Gixer Indy
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| posted on 24/7/07 at 10:25 PM |
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What caster angle should I have to get steering to self centre???
My steering wont self centre, what sort of angle should i have to correct this? it's an Mk with Sierra uprights
Cheers
Colin 
Flat out til you see God, then BRAKE!
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graememk
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| posted on 24/7/07 at 10:31 PM |
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i'm off to put the kettle on.
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bigrich
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| posted on 24/7/07 at 10:37 PM |
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popcorn anyone
.JPG)
A pint for the gent and a white wine/fruit based drink for the lady. Those are the rules
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zxrlocost
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| posted on 24/7/07 at 10:51 PM |
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Hi Colin MK's dont self centre some will say they do but they basically dont
blow your tyres right up
if you do a search i put a post on a while back, theres nothing wrong with fitting some valve springs in your steering rack jut remember the more
spring you have the LESS lock
I had some fitted and it drove fine theres to much lock on the front anyway
after the SVA take them off
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907
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| posted on 24/7/07 at 10:53 PM |
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When does the lady with the ice creams come round?
Paul G
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zxrlocost
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| posted on 24/7/07 at 10:56 PM |
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just realised you dont need an SVA Id leave it as it is and get quick on the wheel
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nitram38
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| posted on 25/7/07 at 02:46 AM |
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Do yourself a favour and put the castor in.
You won't regret the feel of your steering or the way the car will handle at speed without wandering.
The tyre inflation, toe in and out are bodges and could be dangerous.
I built 7 degrees into my car, but it is rear engined and lighter at the front than a 7.
Most race cars use around 3 degrees, but for road use you should aim for around 5-7 degrees.
I have heard on here that it equates to around 22mm that your top bones are set back in relation to the bottom ones.
The easiest thing to do is draw a 2 D view on paper looking from your wheel towards your chassis. Draw the ball joint centres and then work out your
angle and measure the set back distance.
You may get away with just adjusting/remake your top wishbones, but make sure that your shock still clears them.
No popcorn required!!!
[Edited on 25/7/2007 by nitram38]
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procomp
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| posted on 25/7/07 at 06:55 AM |
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Hi is Gixer Indy trying to get his car through the sva or is it already registered.
It is a well known fact that the indys have the inherent problem and if it is givving you concern the only fix is as nitram38
says to correct the geometry to have a min 5deg of castor.
I was also able to see the new mk chassis at snetterton last weekend on and guess what. Not enough castor either.
Cheers matt
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ditchlewis
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| posted on 25/7/07 at 07:31 AM |
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I SVA'd mine 3/7/07 and it passed the self centering test with no springs in the rack
i set the musroom insert so that the hole was at the front and dialed in 3degrees of toe out and tires inflated to 30 psi.
others put springs into the rack behind the gators.
what it did fail on was the car had too much lock and pulled on the flexi pipes and the cycle wing stays touched the track rods
ends. I've now restricted the lock.
once SVA is passed i will have the car properly set up
all the best
Ditch
[Edited on 25/7/07 by ditchlewis]
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procomp
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| posted on 25/7/07 at 07:41 AM |
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Hi the offset mushroom makes no difference to the amount of castor.
Castor is only altered if you move the actual joint centers. Some of the indys will pass sva with the higher psi and wild toe out as some do have
some castor on them and some are lacking. So what the hell happens at the factory to give such differing results is beyond me if the jigs wich they
say are correct are used correctly.
cheers matt
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ditchlewis
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| posted on 25/7/07 at 08:35 AM |
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The hole in the top of the mushroom is off centre and moving it to the back would incline the hub by a couple of centimeters. it will also push out
the camber as well.
i have had replacement top wish bones from them as at first they supplied me with 2 left hand side wish bones
the ones i got as a replacement are oval not round, so they may have made changes to the jigs since i first got mine.
i was supprised that there was any self centering as i had heard all the stories.
seems to me very hit and miss.
ditch
[Edited on 25/7/07 by ditchlewis]
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Surrey Dave
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| posted on 25/7/07 at 08:55 AM |
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book
My book built car has 5 degrees of caster could do with more as it still wanders a little and does not easily self centre.
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whitestu
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| posted on 25/7/07 at 11:50 AM |
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My indy has the oval wishbones and has little or no self centring. I can't understand why MK and other manufacturers don't sort it out if
it is as straightforward as has been suggested.
Having said that it isn't a major drawback - it would be nicer to drive if it did self centre, but as far as wander at speed is concerned I
don't think this is related as mine tracks as straight as my tin top.
Stu
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nitram38
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| posted on 25/7/07 at 12:06 PM |
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The trouble with steering is that most people don't notice the wandering very much as they compensate for it.
The real "feel" of your steering is when you power out of corners and let the steering unwind.
Without centring, you are having to do a lot more work to straighten the car up. It's a doddle if your steering is doing the work for you.
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mark chandler
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| posted on 25/7/07 at 01:12 PM |
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My top bone is set back around 20mm to the lower, I can take my hands off at any speed and the car centres, even just pushing out the garage.
I would be inclined to make some new bones and send what you have back for a refund.
Only thing to look out for is shock aborbers catching the bone on full droop.
Regards Mark
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britishtrident
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| posted on 25/7/07 at 01:17 PM |
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I think I must have posted this a hundred times.
Offset mushroom adaptors have no effect on caster.
Caster is all down to wishbone design and where the mounts are fixed on the chassis.
Offset mushroom adators however do effect kinpin inclination and camber and bump/roll steer
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whitestu
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| posted on 25/7/07 at 01:49 PM |
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quote:
The trouble with steering is that most people don't notice the wandering very much as they compensate for it.
You might be right - although I can let go of the wheel at motorway speeds and it keeps going in the same direction. Either way it isn't a
noticable problems.
quote:
The real "feel" of your steering is when you power out of corners and let the steering unwind.
Without centring, you are having to do a lot more work to straighten the car up. It's a doddle if your steering is doing the work for you.
This is where the real benefit of proper self centring would be. It is a pain, particularly at low speeds. Rather than 'feeding' the
steering as you come out of a bend you have to deliberately steer.
stu
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C10CoryM
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| posted on 25/7/07 at 02:11 PM |
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Caster makes low speed handling much easier as you can let go of the wheel and let it spin back to center while shifting etc. With the proper amount
of caster you can be at full lock from a stop, accellerate and the steering wheel will spin back to center quickly.
I can't imagine building a car and not allowing for caster adjustment...... seems odd.
"Our watchword evermore shall be: The Maple Leaf Forever!"
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nitram38
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| posted on 25/7/07 at 02:24 PM |
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It seems to be a mistake in Ron's first design and because of all the "copies" no one seems to have picked it up.
When I built the F1-2 I put 3 degrees in first but after driving it I realised that it was not enough.
Now that it has 7 degrees, the steering is really good. I am just glad that I didn't take the short cuts.
It only took me 2 hrs to knock up a new set of top bones.
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Gixer Indy
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| posted on 25/7/07 at 02:46 PM |
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Thanks guys, im out of popcorn now! and got no ice cream in the freezer either There i was thinking there would be a fairly simple solution to
this.I'll have a fiddle and see what happens,the whole car needs sorting,just getting the tools and kit together,and the knowledge(from you
lot,as im as thick as a plank me!) to go through it.I've already ordered a quick rack.
It's already on the road,but sva failure sheet that came with the car, noted steering in the failure section,I know that it's never going
to be a perfect car,handling wise,if i wanted perfect id only ever drive my beemer,but it's a bit of fun,and gives me something to tinker
with.
Thanks for the info everyone, never had to do any of this before,so will probably have a few more questions,spent 18 years spannering on trucks,but
didn't need to know this stuff as we had a specialist firm in to do vehicle alignment and tracking.
Colin
Flat out til you see God, then BRAKE!
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britishtrident
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| posted on 25/7/07 at 04:54 PM |
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What tyre presures are you running ?
Senenish cars use very low tyre pressures compared to tintops (or trucks !)
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Mark Allanson
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| posted on 25/7/07 at 06:50 PM |
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I think the self centring issue is mainly a Sierra upright problem, the Cortina will self centre nicely with 5°30' of castor, but it seems that
most complainers are running with Sierra uprights.
Unless you know different
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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Gixer Indy
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| posted on 25/7/07 at 10:08 PM |
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quote:
Originally posted by britishtrident
What tyre presures are you running ?
Senenish cars use very low tyre pressures compared to tintops (or trucks !)
pressure were about 13 when i got it,now on about 24 all round,previous owner said he ran them at 28,tyres are 195/50x15
Flat out til you see God, then BRAKE!
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Mad Dave
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| posted on 28/7/07 at 01:42 PM |
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quote:
I was also able to see the new mk chassis at snetterton last weekend on and guess what. Not enough castor either.
I've just checked the CAD model and there is 6.51 degrees of castor.
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NS Dev
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| posted on 29/7/07 at 09:03 PM |
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with tina uprights you need between 5 and 7 deg of castor, how you get it is up to you!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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