Coil overs and torsion bars

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Coil overs and torsion bars

Post by Captn. Crunch »

Hey
I did a body lift on my 99 AWD along with S-10 rear leafs and some new Goodyear ATR's. the front in lower than the rear and I want to raise it to match. I don't want to crank the t bars to do it. I don't like the strain it puts on the front end components. I thought a set of coil over shocks might do the trick but was wondering if you can/should run coil overs with t bars.
Any thoughts??
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Re: Coil overs and torsion bars

Post by Stroverlander »

The shock mounting brackets on the frame and lower control arm aren't designed for that load and there isn't room to fit much of a larger diameter shock let alone a coilover due to upper control arm interference.

You would effectively be doing the same thing as adjusting the torsion bars anyway and so would be dealing with the same angles on the control arms and cv joints. Torsion bar is a linear rate spring so turning the adjuster doesn't change rate, it changes the angle of the lower control arm.

What is the difference and how much front end lift are you trying to achieve?
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Re: Coil overs and torsion bars

Post by SilverBullet1997 »

Image

I agree with Stroverlander, Your best bet would be to do the re-indexed torsion keys from OverlandVans or AirBagIt.
The keys will allow the the front suspension to still move up and down will keeping the same ride comfort with out fully cranking your t-bars.
When you install the keys count the amount of turns you do to take the keys out, then re-crank the new keys to the same amount of turns and you will effectively have lifted the front end another 2"
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Re: Coil overs and torsion bars

Post by markinnh »

Or use a body lift kit.
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Re: Coil overs and torsion bars

Post by Captn. Crunch »

Ya I thought that might be the case. Looking at the t bars the last time I was under the truck, there was a lot of thread showing as in lots of room to crank. The bars look new so I'm thinking p.o had a set installed. I will put a couple of turns in and get it re-aligned.
Thanks for your thoughts
Captn. Crunch
"I don't beat my rig-I use it to it's maximum potential"
1994 Safari conversion (sold) and miss'n it!
1999 Safari SLE AWD junked
2003 GMC Safari AWD SLT
cast iron Torsen equipped front diff
S-10 leafs-G80 rear w/3.73’s
2” body lift w/Falken Wildpeak AT’s
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Re: Coil overs and torsion bars

Post by Herbie »

SilverBullet1997 wrote:Image

I agree with Stroverlander, Your best bet would be to do the re-indexed torsion keys from OverlandVans or AirBagIt.
The keys will allow the the front suspension to still move up and down will keeping the same ride comfort with out fully cranking your t-bars.
When you install the keys count the amount of turns you do to take the keys out, then re-crank the new keys to the same amount of turns and you will effectively have lifted the front end another 2"
I'm not sure I follow all of this post.

For the same "setting" of front suspension height, there should be no difference between re-indexed keys or re-adjusted (cranked) stock keys - both are just changing the preload on the aft end of the torsion bar. With the re-indexed keys you're twisting the bar to a certain position by changing the orientation of the bar in the key. With the stock keys, you twist the bar by moving the whole key. The only difference between the two will be whether or not the adjusters are in one position or the other. Certainly the re-indexed keys should let you preload the bar MORE, but for a moderate lift on torsion bars that aren't "worn-out", there will be no other difference for a given front-end height.

In both cases, you're trading lift for a loss of droop. You're basically pre-drooping the suspension. You will have more up travel, but less overall down travel.

Regarding your needs, as others have said, a body lift will get you tire-to-body clearance without changing anything in the suspension, obviously. I'm really wishing there was a ready-made front-diff drop kit. Just a couple of inches. It would be nice to be able to correct some of those front axle angles but keep the extra up-travel.
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Re: Coil overs and torsion bars

Post by Stroverlander »

Exactly, well put Herbie. :cheers:

This is the draft I had saved:
Even so, with re-indexed keys the control arm and cv joint angle will increase to the same degree as stock keys for given amount of lift. The lift torsion keys only further relocate that adjustment range via the "indexing".

The difference in ride and feel comes from the greater control arm angle and lessening of downward (extended) suspension travel due to the control arms being moved that much closer to the bump stop on extension or full droop.

Consider front shocks with slightly more travel to help minimize the harshness by not allowing the shock to top out or operate at the very end of it's range of travel.

It's all a series of compromises to try and achieve what you're after without giving up too much in other areas.
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Re: Coil overs and torsion bars

Post by Captn. Crunch »

http://m.rennlist.com/rennforums/showth ... styleid=21

This was a discussion I found with Porsche guys running coil overs with torsion bars on the rear of their 944's. some good data for t bar rates. I'm still researching small import rear coil overs that would fit. I did do the body lift as described by Markatanium? In the lifted section. My thoughts were to gain a couple of inches of lift with the coil overs and still maintain a "neutral" t bar with the van at rest.
Captn. Crunch
"I don't beat my rig-I use it to it's maximum potential"
1994 Safari conversion (sold) and miss'n it!
1999 Safari SLE AWD junked
2003 GMC Safari AWD SLT
cast iron Torsen equipped front diff
S-10 leafs-G80 rear w/3.73’s
2” body lift w/Falken Wildpeak AT’s
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Re: Coil overs and torsion bars

Post by Stroverlander »

You're missing that the no matter what, when lifting the van via "spring" the control arm and cv angles are going to change the same as adjusting torsion bars, that is just the nature of our IFS design.

Besides, OE shock or equivalent is around 1.75" diameter body, Rancho RS9000XL is 2.18" body and makes contact slight contact with upper control arm at full extension (being a twin-tube design this isn't as much of a concern, the piston rides on the inner tube not the outer) so not much room for a coilover to fit with a spring that offered any meaningful increase in rate. Just because something might fit doesn't mean the valving/damping is going to be even close to what is required for your application.

I looked into coilovers and higher end shocks that I could rebuild/revalve/spring to suit my needs as I perhaps added additional weight to my van (bumper, winch, etc) and determined that it spirals out of control pretty quickly to do it right - reinforced lower control arm shock mounts, reinforced or new upper shock mounts, custom or modified upper control arms for clearance and that if I was going to do that, I'd prefer to invest the time and resources into a solid axle swap. :D

I still may decide to do add Fox or King remote reservoir shock later on (not a coilover) but even that is going to require some time to sort out valving methinks.
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Re: Coil overs and torsion bars

Post by Captn. Crunch »

....and that's why I love this place. A suspension lift kit for these things would be cool. Ah well crank on the bars and get on with your day
Captn. Crunch
"I don't beat my rig-I use it to it's maximum potential"
1994 Safari conversion (sold) and miss'n it!
1999 Safari SLE AWD junked
2003 GMC Safari AWD SLT
cast iron Torsen equipped front diff
S-10 leafs-G80 rear w/3.73’s
2” body lift w/Falken Wildpeak AT’s
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Re: Coil overs and torsion bars

Post by Stroverlander »

An easy, cost effective method to increase suspension travel would be excellent! :)
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Re: Coil overs and torsion bars

Post by photo_van »

This is a little old, but I just came across it.

Re: more downward travel. Upper ball joint relocation below the upper control allows for ~1" more downward travel at the stop. This will project to more than an inch out at the wheel. New shocks will be needed to accommodate the longer travel. I'm hoping to do this when I need new shocks.

At some point I'd like to see a thread on what people have done regarding longer shocks on lifted vans. I've measured the travel on the rear end of mine (w/shocks disconnected) and it exceeds the length of the shock :yikes:

While I've found shocks with appropriate travel on the shock charts, as Stroverlander mentioned, it doesn't mean they are designed for the application....
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