Thanks and Toyota T100 Torsion Bar Adjustment

[XL Bar]

Howdy all,

I would like to preface this question by first thanking all of you who are active in this forum and the Portal in general. You have been so informative and willing to share your knowledge. You have definitely shortened my Toyota truck learning curve!

I have a question about adjusting the Torsion bars on my new T100. The previous owner had an add-a-leaf installed when he put on his camper shell. I believe the shop then cranked the torsion bars up to match the rear ride height.

I would like to relax the bars so as to improve the ride quality. I noticed that there was very little (less than a fingers width) of distance between the droop stop and the A-arm (the compression stop had 2 fingers of gap). I began backing off on the adjustment bolts equal amounts per side and measuring the rim to fender distance. I was able to drop the drivers side 1" with only 4 revolutions of the bolt. I have turned the passengers side 9 revolutions and it has only dropped 0.75". I now see a lot less bolt exposed above the nut on the passenger side bar.

Am I missing something here? Could something be seized up in my suspension?


Thanks,

Brian

 

[Scenic WonderRunner]

This is a site I used to learn how to adjust mine on my 4Runner.

http://www.off-road.com/trucks4x4/article/articleDetail.jsp?id=398514

Do a search on the net for your T100. I bet they are pretty much alike.


I'm wondering if you might have one worn out torsion bar. How many miles on the truck?


Might not be a bad idea to start off with a set of new ones.




.

 

[Northern Explorer]

I would drive it around for a few days to see if it settles.

 

[BLKNBLU]

I would drive it around for a few days to see if it settles.

Ditto. And please don't forget to have it aligned once you are sure you have it where you want it. (I imagine you already know that)

 

[XL Bar]

Thanks guys. Yes I have driven it around a few days. Even have taken it off road a bit to help compress and extend things. It still is showing the same discrepancy.

Could my shocks be holding the truck up? The bushing on the drivers side shock has some slop in it. Maybe I should remove both front shocks and see what effect that has.

And yes I know about the alignment issue.

Brian

 

[XL Bar]

I have 134,000 miles on the truck. Should the distance between A arm and bump stops be equal for both the upper and lower stops?

Brian

 

[slosurfer]

I don't think so. I think you will have more room on your lowers.

 

[XL Bar]

So you are saying that is better to have more up travel than down travel?

I cranked the bolts down so that there were equal amounts of travel between the upper and lower stops and the ride quality was much improved. I then cranked them back up to their old position (one finger between the droop stop and two between the compression stop) and the ride was much harsher.

I'm just trying to get this figured out before I go have the alignment done. I don't want to have to get multiple alignments.

Brian

 

[XL Bar]

I also don't think I am getting an accurate reading measuring from the fender to the rim. Should I be measuring from the ground up to a point on the lower control arm?

Brian

 

[ntsqd]

This probably isn't going to help much, but where you set it up depends on what you want.

In talking to Brett King of King Shocks a couple years ago he said that he prefers to set up a desert racer with the shock at mid-stroke at ride height.

With short travel suspensions the trend is to have more compression travel than rebound travel. The idea being that you can soak up the bump better if you bias the ride height in that direction. As you've found out, T-Bar Toyotas are notorious for a harsh ride if this is taken too far.

I don't think that there are any hard and fast rules about "X many turns of the Adjuster nut/bolt." What is more important is the the ride height appear to be even and that the frame be parallel to level ground across the width of the truck while at ride height. To do this means measuring from some point of reference on the body or the frame, but not on any suspension component, down to the ground. Fender lips are OK ref points. Suspension inner (frame mounted) pivot bolts are usually great reference points. The upper control arm inner pivot bolts are usually wider apart than the lower bolts, so if a straight line from them to the ground presents itself I would use those. Otherwise the lower pivot bolts will work.
If you find that the adjuster bolt settings are radically different in achieving this I would suspect that one of the bars is dying. It will be the one with the most pre-load on it. Best to replace them in pairs.

 

[jatibb]

related maybe? when i was younger, waaaaay back when there was a trend for what was called mini-trucks, remember that kids. anyway, i had a 73 datsun 620 then graduated (although i always liked the datsun more) to a 1980 toyota. anyway, the trend for lowering them was to loosen the bar . i realized when messing with mine that all i was doing was taking the "torsion off of the bar". i realized this when autocrossing the trucks, the front was loose even though there really was no travel. so i removed the bars, letting the truck sit all the way down, reinstalled to bars and cranked the truck up from there to where i wanted it. seems that as soon as the pressure was off the bumpstops than the "torsion on the bar" stayed the same within a small amount of lifting or lowering. just a thought if the bars can be removed (the older trucks had a spline in one end) then jack the truck up and reinstall the bar to hold it there. anyone try this? interested cause soon may purchase amigo sport with torsion front end.

 

[ntsqd]

Called "Indexing" or "Re-indexing" the t-bars.
If the leverage is the same, the weight of the truck will twist the t-bars nearly the same amount regardless of the pre-load in the bar. What will change is the resulting ride height.
What complicates this is that the leverage doesn't stay the same because the control arm travels in an arc. And what further complicates this is that t-bars have a large rising rate (the more they are twisted, the larger the force needed to twist them further). Where the spring load of the t-bar is first applied relative to that arc will affect the results. So if you re-index the bars for more lift and then you put a lot of pre-load on them the arms will be in a position of reduced leverage so the result will be a tall ride height and very stiff springs.

It is a good thing to have a Factory Service Manual (FSM) when working on these sorts of things. Call Toyota direct for these. I recently bought the whole set of manuals for my '84 FJ60 and the bill was roughly $100 Money well spent!

 

[XL Bar]

Thanks ntsqd. Your explanation is one of the best I've read about the relationship between the torsion bars and the control arms.

Brian

 

[ntsqd]

You're welcome.


Thom