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T O P I C    R E V I E W
DynorogPosted - 30 Sep 2018 : 11:41:44

Hi
I have an Fn/s tyre rubbing on the inner wing and It did it was doing so prior to the recent work carried out during project “Dilemma.”
When rebuilding the suspension I noticed that the lower F n/s had been repaired, welded up and thought that this was the problem, so I changed it for an undamaged one I have, assuming that this would solve the problem. It didn’t.
When the car is suspended, level on axle stands the tyre doesn't touch the wheel arch.
I replaced the trimming shims as I had found them about 6mm worth in all four locations.
Nothing is obviously bent i.e. Track control arms, steering arms etc.
I haven’t yet renewed the wishbone bushes.
I read in a post by Derek - “Even the standard 155 can rub on the rear of the inner wing on some cars.”
Derek, do you or anyone else have more information on this?
I knocked up what could loosely be termed a camber angle” gauge”, just to try and see in very crude terms what’s going on.

[/url]

In terms of settings this is what I found:
Camber:
OSF -1 degree
NSF +1 Degree
Caster:
OSF +1 degree
NSF +1.5 degree
Any advice?



Dynorog
15   L A T E S T    R E P L I E S    (Newest First)
DynorogPosted - 21 Mar 2019 : 10:00:30
Not much progress on this but found this on the SOC site from SAAB Driver circa 1974



Cheers

Dynorog
DynorogPosted - 07 Nov 2018 : 14:47:40
I've done some more work on the rack drawing and taken further measurements.

Wheels Straight and Zero Toe.


22.5 Degree lock left


Full lock Left
Based on measured full extent on spare rack.


I have some other scenarios drawn which I'll post later. From the pics you will see that at full lock the NS tyre is very close to the engine bay floor panel.
The rough figures from my car (i.e. marked in chalk on the driveway and the angles measured with a adjustable set square after the wheels have scrubbed around )are
full lock left 26.5 degrees NS and 29 degrees OS
I don't think the 96 steering follows the ideal ackerman curve too closely from doing a bit of maths and some reading. I don't quite know what my efforts are telling me yet but from the time its taken me I must be learning something -I hope.
Cheers

Dynorog
stevebodPosted - 16 Oct 2018 : 15:19:18
Good work Roger.
I'm interested to see where this leads.
From your reading of the manual though - it sounds like we should expect different left and right steering angles, which I didn't know.
DynorogPosted - 16 Oct 2018 : 13:27:44
Thanks Derek, I think I’ve printed off the wrong revision of my efforts to make into a JPEG image. I’ll reprint. The ackerman angle is the next to incorporate to see how it influences my physical measurements of the spare rack movement.
Cheers

Dynorog
DerekPosted - 16 Oct 2018 : 12:52:52
Something wrong there I think, especially the right lock where you appear to have both wheels angled the same. See
https://en.wikipedia.org/wiki/Ackermann_steering_geometry

Wiki is example only, there are videos and other articles available.
DynorogPosted - 15 Oct 2018 : 19:57:41
Hi Steve, You’ve got me at it now with the steering drawing, I think I’m becoming obsessive in my retirement.
I took some basic measurements on a spare rack I have and I drew it out to “scaleish”
My drawing doesn’t concur with yours for some reason. If anything, mine shows the longer track
length side giving a shallower angle.
On further reading the workshop manual I noted that that when referring to checking the overall turning angle , the offside side should be 20o and the nearside 22.5o with a tolerance of +/- 1.5o.

What it has shown me however is that either way it doesn’t make a lot of difference to the problem I have. I am pretty sure its wear in the rack which has altered the stop position.







Cheers

Dynorog
DynorogPosted - 14 Oct 2018 : 16:03:33
Just testing to see if a drawing I've done re steering geometry comes out like.
I may delete it depending on what it looks like.






Screen shot of pdf didnt come out very well.
Must try harder.

I still cant read it Properly and I drew it!
I'll try again. Its not bad if you open it in a new tab though.
Cheer

Ill put the others on.
cheers
RhysNPosted - 08 Oct 2018 : 19:22:38
Thanks for posting Steve, it's a very good way of showing something difficult to put in words.
stevebodPosted - 08 Oct 2018 : 15:02:54
Hi Roger.
Well I had to draw it out in the end to satisfy my own curiosity. I'm posting the sketch here in case it helps with the problem you are seeing.
I agree that rack movement left and right is the same, but the angle change I get at each wheel is different if the track rod ends are different lengths. Hopefully the drawing is clear and ignore the actual values because this is not to scale, but it looks like the side with the shorter track rod end tucks in more for a given rack motion than the side with the long track rod end. This might apply to Derek's comment about some cars rubbing one side only, I dunno.



Yawn.....sometimes I bore myself.
andydeans3Posted - 07 Oct 2018 : 10:55:13
Roger
I had the same problem with trying to get my wheels aligned.
I did finally find an outfit called Farmer Autocare, who have the equipment shown in the photos below.

In spite of the fact that the manager told me that he couldn't hang his measuring devices on the back wheels, a little bit of ingenuity, did the trick.
Downside is that Farmer Autocare only exist in Scotland.
You can see the brand name of the equipment in the photos. perhaps try and track down a local tyre place that has this equipment?
Worked very well in the end.

Andy









1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
DynorogPosted - 06 Oct 2018 : 11:10:48
No real progress. Wasn’t able to have camber castor set, the guys equipment must be connected to all 4wheels to work even when you’re only concerned with the front wheels and the kit won’t fit in the rear wheel arches. The kit cost him 10K and it looks like it did.
I know a guy who has a supper tracker rip off copy of the old super tracker kit and I try him. A mechanic mate of mine is convinced it’s down to something inside the rack. I’ll investigate that as well.
Cheers

Dynorog
Ps wheels look great Digger
diggerPosted - 04 Oct 2018 : 20:19:53
Hi, I fitted the car with 165 Vredestein snow classics on 5J HSP compomotives and they rub on both sides. Looking on the bright side the steering and suspension geometry must be similar on both sides. They only just touch on full lock so it's something I'll live with unless someone has a clever solution.


DynorogPosted - 04 Oct 2018 : 15:43:53
Hi Steve, I’m not sure because my head is starting to hurt now, but the rack would only travel the same axial distance at whatever point on the steering wheel position the tracking was set up at. I think #129300;
Not having camber etc. Checked until tomorrow now.
Cheers

Dynorog
stevebodPosted - 04 Oct 2018 : 14:10:23
Hi Guys,
Just catching up with this discussion.
I haven't fully thought this through but could this be reduced by centring the steering rack?
What I mean is, your tracking could be correct but if one track rod was significantly shorter than the other, could this cause one wheel to "tuck-in" more at full lock due to ackerman geometry?
I could imagine this happening if the steering wheel was removed and put back a few splines different. Then you would adjust track rods to get the car running straight with the steerng wheel straight but the track rod legnths would different.
My brain is not clever enough to work out if this matters.
DynorogPosted - 04 Oct 2018 : 08:44:32
Thanks both.

Mos - I have already tried the wheel swop to no avail.

Derek- Your thoughts are similar to mine, that it's not likely to be of any real concern,not dangerous but things like this just annoy me.
I hope to get the castor and camber properly checked today and take it from there.
Your mention of stops though has given me food for thought. I'm wondering if the axial movement on the rack in the direction in question is greater than it should be, so I will have the steering angle checked today as well. Maybe it's wear in a spacing washer or something in the shaft bearing cap.I have a spare rack and I will compare the travel.
I may also look at putting some sort of split collar on the rack to act as a stop if possible.
If all this fails I will probably go for the spacers as you suggest.
I'll let you know the outcome.
Cheers

Dynorog

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