Author | Topic | |
Kooda V4 Fanatic
United Kingdom 250 Posts | Posted - 10 Apr 2007 : 13:20:33
| I need to get the front suspension geometry reset as I have lowered the car (50mm front, 25mm rear) and fitted a 2.25 ratio rack in place of the standard 2.7.
I've driven it with the 2.7 rack and the lowered suspension and the handling is much better, but the steering is quite light, indicated that the caster has been reduced in the lowering process. I feel the addition of the 2.25 ratio rack is going to make it pretty twitchey on the motorway.
Ive rung around a few local "wheel alignment" places, none of whom can do the full set up, or give me any sensible answers as it seems to be a little out of the norm.
To adjust the camber I'm guessing that it is a process of adding/removing shims from under the top wishbone mounts?
How is the castor adjusted? I'm guessing this involves moving the top wishbone fore and aft? |
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Genty V4 Mad
628 Posts | Posted - 10 Apr 2007 : 17:05:30
| As I understand it (and confirmation from others would be helpful!) Both Camber and Castor are adjusted with the shims at the top wishbones.
Inserting or removing equal amount of shims at both front and rear of the top wishbone will increase or reduce camber. i.e. you are bringing the upper wishbone in or out while maintaining its angle.
Increasing the shims in the 'front' of the top wishbone without adding any to the rear will increase the castor. I.e. you are increasing or decreasing the angle it is at in relation to where it is attached.
Just read it through and don't know if it will make sense to anyone else. maybe someone can be a bit more erudite?
Genty www.geocities.com/saab96v4 | |
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Kooda V4 Fanatic
United Kingdom 250 Posts | Posted - 10 Apr 2007 : 17:39:21
| Genty, Sounds reasonable to me. A question: to increase +ve camber the outer ball joint on the upper wishbone would need to move back relative to the lower ball joint? To achieve this one would need to add shims to the rear upper wishbone mount rather than the front?
I'm guessing changing the shims involves, wheels off, springs out (compressed), then unbolt the upper wishbone mounts (probibly dont need to remove the mounts just slacken and slide the shims in/out)
After much phoning around I've found a place that are happy to do the job, but I need to know what effect an extra mm shim here or there has on things. If anyone has any experience with this I would be most greatful.
Ive got a bunch of shims (6x1mm (ish), 2 x .5mm(ish) does anybody have a few they might want to sell?
Cheers | |
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jdt V4 Fanatic
United Kingdom 340 Posts | Posted - 10 Apr 2007 : 21:00:55
| Hi Shims are slotted so should slide in - no need to compress spring or dismantle anything - just slacken bolts (not too much!) and lever to create a gap and slide shim in. Not sure about changing castor angle - this would involve moving wishbone forwards / backwards which shims will not achieve and no adjustment is provided in this plane as standard. Cheers John | |
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Woody V4 Guru
United Kingdom 2758 Posts | Posted - 10 Apr 2007 : 22:54:11
| The factory workshop manual indicates movement of shims to vary caster and camber. There is a detailed table that shows what front or back shims need to moved to vary the degree of caster and camber. I set my own with a plumb line and a protractor. Need to have it checked with laser to see if I was accurate or not. It is interesting to note that the geometry had not changed from 1964 to early 70s as the table is identical in both manuals. | Edited by - Woody on 10 Apr 2007 22:56:52 | |
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Derek V4 Guru
United Kingdom 2187 Posts | Posted - 10 Apr 2007 : 23:10:34
| "It is interesting to note that the geometry had not changed from 1964 to early 70s as the table is identical in both manuals."
As 1964 is still 2-stroke production it's surprising that they didn't make some changes to compensate for the extra weight of the V4. Looks like there might be a much better set of numbers out there which would help with the heavy steering/understeer. Most early strokers were still on crossplies as well. | |
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Kooda V4 Fanatic
United Kingdom 250 Posts | Posted - 11 Apr 2007 : 00:21:39
| Woody, Do you know where I might be able to get hold of those tables?
Once I get the wheels back on I'm going to do a rough toe in check and go from there. I have only driven around town & its on radials (I'm guessing the factory angles where for x-plys). I've have to head down the M4 to Cardiff on Saturday which should give me more of an idea.
Cheers | |
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Woody V4 Guru
United Kingdom 2758 Posts | Posted - 16 Apr 2007 : 23:41:49
| A little late but for the benefit of the forum, tables have been emailed. | |
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jdt V4 Fanatic
United Kingdom 340 Posts | Posted - 19 Apr 2007 : 17:24:28
| Could I have a copy of the file please
I have been pondering how the shims change castor and the geometry of the wishbones is complex - they are not not parallel to the centreline of the car so altering the shims will alter more than camber.
Cheers
John | |
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Woody V4 Guru
United Kingdom 2758 Posts | Posted - 19 Apr 2007 : 17:32:01
| On its way shortly, John
Woody | |
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Kooda V4 Fanatic
United Kingdom 250 Posts | Posted - 20 Apr 2007 : 11:30:36
| Woody - Thanks alot, thats exactly what I need. | |
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jdt V4 Fanatic
United Kingdom 340 Posts | Posted - 23 Apr 2007 : 19:44:07
| Kooda
Where did you get the tracking done? would you recommend the company?
Thanks
John | |
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Kooda V4 Fanatic
United Kingdom 250 Posts | Posted - 27 Apr 2007 : 17:39:54
| I haven't had it done yet, but the chap I was talking to was Mark at Kipling motorist centre in Hemel hampstead. He has the chart that Woody gave me, so should be able to have an informed discusssion with you. I found him via an article in a classic Car magazine.
I rang about 10 places local to work & home. Most dont have the kit to do a full set up. A couple did, but refused to touch the Saab as the adustment was via shims and not cams. | |
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Ian Wilson Starting Member
United Kingdom 14 Posts | Posted - 09 Sep 2020 : 16:43:32
| Woody, please could you send me a copy of the shim table as mentioned above? I cant find this anywhere.
Ian Wilson | |
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