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Playing with steering boxes. SPA S fixed ratio, SPA AF variable ratio. Firebird 12.7


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Just happened to come across this video on YouTube. They do an excellent job of explaining how a power steering box works. The guy is a little dry, but the cutaway and animation of how the valve works are both awesome.

 

In the video they refer to the torsion bar as the metering rod. So with that bit of translation you can get a pretty clear picture of how the box in the Mustang works, and see why you won't get increased feedback without swapping in a larger T-bar / torsion bar / metering rod.

 

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  • 3 months later...
  • 2 weeks later...

I edited most of my posts, added descriptions to many of the pictures and tried to make the whole process a little clearer. I did not remove any wording, only added. Hopefully this will help someone on the forum to tackle their own quick ratio conversion. Really it is a pretty inexpensive and rewarding little project if you have some time and want to tackle it. Plus who does not love a trip to the self service wrecking yard?

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  • 2 months later...

More donor applications cut and pasted from Jim Shea

 

1983-96 SAGINAW 800 FAST RATIO (12.7:1) POWER STEERING GEARS

(Not including F-Car)

YEAR ALPHA CODE ORIGINAL APPLICATION GEAR RATIO EFFORT T-BAR SIZE TRAVEL

1983-84 Olds G YA Hurst 12.7:1 24-30 0.204 Dia 39deg 15min

1985 Chev G (MC) YA Monte Carlo SS 12.7:1 24-30 0.204 Dia 39deg 15min

Olds G " Hurst " " " "

Buick G " Sport Coupe FE3 Turbo " " " "

1986 Chev G (MC) YA Eurosport 12.7:1 24-30 0.204 Dia 39deg 15min

Olds G " V8 " " " "

Buick G " w/HO " " " "

1987 Chev G (MC) YA Monte Carlo SS 12.7:1 24-30 0.204 Dia 39deg 15min

Olds G " V8 " " " "

Buick G " w/HO " " " "

1988-89-90 Chev B WZ F41 12.7:1 20-26 0.195 Dia 43deg 30min

CP FE2 12.7:1 17-22 0.185 Dia 43deg 30min

1991 Chev B CP FE2 12.7:1 17-22 0.185 Dia 43deg 30min

1992-93-94 Chev B CP FE2 12.7:1 17-22 0.185 Dia 43deg 30min

FB Police 12.7:1 20-26 0.195 Dia 40deg 45min

HL Police 12.7:1 24-30 0.204 Dia 40deg 45min

1994 Buick B KL FE-1 12.7:1 17-20 0.185 Dia 43deg 30min

1995 Chev B CT FE2 12.7:1 19-22 0.185 Dia 43deg 30min

DU Police w/FE3 12.7:1 20-26 0.195 Dia 40deg 45min

1995 Buick B FK FE 12.7:1 17-20 0.185 Dia 43deg 30min

1996 Chev B TW FE2 12.7:1 19-22 0.185 Dia 43deg 30min

MX Police w/FE3 12.7:1 20-26 0.195 Dia 40deg 45min

KW FE 12.7:1 17-20 0.185 Dia 43deg 30min

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Excellent video.... like he says i need to watch it couple times but makes me understand better. Thanks for the link.

 

1971 M-code Mach 1

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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  • 2 weeks later...
  • 2 weeks later...

Another resource, lots of info at this link. A couple very good scans of the Saginaw manuals including a long version for the 800 box (what our cars have)

 

https://midweststeering.com/wp-content/uploads/Saginaw-800-PS-Comp.pdf

 

https://midweststeering.com/service-information/

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Good find, good trouble shooting information on the entire front steering system in the manual. :goodpost:

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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  • 11 months later...

Yes, well sort of! This will be a bit of a story but..................

About 5 years ago, I switched my Mach from manual to power steering. I was fortunate to pick up a SPA-T box and pump for a hundred bucks. The hard part was finding the appropriate pulleys. In short, it worked fine for a couple of years, but started leaking. Being capable, I stripped it down, installed new bearings and seals, made adjustments to the sector shaft, but still had too much play at the S wheel.

SO, I sent it to a local steering and brake rebuild company. It seemed to work better, less free play, but it then lost power on right hand turns. I was told the rotation valve was shot. Okay now what. I saw on here that someone else, possibly in this thread, was looking for a "T" box and Don from OMS replied saying he had a couple. I bought on of those, took it back to the shop for them to switch the rotation valve. When I got it back it took me about 2 seconds to realize something was wrong. It only had a little over two turns lock to lock, should be 3 1/8th (according to my Ford manual). So back I went. Now, here is the part that was unbelievable. The so-called "expert" took the end cap off and removed four, yes 4 balls from the space between the ball screw and plug. At this point, I forced myself to shut up when he told me the screw was full still, they must have been "extras" !!! Really? I'm not dumb, I know what happened, but he couldn't admit it, the balls came out of the screw when he pulled the rotation valve out. I took only 20 balls out, so 4 missing.

The old adage "if you want a job done right, do it yourself" is very appropriate here. I have since stripped it and redone it, but not yet installed it. The car has a 17.5:1 fixed ratio box in it at present, so it's drivable and only just out of storage.

The point of this saga is that good people and good parts are hard to find, around here anyways. What I have learned is there are several factors to remove free-play, but getting the parts is my problem. I need bigger balls!!  According to the manual, there are several sizes, but where can I buy these? I tried the local GM dealer, no go there.  Adjusting the sector shaft alone is not going to remove rotational play.

So, after all this, does anyone know where I can buy new or remanufactured parts? I'd like to build up a good spare box just in case, but I do have to consider the dollar exchange rate to make it worth while.

Geoff.

Geoff.

 I learn something new every day!

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I had a 5 turn that I rebuilt because it started leaking and ran it for ten years in the 72 mach. Two years ago I came across a 87 jeep wrangler with a better ratio (3 1/2 turns). Took the guts out and put them in an other Saginaw box that I had laying around that also leaked. Again with all new seal kit, but ended up having 4 full turns. I had to use the stop that was in the ford style box to get full pitman arm travel needed. So that's how I ended up with 4 and not 3 1/2 turns. I'm happy with faster ratio.

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Geoff,

I don't know if I would swap out just balls, safer bet would be the entire ball screw assembly. I have not found a source to get new parts, Midwest Steering is a strong maybe, if you do find someone be sure to post where you found parts. That is pretty crummy that the "pro" you used screwed up that bad. Did you try setting up the thrust bearing preload like shown in the Saginaw paper?

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I also had an issue with a "pro". Lee (not longer in business) remanufactured my steering pump. First it was leaking between the housing and body because the housing was out of round. Granted it was not his problem the housing was bad but they should have cough it and told me. I eventually did get another housing and fixed that leak. Then a year later the pump failed foaming and making a big mess.

 

Sent from my SAMSUNG-SM-G930A using Tapatalk

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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Geoff,

I don't know if I would swap out just balls, safer bet would be the entire ball screw assembly.   I have not found a source to get new parts, Midwest Steering is a strong maybe, if you do find someone be sure to post where you found parts.  That is pretty crummy that the "pro" you used screwed up that bad.  Did you try setting up the thrust bearing preload like shown in the Saginaw paper?

 

 Reading the Ford manual, the pre load is a very low inch/pound number. I've not been able to find a suitable needle torque wrench for that. I did set the input shaft as described by tightening then reversing the nut 1/2". Seems to be pretty close by feel.

I would tend to agree on replacing both screw and balls, but again my manual refers to just going to a larger size ball if the pre-load is off. I don't have the manual in front of me to actually quote it, but that's pretty much what it says. The thing that got me is the ball diameters are given to 5 decimals. As a machinist, I have never needed to go more than 4 or to the 1/10,000", nor have I seen a micrometer that will read to that accuracy. Don't forget, this manual was written 47 years ago. Today with CMM tech, it is probably quite easy.

There is a company near Toronto that does custom rebuilds on Saginaw boxes, so I may give them a call. Maybe they can offer up some information.

Another problem I noticed on the parts box I have is the bore for the rotation valve is worn quite a bit from the Teflon seals, far more so than on the "good" box. I have no idea if this can be recut and or sleeved. I would think that just honing the bore would not be an option, so I guess that casting is junk. I'm hoping that the box currently in the car will give me a usable casting, but I won't know until I get it changed. I would like to build a 12:1 ratio, but that depends on the availability of good parts.

Geoff.

 I learn something new every day!

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  • 3 years later...

Wow, just found this thread, great info, just need to get my head around it.  My current 71  steering box is leaking fluid out of the top where the locking nut locates and the steering coupler joins onto the splined shaft, looks like its way more complicated than I thought it would be :( 

Edited by 92GTS-R
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5 hours ago, 92GTS-R said:

Wow, just found this thread, great info, just need to get my head around it.  My current 71  steering box is leaking fluid out of the top where the locking nut locates and the steering coupler joins onto the splined shaft, looks like its way more complicated than I thought it would be :( 

It is possible to buy a seal rebuild kit and do it yourself from RockAuto.com. The trick is getting it back together and set up correctly. If you have doubts about doing it, overall it might be better to bite the bullet (again) and buy a new or rebuilt PS box already done. If that were to be the case, you might want to get one that is converted to fast 12.7:1 ratio. I've done my own V/R boxes, so have no experience with companies like Red Hat or Powersteering.com I think it is. If you decide not to get a fast ratio, I would definitely get the variable 16 to 13:1 box, SPA-T or V. While you're in there, do the pump as well, then add new H/P hose and return hose. In other words, do it all, do it right.

  • Like 1

Geoff.

 I learn something new every day!

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I have just done the seal replacement on my Eaton pump, But I do require new lines and now it seems a new steering box :(   

Being in the UK the problem is going to be the weight of the unit and shipping :( 

Edited by 92GTS-R
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1 hour ago, 92GTS-R said:

I have just done the seal replacement on my Eaton pump, But I do require new lines and now it seems a new steering box :(   

Being in the UK the problem is going to be the weight of the unit and shipping :( 

 There are some good, some not so good videos on YouTube for rebuilding Saginaw 800 steering boxes. If you do not have excessive free paly at the steering wheel or more importantly, a leak at the bottom of the sector shaft, a rebuild / reseal is doable. The kit(s) I use from RockAuto are Edelmann EDL 7860 and/or Edelmann 7858. From the price, I think this is the one that has all the bearings. From my experience, I would buy both because the hardest seal and easiest to break is the feflon one on the rack piston and you only get one per kit. It's a bi*ch to get into the body without breaking it. There is a fluid return hole that tends to have a very sharp edge, but there's a trick for this. If you decide to give it a go, between our friend Bentworker and I, we can probably get you going. I have a lot of pics to explain things.

Unfortunately you wont know how bad the old box really is until you get it stripped. At that point, it's either rebuild it or buy another. There are several factors we can go over at that point before you order a new box. To get the pitman arm off, you may need to go see your favorite garage and have them blow it off with a good impact wrench and puller. Those suckers are on there!!

  • Like 2

Geoff.

 I learn something new every day!

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Ordered that rebuild kit at rockauto, it's very complete. My box is fine, but it would be silly not to service it after 50 years and their affordable pitman puller that did fine too.  

73 modified Grande 351C. (Finally back on the road woohoo!) 

71 429CJ. ( In progress )

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Something else I looked at without success so far, is finding the correct size teflon seals and "O" rings separately, especially the rack piston seal. I have at least two partial kits that now, are no use for much. I have a spare casting that has a .005" deep groove in the rotation valve bore at the outer most seal ring that I'm sure, if I could find an "O" ring slightly thicker cross section than stock, I could put that box back into use. That .005" deep groove is enough for that seal to leak, causing poor performance.  Boring and adding a sleeve is just way too expensive and not worth it. Way cheaper to look for another casting. It's a shame because it is/was an otherwise good casting. Oh well, I have another V/R box ready to go, I just like playing with "stuff".

Geoff.

 I learn something new every day!

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