Gremlin
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| posted on 22/4/03 at 02:58 PM |
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Front wishbone mounts Revisited.
I know this has been visited a couple of time on here and have read all articles but am now confused.
Does the centerline of the top front wishbone line up with centerline of bottom wishbone like at http://www.designdraughting.pwp.blueyonder.co.uk who
also have a nice friendly jig to line up brackets before welding.
OR!
Is there a 5 degree 30 minute angle between them like discussed previously and described at http://locostbuild.tripod.com/
If there is a 5 degree 30 minute angle and the front top bracket is overhanging on LA and LB can I put a panel between LA and FU1 and mount brackets
on that and equivalent on the other side?
[Edited on 22/4/03 by Gremlin]
[Edited on 22/4/03 by Gremlin]
EZy GreMLiN
"The only way to get rid of temptation is too give in to it..!"
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Rorty
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| posted on 23/4/03 at 01:50 AM |
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Gremlin, the ball joints/rodends at the outer ends of the wishbones should not lie in the same vertical plane. In other words, the top one should not
be directly above the bottom one.
The top one should lie to the rear of the bottom one, by somewhere in the region of 5 degrees.
quote:
If there is a 5 degree 30 minute angle and the front top bracket is overhanging on LA and LB can I put a panel between LA and FU1 and mount brackets
on that and equivalent on the other side?
I don't understand what you mean, but I would recommend keeping it simple. Just attach the upper wishbones to LA/FU2 and LB/FU1 as in
the book.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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Hornet
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| posted on 23/4/03 at 07:01 AM |
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Must disagree Rorty, LA and LB are wrong in the book. They need to lie back another 25.4mm to give the desired 5.3 degrees.
I have learned the hard way.... double the work 
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eddymcclements
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| posted on 23/4/03 at 08:49 AM |
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The upper balljoint (Transit) needs to be 20mm behind the lower balljoint (Cortina or Maxi) when viewed from directly above. Following the misleading
Book instructions for fabricating the top wishbone will reduce this to only 10mm, giving you only half the 5-and-a-half degrees caster that you
need.
I've had a look at Dougie's jig - the first link Gremlin posted - and it places the inner wishbone ends symmetrically. If you then make a
correct upper wishbone you'll get the caster required.
Hope this makes sense - I don't seem to be very at expressing myself this morning. Need more coffee!
Eddy
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Hornet
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| posted on 23/4/03 at 09:23 AM |
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I agree the jig will give you correct castor, but if you build the chassis as per the book, the brackets will be hanging off LA and LB
So.. you have been warned.
[Edited on 23/4/03 by Hornet]
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Gremlin
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| posted on 23/4/03 at 10:20 AM |
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So let me get this right the jig will work if i go with book wishbones?
If i lean la/lb back 25mm at the top i assume the top l bar has to be moved back 25mm. Does this cause any problems later on in engine fitting or nose
cone/radiator fitting?
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Hornet
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| posted on 23/4/03 at 10:28 AM |
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You are correct m8.... check earlier topics on this, it has all been cover before.
I havent fitted nose cone yet so cant answer that question.
But, safer steering is more important 
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Gremlin
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| posted on 23/4/03 at 02:40 PM |
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When i looked at the jig it was used both sides and had all bottom and top brakets lined up on a central plane and thought that was wrong? How does
the wishbone produce a 5 Degree angle?
EZy GreMLiN
"The only way to get rid of temptation is too give in to it..!"
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eddymcclements
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| posted on 23/4/03 at 03:04 PM |
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quote:
Originally posted by Gremlin
When i looked at the jig it was used both sides and had all bottom and top brakets lined up on a central plane and thought that was wrong? How does
the wishbone produce a 5 Degree angle?
The top wishbone is not symmetrical. See my earlier post - it should place the top balljoint 20mm behind the lower balljoint.
The book diagram is wrong for the top wishbone - it places the top balljoint only 10mm behind the lower balljoint. Have a careful look at the book and
you'll see what I mean.
Cheers,
Eddy
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Simon
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| posted on 23/4/03 at 03:57 PM |
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Shoulda used Sierra uprights.
Then you could have used a concentric top mount that allows camber and castor changes.
Sorry, just had to get that in!!
But others correct. Top w/bone assymetrical so should (but doesn't) give you the 5deg of castor .
ATB
Simon
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Gremlin
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| posted on 23/4/03 at 11:05 PM |
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I see so the 4 mounting brackets are symmetrically placed on the chassis either side of the center line but the book upper wishbone needs to be
modified to drop back another 10mm to give an overall 20mm on the top ball.
So the attached picture of mounting brackets is wrong. The top front bracket should be inset the same from the bottom front bracket as the top inner
is from the bottom inner?
I do have a couple of sierra uprights how easy is it to use those instead simon?
[Edited on 23/4/03 by Gremlin]
 
Rescued attachment 0601c080.jpg
EZy GreMLiN
"The only way to get rid of temptation is too give in to it..!"
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Rorty
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| posted on 24/4/03 at 12:35 AM |
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Hornet:
quote:
Must disagree Rorty, LA and LB are wrong in the book. They need to lie back another 25.4mm to give the desired 5.3 degrees.
OK, I'm not building a locost, so I wasn't aware of that particular discrepancy in The Book.
The point I was trying to make though, is still valid, ie the outer, upper wishbone balljoint wants to be "X" mm behind the lower one, not
directly above it.
I believe the upper wishbone should be attached to LA and LB. It's always easier to redesign the shape of a wishbone, rather than trying to
alter the chassis, or having to employ sky brackets.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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Hornet
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| posted on 24/4/03 at 07:01 AM |
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Agreed Rorty. Your point is valid.
However, Gremlin... 3 points.
Point 1. The top wishbone dimensions in the book are the same as those for sale at a number of vendors.
Point 2. I believe that if you manufacture a modified top wishbone, you will have problems with clearance for your coil and damper.
Point 3. The latest attachment you have added has wrong dimensions on it,
Hope this helps. 
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Peteff
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| posted on 24/4/03 at 08:31 AM |
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Book layout.
I built mine as per the book before I found out about any castor problems so it only has a little castor, but it still works. You just don't
generate as much self centring force. If you are not a driving critic you probably won't even notice. All it seems to mean to me is that I have
to turn the wheel to straighten up after a corner. I'm not going to start hacking it about to fix what I don't see as a problem anyway.
yours, Pete.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Gremlin
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| posted on 24/4/03 at 09:13 AM |
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So is there a correct answer to what needs to be done?
Is it best to go with the jig for the bracket placement and then modify top wishbone by 10mm or will that cause problems with coil over’s?
Is it best to move upper wishbone brackets back 10mm?
Argghh Just as I thought I was getting somewhere with the chassis!!!!
If the book dimensions set the top balljoint 10mm back from the bottom this surely gives 2.65 Degrees instead of 5.3 How much of an issue is the extra
2.65 Degrees???
EZy GreMLiN
"The only way to get rid of temptation is too give in to it..!"
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I love speed :-P
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| posted on 24/4/03 at 05:40 PM |
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Are the drawings wrong in the 2nd addition
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Hornet
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| posted on 25/4/03 at 07:18 AM |
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Yes m8, the drawings are wrong in the 2nd edition.
If you look at some "manufactured chassis" where they have realised the mistake, you will see the front top brackets hanging off LA and LB
and then a gusset welded into postition to try and achieve some much need strength.
It is nice to see some comments from guys that did not notice the problem and say that it only causes minor handling problems. I suppose the choice is
up to the individual.
I chsoe the modification of the chassis route as i wanted full contact on LA and LB. i have pics if it helps?
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Gremlin
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| posted on 25/4/03 at 08:46 AM |
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Hornet a picture would be good if you have one.
Have you modified the top wishbone as well as the mounts or just moved top wishbone mounts back 10mm and built the wishbone as the book?
[Edited on 25/4/03 by Gremlin]
EZy GreMLiN
"The only way to get rid of temptation is too give in to it..!"
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Hornet
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| posted on 25/4/03 at 09:31 AM |
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Hi Gremlin
I have used standard wishbones as per book.
And placed brackets as per the attachment
[Edited on 25/4/03 by Hornet]
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Hornet
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| posted on 25/4/03 at 09:34 AM |
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And the end results are as below
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Gremlin
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| posted on 25/4/03 at 09:47 AM |
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Looks good.
So just to check all you have done is lent LA and LB back another 25mm so LC is actually 4" behind LD not 3".
I think i might to that then. Although i have only tacked it in place its going to be a pain in the backside having to move S T and R. Oh Well
EZy GreMLiN
"The only way to get rid of temptation is too give in to it..!"
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Gremlin
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| posted on 25/4/03 at 09:57 AM |
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If i do what you suggest and move LA LB back i take it this jig is wrong.
The jig would only be correct with book chassis and only then put the top wishbone 10mm behind bottom unless i modified the top wishbone?Image
deleted by owner
EZy GreMLiN
"The only way to get rid of temptation is too give in to it..!"
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Hornet
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| posted on 25/4/03 at 11:32 AM |
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Yes m8, jig is wrong.
And i will say again.... if you modify the top wishbones.... you will not be able to get spares of the shelve and possibly interfere with the
shocks.
I have a CAD of the dimensions at home if thats any help?
PS i was looking at some pictures and if you look at this picture from Wadders section, you will see the brackets hanging off LA and LB with the
gusset added for strength.
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Gremlin
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| posted on 25/4/03 at 02:15 PM |
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Drawings would be good thanks.
Email that works is mike_coutanche@weymouth.ac.uk
EZy GreMLiN
"The only way to get rid of temptation is too give in to it..!"
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skint scotsman
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| posted on 17/3/05 at 08:48 PM |
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spot the difference
any body able to circle (and explain) the difference between this and the book, Have just looked at the pic at the top of page 64 of the second
edition and cant see the difference????????????
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