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  #41  
Old 07-02-2010, 09:59 PM
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Originally Posted by AxleIke View Post
Not sure what you mean there. It doesn't really matter what vehicle it is. If it rubs, cut it.
You aren't thinking about this correctly (ignoring the last sentence ). With much larger tires, you need to space down the entire suspension travel. Longer shocks, or shocks used with pin to eye adapters, will reduce available up travel because you have less available compression travel.

Longer bumpstops are needed to protect the shocks and have the additional benefit of stopping up travel before the tire makes contact.

If you look at my suspension, I have a 3.5" lift with a 10" travel shock. I have 2" bumpstop drops up front (although they are not needed for articulation, just there for pure impact compression) and 2.5" in the rear, 37" tires.

My shock travel is balanced almost exactly 50% up and 50% down. I have not lost any travel as the bumpstops protect about the last 3/4" of shock up travel and you have to account for some degree of bumpstop compression, and my suspension is properly balanced to allow max articulation across the range of motion before one end is either hanging on a shock or up against a bumpstop rather than the entire system moving freely.

If I were to decide to cut the body to preserve original up travel (no downward spacing of shock travel) I'd basically have about 7" up and 3" down, which is why you see OME users go to L shocks to space down their travel at 3"+ lifts. This unbalance is undesirable for rock crawling, although you might like it for high speed overland travel where you are hitting big bumps at speed - you would also probably keep smaller tires for this usage and not have the contact issues.

The bottom line is you need to look at where your shocks actually fully compress and ensure your bumpstops are protecting the shocks. If at full compression you have tire/body contact, spacing the shock travel down while ensuring you keep a good compression/droop balance is the goal.

This is easily accomplished on the 80, and using eye adapters without increasing shock travel will help keep the rear tires from angling so much into the wheel wheels. I have no issues picking up rear tires and have avoided the issues that come with adding too much travel. Plus, the front of the 80 can't use any extra travel anyway, so front to rear balance should always be a consideration.

This is why I wheel with my front swaybar removed and rear attached. It is well balanced for such a big pig.

No substitute for measuring on your rig - you can tune from there
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  #42  
Old 07-02-2010, 10:47 PM
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Quote:
Originally Posted by Nay View Post
You aren't thinking about this correctly (ignoring the last sentence ). With much larger tires, you need to space down the entire suspension travel. Longer shocks, or shocks used with pin to eye adapters, will reduce available up travel because you have less available compression travel.

Longer bumpstops are needed to protect the shocks and have the additional benefit of stopping up travel before the tire makes contact.

If you look at my suspension, I have a 3.5" lift with a 10" travel shock. I have 2" bumpstop drops up front (although they are not needed for articulation, just there for pure impact compression) and 2.5" in the rear, 37" tires.

My shock travel is balanced almost exactly 50% up and 50% down. I have not lost any travel as the bumpstops protect about the last 3/4" of shock up travel and you have to account for some degree of bumpstop compression, and my suspension is properly balanced to allow max articulation across the range of motion before one end is either hanging on a shock or up against a bumpstop rather than the entire system moving freely.

If I were to decide to cut the body to preserve original up travel (no downward spacing of shock travel) I'd basically have about 7" up and 3" down, which is why you see OME users go to L shocks to space down their travel at 3"+ lifts. This unbalance is undesirable for rock crawling, although you might like it for high speed overland travel where you are hitting big bumps at speed - you would also probably keep smaller tires for this usage and not have the contact issues.

The bottom line is you need to look at where your shocks actually fully compress and ensure your bumpstops are protecting the shocks. If at full compression you have tire/body contact, spacing the shock travel down while ensuring you keep a good compression/droop balance is the goal.

This is easily accomplished on the 80, and using eye adapters without increasing shock travel will help keep the rear tires from angling so much into the wheel wheels. I have no issues picking up rear tires and have avoided the issues that come with adding too much travel. Plus, the front of the 80 can't use any extra travel anyway, so front to rear balance should always be a consideration.

This is why I wheel with my front swaybar removed and rear attached. It is well balanced for such a big pig.

No substitute for measuring on your rig - you can tune from there

Why not just get longer shocks then? If they are just moving the travel down, and not giving you more travel, then the whole lift is pointless. You could cut the body, run the same sized tires, and keep the COG lower. Now, if you have the longer springs, chances are you can get more travel from them, and thus the lift makes sense. But not if you are only using part of the travel you just gained.

In your case, you have 10" of travel with a 3 " lift. Go to a 12" or 14" shock, and get more travel, leaving the original bumpstops in place. Now you can use the full benefit of those longer springs. And you can keep the 50 50 split you desire.

You make a good point for the front balancing the rear. The main issue with the 80 rear's is likely the same as modern runners. 5 link with a panhard means more arc which means more rubbing the more travel you gain.. Running new link set ups front and rear would be the ultimate fix for the 80, but not particularly feasible for most.

For Myself, dave, and farnham, the front to rear balance is a total joke, as with IFS rigs, we do not come close to having balanced rigs. The rear does all the work, and the front is just along for the ride.
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  #43  
Old 07-03-2010, 08:32 AM
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Nay, I would say I have the same suspemsion philosophy as you, but simply can't afford the "kit" I want right now. This Iron Man is an affordable solution to a worn out stock suspension which IMO has become a safety issue while daily driving.

Does anyone have the eye to eye measurements for OME shocks? I have not been able to find a source to compair them with the Iron Man's. I'm considering getting the shocks from the Iron Man's 4" kit to help space down the lift. But I'm worried that even with spacers on the springs I might unseat a spring at full droop.

The springs I'm getting are very similar to the OME 850/863 but 5mm longer unloaded.

Front: TOY024C, +242 lbs over stock, 500/505mm unsprung
Rear: TOY013B, +660 lbs over stock, 485/495mm unsprung

If I choose to go with the longer shocks they are 20mm longer at full compression and about 50mm longer at full extension over the shocks that come with the 2" kit. So dropping my bumpstops 2" to prevent 35's from rubbing will definitely take up the extra 20mm length of the longer shock at full compression but I'm not sure if my springs will stay seated even with 30mm spacers on top of them.
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Last edited by Corbet; 07-03-2010 at 08:55 AM.
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  #44  
Old 07-03-2010, 02:37 PM
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OK, I found some OME shock specs on Christo's website. Looks like the Iron Man shocks are within 2-3mm of the N73/74 and L's

Has anyone ever gone to L's with an OME "heavy" kit and spring spacers? Or have the the normal shocks always had enough additional droop?
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  #45  
Old 07-03-2010, 04:24 PM
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I can measure my unarmored 850/863's with standard OME shocks if it would help, would just need to know where you want me to measure to/from. (Maybe the bumpstop outside of the spring to the axle?) I'm already battling a brake issue so all the wheels are off and easy access :\

My gut feeling is that this setup doesn't leave much droop left. I'd be interested to see where a stock truck sits in terms of both up and down travel to compare to.
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  #46  
Old 07-03-2010, 06:07 PM
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Corey, I'm just courious how much more droop your shocks could allow? Do your springs unseat before your shocks fully extend?
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  #47  
Old 07-03-2010, 06:36 PM
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Quote:
Originally Posted by Corbet View Post
Corey, I'm just courious how much more droop your shocks could allow?
This is on my list of things to do. I suspect there is about 4 more inches droop avail, maybe less in the rear.

Quote:
Originally Posted by Corbet View Post
Do your springs unseat before your shocks fully extend?
Nope, but I'm running the standard OME shocks, which have the same dimensions afaik as the OEM shocks. I'm hoping to go L's in the front in the near future as I think more available down travel might be a safer option, though I still need to do some more measurements. Check out this thread, its got some good info. http://forum.ih8mud.com/80-series-te...-shocks-2.html

Here are some pics...not terribly useful without another OME shock to reference, but here you go.

Corey

http://picasaweb.google.com/hobogoesrogue/Shocks#
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  #48  
Old 07-06-2010, 01:17 AM
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Quote:
Originally Posted by AxleIke View Post
Why not just get longer shocks then? If they are just moving the travel down, and not giving you more travel, then the whole lift is pointless. You could cut the body, run the same sized tires, and keep the COG lower. Now, if you have the longer springs, chances are you can get more travel from them, and thus the lift makes sense. But not if you are only using part of the travel you just gained.

In your case, you have 10" of travel with a 3" lift. Go to a 12" or 14" shock, and get more travel, leaving the original bumpstops in place. Now you can use the full benefit of those longer springs. And you can keep the 50 50 split you desire.

You make a good point for the front balancing the rear. The main issue with the 80 rear's is likely the same as modern runners. 5 link with a panhard means more arc which means more rubbing the more travel you gain.. Running new link set ups front and rear would be the ultimate fix for the 80, but not particularly feasible for most.

For Myself, dave, and farnham, the front to rear balance is a total joke, as with IFS rigs, we do not come close to having balanced rigs. The rear does all the work, and the front is just along for the ride.
Longer shocks = more suspension travel unless some restriction is designed into the system (see 80 series radius arms). This is not always a good thing. On an 80, a longer shock will have zero effect on the front suspension without some other modification - it cannot even use the articulated travel of a 10" shock. I initially was sure I would "re-link" the front of my 80, but I am now a pretty strong advocate of leaving it alone because it adds so much stability in so many situations where you really need to feel the limits without getting far enough to risk a flop or worse.

Lifting an 80 has some particular issues. First, the lift is never pointless from a clearance perspective given the 80's low hanging frame, and to be honest while you can run 37's on a pretty small lift frame and bracketry clearance remains an issue vs. going taller. The larger issue, however, is that 80's springs don't tend to get much longer, if at all, as you lift. This is because the top heavy pig needs a lot of extra spring rate as you go higher. A 12" or 14" travel shock is going to generally exceed the sweet spot of the spring motion on a lifted 80, probably dropping the spring off the tower. This is particularly true when you buy springs made for expedition weight and then try to rock crawl with it. Anybody who has noticed how much relatively easier it is to lift a leaf sprung 60 "big" vs. an 80 is seeing this issue on display.

Now, my coils are progressive with a series of dead winds at the top that will unstack during articulation - this allows a balance of a very firm underlying spring rate with a somewhat longer coil, but I am still using almost all of the effective travel of these springs with just a 10" travel shock. Adding travel would simply place more of the suspension movement outside of the range where the spring itself is functioning as designed. This makes for nice web pics, but may not be optimal in situations where you don't want any sudden suspension geometry surprises.

The bottom line is an 80 has a really solid sweet spot right at 3-4" of lift. You can go to a DC shaft and have perfect caster and pinion alignment, you have enough lift to run 37's if you want to without any major trimming with a good balance of COG and clearance (within "typical" usage), and a 10" travel shock mounted inboard on the axle tube is generating a very nice amount of travel in the rear 5-link at the wheels without causing any excessive issues or forcing higher spring rate coils to operate outside of preferred range of motion.

You can try to design an 80 series suspension outside of these parameters, but that is a tuner's game and mostly you'll end up sounding like me in posts like this (the "inch here, performance there" arguments ). Most 80's that are pushed well outside of these parameters end up getting sold, whether it is portal axles, 3-link fronts, chopped tops, or whatever. I see plenty of 6" lifts on 35's. I'd rather be at 4" on 37's in the great majority of situations.

So in the end, adding a bunch of travel to an 80 doesn't really make any major positive performance difference IMO. Its size, weight, and (lack of) clearance will always dominate with dual lockers, surprisingly good balance, and ability to run huge tires on a smallish lift largely offsetting those characteristics.

This video starting at 2:48 I think shows it perfectly - as the rear drops there is almost no body movement, no tires pick up, balance stays perfect. The second video also shows the 80's limitations perfectly as those rear control arm mounts will beach you in rock gardens again and again. No amount of flex will care for this, but you have to introduce the considerations of more lift to deal a condition you may see a couple times a year.

Chinamans Flex:

http://www.vimeo.com/7951992

Spring Creek Hanging. Again.

http://www.vimeo.com/12729246


YMMV, but it isn't likely in an 80

Last edited by Nay; 07-06-2010 at 01:50 AM.
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