Friday, January 4, 2008

Torsion Bar Height Adjustment

Cranking down the torsion bars a bit is an acceptable way to create more front end lift on your Pathfinder. The main reason people want to lift the front only is, after larger tires(31x10.50 for example)have been installed, they will generally contact the lower rear lip of the wheelwell when you turn and it tends to make a nice loud grating noise. Lifting the front end a little will correct the problem. If a lift of more than one or one and a half inches is desired, a ball-joint angle correction is required.

Looking at a pic of a stock Pathfinder from an ad or brochure back in the day, you'll see that they all sat lower in the front than in the rear. This is due to the fact that the 5-link rear axle has more travel(up and down movement) than the front suspension. Therefore, when the people at the factory set the suspensions up, they were set in the middle of their respective travel lengths, the front sitting lower than the rear.

The front suspension of the Pathfinder is suspended not with a leaf or coil spring, but with a linear spring called a torsion bar. Torsion bars have been in use for a long time in many different kinds of cars and trucks. A torsion bar is a spring constructed of a steel rod, splined at both ends. The ends are held in place by a grooved socket in the lower A-arm with the other end residing inside a sleeve with an adjuster arm welded to it inside the transmission crossmember.

The torsion bars are adjusted by loosening the locknuts on the adjuster bolt and screwing the bolt clockwise from below(as if tightening it). It's best to make sure both adjuster bolts are even(adjusted the exact same), otherwise the Pathfinder will sit crooked. When the torsion bars have reached the limit of their upward adjustment, the control arms will contact the bumpstops and there will no longer be any available upward travel in the front suspension, only downward. This causes a stiff ride and increased vibration in the front end. The C/V joints and ball joints will also be much more susceptible to early wear and failure than if the Pathfinder were left at it's stock height. The tires will also be off alignment and may show increased wear on the inner tread section than the opposite side. Any adjustments to the torsion bars should be accompanied by an alignment.

Picture of the adjuster's topside bolt and stopnuts. This adjuster is completely maxed out at around three and one half inches as measured from the top of the upper nut. My torsion bars are in need of replacement!

An alignment is sometimes not possible after the torsion bars are cranked up too far. This can be taken care of by installing either new upper a-arms (control arms) or a special ball joint spacer made exclusively by Automotive Customizers( Upper control arm replacements are available from several different companies. Superlift and Automotive Customizers are the most popular.

After lifting the front end of your Pathfinder, you might want to consider replacing the sway bar end links. While the factory end links will work fine as they are, the increased height of the front control arms will wear out the old rubber bushings and the front end will seem loose when driving down the road. It's also just nice to know you have new parts under there as well. I used new Addco end links from Pep Boys with poly bushings that were about one inch longer than the stock ones to accommodate the increased height. They work great and allow the front end to droop a bit more than stock for better traction offroad.

No comments: