Torsion Bar lowering

Post by **yevntry70** » Wed Dec 31, 1969 5:00 pm

I have a '70 521 pickup. I have read and pretty much understand how to lower the front end using the torsion bar adjustment. I was wondering if any of you have done it and know what is the max you can get out of this technic? Are we talking 1 to 2 inches or 3 to 5? Just curious so I know what size blocks to get for the rear.

Post by **IMH** » Wed Dec 31, 1969 5:00 pm

If you get longer bolts (make sure they're grade 8) you can take it down as much as the front of my 320 in my signature picture. I hate lowering blocks because they bring the bottom of the u bolts so close to the ground that if you ever had a flat they'd hit the ground. I had my rear springs de arched.

Post by **famousyellowz** » Wed Dec 31, 1969 5:00 pm

I had a '78 620 and was able to lower it all the way to the rubber stops. Most would lower the rear using 2" blocks. Could go lower though.

Good luck.

Post by **phlebmaster** » Wed Dec 31, 1969 5:00 pm

I lowered mine with the torsion bars, and have left the rear stock hight. I like the raked look.

Post by **LilDat** » Wed Dec 31, 1969 5:00 pm

Stephen and Aaron, for those of us who never dreamed of lowering their front, give us more details/pictures of how you did it. I think it would be a great instructional tool. Ken

Post by **phlebmaster** » Wed Dec 31, 1969 5:00 pm

You got it! I will post it tomorrow.

Post by **IMH** » Wed Dec 31, 1969 5:00 pm

The front is simple. You just replace the torsion bar anchor bolts with longer bolts which will give you more downward adjustment. Use grade 8 bolts for this.

Post by **phlebmaster** » Wed Dec 31, 1969 5:00 pm

Thanks Stephen! I have never thought of that...that is much simpler than re-indexing.

Post by **phlebmaster** » Wed Dec 31, 1969 5:00 pm

I like Stephen's idea, but here is another option:

Quote »Originally Posted by Bleach How to Reindex Torsion Bars [/quote]in front of the middle crossmember, you pull the boot forward to reviel the lock ring

Work a thin screwdriver into the edge of the ring. It will be tight. I had to work the angle back and forth while occasionally tapping the back of the handle with a hammer

Once you get under the ring, work it out slightly. Do not pull the screwdriver away or the ring will pop back on

After you have worked it off part way, use some pliers to pull the ring off the rest of the way. Be sure to still keep the screwdriver under the lock ring

Tap the rear arm of that holds the adjuster bolt out of the crossmember. Hang onto the torsion bar. It can slide out at either end. I was able to feel the splines in the end of the bar and I moved it two notches. editbut you only want to move it one notch!) The reindexed bar is on the right.

after the bar is reindexed, just hold the lock ring up and hit the back of the ring with a hammer. It pops on real easy. Put the dust boot back

Post by **IMH** » Wed Dec 31, 1969 5:00 pm

I'm not certain but won't your method soften or stiffen the ride depending on which way you turn the bar?

Post by **phlebmaster** » Wed Dec 31, 1969 5:00 pm

You are correct Stephen.

If you turn the bolts in you will stiffen the ride and raise the front end. The opposite is true when turning the bolts out. You will run into your rubber bump stoppers if you do not remove them, so be sure not to let your suspension ride directly on your frame.

Post by **IMH** » Wed Dec 31, 1969 5:00 pm

I lowered my truck about 15 years ago. I shortened the insulators and had my rear springs re arched. No lowering blocks. Mine could actually go lower but I like it how it is. Both ends are lower than stock with a slight rake. I actually have a rear sway bar on mine and it handles about as good as you'll ever get a 320 to handle without more extensive mods.

Post by **phlebmaster** » Wed Dec 31, 1969 5:00 pm

Nice!

Do you have any recent pics of your 320?

Post by **IMH** » Wed Dec 31, 1969 5:00 pm

The signature pic is only about 3-4 months old and nothing has been done to the truck since it was taken.

Post by **phlebmaster** » Wed Dec 31, 1969 5:00 pm

IMH wrote: Quote »The signature pic is only about 3-4 months old and nothing has been done to the truck since it was taken.[/quote]That is an incredible looking truck! :

Post by **famousyellowz** » Wed Dec 31, 1969 5:00 pm

I do not think that the torsion will change at all when you turn the bar. It's a bar spring and the indexing has nothing to do with it's ability to twist.

In order to make it stiffer you would need to shorten it. This can only be done one way without cuting it and relocating your rear mount points. That would be to add splines (not really an option) and add another arm with splines that attach to the new spline location and the arm would need to bump up against a location onthe frame.

I have this dual torsion set up on my hardbody. The torsion bars were an option from the Nissan catalog. It works normal unitl you put a load on the torsion bar and as it twists the additional arm will stop the bar from twisting from its location thus making the bar shorter between the A-arm and the rear torsion bar mount.

Post by **phlebmaster** » Wed Dec 31, 1969 5:00 pm

famousyellowz wrote: Quote »I do not think that the torsion will change at all when you turn the bar. It's a bar spring and the indexing has nothing to do with it's ability to twist.

In order to make it stiffer you would need to shorten it. This can only be done one way without cuting it and relocating your rear mount points. That would be to add splines (not really an option) and add another arm with splines that attach to the new spline location and the arm would need to bump up against a location onthe frame.

I have this dual torsion set up on my hardbody. The torsion bars were an option from the Nissan catalog. It works normal unitl you put a load on the torsion bar and as it twists the additional arm will stop the bar from twisting from its location thus making the bar shorter between the A-arm and the rear torsion bar mount.[/quote]You are correct when it comes to re-indexing, and thanks for the input.

But, as you twist the torsion bar the resistance is progressive. So...if you turn the bolts in and raise the front end, then you are changing the resistance at the end of the travel. You will have more force pushing back as you reach the end of your travel due to the nature of the torsion bar wanting to return to center.

That is what I meant by stiffening up the suspension. lol :P

Post by **Desert Rat** » Tue Oct 28, 2008 9:48 am

It's a common misconception that lowering/raising Tbars stiffens or softens the ride. It simply changes the ride height. The only way the ride stiffens or softens is via a different spring rate (meaning a different spring).

Obviously I'm a 4x4 guy and am more concerned with lifting. Cranked tbars can make for a harsher ride due to the limited down travel and the frequency the UCA hits the bumpstop, and I'd assume the same holds true for adjustments in the other direction. Reindexing is a better method for adjustment than having the anchor hang below the crossmember, exposed to speed bumps, etc.

Also, after any adjustment like this, you've at the very least affected the toe-in setting on your alighnment. If you have a buddy with a tape measure, you can adjust this back into spec with the right wrenches. Ideally you want around 1/8" of toe in on the smaller tired trucks.

I'll be over in the Nissan trucks forum

Post by **phlebmaster** » Tue Oct 28, 2008 10:08 am

Nice!

Thanks for the input, I will be trying the camber adjustment this weekend.

Post by **famousyellowz** » Fri Nov 21, 2008 12:45 pm

I think that's what I was trying to say or what I was thinking.

Actually, nissan did offer two-stage torsion bars. I had them on my 86.5 hardbody. They added another set of splines about a foot back from the front of the bar with another arm that allowed you to set your next level of spring if I can say that.

It would allow you to have normal torsion or spring rate until the next arm hit the frame thus making your torsion bar only a foot or so long which increases your spring rate.

Post by **PEZi** » Wed Dec 17, 2008 9:41 pm

longer bolts... that's it?

Post by **Old Rob** » Mon May 18, 2009 7:03 pm

Having the spring eyes reversed will drop the rear approx 2" without any change in ride or load capacity. Then use a block to get your final height. Check your driveline angles.Be sure any changes in height to check your bump stops and adjust them. Do not just remove them. That rubber block keeps the suspension from banging. The banging can shorten the life of the suspension components and is extremely annoying.

Post by **keiffer671** » Sun Oct 11, 2009 2:07 am

question??

if goin with the torsion bar lowering. would it be wise to change the shocks to smaller ones or will stock shocks be enough to do the job? if it were to be changed any suggestions on drop shocks, any brand come to mind. also i heard of guys using ford pinto shocks for nissan 720. will this work or an 81 reg cab

Post by **PEZi** » Sat Oct 17, 2009 7:00 pm

ford pinto shocks aren't going to work unless you make some mounts for them...

you don't need new shocks for the front if doing torsion bar lowering the regular ones are fine... drop shocks are for drop spindles

Post by **keiffer671** » Sat Oct 24, 2009 12:28 am

thanks i appreciate the info pezi

Post by **jdamion** » Fri Jan 15, 2010 12:31 am

no need for new shocks if you put blocks on the rear end?

Post by **PEZi** » Fri Jan 15, 2010 8:19 pm

well... technically drop blocks and drop spindles both call for drop shocks as well

i personally still run a regular type shock instead of the drop shock but its not exactly recommended

Post by **Charlie69** » Wed Jan 20, 2010 8:37 pm

Should you start by jacking up the vehicle until the tires are off the ground and secure with jack stands?

Is the picture of the re-indexed torsion bar 1 or 2 splines?

Thank you for this it is a big help

Modified by Charlie69 at 10:45 PM 1/20/2010

Post by **PEZi** » Sat Jan 23, 2010 7:41 pm

yes... jack it up and secure with stands

not sure about the pic... i've heard 2 splines is generally used for most applications of 3+ inches

Post by **kris127** » Tue Feb 28, 2012 1:09 pm

this might be a dumb ? but i am getting ready to lower my 84 front with the T bar do i crank the bolts down to lower it or adjust the bolts up wards to lower it

Torsion Bar lowering

Re: (phlebmaster)

Re: (Desert Rat)

Re: (Desert Rat)

Re: (IMH)

FN-QR

Re: FN-QR (PEZi720)

Re: FN-QR (PEZi720)

Re: FN-QR (jdamion)

Re: (phlebmaster)

FN-QR

Re: Torsion Bar lowering

Nissan Forums

Infiniti Forums

Datsun Forums

Technical Forums

Classifieds / Marketplace

Nissan Motorsports

General Forums