Steering box, a question of feel?

[jaybee]

This might be a question for someone who's built a late A/G body GM product or perhaps someone who's raced one at your local circle track.  These cars seem to work just fine on the street or on the track with the stock Saginaw 605 steering box.  That box has also been the standard p/s retrofit for Tri5 Chevys until recently when all-new boxes based on late GM truck boxes became available.  In the early cars this same steering gear has a reputation for being over-assisted and difficult to drive.  Dialing in 4-6* caster seems to help, which requires aftermarket upper control arms, offset control arm shafts, or modification of the control arm mounting points on the frame.  Why does this steering gear work well in the stock application, but not so well in a different car of similar weight?

[wayne petty]

this is my limited knowlege of power steering boxes..

there is a torsion shaft/valve built into the input shaft..

when you turn the wheel it twists a little and diverts fluid from both sides of the piston to more on one side and releases the other.  
this forces the piston to move and catch up with the inputshaft .. once it does, it recenters the valve openings do to no more fluid passing.. if more control input happens the chase is back on...


this is a bypass type of system but there is pressure held somehow on both sides of the piston to prevent kickback of the wheel if you hit a pot hole..

differnt torsion bar thickness will change the input /power of the system.

i have has some systems that were so light that the customer complained about it..

there was some discussion on an earlier post about gm pumps and ford racks...

it seems those are also effected by over control. the output fitting on the back of gm pumps have differnt sized openings to limit fluid flow...
seems ford racks like 2 gallon per minute  down from 3.5 to 4.5gpm   there is also a way to vary the pressure releif setting in the back of the pump ...    limiting the output flow will take care of the pressure do to the restrictors built into the boxes or pumps...


the gm steering pumps must work like an engine oil pump bypassing the excess flow back into itself..so a smaller output opening will reduce feel..   kinda like having a loose belt...
this must be what the inline restrictors are for.


on the side.. i was even thinking of using a power sterring rack as a hi speed hydraulic press. i do have a remote steering control valve that came out of a little white bug (53)where the driver was hidden..
next.......

[enjenjo]

Basically Wayne is correct, but I don't know if he answered your question. The eason it feels too sensitive is it's designed for a car with more weight on the front, even though the total weight is about the same. Going to a box with a thicker  torsion bar thickness, like an S10, should help the problem.

[jaybee]

Thanks guys, that makes sense.  If I remember correctly an A/G has the front wheel centerline at about the midpoint of the engine block, while a 55/6/7 has the front wheel centerline right about at the front spark plug location.  That would be enough to put considerably more weight on the front wheels.  Can anyone steer me toward some info about the S10?  The 605 conversion isn't a bolt in.  It involves some slight modification of the Tri5 sector shaft so it can be dropped into the 605 box, because the 605 has a sector shaft that is far too short to mate with the stock 55/6/7 cross link.  The new "670" boxes for the old Chevys use late model Tahoe/Suburban/Pickup internals with a longer custom sector shaft and casing to put the pitman arm in the correct location.  If there's a power box out there that would sit on top of the frame with the sector shaft dropping down the inside of the frame too place the pitman arm below the frame that would be even better but I don't know that there's anything out there that's readily available and appropriate to the task.