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Old 11-09-2017, 03:52 PM   #21
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Originally Posted by carringb View Post
If I stomp the go pedal, even loaded on dry pavement, it'll roast all 4 rear tires and kick the back end around.
I think we have vastly different goals with our vans.

-Eric

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Old 11-10-2017, 09:53 AM   #22
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FYI - Stiffer rear springs also increase roll stiffness, so if you upgrade your rear springs, that may reduce the need for a rear sway bar. Or at least allow a smaller sway bar. That's why the stabil-loads work.... I just can't stand the "bang" every crack and expansion joint cause when the overloads are engaged.

I tend to drive pretty fast, and don't use the brakes so much, so I went with a 1.5" rear sway bar. But... I also have lots of rear tire, so that helps cancel out the oversteer tendency a giant rear sway bar would normally induce. That said... If I stomp the go pedal, even loaded on dry pavement, it'll roast all 4 rear tires and kick the back end around. I guess I've just had it setup this way for long, steering the opposite way I'm turning seems pretty natural at this point. My dad's van OTOH, which has the same rear bar and stock wheels and tires, can't spin a tire on wet leaves since it has the 5.4L, so it feels impossible to make the rear end kick out. I did install some adapters to widen the rear track, to also help mitigate the oversteer affects of a giant rear sway bar.
Hello carringb,

I follow you on the springs and StableLoad product, and I very much appreciate your knowledge about both. I would not like the feel and banging of the stabi-loads either, so they are definitely out.

As for the upgrade on the rear springs vice the 1 & 3/8 inch Hellwig swaybar, which one would you recommend and why? And what about a comparison in cost?

Did the rear sway bar help your Dad's van improve in this area, without having to deal with a new issue due to its addition?

James
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Old 11-10-2017, 10:01 AM   #23
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Originally Posted by MountainBikeRoamer View Post
It does sound like adding a rear sway bar likely couldn't hurt, if you feel like your van sways too much in turns --- but there are definitely trade-offs to every suspension modification.
Hello Mike!

What kind of trade-offs might crop up with the addition of a rear swaybar or an upgrade on springs, that would require another fix?

James
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Old 11-10-2017, 10:35 AM   #24
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Hello Mike!

What kind of trade-offs might crop up with the addition of a rear swaybar or an upgrade on springs, that would require another fix?

James
REAR SWAY BAR:

Rear sway bar can*:
1) Introduce a tendency towards oversteer.

2) Under certain rough/uneven/broken pavement situations, the rear axle is less "free" to articulate independently left/right, so the rear axle can possibly skitter or hop a bit more than it would have (temporarily affecting braking and stability.)

*These are just generalized effects of a rear sway bar. But as others are noting, each vehicle is different and will respond uniquely. Front/rear weight bias, spring rate, tire make/model/air pressure, front/rear track width, etc....these all make up the many elements of what is really a tuned "symphony" when sorting out each vehicle's suspension setup.

(And, as noted/illustrated by both carringb and Shuttlepilot --- each driver's perceptions, chassis performance preferences/goals, and driving style will all vary widely.)

REAR LEAF SPRINGS:

In lieu of a rear sway bar, a different set of stiffer rear springs could be fitted to make the van handle/corner "flatter," but this solution would possibly yield some of the same trade-offs as a rear sway bar: namely, rear axle hop over rough surfaces and potentially unpleasant harsh ride.

(NOTE:
If your current set of leaf springs is tired/worn, and is sagging down onto its overload leaves....then you definitely want new rear springs as your focus first! Don't even think about adding a sway bar if your springs are sagged onto the overload leaves. Adding a rear sway bar to a worn-out set of rear springs would yield a ride-and-handling basket case. There'd be so much wrong with that setup it's not even funny.)

Leaf springs can be rebuilt in a multitude of different ways, with widely varying effects on handling. I had custom, longer-travel rear springs built that are properly spec'd for the weight of the rig (loaded).....and they both ride better AND hold the road better than the stock springs that were on there before. This is because:

1) they never sag low enough to touch their overload leaves under normal use (so they stay active over bumps)
and
2) they have a heavy-duty, double "military wrap" at their ends of their leaves where they wrap around the securing end bolts --- and this gives the springs more side-to-side torsional resistance....acting to keep the rear axle from "yawing" or twisting as much under cornering or dynamic chassis load shifts.

Again, it really comes down to personal preference and a willingness to accept that there's no "perfect" suspension setup. What works well for "ultimate highway stability" might be terrible for cornering....or for hitting bumps without collapsing some of your spinal segments. It's all a careful balancing act and usually requires experimenting with a couple different setups before you decide what works best.

Just like the Italians who dialed in your old Alfa's suspension, right?
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Old 11-10-2017, 11:06 AM   #25
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Mike,

I've really put you to a lot of work here. Thanks for all the time that you have put in for me and any newbies to the SMB world, or to anyone else who might be considering a suspension upgrade of some sort, for whatever reason(s)

I don't know of anyplace in the Seattle area that might be able to both test and possibly dial-in an upgrade(s) to my SMB, especially when it might well be satisfactory to them as it sits. Remember, this is my first SMB/Van, so the way they handle is new to me. I probably will not be going through Southern California until April next year, so I just might postpone things until then.



James

P.S. An old Alfa race driver and mech for their company, proud Italian at that, dialed in my last Alfa with carbs and all sorts of goodies!
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Old 11-10-2017, 01:21 PM   #26
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Mike summed it up very well.

I was concerned the rear large bar would be too heavy for my dad's van, but turns out not to be the case. Being an EB, it still has a very rear weight bias when loaded, and having the 5.4L and 3.55 gears means it just doesn't break traction, even with the large rear bar. I think it's a good match for any EB, but I think the smaller option is probably better matched.

FWIW - All Transit vans get a large rear sway bar. But I also pull more Transits out of the dirt than all other vehicles combined. They are so far on the torsional stiffness extreme, that the slightest road imperfection unloads a tire and they spin a tire.
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Old 11-11-2017, 09:33 AM   #27
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Mike summed it up very well.

I was concerned the rear large bar would be too heavy for my dad's van, but turns out not to be the case. Being an EB, it still has a very rear weight bias when loaded, and having the 5.4L and 3.55 gears means it just doesn't break traction, even with the large rear bar. I think it's a good match for any EB, but I think the smaller option is probably better matched.

FWIW - All Transit vans get a large rear sway bar. But I also pull more Transits out of the dirt than all other vehicles combined. They are so far on the torsional stiffness extreme, that the slightest road imperfection unloads a tire and they spin a tire.
Thank you, carringb.

I checked with a local spring company that reaches the existing springs and adds a spring or two. The fellow told me that it might add a couple inches of lift to the rear.

James
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Old 11-11-2017, 11:28 AM   #28
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Thank you, carringb.

I checked with a local spring company that reaches the existing springs and adds a spring or two. The fellow told me that it might add a couple inches of lift to the rear.

James
Hey James --- have you looked under your van to see if the leaf springs are settled down/sagged into the overload springs? Or does or appear that the rear of your van sits too low, compared to the front end?

If possible (and if you're interested to do so...), it would help us in offering opinions/guidance quite a lot if you could take a picture of:

1) the rear leaf springs where they bolt to the axle, showing how their arc looks in comparison to that stiff/straight lower-most overload spring. (They shouldn't be collapsed together completely into each other.)

and

2) a good side-view photo of your van, taken far enough away so that it's possible to see how the van "sits" front and rear. (See how level it does, or doesn't already sit.)

If you're going to have rear leaf spring work done, again --- like with all of this stuff....have a clear idea of what you want to accomplish and be sure the remedy is appropriate for what's actually "wrong." (Or isn't.)!

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Old 11-11-2017, 07:39 PM   #29
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We had a 24 foot class C and it wandered down the road badly. Cross winds were terrifying. We added the rear helwig and it helped a LOT.

Our current rb only weighs about 7500 lb and goes pretty straight. However we have a 24 inch hi top and turning sharp corners is a two step process: initial under steer until the van tilts a bit, then add throttle to steer it around the corner. I'm sure a rear bar would make slalom runs more comfortable, but I too am worried about more impact from potholes/washboards and maybe articulation.
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Old 11-12-2017, 11:29 AM   #30
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Mike T,

I'll try to get some pics of the leaf springs point you mention, plus one side view of the van tomorrow. It's parked on an incline right now and it and I need to put it on a level surface for the best results. The rear end of it sits, as I recall about one half inch higher than the front.

James
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