Can I turn down the torsion bar in my steering box?

[nukegoat]

Switching to Part-time and removing the front drive-axles would help lighten it a little.
Have you already flushed the system and rebuilt the pump? clean fluid and fresh seals in the pump would also give an incremental change.

How much reduction are you looking for?

I have never rebuilt the pump. Maybe I should

 

[baldilocks]

I have never rebuilt the pump. Maybe I should

Just buy a new pump. Hey, you sport some pretty big tires that probably lend to your poor opinion of the effort it take to steer your beast. Perhaps a set of narrower tires in the form of Michelin Military tires in 39" would help. You haven't done hydro-assist?

 

[nukegoat]

Just buy a new pump. Hey, you sport some pretty big tires that probably lend to your poor opinion of the effort it take to steer your beast. Perhaps a set of narrower tires in the form of Michelin Military tires in 39" would help. You haven't done hydro-assist?

I have done it. But it sucked with 36s too

 

[scottryana]

Increasing pump flow would be a nice option for those wanting to run hydro assist, etc. let’s us know what you find out @Goglo13

 

[Malleus]

IIRC, this is a fixed displacement pump. You can alter the pressure, but not the volumetric flow. Someone correct me if I'm wrong.

 

[Tools R Us]

I have never rebuilt the pump. Maybe I should

If it's not leaking, resealing isn't likely to help. What bore ram? My guess, fluid volume/displacement is your problem. The gear drive setup is nifty, trouble free, but makes over driving the pump about impossible. Don't know if there is a higher displacement Toyota pump? Have a spare pump, going to play with porting/blueprinting, likely to reduce restriction, doubt that it will have much effect on flow?

Maybe mount a higher displacement pump, like a Saginaw, over the A/C compressor?

 

[nukegoat]

If it's not leaking, resealing isn't likely to help. What bore ram? My guess, fluid volume/displacement is your problem. The gear drive setup is nifty, trouble free, but makes over driving the pump about impossible. Don't know if there is a higher displacement Toyota pump? Have a spare pump, going to play with porting/blueprinting, likely to reduce restriction, doubt that it will have much effect on flow?

Maybe mount a higher displacement pump, like a Saginaw, over the A/C compressor?

1.5" - you can crank the wheel really fast and feel the pump starve but the problem here im trying to mitigate is the amount of force required to initiate power assist. Sort of unrelated to pump flow

 

[Malleus]

Agreed. Probably not one available, but a new pressure regulating valve would provide more force to the gearbox, which is what you're looking for. IIRC, the system is overrated for the operating pressure, so you may have a couple of pounds to play with.

 

[DylanICON]

I've always thought the steering was a bit heavy.

I've done the torsion bar on vehicles, you can get any sensitivity you want with the size of the bar.

if I ever have to replace or rebuild the box I would definitely turn down the bar. Not goanna go through the work for an otherwise good box though.

let me know what diameter you end up at????

 

[Tools R Us]

1.5" - you can crank the wheel really fast and feel the pump starve but the problem here im trying to mitigate is the amount of force required to initiate power assist. Sort of unrelated to pump flow

With the motor at idle or all of the time? Mine (different setup) is somewhat sluggish at idle, one of the reasons that I two pedal, a few extra rpm makes a big difference.

Turning the torsion bar shouldn't be that difficult. Take the input apart and put it in the lathe, the question would be how much?

 

[nukegoat]

With the motor at idle or all of the time? Mine (different setup) is somewhat sluggish at idle, one of the reasons that I two pedal, a few extra rpm makes a big difference.

Turning the torsion bar shouldn't be that difficult. Take the input apart and put it in the lathe, the question would be how much?

I dont notice steering slowness. I think a 1.5x8 ram is fine with the stock pump. Any larger volume would be iffy.

Im thinking the 50 cent approach for how much to tune it. Not a lot baby girl. Just a lil bit. I think you can mathematically figure out spring rates so...

 

[mudgudgeon]

There was a thread in the diesel tech section recently about improving power steering in HDJ81.
Several guys did the same thing with good results, I can't remember exactly what was done. Basically just a bit of TLC on an old system. I think cleaning a flow restrictor or valve.

I'll try and find the thread

 

[mudgudgeon]

So, this thread may not be very relevant

Variable assist power steering

It was about improving the variable rate power steering box found in HDJ81 VX.
I'm not sure this was in FJ, FZJ80?

 

[Tools R Us]

... you run the risk of it breaking and losing your power assist completely. ...

Haven't seen it, but my guess; that isn't what would happen? The spring holds the valve centered, without it, any tire wander or steering input could net full assist and the valve could randomly wander. in other words driving would be like herding cats, especially at speed.

 

[nukegoat]

I've always thought the steering was a bit heavy.

I've done the torsion bar on vehicles, you can get any sensitivity you want with the size of the bar.

if I ever have to replace or rebuild the box I would definitely turn down the bar. Not goanna go through the work for an otherwise good box though.

let me know what diameter you end up at????

OK, glad to hear this is the right way to approach the problem. I have a bunch of spares that I swap out from time to time. I'll screw with one of them and come back to this thread. I'll probably start small in case there's unintended consequences.

One thing I do like about a beefy torsion bar is that it's unlikely to break, especially in a manual steering situation (power loss, etc). But I'll mess with it and see how far I get.

 

[Tools R Us]

...
One thing I do like about a beefy torsion bar is that it's unlikely to break, especially in a manual steering situation (power loss, etc). But I'll mess with it and see how far I get.

The travel on the spring is not that great, maybe a few degrees in each direction before the splines contact.

Attempted to measure the force, couldn't tell if I was maxing the 60in/lb wrench, or if the splines were contacting? So nothing definitive.

Took one apart, wasn't easy, the pin took a bunch of force to move, then the input didn't want to come off the spring. Maybe Toyota didn't want them taken apart, or more likely, this box is one Richard dredged out of a lake?

The splines that allow/restrict movement.

The spring is pretty wimpy, easily flexed. Haven't attempted to cut it, but guessing the tool post grinder would be the weapon of choice. There is no divot in the end of it, so make a cap to press over it, with a divot to hold it centered with the tail stock center?

The spring extends ~1" into the bore, appears to be permanently pressed in. The relationship between the spring hole and the pin on the worm would be critical to valve operation, so don't think it would be a good idea to remove it? I marked the input to spring, maybe it could be installed 180 out. but why risk it?

Could only machine ~2.5" of the ~3.5" spring?

 

[nukegoat]

The travel on the spring is not that great, maybe a few degrees in each direction before the splines contact.

Attempted to measure the force, couldn't tell if I was maxing the 60in/lb wrench, or if the splines were contacting? So nothing definitive.

Took one apart, wasn't easy, the pin took a bunch of force to move, then the input didn't want to come off the spring. Maybe Toyota didn't want them taken apart, or more likely, this box is one Richard dredged out of a lake?
View attachment 1644570

The splines that allow/restrict movement.
View attachment 1644571

The spring is pretty wimpy, easily flexed. Haven't attempted to cut it, but guessing the tool post grinder would be the weapon of choice. There is no divot in the end of it, so make a cap to press over it, with a divot to hold it centered with the tail stock center?
View attachment 1644572

The spring extends ~1" into the bore, appears to be permanently pressed in. The relationship between the spring hole and the pin on the worm would be critical to valve operation, so don't think it would be a good idea to remove it? I marked the input to spring, maybe it could be installed 180 out. but why risk it?

Could only machine ~2.5" of the ~3.5" spring?
View attachment 1644573

That torsion bar does not look like it was a field replaceable unit. Hmmm. Since you have it apart, are you going to run the experiment? I think turning down a section would be ok. Youve gone this far

 

[Tools R Us]

That torsion bar does not look like it was a field replaceable unit. Hmmm. Since you have it apart, are you going to run the experiment? I think turning down a section would be ok. Youve gone this far

But then I would have to put it back together? I'm pretty good at ripping things apart....

IIRC, Toyota lists the whole input, including housing as a part. No user serviceable parts, no drag spec, etc, if it leaks or has other problem, replace the whole unit at huge $$$$.

 

[inkpot]

Maybe we can git Richard to test it for us?

 

[nukegoat]

But then I would have to put it back together? I'm pretty good at ripping things apart....

IIRC, Toyota lists the whole input, including housing as a part. No user serviceable parts, no drag spec, etc, if it leaks or has other problem, replace the whole unit at huge $$$$.

For science tho?