Fast Ratio Steering Box For OBS-GMT 400-Here's How I Did It Cheap

[tayto]

On the "steering stops" I simply used the large aluminum end-cap off my truck box so nothing changed as far as # of degrees of steering.. It's the end cap that determines total # of degrees that the pittman arm can turn, based on the distance that the rack piston can travel.

the internal stops are set by end cap thickness and internal snap ring thickness. i have seen guys that swap (for example) the quick ratio f-body boxes and claim it's only 2 turns lock lock. when in reality they have lost turning radius (ie: it corners like a school bus). if you are hitting the stops on the control arm first, that is good but you should also be hitting bypass too. it is hard on the internals of the box, to what extent i'm not sure but i have always used the vehicle specific box and then swapped over the worm and spool valve from a quick steer high effort box to make sure there is no funny stuff.

I have found the pump mod made the steering more responsive m I don't want to use the term sensitive or twitchy it just worked better.

 

[BOOT]

Found an article with a chart of the boxes https://www.motortrend.com/how-to/ccrp-0901-gm-steering-box-upgrade/

Seems the difference is effort w/e that is, idk I'm no steering expert.

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[evilunclegrimace]

certain boxes have a larger diameter torsion bar in the spool valve an will give a heavier steering feel. I believe XH box is one of the firmest.

@Kawabuggy there is also an accompanying mod that needs to be done to the power steering pump:

Valve mod page

There is quite a bit of incorrect information in this mod. What he has listed as a "pressure fitting" PN 26009894 is the flow control valve and it does NOT affect pressure ( it controls the GPM that can leave the pump by the diameter of the orifice), Most of this is NOT required. Here is a more useful article on pumps.

 

[1998_K1500_Sub]

Here's how GM labelled the parts.

The "flow control valve" is illustrated as #21 in the Figure.

GM PN 26009894 is referred to as a "union" and is illustrated as #1.

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The above image taken from this document:

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[evilunclegrimace]

Here's how GM labelled the parts.

The "flow control valve" is illustrated as #21 in the Figure.

GM PN 26009894 is referred to as a "union" and is illustrated as #1.

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The above image taken from this document:

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Lets try and keep up with more modern documents.

 

[evilunclegrimace]

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this is a flow control valve, it has been called this for over 40 years.

 

[1998_K1500_Sub]

Lets try and keep up with more modern documents.

I have to agree, the incorrect use of terminology simply confuses everyone.

Have you a more recent document? Please post it or a link to it.

What you've pictured above... GM calls that a "union" but that term seems undescriptive, doesn't it.

What you've pictured seems to function as a flow measurement device (pictured below), not a flow control valve, and it would appear to feed back a pressure signal to the "flow control valve" (#21 in the illustration I posted), enabling the flow control valve to provide a constant flow somewhat independent of pressure (e.g., the flow probably changes once a pressure threshold is exceeded).

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(this illustration from the document @evilunclegrimace cited, attached below)

Oddly, whomever wrote this (below, which was cited earlier in this thread) pictures a "valve" that is item #21 in the picture I posted.

Power Steering box valve mods for the XH and other quick ratio, high effort boxes​

Valve mod page

Interesting.

 

[tayto]

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this is a flow control valve, it has been called this for over 40 years.

this is not the flow control valve. i think you need to reread the document you posted. The picture is of the "discharge connector fitting".

 

[evilunclegrimace]

Hydroboost Flow Control Valve

www.purechoicemotorsports.com

 

[evilunclegrimace]

https://www.bing.com/aclk?ld=e8h8bh3woYXdK-2LTws2mtzDVUCUxxmJYVWmQc9cV1PEcNOAl5bpkvDNzKw8eYkZGiQhscBdGAW1Fe37GW4T4Uh2A2VVZ7bPsR2re1YRJgS0Xci_2Ma7icRnXn-VtagoC3V-rkrs1UZJfFvzqcdX_JryH7aHxgGkVEVKFfyrVqkj5TpJ8SXvzE_qGJFgUErP8r1bqj-A&u=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&rlid=0c0735926e4d1f03881056f6bdda6102&ntb=1