steering rack build - the FSM way?

Hands up on here who's rebuilt a steering rack!? How did you set it up? I've followed the FSM like the pics? is this how you did it? the inner track rods are quite stiff at this torque setting, did you notice that?


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MaximG

Well-Known Forum User
I know when I put it all back together again that I struggled putting the balljoints back onto the end of the rack. I was worried at the time that I did them up tight enough. I must have done some checking as I bought a weight gauge to check it. Haven't experienced any issues so far though, fingers crossed.
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
I haven't done an S30 rack but I rebuilt a leaking Audi 100 PS rack a few years ago and I couldn't believe how many parts and seals there were. Never again.

On the S30 are the inner ball-joints adjustable?

I would guess that the rack is better stiff than 'free' when in the vice because on the car it will seem easier. Have you tried turning it with a wrench?
 
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Wally

Club Member
Good work so far. I'm keeping an eye on your progress as I'm doing mine soon.

I've managed to find a new bearing for the pinion but no bushings for the ends of the rack. I'm hoping they're are in good condition when I pull it apart.

What billows are you going to use? I've read Peugeot 205 fit pretty well.
 

Albrecht

Well-Known Forum User
If its any consolation, I don't think I've ever managed to test a 'rebuilt' rack (mostly taken apart, then put back together...!) to match the factory figures. Always seems a certain amount of stiction in getting the first movement going, both in rack preload and pinion rotation torque, which skews the results. Not linear.
 

Albrecht

Well-Known Forum User

One thing I would say is that the FSM shows a setup for measuring the pinion rotation torque which has a fixture (looks like half of the lower steering shaft with no U/J in it) with a rod through it at 90 degrees to the pinion, and that rod looks to be about 30cm-ish long. The FSM doesn't give any length for that rod, or where on it to attach your spring gauge...

Since the length of that rod - and where you attach your spring gauge - will vastly change the readings, I wonder if it is worth trying to make a test tool that replicates it as closely as possible?

Hang on, I'll try to find the photo I'm talking about.
 
I haven't done an S30 rack but I rebuilt a leaking Audi 100 PS rack a few years ago and I couldn't believe how many parts and seals there were. Never again.

On the S30 are the inner ball-joints adjustable?

I would guess that the rack is better stiff than 'free' when in the vice because on the car it will seem easier. Have you tried turning it with a wrench?

inner ball joints are adjustable, with a 'torque' spring setting in the fsm!
 
Good work so far. I'm keeping an eye on your progress as I'm doing mine soon.

I've managed to find a new bearing for the pinion but no bushings for the ends of the rack. I'm hoping they're are in good condition when I pull it apart.

What billows are you going to use? I've read Peugeot 205 fit pretty well.

Its a bearing at the top, bronze bush lower on these(bronze bush is far too easy to knacker putting the pinion back in. for the cover I got some off rock auto for about $6 each!
 

Wally

Club Member
Its a bearing at the top, bronze bush lower on these(bronze bush is far too easy to knacker putting the pinion back in. for the cover I got some off rock auto for about $6 each!

Perfect, I'll get one ordered now. Thanks for the heads up.
 

Wally

Club Member
Its a bearing at the top, bronze bush lower on these(bronze bush is far too easy to knacker putting the pinion back in. for the cover I got some off rock auto for about $6 each!

I don't suppose you have a link as I'm struggling to find it on there. I did see this seal which I didn't know you could get hold off. Definitely getting added to the list.

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Pete

Well-Known Forum User
One thing I would say is that the FSM shows a setup for measuring the pinion rotation torque which has a fixture (looks like half of the lower steering shaft with no U/J in it) with a rod through it at 90 degrees to the pinion, and that rod looks to be about 30cm-ish long. The FSM doesn't give any length for that rod, or where on it to attach your spring gauge...

Since the length of that rod - and where you attach your spring gauge - will vastly change the readings, I wonder if it is worth trying to make a test tool that replicates it as closely as possible?

Hang on, I'll try to find the photo I'm talking about.
Not really, as long as you know the distance from the pivot to the spring gauge position, you can measure it along any point of the rod. Torque= gauge force x dist.
 

Albrecht

Well-Known Forum User
Not really, as long as you know the distance from the pivot to the spring gauge position, you can measure it along any point of the rod. Torque= gauge force x dist.

Well, thank god a real engineer has shown up.

Question: What are your thoughts on the (apparent, to me anyway...) problem of overcoming initial stiction from static when trying to take an accurate reading? Factory manual says pinion rotation torque should be 8 to 20 kg-cm, but I have found that the spring gauge indicates a much higher force to start the pinion moving than it does to keep it moving, if that makes sense? Same when measuring rack preload.

I think it is just stiction (rack and pinion both lubricated before assembly) rather than abnormal wear/mis-assembly.

Edited to add: Once said rack(s) had been installed and tested on the cars (fully assembled, but wheels off the ground) I didn't notice any abnormal free play, heaviness or notchiness.
 

Pete

Well-Known Forum User
Well, thank god a real engineer has shown up.

Question: What are your thoughts on the (apparent, to me anyway...) problem of overcoming initial stiction from static when trying to take an accurate reading? Factory manual says pinion rotation torque should be 8 to 20 kg-cm, but I have found that the spring gauge indicates a much higher force to start the pinion moving than it does to keep it moving, if that makes sense? Same when measuring rack preload.

I think it is just stiction (rack and pinion both lubricated before assembly) rather than abnormal wear/mis-assembly.

Edited to add: Once said rack(s) had been installed and tested on the cars (fully assembled, but wheels off the ground) I didn't notice any abnormal free play, heaviness or notchiness.
The reading should be taken whilst the pinion is rotating at a constant speed. As you have mentioned the force required to overcome static friction is generally greater than the force required to maintain constant speed against dynamic friction forces, it is normally these dynamic forces that we are interested in therfore convention is to measure torque at constant speed. Glad I could help.
 
problem being is that they've not said what distance, I think that's the point Alan and myself are saying. As you point out, a shorter distance will require more turning force for the same result.
 

Pete

Well-Known Forum User
problem being is that they've not said what distance, I think that's the point Alan and myself are saying. As you point out, a shorter distance will require more turning force for the same result.

Nope. And you have to be careful withe the nomenclature. If you mean torque when you say turning force then no, it won't require more turning force if the gauge is a shorter distance out. It will however require more applied force, however we are not interested in the applied force really, only the torque required to overcome dynamic friction.
Albrecht has mentioned above that the spec is 8-20kg-cm. It's irrelevant where you position (dist) the spring gauge. eg

Torque = gauge force x dist Gauge force=Torque/dist

If you set the spring gauge at 10cm from the pivot along the rod it should read 0.8-2 kg to be in spec
If you set the spring gauge at 100cm from the pivot along the rod it should read .08-0.2kg to be in spec.
 
Nope. And you have to be careful withe the nomenclature. If you mean torque when you say turning force then no, it won't require more turning force if the gauge is a shorter distance out. It will however require more applied force, however we are not interested in the applied force really, only the torque required to overcome dynamic friction.
Albrecht has mentioned above that the spec is 8-20kg-cm. It's irrelevant where you position (dist) the spring gauge. eg

Torque = gauge force x dist Gauge force=Torque/dist

If you set the spring gauge at 10cm from the pivot along the rod it should read 0.8-2 kg to be in spec
If you set the spring gauge at 100cm from the pivot along the rod it should read .08-0.2kg to be in spec.

perfect. Thank you.
 

Pete

Well-Known Forum User
Albrecht said:
Well, thank god a real engineer has shown up.

Question: What are your thoughts on the (apparent, to me anyway...) problem of overcoming initial stiction from static when trying to take an accurate reading? Factory manual says pinion rotation torque should be 8 to 20 kg-cm, but I have found that the spring gauge indicates a much higher force to start the pinion moving than it does to keep it moving, if that makes sense? Same when measuring rack preload.

I think it is just stiction (rack and pinion both lubricated before assembly) rather than abnormal wear/mis-assembly.

Edited to add: Once said rack(s) had been installed and tested on the cars (fully assembled, but wheels off the ground) I didn't notice any abnormal free play, heaviness or notchiness.




The reading should be taken whilst the pinion is rotating at a constant speed. As you have mentioned the force required to overcome static friction is generally greater than the force required to maintain constant speed against dynamic friction forces, it is normally these dynamic forces that we are interested in therfore convention is to measure torque at constant speed. Glad I could help.


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