Anyone know about steering rack updates?

[destrux]

I was reading this:

http://www.mustang50magazine.com/techarticles/m5lp_1207_power_steering_steered_straight/viewall.html

....While searching for information about why older rack and pinion cars seem to have crappy steering feel and precision compared to new cars. So if Ford was updating the spool valve in the mustangs all those years, did toyota do the same thing with the Supra racks? Are the 1992 racks better than the 1987 (ignoring the obvious addition of PPS)? Does anyone know if a 1992 rack will fit in a 1987 subframe?

Also, while we're on the topic, did all the models have PPS once that came out or was that optional?

Still not happy with the steering precision in my 87. If there were improvements made to the rack over the years I'd be all up for swapping to a newer rack even though they cost twice as much ($300 vs $150). I don't want to waste the money though if the newer MKIII's steer just as sloppily as my car does.

This is a video of the slop I'm taking about. I've isolated the movement to either the spool valve or the steering rack gears. Moving the wheel like I am in this video doesn't move the inner tie rods at all, but the shaft going into the rack is spinning back and forth.


http://www.youtube.com/watch?v=fukJc1XjiOI&feature=plcp

The video embedding thing isn't working for some reason, so just click the link.

 

[destrux]

I found this guy's page:

http://www.mk3ukr-supra.net/Handling, Steering.htm

...and he fitted a mustang rack by welding on new rack mounts. This looks like a good way to go if the 89-92 rack is no improvement. He used a manual rack, but I'd go with a power rack. Probably the newest compatible mustang rack... from the 04' Cobra. I drove an 01' Cobra once and the steering was really nice. Zero slop, the car was on rails. This rack is only $210 including the core. No idea what sort of tie rod ends to use though.

I'm pulling my rack and tearing it down tonight to look for internal problems again and check the condition of the rack and pinion gears. If I find no problems I think a rack swap is the only option I have left.

I saw that the 2nd gen RX7 rack is very close to ours too. Interesting option if it was an improvement, it looks like it almost would bolt right in. It's just as old as our existing rack though, so it's probably just as sloppy and outdated feeling.

 

[Orion ZyGarian]

Seeing as mine requires replacement, I'd love to hear what other people thought about this. Air conditioning compressors have come a long way since the 70s and 80s and are variable displacement now; no reason other parts like a steering rack couldnt as well.

 

[Poodles]

I bet your rack is simply worn out. Also, didn't they have steering dampeners on that year?

There's all sorts of bearings and bushings in there that can and will wear over the years.

 

[Dylan JZ]

my rack, pretty sure it's original, actually feels great until you go above about 80mph.. after that it gets really light and honestly scary as hell, and I always figured that's why they ended up adding PPS.

personally, I'm gonna do the PPS rack in my car and have a standalone control the valve.

 

[IJ.]

my rack, pretty sure it's original, actually feels great until you go above about 80mph.. after that it gets really light and honestly scary as hell, and I always figured that's why they ended up adding PPS.

personally, I'm gonna do the PPS rack in my car and have a standalone control the valve.

Did this in my Mk3 using the Chev Pump and a PPS Rack/MoTeC, you have to set up a variable voltage channel to control it as you're driving a valve to a position, I can dig out a file if you need numbers.

Most "old" racks will have a wear mark in the tube around the straight ahead position so no amount of seals/reco work is going to make a difference, the "Tube" from Toyota was $1K on it's own last time I checked...

 

[AbsoluteSpeed]

I found this guy's page:

http://www.mk3ukr-supra.net/Handling, Steering.htm

...and he fitted a mustang rack by welding on new rack mounts. This looks like a good way to go if the 89-92 rack is no improvement. He used a manual rack, but I'd go with a power rack. Probably the newest compatible mustang rack... from the 04' Cobra. I drove an 01' Cobra once and the steering was really nice. Zero slop, the car was on rails. This rack is only $210 including the core. No idea what sort of tie rod ends to use though.

I'm pulling my rack and tearing it down tonight to look for internal problems again and check the condition of the rack and pinion gears. If I find no problems I think a rack swap is the only option I have left.

I saw that the 2nd gen RX7 rack is very close to ours too. Interesting option if it was an improvement, it looks like it almost would bolt right in. It's just as old as our existing rack though, so it's probably just as sloppy and outdated feeling.

http://www.supramania.com/forums/showthread.php?122163-Mustang-5.0-Rack
http://www.supramania.com/forums/showthread.php?136900-manual-rack-convresion.-has-anyone-done-this

Take a look; these two threads go over what you are talking about.

If you read some of the comments you’ll notice people point out how dangerous (and illegal) it is to cut/weld suspension components. You would have to find a way of doing so without welding like custom u-joints for the steering linkage.

 

[Dylan JZ]

Did this in my Mk3 using the Chev Pump and a PPS Rack/MoTeC, you have to set up a variable voltage channel to control it as you're driving a valve to a position, I can dig out a file if you need numbers.

Most "old" racks will have a wear mark in the tube around the straight ahead position so no amount of seals/reco work is going to make a difference, the "Tube" from Toyota was $1K on it's own last time I checked...

I will contact you for sure when I'm prepping for this. thanks man.

 

[destrux]

I tore the rack apart last night and I found a burr in the spool valve that was causing an excessive gap between the valve switching the fluid transfer from the left to right side of the steering ram. I'm guessing the burr developed from years of the valve sliding back and forth. I took the burr out and assembled the rack via the TSRM methods and the steering is much better. There's still a small dead spot in the middle. I'm going to tear apart some other racks from newer cars and see what design changes have been made and see if I can swap any spool valve internals from other cars into this rack. I checked my rack gear for center wear and there was none visible. This is reinforced by the fact that the "loose spot" is there during the entire area of travel, not just in the center.

I understand the thing with the steering shaft... you don't want to half-ass something that's so important.... I agree. However, I have seen many custom cars over the years and I don't ever recall anyone saying they had anyone certify their steering shaft. Go to a street rod show and see how many welded and fabricated steering shafts you see. I have never heard of one breaking in all the years I've been dealing with the street rod and custom car crowd. I have, ironically, seen a factory GM F-body steering shaft fail when the u-joint fell apart because they failed to stake it together properly at the factory.

Also, senna was driving an F1 car, correct? The stresses on a street car are not comparable. That's like worrying that the recovery chutes on my model rockets aren't NASA certified and the rocket could come down on my head and kill me. Not to mention there's probably an instance of spectacular failure for every single part of a car that could illustrate why modifying it is a bad idea.

 

[IJ.]

Dead spot in the Middle is the Tube wear I mentioned earlier.

 

[Orion ZyGarian]

Did this in my Mk3 using the Chev Pump and a PPS Rack/MoTeC, you have to set up a variable voltage channel to control it as you're driving a valve to a position, I can dig out a file if you need numbers.

Most "old" racks will have a wear mark in the tube around the straight ahead position so no amount of seals/reco work is going to make a difference, the "Tube" from Toyota was $1K on it's own last time I checked...

Oooo! My rack is gone and I've been debating exactly what to do about it. I'm going AEM, so that could work...

 

[te72]

I'll probably be looking into a new rack as a means of my mini-restoration on the widebody. If it's more than beyond a reasonable price, does anyone know of a good reman unit for our cars?

 

[Orion ZyGarian]

That's one of the things I've been considering. For instance, I could go to AutoZone/Discount Auto (sorry...AdvancedAuto) and get a rack with a lifetime warranty (honestly plan on keeping the car for that long), or I could get one from Toyota. Toyota only has a 1 year warranty, but could be made better than the generic ones and last longer. Question is if I really feel like replacing it whenever it goes bad, and how often will it go bad? Also whether or not to convert to PPS

 

[destrux]

Last time I checked there were no new ones, just reman. I don't imagine toyota does anything that the other reman companies do, they might even be buying them from them.

I understand what you're taking about now IJ... I had to think about it for a bit. The rack gear wears on the tube and then slides up and down (parallel to the pinion gear) as the pinion tries to move it, correct? I'll have to look again and check for that. I saw that problem on a Mazda MX6 rack a while ago. The car was acting just like mine too come to think of it... the guy said "it tries to kill me on the highway".

 

[destrux]

Well I checked for the tube wear and it seems to be fine. It's tight, no play between the rack and the rack housing.

I had an idea on how to isolate the movement, because sometimes your eyes just play tricks on you when you're dealing with a few degrees of movement like this and I wanted to be sure I wasn't chasing ghosts.

So I got a pair of vice grips and locked them onto the pinion shaft going into the rack, and had a helper hold the vice grips against the subframe to stop the pinion from moving at all.

Then I moved the wheel again.... and the movement was still there just the same as when the pinion gear was allowed to move. So it seems that my readjustment of the steering rack did get rid of all the play in the rack itself. Now the only remaining play is in the steering shaft/column.

So I moved the vice grips up to lock the steering shaft where it exits the firewall. Steering wheel was nice and tight. So That leaves the steering u-joints and the lower slip section of the steering shaft. I think I may be able to tighten up the slip section with some steel shim stock, or possibly by powder coating the male side of the shaft to make it fit more snugly (but still allow it to slip).

The U-joints are another issue... does Toyota even sell those anymore? I can't find any steering shaft parts in the parts diagrams.

 

[Orion ZyGarian]

Not sure where you heard the steering rack no longer being available, but I checked and I can still get an OEM one without PPS at least.

 

[IJ.]

Well I checked for the tube wear and it seems to be fine. It's tight, no play between the rack and the rack housing.

I had an idea on how to isolate the movement, because sometimes your eyes just play tricks on you when you're dealing with a few degrees of movement like this and I wanted to be sure I wasn't chasing ghosts.

So I got a pair of vice grips and locked them onto the pinion shaft going into the rack, and had a helper hold the vice grips against the subframe to stop the pinion from moving at all.

Then I moved the wheel again.... and the movement was still there just the same as when the pinion gear was allowed to move. So it seems that my readjustment of the steering rack did get rid of all the play in the rack itself. Now the only remaining play is in the steering shaft/column.

So I moved the vice grips up to lock the steering shaft where it exits the firewall. Steering wheel was nice and tight. So That leaves the steering u-joints and the lower slip section of the steering shaft. I think I may be able to tighten up the slip section with some steel shim stock, or possibly by powder coating the male side of the shaft to make it fit more snugly (but still allow it to slip).

The U-joints are another issue... does Toyota even sell those anymore? I can't find any steering shaft parts in the parts diagrams.

I bought the section with the Slip Joint in it new for mine a few years back.

Mine was DOA...

 

[destrux]

The dealer wants $225 for it. I tightened up the slip section by pressing the outer tube tighter around the inner part. I'm going to see if I can match the u-joints up at the local industrial bearing supply. I've had luck with them on steering shaft joints before.

I'm not entirely convinced this is the only problem now anyway. I've been looking at the steering in every late model car that's come through my shop for the past few days and there were a few cars with very precise steering that had the same slight amount of play in the steering u-joints and slip shafts that my supra does.

So I'll try the u-joints, but I think I'm going to keep looking for another solution. I'm betting that since 90% of Toyota steering racks use the same input spline (11/16"-36 spline) that there are many spool valves that will interchange from newer cars into our rack. I just need to do some junkyard research.

If that's not a viable route... I did more looking into the Ford rack swap. The 04' Cobra rack (and all the desireable 94' and newer Mustang racks) have a proprietary "V" cut input shaft. The steering shaft in our Supra is not a direct bolt-up affair, BUT... the steering shaft in our Supra is a very common size shaft so there are some simple solutions. The tube above the lower u-joint is 1" OD, and the upper slip shaft is a common 3/4" OD .550 "DD" type shaft. So there are two easy solutions to connect a Mustang rack to our steering column.... no rigging involved.

Method 1: Buy a Borgeson U-joint assembly with a mustang 3/4" "V" lower socket and a 1" round upper socket (You have to phone this one in as they don't have a part number for this exact combo, but it is available). Cut the lower u-joint off the OEM Supra lower steering shaft. Drill the cross hole in the shaft to bolt the Borgeson joint on. If you'd rather you can also weld the joint on. Assemble and you're done.

If you don't like cutting your stock shaft there's method #2: Buy the Borgeson joint as above except with a 1" DD upper end (part number #015255), and also buy their 1" DD tubular to 3/4" "DD" slip shaft assembly (http://www.borgeson.com/xcart/catalog/Telescopic_Steering_Shafts-orderby_0-p-1-c-22.html). Assemble their joint and lower slip shaft tube, and cut the tube to proper length. Discard their upper 3/4" DD shaft. Then mate their lower tube with the OEM Supra upper 3/4" "DD" shaft.

There are other places other than Borgeson of course. They also sell this stuff in stainless and aluminum, but I prefer working with normal steel.

Mounting the rack on the subframe is the hard part. I found out the 94+ racks use 12MM bolts to mount, and the inner tie rods have M14-1.5 threads. (http://www.maximummotorsports.com/store/index.php?main_page=tech_steering_rack)

I wonder what the chances are the Mustang outer tie rod ends are the same taper as the Supra. Cheap OEM tie rods would be nice. I also wonder if the Supra outer tie rods are M14-1.5 (I'll check when I get time) and if they would thread onto the mustang rack. If not... this is probably a viable solution for tie rod ends... http://www.maximummotorsports.com/s...e=product_info&cPath=514_3_13&products_id=450.

Then there's connecting the power steering hoses... and they sell adapters to go from the goofy Ford teflon seal fittings to AN fittings, so I'm sure I can further adapt those to what I need.

This would be a $500-600 swap when all is said and done. I think it would be worth it though, if nothing can be done to update the existing rack.

 

[te72]

Destrux, thanks for all the work you've put into this, and thanks for sharing. Really is nice to have members who keep a thread alive and useful like this. Hi-five to you sir.

However, has anyone driven a car with absolutely NO dead spot in the center of the steering? I always figured that was engineered in, as a way to allow a bit of movement for road imperfections, so that you don't notice them while driving. Remember, your average car buyer isn't an enthusiast, and might perceive their wheel reacting to every bump in the road as being 'something wrong'...

 

[destrux]

My Mazdaspeed 3 has absolutely zero dead spot or slop in the steering, even now at 5 years and 120,000 miles. Every micro movement of the steering will move the car, but it's not nervous. I believe it has a variable ratio rack (could be wrong). I recall reading that the cobra rack is also variable ratio. I need to look into that more though.