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Lifting/stiffening '01 OBW rear suspension


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Just got back from a few days in Montana with all the crew and kit.  The new KYBs (inside old springs) in the rear have certainly helped, but more is needed.

When fully loaded and with trailer, the rear of the car is depressed by as much as 3", based on quick measurements taken along the running-board trim.  The trailer w/ boats is, based on the published weights, roughly 1200 lbs., so the tongue weight should be about 120 lbs.  I'm going to measure this (as well as try to confirm the trailer's gross weight), and suspect it's on the high side. Since I can't really do anything about the load distribution (the Sea-Doo and sailboat fit where they fit), the tweak that's available to me is moving the (single) axle forward - I think I have about 6"of latitude there.

But if I want to stiffen and/or raise the rear end so it's as close to level as possible under load, what are my options?  I'm trying to be purely practical here and not look like some jacked-up dope.  I seem to recall discussions of Forester components being used in cases like this.  Or do I just have to shop for stiffer springs?

Any direction greatly appreciated.

Edited by jonathan909
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  • jonathan909 changed the title to Lifting/stiffening '01 OBW rear suspension

Baja turbo rear springs offer minor improvements decent for many OBW situations. They can stay level or better with a couple hundred pounds of two average/light rear passengers and gear in the rear and towing…depending on weight distribution and tongue weight of course.

For really high loads, heavy passengers and gear, heavy towing and zero tolerance - then king springs. 

Edited by idosubaru
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11 hours ago, idosubaru said:

Baja turbo rear springs offer minor improvements decent for many OBW situations. They can stay level or better with a couple hundred pounds of two average/light rear passengers and gear in the rear and towing…depending on weight distribution and tongue weight of course.

For really high loads, heavy passengers and gear, heavy towing and zero tolerance - then king springs. 

Thanks.  I'm going to cast about for the Baja Turbo springs, but at first glance that doesn't look like an easy acquisition - Bajas are pretty rare (at least around here, and none listed in either of the local P'n'P's inventory), making a turbo tougher yet.  Rock doesn't list springs for them, and I shudder to think what a dealer will ask.  I'll check with the usual local aftermarket parts shops today and maybe see if the full-service wreckers have anything.  Previously unfamiliar with King - that experiment looks like it'll cost as much as the car did, esp. factoring in shipping from Oz...

Any hints where I might have better luck looking?

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I've never used one; not hard to understand how and why it works, but I don't think it's appropriate here.  When you look into them, you find assumptions like "pickup truck" and "trailer weight 5000 lb and over", so that suggests that they're pretty severe overkill for this application.

I just got back from the scales, and the weight came in at exactly 700kg (1540 lb), which isn't a surprise given the published weights don't include the added front wheel/stand, boat mounts, gear stowed in the sailboat, or (probably) the gas in the jet ski.  So the question now is what the actual tongue weight is and whether it can be dialed in to ~150 lb, which is pretty modest.  And since it's a 20+ year old car it seems to me that the springs are softer than they should be, so does it make sense to add all that heavy-duty hardware to correct what's really a pretty small deficiency?

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Availability:  The dealer tells me that Baja parts are being discontinued fast, but they do have a few pieces of the 20380AE50A spring at a reasonable price - $104 canuck.  Curiously, they also have one piece of the 20380AE52A for a little more ($114) but have no indication what the difference is, if any.

As far as the wreckers go, the local full-service yard I spoke to says there are no Bajas listed on the entire continent.

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57 minutes ago, 1 Lucky Texan said:

There are these gadgets called Coil Sumo springs (they sell other products that seem less gimmicky), but I have severe doubts about their performance and longevity - anyone here tried them? I know only what the ads say.

 

https://www.superspringsinternational.com/coil-sumosprings/

 

probably a bit better than the old school twist in coil spacers, but yeah... gimmick... and not the right way to "fix" things..
short term, maybe, but not long term

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4 hours ago, jonathan909 said:

Why the Forester springs rather than Baja?

because there are a lot more Foresters around than Baja's? Just a wild guess, but probably pretty accurate..

I put Forester struts & springs on a 95 Legacy i had and absolutely loved it. better ground (snow) clearance & a little stiffer, so less body roll. Just made the car all that more enjoyable to drive to me.

Edited by heartless
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Look for a set of aftermarket springs that have a progressive spring rate. 

These are good for daily driving unloaded while also maintaining some height when loaded. They will compress when loaded but not as much as a set of linear springs and even less than an old set of linear springs! 

Just swapping out springs for new units will make a huge difference! 

Cheers 

Bennie 

Edit: I can vouch for King Springs. Had them in my L series and in both of our Gen3 Pajeros/Monteros/Shoguns. I get the shipping costs from Oz - probably an arm and a leg but you can only ask!

Edited by el_freddo
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On 9/17/2022 at 8:18 PM, heartless said:

because there are a lot more Foresters around than Baja's? Just a wild guess, but probably pretty accurate..

I put Forester struts & springs on a 95 Legacy i had and absolutely loved it. better ground (snow) clearance & a little stiffer, so less body roll. Just made the car all that more enjoyable to drive to me.

Okay, but now we're going in circles.  I originally asked about Forester springs because that's what I recall having been previously discussed.  Then someone said "Baja", and now we're going back to the Foresters.  From a cost perspective, I'd prefer Foresters because right now there are half a dozen of them in the local P'n'P yards, and as I said above, Bajas would have to be bought new.

So is one taller and/or stiffer than the other?  Which is preferable from the performance (load) standpoint?

The good news (at least for my trailer) is that the tongue weight is spot on - 158 lb., right where it should be.

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i guess you really should be looking at what style struts your 01 has
does it bolt directly to the knuckle? or not?

that will be a deciding factor on what you can or cant use.

Forester rear struts bolt directly to the knuckle (two bolts)
not sure what year it started, but the newer legacy/outbacks went to a completely different style..
and i have no idea what the Baja uses.

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8 hours ago, jonathan909 said:

Remember, we had this whole conversation over whether the rear coil-over-spring qualifies as a "strut" at all.

This OBW has a single bolt through the knuckle.  But that shouldn't matter, because the shocks are new and all I want (hope?) to do is replace the springs.

yeah, ok, i do remember that conversation..
the forester strut swap i did is completely irrelevant to this application.. was the older style..

not sure if this will help, or confuse you more, lol, but found this...
https://www.northursalia.com/techdocs/spring/spring.html

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Interesting, thanks.  But I quickly note that the springs for the three models we're actually talking about:  '01 OBW, Baja, and Forester (all stock) aren't included!  I can't imagine Subaru burying the spring specs in the service manual under a testing procedure, but I suppose it's possible and worth a look.

I was actually thinking about gathering some empirical data - putting a spring in the hydraulic press and seeing if I can get any meaningful readings out of it.  Easily enough done with the spring from my car and a Forester spring from the junkyard, but I don't think my pal with a Baja is going to want to let me yank one of his out just for fun and games...

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40 minutes ago, jonathan909 said:

putting a spring in the hydraulic press

:eek: I would not recommend this unless you have proper safety procedures in place and you know exactly what you’re doing and what the potential outcomes could be! 

Also remember that if the spring doesn’t randomly exit stage left, right, wherever it wants under compression (potentially resulting in serious physical harm or death) that you could run the risk of deforming the spring. 

And it was the Gen3 Legacy/outback platform that changed the rear suspension to a multi link setup with the coil over shock setup, this started in 1999 in Oz.

Cheers 

Bennie

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Yeah, I know what I'm doing. Engineer accustomed to working on and around dangerous things, etc.  Jig it up so it's not going to be inclined to exit in any direction, and only for the purposes of compressing a couple of inches and seeing if the readings that come back make any sense.  In this case absolute accuracy isn't even important, as the measurement will tell me whether I can expect a relative improvement between one spring and the next.

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