This a private discussion that me and Peter decided to publish for all
Finlandese
Posted August 21, 2008 12:49 PM
Hi!
My car is progressing, and now it is time for fine tuning. Prior to that I would need to adjust the power steering, as it has massively more assistance when turning left, than turning right. When at speed it is fine, as there is no assistance at all, so the basic geometry seems to be fine.
You mentioned in an earlier thread about the adjustment procedure, so I thought I´d bother you with this plea for help.
-Jani
Turin 1972
Location: Helsinki, Finland | Registered: May 30, 2006
Oz longchamp and pantera
Posted August 21, 2008 05:24 PM Hide Post
Hi Jani,
good to hear you're progressing. I had to go back a few posts to recall that your car is the same age as mine, 1975, so should be the cam gears rack. In the earlier post I said it was a long time ago, but as I recall there was a small hydraulic pilot valve on the outside of the rack. When you turn the steering wheel at say parking speed, there is a reaction force back through the tie rods which tends to push the pinion housing the opposite way to that which you steered. The pilot valve is attached securely to the rack body and has a rod which is attached the pinion housing. Thus when the rack body experiences a reaction, the housing moves a tiny bit, and that changes the relative position of the pilot valve rod in its housing.
When the pilot valve rod moves from its neutral position, it allows some hydraulic fluid to feed either left or right and operate a normal style piston in the steering rack to boost the effort.
When the car is at cruise speed the reaction force on the rack is much less, so it is not enough to move the pinion housing and operate the pilot valve. My car is a bit inaccessible, so if you were able to get some close up pics from underneath or even with the rack off the car then it would be easier to explain. Please send them and I can annotate this description better (and I'll remember more!)
The pulling at low speed is when the pilot valve and or steering rack is not precisely centred. I'd suggest as a reference you try and get some measurements from under the car (preferably from a pit) while an assistant turns the steering wheel a few cm until the boost can be felt. Hopefully after a few goes you'll be able to measure a deflection between the rod and the pilot valve body. With luck you'll see a greater deflection on one side or the other for the same turn of the steering wheel, and that should confirm the direction of pulling.
Once you have identified this, adjustment requires some shims, which I'm pretty sure are within the pilot valve assembly. Pilot valves are simple hydraulic devices, (sort of similar to a brake balance valve) so if you are competant enough to do master cylinder rebuilds this should be quite do-able. Just be prepared to take the rack in and out a couple of times till you get it right. And take lots of pictures at each stage - unfortunately we didn't have digital cameras when I did mine in 1992 and I didn't realise how useful the info might become.
regards
Peter
This message has been edited. Last edited by: Oz longchamp and pantera, August 27, 2008 12:32 AM
Location: Sydney | Registered: October 12, 2007
Ignored post by Oz longchamp and pantera posted August 21, 2008 05:24 PM Show Post
Finlandese
Posted August 25, 2008 11:50 AM Hide Post
Peter,
Thank you for your prompt reply. I haven´t had a chance to take new photos, I do have an old one that might (or might not) help.
-Jani
Turin 1972
Location: Helsinki, Finland | Registered: May 30, 2006
Ignored post by Finlandese posted August 25, 2008 11:50 AM Show Post
Oz longchamp and pantera
Posted August 25, 2008 06:56 PM Hide Post
H Jani,
one difference I can see is that yours has the nice little rubber boot over the end of the pilot valve. I crawled under my car and took attached shot. Since worst case you will have to remove the rack anyway, I'd start with trying to adjust the pilot valve while the car's still driveable - but make careful notes of any change (number of turns of bolt etc) so if it feels worse, then you can go the other way and restore or head in the other direction. Remove the rubber cover carefully and then loosen the outer locknut, hold the main nut and try to rotate the slotted bolt maybe 1/2 turn. See my pic to make it easier to follow. The angle of the slot in the bolt is likely to be the critical thing. You shouldn't have to replace the rubber cover for a test drive - mine hasn't had one for 20 years and oil doesn't seem to escape there, its just stopping the dirt getting onto the bolt. Give that a try first, before doing anything more serious.
Having looked at the system my description the other day is a little rough, but the concept of the reaction fores moving the rack and the pilot valve is the main thing.
I found a good operating description from the original Cam Gears Ltd patent which will follow in next post.
regards
Peter
This message has been edited. Last edited by: Oz longchamp and pantera, August 27, 2008 12:35 AM
Location: Sydney | Registered: October 12, 2007
Ignored post by Oz longchamp and pantera posted August 25, 2008 06:56 PM Show Post
Oz longchamp and pantera
Posted August 25, 2008 07:19 PM Hide Post
see if you can download GBpatent 1243854 from european patents office at the following link - the pdf version is too big to post.
http://v3.espacenet.com/origdoc?DB=EPODOC&IDX=GB1243854&F=0&QPN=GB1243854
then look for the link save full document in red font to get the file. The description is pretty good. and the diagram helps.
regards
Peter
Location: Sydney | Registered: October 12, 2007
Ignored post by Oz longchamp and pantera posted August 25, 2008 07:19 PM Show Post
Oz longchamp and pantera
Posted August 25, 2008 08:44 PM Hide Post
having had a careful read of the patent, the other thing to check before making ny adjustment is whether the rack housing and the pinion housing can move relative to one another. I don't know whether blue or black is the original colour but mine has several areas where there is no paint which appear to allow for sliding movement. Yours seems to have more paint and its possible paint or grease may be restricting the movement one way or the other. This would also make sense, since unless someone's worked on the rack, I'm not sure why the adjustments I mentioned earlier would have "gone off". In my case the rack had been out of the car and completely dismantled, and it was in the reassembly process that I know I didn't get the adjustment quite right.
Peter
This message has been edited. Last edited by: Oz longchamp and pantera, August 27, 2008 12:36 AM
Location: Sydney | Registered: October 12, 2007
Ignored post by Oz longchamp and pantera posted August 25, 2008 08:44 PM Show Post
Finlandese
Posted August 26, 2008 12:59 PM Hide Post
Amazing, Peter!
I think that you might be into something about the paint and grease restricting movement.
It not pulling to either side, just uneven assistance, and the uneveness seems to be decreasing with more use.
In any case, thanks to you I should´ve all the info necessary to solve this issue.
Thank you again. I really don´t know how people maintained cars like this before the internet...
-Jani
Turin 1972
Location: Helsinki, Finland | Registered: May 30, 2006
Ignored post by Finlandese posted August 26, 2008 12:59 PM Show Post
Oz longchamp and pantera
Posted August 26, 2008 04:52 PM Hide Post
I know i spent a lt of time in the local library looking at workshop manuals for all sorts of vehicles, then just eventually pulled it apart. I think that's why so many of them fell into such disrepair - no-one could afford the dealer service costs. but I was pretty pleased to find the patent stuff, I'm in engineering and have used the patents system a lot recently and once you know how to look, it can be a gold mine of info.
BTW, after my earlier post a few months back, Roland Jaeckel PM'd me to say he had a rack (new?) if needed. Worth bearing in mind anyway.
depending on your success with repair, we may put this info up as a public post some time?
regards
Peter
Location: Sydney | Registered: October 12, 2007
Ignored post by Oz longchamp and pantera posted August 26, 2008 04:52 PM Show Post
Finlandese
Posted August 27, 2008 12:01 AM Hide Post
quote:
Originally posted by Oz longchamp and pantera:
depending on your success with repair, we may put this info up as a public post some time?
regards
Peter
I was thinking just the same. Actually this info is so good, that whether I will be succesful or not is not relevant. This should be public.
-Jani
Turin 1972
Location: Helsinki, Finland | Registered: May 30, 2006
Ignored post by Finlandese posted August 27, 2008 12:01 AM Show Post
Oz longchamp and pantera
Posted August 27, 2008 12:39 AM Hide Post
Jani,
happy to publish now, I have corrected the spelling and misinterpretations from the earlier posts.
regards
Peter
Original Post
