Hi all
Now that i have finished building my Spire GTR, i have taken it on a couple of track-days i am starting to notice areas of handling that could maybe
improve if there was more adjustment in the suspension and geometry etc.
At present i have poly bushes all round, but was wondering whether the step towards fully rose jointed solution is really worth it.
Its mainly on the exits of corners that i have experienced the car wanting to let go (back end) as you get back on the power. Whilst its quite
entertaining and looks good to the spectator, it aint the fastest way round the track. I want to get back on the power and be sure the car is planted.
Whilst i am a novice driver and i am sure driver tuition is something i need, i do think the mechanical grip is lacking. For road purposes i am sure
there is bags of grip but as i am not IVA ing it, it is only going to be driven on track.
Firstly, what are the pros and cons of rose jointing and secondly, are there any bods out there that are able to provide or talk me through a gradual
progression in developing the car further?
Thanks
I got my Indy-R all rose jointed, so that i could do exactly what your talking about in the future
as im a complete noob, this has been a nightmare in trying to get anything remotely aligned for IVA and as few people seem to get it done, the help
available is limited
im sure it will be worth it in the end but for now its a complete pita
properly rosejointed suspension wont be adjustable.
I would suggest that the principal difference would be in the inspection and maintenance regime that you must employ when the car is all rod ends as
opposed to bushed with a degree of compliance in them.
Even a poly bush will have a measure of compliance inherent compared to a rod end. Much less than a rubber bush, but still more than a rod end.
The rod end has to accept and deal with every little load and shock it is sent.
A friend had one fail at the weekend.
Now, before I go any further, I'll state for the record that this was a rally car and I absolutely accept that there are potentially greater
shock loads in such an application.
Nevertheless, the net result of this single failed road end is a wrecked shell.
I have an image of the failed part, but not necessarily permission to share the image, so you'll forgive me for not sharing without getting
express permission first.
I'm not suggesting for a second that this should cause you to shy away from using rod ends, but equally I would suggest that you should get used
to what amounts to forensic examination of the joints on a regular basis.
I would also suggest that if you were to search out the place in the uk which is pretty well known for selling rod ends at the most competitive price,
and based on my above monologue, you may wish to choose to spend a little extra and avoid the cheapest ones.
Outwith the issued of rod ends.
What tyres are you running ?
What pressures are you running ?
Springs / dampers etc ?
You may have a lot of tweaking to do before major alterations to the car even become necessary, far less essential.
quote:
Originally posted by alistairolsen
properly rosejointed suspension wont be adjustable.
The rose joints won't have their holes running horizontally as I believe the "correct" orientation is to have them vertically pointing
to avoid the bearing popping out under high loads. The bones wouldn't be able to be moved up and down the bolt shaft to adjust them more towards
the front or back of the car and then fitted with spacers. You would still be able to unscrew the rose joint at the front a bit to try and point the
bone backwards but it's generally recommended that the whole threaded part of the joint is screwed in to prevent creating a stress point on the
shaft.
That's the official view I believe and a summary of what I read off here before deciding to do mine anyway.
i posted a quesroom about spherical joints and this was the result. linky
A full rod end set-up might increase the range of adjustment and allow for finer tuning. However it won't address any inherent short comings in
the suspension geometry. The start point (IMHO) is to check the chassis and suspension pick-up points are true and and within tolerance (typically
+/- 1mm). After that check that the existing wishbones and uprights are also true and again in tolerance. Once done and corrected if necessary you
have a start point to work from and can identify where to make improvements - e.g. a full rod end set-up or re-positioned pick-up points etc.
Hopefully not teaching you to suck eggs here BTW.
Des Hammill's book on suspension set-up is a worthwhile read....
http://www.amazon.co.uk/Modify-Sportscar-Kitcar-Suspension-Spee
dpro/dp/1903706734
quote:
Originally posted by mistergrumpy
The rose joints won't have their holes running horizontally as I believe the "correct" orientation is to have them vertically pointing to avoid the bearing popping out under high loads. The bones wouldn't be able to be moved up and down the bolt shaft to adjust them more towards the front or back of the car and then fitted with spacers. You would still be able to unscrew the rose joint at the front a bit to try and point the bone backwards but it's generally recommended that the whole threaded part of the joint is screwed in to prevent creating a stress point on the shaft.
That's the official view I believe and a summary of what I read off here before deciding to do mine anyway.
I totally agre Tim. This is what I considered to before I did mine. I'm just messing with the fine tuning and in fact I'm going to go out
and have a play with them now
My intention is to make some adjustable ones until I get the geometry perfect and then do a proper set with enclosed housings from those.
Cons:-
Cost - Don't last that long in comparison to polybushes
Pros:-
Less friction = more grip.
Less movement = more stable geometry
Ideally from a strength and friction point of view they would be mounted with the bolts vertically, but as it would be replacing polybushes you would
be forced to use them where the bolts were horizontal, no biggy really. Ideally you would use a smaller rose joint than the polybush bolt size will
allow so again its no real biggy but would have saved weight.
Be worth checking what spring rates and damper setting you are currently using as this kind of over steer might be cured with softer rear
springs/damping or stiffer fronts.
With a set of suspension to use as a pattern we could make all the parts required to what you want.
Putting rose joints aside, all they will do is get every thing pointing the same way. I think you need to look at why the back end steps out while on
the power.
What size tyres are you using on the back, are they too wide or too narrow, are they cheap road tyres or semi slick, what pressure are you running in
them?
What are the rear spring rates have you corner weighted the car, are the dampers set up correctly for bump and rebound?
What torque is the engine making are you asking too much of the chassis?
What diff is in the car is it a LSD or do you need one?
Before spending time and money on joints I would talk to some one who knows what they are doing with car suspension, there is alot more to it than
making it so adjustable that you don't know what to play with next.
There's no reason not to use nylatron bushes for the inners, with rodends on the outers.
The inner mounts will necessarily need to be very accurately placed, to ensure free movement. Alignment takes time, but the bushes will last a
lifetime. I know of at least one big name GT car team whose development mules use this setup, and a couple of others who have used it in the past. One
even raced at a high level, found the setup better than rodends, but relented eventually and went to rodends purely because 'that's what
everyone does'. Not a good reason at all.
Whatever floats your boat..., as they say.
Cheers,
Nev.
quote:
One even raced at a high level, found the setup better than rodends, but relented eventually and went to rodends purely because 'that's what everyone does'. Not a good reason at all.
my suggestion would be to soften the front or stiffen the rear dampers before you go to all the trouble.
quote:
Originally posted by alistairolsen
http://www.formulastudent.de/academy/pats-corner/advice-details/article/pats-column-rod-ends-in-bending/
quote:
Originally posted by edsco
Hi all
Now that i have finished building my Spire GTR, i have taken it on a couple of track-days i am starting to notice areas of handling that could maybe improve if there was more adjustment in the suspension and geometry etc.
At present i have poly bushes all round, but was wondering whether the step towards fully rose jointed solution is really worth it.
Its mainly on the exits of corners that i have experienced the car wanting to let go (back end) as you get back on the power. Whilst its quite entertaining and looks good to the spectator, it aint the fastest way round the track. I want to get back on the power and be sure the car is planted. Whilst i am a novice driver and i am sure driver tuition is something i need, i do think the mechanical grip is lacking. For road purposes i am sure there is bags of grip but as i am not IVA ing it, it is only going to be driven on track.
Firstly, what are the pros and cons of rose jointing and secondly, are there any bods out there that are able to provide or talk me through a gradual progression in developing the car further?
Thanks
http://boardroom.wscc.co.uk/cgi-bin/ikonboard.cgi?act=ST&f=3&t=84209
quote:
even the current cars use them in that manner - perfectly standard use.
If you do not know the front of a car from the rear you are in trouble........................
Does not use rod ends, too heavy, uses spherical bearings pressed into the wishbones.
<grin> - actually pasted the wrong URL into the damn box. Funny. How much of a berk do I look now!
I'm guessing there's some confusion with people about what rod ends are hence people commenting on their use when they're not used
(that I can see). A spherical bearing does not a rod end make, as you point out gpm.
[Edited on 4/10/11 by coyoteboy]
[Edited on 4/10/11 by coyoteboy]
If you want to be very up to date, don't use any type of pivot on the inner end. Just bolt the carbon fibre flat moulded into the wishbone end
straight onto a flat projecting from the chassis.Two little 6mm bolts.The flex of the carbon flat is enough. For a race or two anyway, before you
change them out.
ON the FS subject; Ross Brawn when judging, gives an immediate negative or downmarking if he sees rodends in bending. It's very poor engineering.
Top and bottom outers should be sphericals in proper housings. Castor adjustment is in the inner mount. Camber should be by adjustment shims. This
all comes from Brawn's own comments.
Cheers,
Nev.
The nylatron ends will outlast a rodend by a multitude of lifes. But takes a bit more care in manufacture of the chassis and wishbone. The rodend
setup is forgiving and allows for 'tolerances' in manufacture, and is much quicker to service on the day. That's why the mules used
nylatron, the racecars rodends. Not rocket science by a long way!
[Edited on 4/10/11 by Neville Jones]
Hi
Nope know what a Rod End is - and yup the Reynard that's sat in the garage has quite a few all over it, should know had to purchase quite a
few..
Oddly the picture file of the F3 cars in the Monoposto Champs sans bodywork seems to feature quite a few too..
Now not saying for one minute it's perfect and you'll notice i didn't recommend the OP to do it anyway, but like it or not them being
used like that for donkeys years makes it fairly standard practice, probably because it makes adjustment quick and reasonably accurate for a cheap
initial investement
Brawn / Current GP would indeed just throw different set of bones at 0.1mm longer/shorter of course 
Hi Guys
Thanks all for you all your feedback. Its interesting to hear all the various viewpoints for and against etc.
I think i really need to consider the future of what i want to do with the car before making any decisions on whether to go down the route of rose
joints all round.
Basically i built the car with IVA in mind so therefore should get through the test no problem, but the car is much more suited to the track and hence
why i have not bothered with IVA. I want to compete it in some form of lower league motorsport but am thinking the car is too good a quality build to
start exchanging paintwork etc!! Which leaves just trackdays but these aren't competitive.
I think i am going to go with JimSpencer's advise first. Get it properly sorted with the tools i have first....i.e. corner weighted, have the
shocks properly set up, decent tyres etc and try a few more track days and see how things progress.
This particular car i don't think it'll be used to compete with, but if anyone has anything eligible to compete in RGB or bikesports or even
kit car series give me a shout. Might consider a part- ex or something.
quote:
Oddly the picture file of the F3 cars in the Monoposto Champs sans bodywork seems to feature quite a few too..
Surprised we've not had any input from Procomp Matt on this thread?
YEP, After all the Spire was originally built by MK,
tony
quote:
Originally posted by nick205
Surprised we've not had any input from Procomp Matt on this thread?
I believe that Allan Stanniforth advocated the use of Female ends secured with high tensile bolts of appropriate length/size. This allows you to
replace them on a regular basis to ensure that fatigue does not become an issue. A big bag of bolts would cost less than one good joint and they
could be replaced for every event if you were so inclined.
OF COURSE you lose the adjustability!! I guess some machined spacers could give a range of adjustments?
Steve
quote:
Originally posted by afj
quote:
Originally posted by nick205
Surprised we've not had any input from Procomp Matt on this thread?
maybe hes fed up giving out sound advise and getting bashed on here for his trouble.
