Torsion Bar Front Suspension on N_Pathfinder

MolaKule · Nov 2, 2003

Question on 2003 PathFinder LE:
I though some of you mechanics, technicians, and weekend-wrench twirlers (like me) might be able to answer this question. This particular front suspension set-up is new to me. Now my '92 Burb has the torsion bar suspension, but no adjustments like this one.

While changing fluids, I noticed the front suspension system is a torsion bar type. Separate torsion bar to each front wheel assembly of course. At the back end (toward the rear), there is a cam that appears to adjust the position of the torsion bar (CCW, CW), and has two nuts on it, one of the nuts appears to be a stopnut. Can one adjust this cam so that one gets more torque to the individual wheel assembly, as when cornering, such as for better cornerning? Secondary question, does this torsion cam affect the front-end alignment?

No technical repair manuals are out yet (should I say the standard books). And of course, Nissan wants $325 for a complete set.

Shannow · Nov 2, 2003

Molakule,
assuming the front end is the same as my Nissan, and similar in concept to most Japanese torsion bar systems, the bolt/locknut arrangement acts on a lever arm attached to the non-wheel end of the torsion bar.

Rotating the torsion bar simply alters the ride height. When the control arms get to extreme angles, it also affects spring rate, but it's predominantly ride height.

For the Navara, Nissan Oz want $450 for the maintenance manual, plus another $135 for the Engine suppliment.

shortyb · Nov 2, 2003

As Shannow states, its for ride-height adjustments. These made mostly at the factory as part of assembly adjustments. If you crank them up (or down for that matter) you will alter the camber slightly. This also would happen at suspension top-out or bottoming so is not a big deal except for the increased tire wear. If you need/want higher rate bars, there are a few aftermarket pieces available. I'll see if I can dig up some info for you.

BTW, hows the VQ? Neat motor, huh?

Service manual available on CD format also, approx $250 at www.nissan-techinfo.com

[ November 03, 2003, 09:25 AM: Message edited by: shortyb ]

Steve_RI · Nov 2, 2003

I installed Sway-A-Way t-bars on my 89 to cure a sagging front end. As far as I know most of the aftermarket torsion bars will stiffen up the ride quite a bit, which is something to consider if you decide to swap them out in the future.

Here's a link to NOR (nissan off road). They have a good write up on adjusting these things. It's for an Xterra, but they are all essentially the same (as mentioned previously), even for my 89.

http://www.nissanoffroad.net/xterra/how_to/torsion_bars/default.asp

MolaKule · Nov 3, 2003

Thanks all of you for the links and the info. I guess I will keep my gritty hands off it until I decide to increase T-Bar stiffness for Off-Road. Sounds like what I need are larger diameter or stiffer T-bars.

The suspension is great for bumpy highways and gravel roads. Ride is similar to a stiffenend Cadddy's suspension, but it does need some added stiffness for Off-Road. I may try stiffer shocks in the interim.

The 3.5L dual cam V6 engine is a definite performer (glad they used timing chains on this puppy).

Currently getting 18.25 mpg with Mobil 1 5W30 and Neutra/FP Mola Fuel Brew at 70 mph. Have almost 9K miles on Speedometer so far.

[ November 03, 2003, 12:14 PM: Message edited by: MolaKule ]

mikep · Nov 3, 2003

Just to add a bit (a tiny bit), cranking the T-bars is a pretty common thing with F-Series owners looking to put oversize tires on. As was already stated, it affects only height and if adjusted slightly usually doesn't require a re-allignment. It would probably be a good idea to at least have the allignment checked after a T-bar cranking.

Mikep

pinoy99 · Nov 3, 2003

quote:

Originally posted by MolaKule:

The suspension is great for bumpy highways and gravel roads. Ride is similar to a stiffenend Cadddy's suspension, but it does need some added stiffness for Off-Road. I may try stiffer shocks in the interim.

Per above, IMO, stiffer sways are not needed then, just better shocks. I'm using

shocks in my truck with great results on/off-highway.

mikep · Nov 3, 2003

quote:

Originally posted by MolaKule:
The suspension is great for bumpy highways and gravel roads. Ride is similar to a stiffenend Cadddy's suspension, but it does need some added stiffness for Off-Road. I may try stiffer shocks in the interim.

The 3.5L dual cam V6 engine is a definite performer (glad they used timing chains on this puppy).

Currently getting 18.25 mpg with Mobil 1 5W30 and Neutra/FP Mola Fuel Brew at 70 mph. Have almost 9K miles on Speedometer so far.

Check out the Rancho RSX. They are a self adjusting shock that do extrmely well on both pavement and trails. I removed the factory shocks on my F150 within the first 10,000 miles and installed the RSX. Major improvement! I do a fair amount of driving on trails (no serious off-roading) while hunting and fishing and have been extremely pleased with their performance.

Also, check out the Rancho web site...every now and then they offer buy 3 get the 4th free. Brings the per shock price down to under $40.00 each.

Have also read tons of rave reviews on the Edelbrock AIS.

Mikep

mikep · Nov 4, 2003

quote:

Originally posted by pinoy99:
Some folks reported leaking issues, especially when used off-highway. Not too beefy, I guess.

Interesting. Never any mention of that problem on the truck forum I frequent. That would be a bummer. If I'm not mistaken the AIS come with a lifetime warranty so at least the cost of a replacement should be covered. Still, the labor and time involved is a hassle.

Mikep

MNgopher · Nov 4, 2003

I'll ditto the good experience with the Rancho RSX / Monroe Reflex shocks (they are essentially the same shock painted with different colors).

I too have heard the same thing about the edelbrock IAS shocks on several boards over many brands - lots of folks have had trouble with leaking shocks. Seems like 1 out of four almost. Always a no hassle warranty swap, but still a pain for such an expensive shock.

JohnnyO · Nov 4, 2003

I have the bars turned up on my 4x4 Ranger just enough to level it. When I got it the front sat so low it didn't look like a 4x4 and my stock tires hit backing out of my parking space at work.

You will have to re-align the front end, I just had the alignment shop do the whole deal, they only charged me $10 extra. A chain shop probably won't do it, you need a local place where the name ends in "...and Son" and the mechanics themselves drive lifted trucks. When you crank up the bars however, you lose downtravel so don't go too far. If anything, mine rides and handles better. See www.therangerstation.com.

pinoy99 · Nov 4, 2003

quote:

Originally posted by mikep:

Have also read tons of rave reviews on the Edelbrock AIS.

Some folks reported leaking issues, especially when used off-highway. Not too beefy, I guess.

TheTanSedan · Nov 4, 2003

Can't speak directly to little trucks, but have been a Chrysler driver for a long time, especially the 1956-1973 variants.

Torsion-bar adjustment is a ride height adjustment to be checked before an alignement. Now, on a Chrysler the t-bars are located off of the lower, not upper, control arms.

Tire pressure, half-tank of fuel, and weight representing driver in front seat are critical. I usually work at perfecting tire pressure a day or two in advance to have them all within 1/2# cold and take measurements at four F/R fixed points to get it right (a touch low in front to keep front end level at high speeds).

Larger t-bars will really alter ride, not always beneficially. Usual recommendation for Chryslers is to go one step up at a time.

T-bar suspensions are not as easily upset as are coil spring front ends, and larger anti-roll bars (which increase roll stiffness) are the direction I would go first with a primarily road vehicle. I went from KYB's ("stiffer shocks will fix it, right?") to KONI Adjustables (rear) and the quality difference is night and day as to roadholding. (A C-Body Chrysler has no "great" shocks as yet for the front, yet the rear is no longer steering in hard manuevers).

I'll likely go with Old Man Emu for our Jeep, but it will be a whole package of springs and shocks.
Larger anti-roll bars will be part of it, along with grease-able poly bushings for them (but not elsewhere, as one winds up feeling every crack in the road). Will also likely go with a 4-WAY steering damper.

I also changed from 225/75-15 horrid oem Goodyears to KUMHO Ecsta STX in 255/65-16 (within 4/10's/inch same height) to have a wider footprint, great wet traction and stiffer sidewall. This "roughened" the ride, slightly, but not like stiffer springs would have. It gave the vehicle "stability" it didn't have before and wear at 10k is perfectly even at factory recommended 33 psi. (This is a Tire Rack described "Street/Sport Truck" tire). I now know that stiffer springs are not needed, just the appropriate overload device for the rear leaf pack.

I say, go with best shocks, one should not compromise here. KONI is always my first choice, but they don't always offer coverage.

Talk with Gordon Benson at [email protected]

or

Edelbrock at [email protected]

or

KYB at [email protected]

or

[email protected]

All of whom have been helpful to me in the past.

I believe it crucial to know:

Shock length in regards rebound and compression length; type of mount (strength and "binding");
as well as rates expressed in .3/meters per sec (and others) as a fair way of evaluating different offerings.

Also, the best shocks (as you are likely aware) can be rebuilt, and the price premium may be to your liking.

mikep · Nov 4, 2003

quote:

Originally posted by TheTanSedan:
...Larger anti-roll bars will be part of it, along with grease-able poly bushings for them...

(snipped)

Great point! Greasable poly is key! I installed a rear anti-sway bar on my F150 (a week after the Rancho RSX install) and while I love the difference it made at keeping the lean and roll at bay, my truck has become affectionately known as Big Squeaky

. The poly bushings in the brackets that surround the bar and are over the rear axle squeak like mad and is really starting to wear on me. So much so that I've resigned myself to remove the bar for the winter then re-install next spring with new brackets that have zerk fittings.

The overall handling improvement with the RSX and rear sway bar has been the best $$ I've spent on any modification in the last 20 years. Price to performance was a huge win.

Mikep

TheTanSedan · Nov 4, 2003

Forgot these:

http://www.proshocks.com/calcs/index.htm

http://www16.brinkster.com/indio2/4x4/leafspringrate.html

http://www.swayaway.com/Suspension Worksheet.htm

http://www.racingpc.com/tips/independent.htm

Torsion Bar Front Suspension on N_Pathfinder

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