luke2152
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| posted on 4/12/16 at 09:04 PM |
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adjustable top wishbones
Any ideas on good ways to make front top wishbones adjustable? I'm thinking some sort of threaded sleeve in the middle of each tube (left
thread on one end right on the other) that can be rotated to change the length. Was also thinking just a threaded rod inside the tube but not sure
that would be strong enough.
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Slimy38
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| posted on 4/12/16 at 09:10 PM |
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Have a look how the Saturn MX5 plans cope with using a ball joint that fits on the MX5 upright. It's a threaded ball joint into a threaded
sleeve in the wishbone. It doesn't give infinitely granular adjustment as it only works on complete revolutions of the ball joint thread. But it
is adjustable.
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Sam_68
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| posted on 4/12/16 at 09:16 PM |
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Adjustable for what, and to what degree?
Obviously, camber adjusters are available off-the-shelf that lengthen or shorten the wishbones by a small amount:
Link
Or you can use a turnbuckle in the middle of a tube, as you suggest, if you want to be able to adjust one 'leg' of the wishbone
independently (which will obviously change length and caster at the same time):
[Edited on 4/12/16 by Sam_68]
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watsonpj
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| posted on 4/12/16 at 09:21 PM |
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do a google search on "mcsorley adjustable top wishbone" he made a video
hopefully the linky works
looks very adjustable but don't know where to source the special balljoint but i'm sure someone will be along who can say or you can
fabricate something similar.
Pete
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luke2152
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| posted on 4/12/16 at 09:26 PM |
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Sam your turnbuckle photo is exactly what I was thinking of. Is the turnbuckle strong enough to be safe? My main intention is to adjust castor but
camber could obviously be done as well.
I actually already made a set with rod ends on all three points which are fully adjustable but you have to completely remove them to do so. And I
have so many spacers where the bushes used to be that it is actually pretty difficult to achieve this. And I heard the rod ends wear out pretty quick
which isn't good on a road going car.
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Sam_68
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| posted on 4/12/16 at 09:51 PM |
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quote:
Originally posted by luke2152Is the turnbuckle strong enough to be safe? My main intention is to adjust castor but camber could
obviously be done as well.
Yes, it's strong enough, particularly on a top wishbone. That image is Googled from a Lotus Elan lower rear wishbone, where it's a routine
method of providing toe adjustment.
There are problems to be aware of, mind you; obviously you won't want the locknuts to come loose, or it could go out of adjustment very easily,
but also it affects castor whether you want it to or not, unless you have one built into each wishbone arm and adjust them equally (which is a
pain in the butt).
You're better off using just standard camber adjusters, and/or or use rod ends set perpendicular to the centreline of the chassis on the inboard
ends of the wishbones which can be screwed in or out to lengthen or shorten the wishbone.
It's also possible to use shims between a bolted connection... there are lots of ways of doing it.
Question is, why do you want to?
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luke2152
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| posted on 4/12/16 at 10:14 PM |
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As to the why: Well even after procomp set up everything as best as they could I find high speed bumpy roads unsettling the car to the point of being
almost dangerous. Steering is just too touchy. Basically it feels like a go cart - awesome at low speeds and progressively unstable as speeds
increase. With standard gbs wishbones I have 3.9* castor left and 5.2* right (not adjustable). I have since added approx 3 degrees castor to try to
counter this and it helped to a degree but caused other problems (large changes in camber as you increase steering angle). So I want to set it back
near to original geo with a little more castor and with the same amount on each side! (and be able to adjust it as I see fit with minimal effort).
As an aside I think my 2.8 escort rack is too fast for mx5 steering arms because I get more than 45 degrees steering angle at full lock so I should
probably look at putting a standard escort rack on to tame things a bit. Perhaps a bit more toe in on the front and I have eccentric adjusters in the
rear wishbone bushes (which were previously not adjustable) although I haven't had a chance to play with these.
Anyone know if I can get those turnbuckles and hardware off the shelf anywhere or if I have to make them?
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Sam_68
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| posted on 4/12/16 at 10:37 PM |
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Well, it's your funeral, as they say!
Bear in mind that when Lotus designed the 77 with all-adjustable suspension, not even Colin Chapman and his team of F1 engineers could sort it - there
were just too many variables involved. The more complex you make the adjustments, the more you'll end up chasing your own tail.
With a turnbuckle arrangement, every time you make an adjustment to the wishbone length, you'll be throwing out the castor setting at the same
time. You're far better off coming up with an arrangement that adjusts wishbone length (camber) and castor independently of each other (eg.
camber by off-the shelf camber adjusters, caster by shimming the wishbones fore-or-aft relative to the chassis mounting brackets).
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luke2152
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| posted on 4/12/16 at 10:49 PM |
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You're probably right Sam - I will end up chasing my tail. But there's really only two variables - camber and castor. Set the castor by
fiddling with the lengths of the tubes. It puts the camber out. But then you correct the camber again using only the rod end closest to the wheel.
(If I'm wrong on this I'm happy to be corrected!).
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Sam_68
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| posted on 4/12/16 at 11:17 PM |
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quote:
Originally posted by luke2152
But there's really only two variables - camber and castor.
...one of which (castor) you'll ultimately want to set, and stay set, the other of which (camber) you may wish to be more readily adjustable.
Honestly; do it the normal way, keeping the adjustments independent of each other. There's a good reason that it's the normal way.
If adjusting the wishbones by means of turnbuckles in the middle of the wishbone arms was a clever idea, everybody would be doing it!
Have you checked bumpsteer?
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Camber Dave
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| posted on 5/12/16 at 08:57 AM |
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Another vote for Bumpsteer
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Mash
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| posted on 5/12/16 at 10:27 AM |
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quote:
Originally posted by luke2152
As to the why: Well even after procomp set up everything as best as they could I find high speed bumpy roads unsettling the car to the point of being
almost dangerous. Steering is just too touchy. Basically it feels like a go cart - awesome at low speeds and progressively unstable as speeds
increase. With standard gbs wishbones I have 3.9* castor left and 5.2* right (not adjustable). I have since added approx 3 degrees castor to
try to counter this and it helped to a degree but caused other problems (large changes in camber as you increase steering angle). So I want to set it
back near to original geo with a little more castor and with the same amount on each side! (and be able to adjust it as I see fit with minimal
effort).
Is this normal?
I'm probably talking rot, but could you not adjust it with the adjustable set you've made already so that both sides are the same, make
the adjustments you want as close to original as possible, then alter the standard ones to the size they should be, copying the adjusted ones, then
put the standard (now modified) ones back on. From then on, normal camber adjusters as suggested above?
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russbost
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| posted on 5/12/16 at 10:33 AM |
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Before you go into loads of work, have you tried adjusting tracking to see what effect that has & also what tyre pressures are you running with
what size tyres.
I know it's a very different car, but with the Furore, if you run ANY toe out it destroys the driveability of the car, as long as it toes in, it
doesn't really seem to matter how much, I normally run around 1 - 2mm toe in. We do run an enormous amount of castor, so as I say a very
different setup to a 7
If tyre pressures are high (particularly at this time of year & particularly if you low profile tyres) then you'll find the thing hopping
all over the road
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Fred W B
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| posted on 5/12/16 at 06:20 PM |
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South African built Birkins have a neat solution for camber adjustment, as shown in the picture, although they use a top ball joint, not a rod end.
The top upright attachment incorporates a internal and external threaded bush between the left hand 1.5 mm threaded 16 mm rose joint and the bush that
will be welded into the top wishbone. A 360 deg rotation gives 3 mm of movement. The black half nut is the locknut on this adjustment bush, the lock
nut on the rose-joint is not fitted yet.
Cheers
Fred W B
[Edited on 5/12/16 by Fred W B]
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
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luke2152
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| posted on 5/12/16 at 09:25 PM |
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I'm not really sure how to check bump steer. I guess I could remove the struts and measure the toe in through the range of suspension
travel.
I have 1.5mm of static toe on the front. Not sure about the back at the moment. Tyre pressures 20psi on T1R 195/45/14
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