ned
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| posted on 8/9/03 at 09:40 AM |
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Suspension Brackets & fu1,2 problems (again!)
I've read previous posts from a search, but thought I'd post this to illustrate the point..
I spent saturday fully welding the tack welded chassis i recently obtained. The centre section went well, though I noticed a peculiarity in the front
suspension brackets and fU1,2 seemed to be mounted 1/2" forward of where they should be.
I've measured the chassis and all seems to be correct. I've also measured the wishbones which only appear to be 1mm too narrow
(loloquality!) though this doesn't explain the offsetting forward of fU1 & 2 by 1/2".
Has anyone built their chassis this way? (see pics below) or do I need to re-position all the suspension brackets and move fU1&2 back to where
they should be?
I looked at a few cars on sunday at the newlands meet and a lot of people had their brackets further back (not central) on LA & LB.
My only concern with moving the FU1,2 back is that the rear bracket for the front bottom wishbone will be too close to FU1,2 respectively.
So should I weld it up as is, assuming the wishbones fit or re-do all the brackets and move FU1,2?
Anyone with any similar experiences or suggestions?
All advise welcomed. (apart from comments on the lolocost wishbones [i already know] which came with the chassis!)
Thanks,
Ned.
[Edited on 8/9/03 by ned]
beware, I've got yellow skin
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JoelP
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| posted on 8/9/03 at 12:17 PM |
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Myself, if the brackets are straight i would get some bones and c how they fit. If wonky i'd start again. Simple!
If bones dont fit then just grind off and put them where they do fit, moving FU1/2 as required and making sure rack and springs still fit in right!
Good luck. Joel. All IMHO of course!
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pbura
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| posted on 8/9/03 at 01:18 PM |
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The builder probably moved FU1/2 forward so he could get a nut on the wishbone bolt. I wouldn't worry about this at all.
If I were you, I'd hold off on finish welding until getting the suspension set up, to make sure evrything fits and to make sure you will have
correct castor and camber.
BoL,
Pete
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ned
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| posted on 8/9/03 at 01:35 PM |
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I have the wishbones, uprights and all ball joints, so just trial fit it all and measure the castor?
Anything else I should check?
Thanks for your help,
Ned.
beware, I've got yellow skin
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pbura
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| posted on 8/9/03 at 02:03 PM |
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quote:
Originally posted by ned
I have the wishbones, uprights and all ball joints, so just trial fit it all and measure the castor?
Anything else I should check?
Well, you could go ahead and set up your steering, too. Nice having a prebuilt chassis, isn't it? 
BTW, I wasn't sure what your final decision was on the rear track: similar to the front? I hope so; otherwise, you'd have more load
transfer at the front and more understeer, might be hard to correct.
Pete
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ned
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| posted on 8/9/03 at 02:10 PM |
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am planning on using MK Indy rear bones and uprights, though with wishbones mounted further in and shortened half shafts to give near/book rear
track.
Ned.
beware, I've got yellow skin
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pbura
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| posted on 8/9/03 at 02:16 PM |
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Had another thought. You could also model your front suspension in wishbone.exe, available for free from RaceTech Magazine:
http://www.racetechmag.com
You'll need MS QuickBasic to run it, copies available with a little digging if you don't have it.
Should be lots of fun, and if you have any problems in your suspension/steering geometry it should bring them to light.
Pete
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ned
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| posted on 8/9/03 at 02:55 PM |
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Pete,
Thanks again, don't have time to look at that now but will save it for a rainy day...
cheers,
Ned.
beware, I've got yellow skin
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burgessj
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| posted on 8/9/03 at 09:59 PM |
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Ned,
In an earlier post of mine, a few people pointed out to me that the positioning of front suspension brackets is wrong in the book, and that in order
to get the top front bracket to sit squarely on the L upright, you must angle the whole L assembly back by a further inch at the top.
Presumably, the guy who built your chassis has not done this, but moved the FU1&2 struts forward by an inch to get the wishbones to fit (easier
option)
I don't know which is the right way because I haven't had to fit my front suspension yet, but I guess if you can get the right castor etc,
then it doesn't matter.
Hope this helps...sorry if I'm way off the mark
JohnB
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Hornet
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| posted on 9/9/03 at 07:52 AM |
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Ned, Have a look in my photo section. Yours looks very similar to mine. I altered the front end after i realised the book was wrong and i wanted the
brackets sitting squarely on the uprights.
As long as the castor angle is correct it wont matter where FU's are positioned.
Hope this helps. 
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craig1410
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| posted on 9/9/03 at 01:17 PM |
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Hi,
Just to add my opinion to the mix...
I agree with hornet that this is probably another case of someone trying to solve the unsolvable problem (ie. Get castor correct on a book chassis
with book wishbones without brackets hanging off the chassis members)
My only concern with this approach (which I considered by the way) is that FU1 and 2 are not aligned with tube E which is not "ideal" for
strength but probably not disastrous in the grand scheme. Just be aware that by having the suspension effectively 1/2 inch forward that you may have
trouble fitting some commercial GRP parts. They will fit but won't fit as well as they should perhaps, especially where there are cutouts for
steering and suspension arms.
My solution to this problem was to fix everything where it was intended to go which means moving FU1 and 2 back 1/2 inch and all four brackets
(including the bottom rear one which would otherwise foul FU1/2) This will leave my upper front bracket poorly supported but instead of leaning the
front (LA/B/C/D) assembly backwards I am just welding an extra piece of 1 inch square tubing onto the rear face of LA and LB to support the bracket
better. I can't lean back the front assembly as my Rover V8 needs every millimeter of length in the engine bay and the water pump would foul the
front assembly if I leaned it back. If you do this then make sure the extra tube doesn't foul the steering track rods or gaiters.
One other thing which springs to mind is that by having your suspension further forward this may adversely affect the relationship between steering
rack and uprights. Again I don't think it will be a big deal but worth checking maybe. You may need to move your steering rack mountings forward
1/2 inch but this may cause the track rods to foul LA and LB.
Final point, as recommended above, trial fit everything to do with the suspension and steering before fully welding if you can but just make sure your
tack welds are strong enough to hold still with the chassis on its wheels and check them for movement after stripping the suspension again ready for
seam welding. Same goes for engine and gearbox and rear axle components. Use strong tack welds on all four mating edges of your tubes and check before
seam welding.
If you do get the chassis on its wheels to check suspension alignment then I'd recommend supporting the chassis in the middle at least to avoid
bending it and then get it absolutely flat on your building surface before welding. Ideally clamp it down to weld one weld on one side before doing
the mirror weld on the other side. This will help minimise distortion but I'm sure you already know this from other threads on this subject.
I hope this helps,
Craig.
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ned
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| posted on 9/9/03 at 01:37 PM |
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Craig, Hornet et all,
thanks for the continuing comments, I checked the wishbones and they don't appear to fit (unless i have to take some material off the lolocost
bushes?) so will probably re-do all the suspension brackets and move fu1,2 back to their position in line with tube e, then put some additional
webbing behind the suspension brackets if they look like they're not well enough supprted on la & lb.
thanks again,
Ned.
beware, I've got yellow skin
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craig1410
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| posted on 9/9/03 at 03:35 PM |
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Ned,
I also have the lolocost wishbones (sigh!) and I had to remove a fair bit of material from the edges of the bush tubes in order to get them a) aligned
and squared nicely and b) finished nicely. I think I filed them down to 36mm by removing material from the faces where the nylaspa bushes push in to.
These should have been done on a lathe before being welded!!
I also found that the two bush tubes on each pair of wishbones were not concentric and had to be twisted carefully to correct it. I found this by
fitting the Nylaspa bushes and crush tubes (which also needed the ends finished properly btw) and then passing a perfectly straight threaded rod
through the centre and checking that alignment was spot on. If you do this for each bush tube of each wishbone and ensure that the threaded rod hits
the exact centre of the opposing bush tube then all should be well. The wishbone with assembled bushes and crush tubes should pivot smoothly on the
threaded rod now with absolutely no binding.
I couldn't even get the threaded rod through mine when I first got them!!! All they needed was very careful twisting to align the bush tubes. It
was only a degree or two but with the distance between bush tubes it resulted in 4 or 5 mm of misalignment which would probably result in fatigue
stresses in use due to the different axis of rotation.
To be honest I wish I had sent my wishbones back as soon as I got them but the various quality issues only became apparent as time went on.
HTH,
Craig.
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ned
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| posted on 9/9/03 at 04:01 PM |
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excellent, so its not just me! I may have a chance to have a quick look at it again tonight, but this weekend is out due to Donny and a race I'm
spannering for at Snet, then holday 'til October 
Did clean up my uprights last night, getting as much done as quickly as poss to make up for a week away!
Ned.
beware, I've got yellow skin
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craig1410
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| posted on 9/9/03 at 04:07 PM |
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Nice job on the uprights. What did you use to clean them?
Craig.
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ned
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| posted on 9/9/03 at 04:11 PM |
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hope this makes sense:
Ned.
beware, I've got yellow skin
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James
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| posted on 9/9/03 at 04:29 PM |
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quote:
Originally posted by ned
hope this makes sense:
Ned.
[img][/img]
Ah, The Tool!
You can't beat it for taking rust off your rusty bits and skin off the back of your hands!
James
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chazpowerslide
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| posted on 17/9/03 at 10:42 PM |
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Why not weld the brackets on as per book and build top 'bones with a bigger offset?
If you use curved tubes like the MK ones pictured on page 172 of the 2nd edition on the book the springs ect will fit ok.
I know this works as I've just built a set for a mate of mine who was all in a panic after discovering the error on the drawings after his car
was finished and thought he'd cocked it all up.
Any chassis that was made to "book" can be retro-fitted with a suitably offsetted pair of top 'bones to get the correct castor.
The set I made have spherical bearings to enable fine adjustment as well.
The castor before was 1 degree and the car felt ok but was a bit wondery and impresise at speed it also had a natrual tendency to understeer with
virtually no self centering effect on the steering.
It was set origionally with 1.5 degrees of neg camber and 1mm toe in.
We set the the castor to 5.5 degrees and re-set the toe and camber as before and the difference while not earth shattering was very noticeable.
The wondery imprecise feeling has gone and it is easier to "feel" what the front wheels are doing due to improved self centering/weighting
up of the steering through turns.
The car also has lost some of it's understeery character as the castor pulls on more neg camber on turns and the front end seems to
"bite" a lot better.
Chaz.
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ned
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| posted on 18/9/03 at 08:37 AM |
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chazpowerslide,
I already have the wishbones, and i didn't make them. not sure I'd trust my welding skills for wishbones, and I'd need to make a jig
etc that i can't be donig with!
i've cancelled my holiday next week and am spending the week on the car instead! so we'll see how we get on. I'm also hoping to
borrow a jig to reposition all the front suspension brackets.
cheers,
Ned.
beware, I've got yellow skin
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timf
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| posted on 18/9/03 at 08:42 AM |
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quote:
Originally posted by nedI already have the wishbones, and i didn't make them. not sure I'd trust my welding skills for
wishbones,
Ned.
but you trust your welding on the brackets that attach these wishbones?
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ned
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| posted on 18/9/03 at 09:06 AM |
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yeah, well maybe i'm just too lazy and make crap excuses! oh and i already have perfectly good, no sorry I mean already made wishbones. they are
lolocost afterall.
Ned.
beware, I've got yellow skin
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burgessj
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| posted on 18/9/03 at 08:21 PM |
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Ned,
Sorry to go off on a slightly different thread,but
do you anticipate having problems fitting a nose cone because of these alterations ?
Or are you making your own nosecone ?
JohnB
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Rorty
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| posted on 19/9/03 at 02:01 AM |
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chazpowerslide:
quote:
The set I made have spherical bearings to enable fine adjustment as well.
What method of adjustment have you devised for the spherical bearings?
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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ned
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| posted on 20/9/03 at 07:45 PM |
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Burgessj,
I don't anticipate any problems, having looked at a load of locosts recently their suspension brackets positions varied slightly.
Ned.
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