 

MaddBaggins

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If the heavies are longer that would explain why my front driveshaft rubbed my swaybar at full droop. I have the heavy lift but don't have any heavy armor. I fabbed up some spacers last night to fix that problem. I was going to post a link to that thread but couldn't figure out how to add a thread link. :cheers:
 
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Romer,


I want to thank you for clarifying a mystery for me.

I've long been wondering why some spring sets come with taller fronts than others.

Personally, I would prefer the longer fronts as they don't require spacers and the rear still comes out an inch or so taller than the front so carrying a load is no big deal. However, that's just me. Others might prefer the even set because their shocks won't be so very extended and it could save them the need for additional expenditures.


Kalawang
 

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e9999 said:
but Christo's site says that both med and heavies give the same lift...

and how do the Js figure in this picture then?

(and btw, why can't I find any good tech info on the arbusa.com site... ?)
All these springs probably lift the vehicle their stated height if you have the weight on your cruiser that they are rated for. In other words, add 200 - 300 lbs. to the back of a cruiser with heavy springs and it will probably sit at the same height as the mediums without the extra weight.

J spings would sit an inch higher than the heavies with the same weight.
 

NorCalDoug

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Fochdog said:
NorCalDoug... you running medium fronts and heavy rears from your sig.

the other backwards... :D

Mediums are 851. Heavys are 850 and are 20mm taller then the 851.
Nope, you're right. I crossed up my numbers like Romer did. :doh:
 
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