View Full Version : caster angle
has anybody played much with caster settings, looking to run maybe 5-6 dergress positive but would like other peoples views and experiences with caster angles :scratch:
Woznaldo
27-10-2012, 23:30
I think the general guidance would be to run as much as possible.
There are a few ways of achieving this:
Moving the Strut Top Mount rearwards - adjustable or custom top mounts required.
Pushing the Lower Wishbone forward - offsetting the pivot bushes rearward (what they did on the Cup cars). You could also use a different Lower Wishbone which is already manufactured to move the lower pivot forward i.e. Valver, Williams and 172/182 but the added track would have to be sorted for these options. You could make a custom Lower Wishbone that could do the job without the extra track.
Pros - more dynamic negative camber, which will give better 'turn in'. It will also add straight line stability.
Cons - the steering will get heavier and could be more prone to bump steer or kick back through the steering wheel.
Pushing the Lower Wishbone forward The anti roll bar will prevent that won't it?
Matt@CodeRedMotorsports
28-10-2012, 07:20
If you are handy with a round file and a welder, caster adjustments are easy.
Well, considering yours is rwd you really want it!
Best option is to fabricate some topmounts that'll do the trick. The con of moving the lower balljoint forward is your wheel is going to be too much to the front.
5 degrees is the least you'll want. That's exactly what all the MR factory cars have.
Scoff had extra castor, Chip-mk1 has it, Andy Bloxsome is currently thinkering with it.
Btw, don't you have extra track anyway? Yours has a bodykit right?
Woznaldo
28-10-2012, 08:25
If you are handy with a round file and a welder, caster adjustments are easy.
Come on then Matt. Elaborate.......
Tutuur's right, i've recently been adjusting castor, and have around 4.5 degrees up front currently. Thats the most i could get by swinging the lower balljoint forward, and redrilling it's outer most mounting point. The difference was amazing.... and i can only think that more is better, so the next plan was to move the strut top mounting backwards. Steering did get heavier, but to be fair it's made it much more positive feeling.
I've also been playing with spherical bearings in the rear lower wishbones to limit toe change under heavy forces. Tbh it didn't make much difference to the handling, but the feedback from the rear improved greatly.
I'd imagine steering was lighter due to less weight anyway?
Since i'm planning to build a MR in the future too i was reading myself into suspension geometry, some seriously interesting info on here:
http://www.rapid-racer.com/suspension-tuning.php
Matt@CodeRedMotorsports
28-10-2012, 09:00
Come on then Matt. Elaborate.......
As per the above post really.......
File the outer hole so the bottom ball joints swivel forwards, plug weld the hole a bit and weld a modified washer to re strenghthen the lost material a, use a cap head bolt to slip into the outer hole and there you go.
Matt@CodeRedMotorsports
28-10-2012, 09:01
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Matt@CodeRedMotorsports
28-10-2012, 09:03
Photos nicked from chip.
Well, considering yours is rwd you really want it!
Best option is to fabricate some topmounts that'll do the trick. The con of moving the lower balljoint forward is your wheel is going to be too much to the front.
5 degrees is the least you'll want. That's exactly what all the MR factory cars have.
Scoff had extra castor, Chip-mk1 has it, Andy Bloxsome is currently thinkering with it.
Btw, don't you have extra track anyway? Yours has a bodykit right?
indeed it does Tutuur:cool:
im running a set of clio 16v wishbones and anti rollbar set up at the front, which has pushed the wheels foward a fair amount, now got 4mm clearance between tyre and front of the arches when on full lock, and the tread is just sitting flush with the outer edge of the top of wheel arch, running phase 1 struts and a set of old tas ajustable top mounts with the 360 degree holes, so can play a bit, think i can get somewhere around 8 degrees + castor at the moment, and 1.25 degree negative camber can play a little bit with the camber corrector bolts 3 degrees+/-
thanks for the imput guys:cool:
Tutuur's right, i've recently been adjusting castor, and have around 4.5 degrees up front currently. Thats the most i could get by swinging the lower balljoint forward, and redrilling it's outer most mounting point. The difference was amazing.... and i can only think that more is better, so the next plan was to move the strut top mounting backwards. Steering did get heavier, but to be fair it's made it much more positive feeling.
I've also been playing with spherical bearings in the rear lower wishbones to limit toe change under heavy forces. Tbh it didn't make much difference to the handling, but the feedback from the rear improved greatly.
good work, and info there Andy:cool:
rose jointed mine a while back,but didnt get chance to try them out, manifold fabrication and other things got in the way:laugh::laugh:
Don't go too wild on the front negative camber, due to the light weight you'll probably make the rear go faster than the front:D
Why didn't Renault add some more castor to the 5GTT originally?
They did, look at ph.2 topmounts
Don't go too wild on the front negative camber, due to the light weight you'll probably make the rear go faster than the front:D
i hear what your saying, but its quite a hard balancing act to dial all the negative camber out and keep a nice angle on the struts, while trying to keep the wider track;):D the original strut angle on both phases of the 5 is rather ****e:cry:
Lol, another problem. Don't you love your car? :D
Lol, another problem. Don't you love your car? :D
i will adore it once its finished, but at the moment its a pain in the arse:laugh::laugh:
I know the feeling :rolleyes:
Hope to see the car in flesh next year at the Sangliers meeting.
Woznaldo
29-10-2012, 10:10
As per the above post really.......
File the outer hole so the bottom ball joints swivel forwards, plug weld the hole a bit and weld a modified washer to re strenghthen the lost material a, use a cap head bolt to slip into the outer hole and there you go.
I was thinking of moving the whole lower ball joint across but, didn't even think about pivoting it. The pivot will actually give a touch more than moving the whole thing across!
Love your work guys, I'm going to crack on with this little gem this week for sure!!!
Woznaldo
01-11-2012, 09:27
Stage one of the Caster Mod done. :D
Looks like there not equal each side but the LH Wishbone Ball Joint was loose when I removed it, so the holes have elongated a bit. I've not touched the inboard hole and so the outboard hole has moved inboard a small amount and so reduce the front track by a couple of mm each side but as I have camber adjustment, it's no big deal.
Just need to get some washers sorted.
http://i196.photobucket.com/albums/aa40/woznaldo/The%20Yellow%20Peril/IMG_2444.jpg
http://i196.photobucket.com/albums/aa40/woznaldo/The%20Yellow%20Peril/IMG_2445.jpg
Woznaldo
08-12-2013, 03:14
I've copied this from my build thread, but I thought it would be good to post it here too.
I just took the car to a local tyre place to have the alignment checked after the Caster Mods (re-drilling the outboard ball joint attachment hole), but he didn't really understand what I was trying to tell him.
We got there(ish) in the end and the figures I have now are as follows:
Front Toe: Zero
Front Camber: LH -2.95, RH -2.90
Front Caster: ??? don't know as he couldn't measure it...
With the extra Caster (I'm going to guess at between 4 and 5 degrees?) -3 Deg Camber is probably a bit excessive!! I've got a track day of sorts on Wednesday (12 Dec 13) so I'll leave it for now.
I did go for a blast before any adjustments and there was a marked improvement to the front end grip, especially during initial turn in. That was with -1 Deg Camber and zero Toe!
I'll ley everyone know how it goes on track, but will reduce the Camber to -2 after. Will probably go for 1mm of Toe out too.
Edit: I forgot to mension that the dude who did the alignment took the car for a short drive first. When he climbed out he said "That was fun. I like it" ;)
B18ftMOJO5
08-12-2013, 07:43
I have leda front dampers and spherical top mounts on mine, the problem I have is the front wheels from the top are way too far in under the arch compared to the bottom of the wheel. (Negative camber???)
how do I adjust the top mounts to get my wheels more flat with the road. Car drives ok with them, especially at speed into bends etc. the problem is have is this eats the inside of the front tyres in about 3 months.
Any help would be appreciated, thanks.
Woznaldo
08-12-2013, 11:28
I have leda front dampers and spherical top mounts on mine, the problem I have is the front wheels from the top are way too far in under the arch compared to the bottom of the wheel. (Negative camber???)
how do I adjust the top mounts to get my wheels more flat with the road. Car drives ok with them, especially at speed into bends etc. the problem is have is this eats the inside of the front tyres in about 3 months.
Any help would be appreciated, thanks.
If your Leda Struts are like mine they will have an elongated hub attachment hole (the upper one) this will allow you to adjust the Camber over a 3-4 deg range.
More importantly you need to check that it isn't something else, like too much Toe out.
I would find a decent alignment centre (any recommendations?) any let them know what you would like. I think anymore than -2 deg Camber is excessive for a road car, hence why I'll be reducing mine post Track Day fun!
While we're on the subject, check that you have the right Top Mount/Strut combo i.e. Phase 1/Phase 1 or Phase 2/Phase 2, don't mix them.
B18ftMOJO5
08-12-2013, 11:43
probably sound stupid but here goes lol, the bit the top of the strut sits into, the speherical top mount, can I open that up and move the top bit round to affect camber or can it only be done from the top nut that you suggested???
Woznaldo
09-12-2013, 00:30
Adjustable Top Mounts allow you to do just that. Some have re-drilled the Standard Top mount attachment holes in the strut tower, but that shouldn't really be needed in a standard type set up.
B18ftMOJO5
09-12-2013, 00:48
thanks then that's what I need to do mate. the top mount has holes for the two mounting bolts to, they extend all the way round the top mount.
at the minute the top of both struts sits facing in towards the engine, I will have a play and move them to the opps side and see if that's any better thanks Woz.:agree:
Woznaldo
09-12-2013, 06:17
Sounds like you have the eccentric adjustable style Top Mounts like those used by 'Compbrake'. Can you take a picture of them and post it so we can give you better advice?
Woz
B18ftMOJO5
09-12-2013, 12:01
They look almost exactly like this
http://item.mobileweb.ebay.co.uk/viewitem?sbk=1&nav=SEARCH&itemId=271337885674
B18ftMOJO5
09-12-2013, 12:07
http://item.mobileweb.ebay.co.uk/viewitem?sbk=1&nav=SEARCH&itemId=281204149418
These ones are exactly the same.
Woznaldo
09-12-2013, 18:30
Then yes, you'll just be able to spin them round to remove some of the negative camber.
Woznaldo
26-12-2013, 02:42
During the Caster Mod I replaced the attachment hardware with high tensile Cap Screws and Nyloc Nuts. A few days ago while driving the car I noticed that steering was sloppy and a lot of torque steer was present under acceleration.
I pulled the wheels off today to take a look and noticed that the new hardware was a little loose. It's only because of the Nyloc Nuts that things hadn't got a lot worse.
I've given everything the once over and then tightened everything up again and all seems to be well again after a test drive.
The Cap Screws I used were M8 x 1.5, but I'm just wondering if a finer pitch thread may have been better for this application? Not sure if they're available, but I might try a M8 x 1.25 or M8 x 1.0?
I'll drive the as is for the time being and see how long before they get loose again, if at all.
The Cap Screws I used were M8 x 1.5, but I'm just wondering if a finer pitch thread may have been better for this application? Not sure if they're available, but I might try a M8 x 1.25 or M8 x 1.0?
Are you sure? M8x1.25 is standard pitch. You can get m8x1 as a metric fine thread.
Woznaldo
26-12-2013, 10:30
Ashy, I'm not sure TBH. I'm just a little concerned that the Cap Screws came loose the first time. I've been out out for a spirited drive and the Ball Joints are holding firm for the time being.
That said, I didn't launch off the line or brake massively heavily.
I've just had a quick google for metric threads and you are right Ashy. The M8 thread comes in
1.25 (coarse) of 1.0 and 0.75 (fine). With the course thread there is more grip strength, but with the finer threads there is less axial movement per nut rotation so won't get as loose as quick as a course thread.
Woznaldo
30-12-2013, 02:39
I've been doing a bit of a search for an appropriate thread to continue a suspension discussion, but this one is as good as any. I generally very happy with the new Caster Mods, but I am looking for more.
I'm happy with my Leda Struts now that I've rebuilt them (the fronts), but I've got into a discussion on the OzRenaultSport about what the effects on geometry are when lowering a car. In this discussion there was a link to a similar discussion on ClioSport.
Detailing aside :cooter:, there a few guys on ClioSport that have a decent amount of knowledge, be it through education or experience, that is both interesting and useful.
So the basic gist of the discussions is centred (pun intended) on Roll Centres (RC). When lowering a car a lot (and we'll stick to MacPherson Struts as it's applicable to us, but the theory is similar on other suspension systems), the lower Wishbone sits at an angle (outboard higher than inboard) that lowers the RC below the road surface.
That might initially sound good, but the vehicles Centre of Gravity (CoG) is statically fixed and lets say it's roughly at a height of the top of the wheel arch extensions. So by moving the RC down, we are increasing the distance between the RC and the CoG. If we think of this distance as a lever, it has now become longer and when the car enters a corner the CoG is being forced to the outside of the corner horizontally. This means the car will roll more as the CoG pivots around the roll centre with a longer moment arm. Effectively achieving the opposite of what we want.
So we need to correct this by moving the RC up to reduce the RC/CoG Moment Arm. How this is achieved is by placing a spacer between the hub and the lower ball joint. You will also need to do the same with Track Rod end to restore the steering geometry too.
The result will make the car feel better to drive and car will respond quicker to steering inputs as the geometry is working more effectively.
Here's the link to ClioSport discussion: http://www.cliosport.net/forum/showthread.php?676358-Suspension-guru-s-needed-stanced-boys-need-not-apply&highlight=roll+centres
Here's some pictures of a Group Buy for some RC and Bump Steer Correction Kit that resulted. Expensive, but looks like very good quality.
http://i196.photobucket.com/albums/aa40/woznaldo/Suspension%20Systems/Clio2RollCentreCorrectionKit2_zps2a95ec35.jpg
http://i196.photobucket.com/albums/aa40/woznaldo/Suspension%20Systems/Clio2RollCentreCorrectionKit1_zps80113f0d.jpg
http://i196.photobucket.com/albums/aa40/woznaldo/Suspension%20Systems/Clio2RollCentreCorrectionKit3_zpse6895d06.jpg
Woznaldo
30-12-2013, 04:58
Here's what the Peugeot fellas did:
http://www.306gti6.com/forum/showthread.php?id=146338
Wowsers, that Clio kit looks very good quality.
Andrew Cooke
30-12-2013, 09:43
That's all similar to what I did on my 5 when I widened the track. Caster mods were from the beginning. You'll notice that I don't run much camber...
Woznaldo
30-12-2013, 13:03
The ClioSport group buy is asking for GBP625 and it includes all parts and some minor machining to the hub. I'm not sure what machining is involved, but it cant be to far off what was required for the Peugeot parts.
I understand that the CS crew have invested a bit of their own cash to get this up and running, but they are being very guarded about material specs?
That said the Peugeot crew are using EN24T and I'd guess the same or similar is being used by CS. Maybe a 4340 steel?
Andy, you've always been ahead of the game in this department, so your input on materials would be great.
EDIT: EN24T is the British Standard, 4340 is the American Standard. They are the same steel. I think I need to step way from the keyboard!....
Woznaldo
25-03-2014, 10:42
That's all similar to what I did on my 5 when I widened the track. Caster mods were from the beginning. You'll notice that I don't run much camber...
Andy, I found your project thread when looking for some Widetrack info and noticed the Roll Centre correction you were rocking in 2008!
http://www.rtoc.org/boards/showthread.php?t=941&highlight=suspension+geometry
I do like the Cliosport Kit, but it's a tad expensive. Did you machine something similar for your track rod ends or was it not required due to using the Laguna hubs?
Matt Cole
22-07-2018, 10:52
Just reviving this as suspension geometry is next on my list. Every time I adjust something on the suspension (take a ball joint off etc) I have to redo the tracking, which I guess is standard cause! My heavier engine upfront highlights any issues with the geometry so I now need to get it handling the best I can. 😁
Woznaldo
30-08-2018, 11:54
Matt, I’ve gone back to school since this started (Uni) and joined the resident FSAE team. My understanding of vehicle dynamics has increased ten fold, but still has a way to go. All the above comments still hold true, but it’s really
All about what tyres you run. Even tyres of the same brand and compound can behave VERY differently in a slightly different size.
Too much digging in this area is worthless without data, so we’ll leave it at that.
Matt Cole
30-08-2018, 19:35
I've reset tracking (pretty much zero toe) and reduced tyre pressures to something sensible 33psi and it has made a big difference! I could probably run the coil overs on max setting as the 45 series tyres seem to have quite a soft side wall. Tyres are Yokohama S drive. 195/45/16's.
Matt Cole
01-08-2019, 07:52
From driving the car a lot now my main is could be bump steer. The steering snatches dependant on what's happening with the road surface.
Now I don't thing my car is excessively lowered although because I use a bigger wheel and tyre, the angle of the steering/wishbone might still be way off from being optimum.
It's where to start really without heavy investment? :crap:
Woznaldo
13-10-2019, 02:02
Matt, you can measure the bump steer with a bit of work. It involves taking the spring off the struts and using a jack to change the wheel height. Setup a laser pointer on the wheel so it’s parallel with the face and then have the laser pointing at a wall in the distance.
Matt Cole
13-10-2019, 19:20
Cheers Woz. Since that post I'm down to 26psi on the tyre pressures. It's much better. The bump steer still might be an issue, or at least a characteristic of the 5? Anyway, my ride height pretty much has the steering arms level, or at least by eye.
I'm in two minds if I should swap out my avo coilovers for something like Gaz units, but firstly, I need to recheck my spring rates. Currently are 400lb coils. Car rides the bumps well but is maybe under damped/oversprung.
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