Anti-roll bar setting
Discussion
Hi,
My car's actually off the road for a couple of weeks awaiting some rust proofing, but I thought I'd look ahead and enquire about ARB settings. What would you suggest running for road use (the car is an ex-race 2001 Roadsport A currently converted back to Caterham road-rate springs)?
At the moment its CR500s are proving extremely exciting in the wet. It's quite neutral and reasonably predictable, so the balance appears to be about right, but the grip is comical in the wet (and probably the dry too, this time of year). I can't actually remember what ARB settings it's running at the moment, or even if there's one present on both ends, but what do people think they should be?
Chris
My car's actually off the road for a couple of weeks awaiting some rust proofing, but I thought I'd look ahead and enquire about ARB settings. What would you suggest running for road use (the car is an ex-race 2001 Roadsport A currently converted back to Caterham road-rate springs)?
At the moment its CR500s are proving extremely exciting in the wet. It's quite neutral and reasonably predictable, so the balance appears to be about right, but the grip is comical in the wet (and probably the dry too, this time of year). I can't actually remember what ARB settings it's running at the moment, or even if there's one present on both ends, but what do people think they should be?
Chris
If the car's neutral, and the balance seems right, why do you want to change it? 
If you disconnect the rear stabilizer bar, you'll induce understeer.
CR500's need to warm up, even over here in Mallorca, my R300 would light up the rears on a dry road when they where cold.
When it's wet, or the tires are cold, moderate your right foot a little.
If you disconnect the rear stabilizer bar, you'll induce understeer.
CR500's need to warm up, even over here in Mallorca, my R300 would light up the rears on a dry road when they where cold.
When it's wet, or the tires are cold, moderate your right foot a little.
The grip seems comically low. The tyres might just be a bit old (they were stored in Northern Scotland for half a decade in a - presumably unheated - shed, dunno what that does to the rubber?) It handles just like you'd expect a well setup Caterham to do on ice! Even after a bit of a warm up it'll spin the wheels at 70mph (in the wet), which seems a bit over the top for 140bhp. Trust me I've tried my best to warm them up! On the whole I quite like the fact you can execute massive powerslides at 15mph round mini roundabouts, but it'd be dangerously slow round a busy track I suspect. I'd like to think it's not just my hamfisted driving - on light or trailing throttle it'll go into (initially mild) understeer at equally low speeds and, conversely, in the dry it seems to be pretty rapid.
Not sure what the problem is, but I mentioned it to a friend who's played with Sevens in the past and he asked about the ARBs. They may well be fine, but I don't have anything to gauge them, barring trial and error, so I thought I'd see what the consensus is.
Hi Fergus - haven't tried disconnecting the rear and corner weights sound like a good idea. Won't have a chance to do anything until into next month, but I'll come and harass you at some point! By the way, December's out now and very good it is too - will see what I can arrange.
Not sure what the problem is, but I mentioned it to a friend who's played with Sevens in the past and he asked about the ARBs. They may well be fine, but I don't have anything to gauge them, barring trial and error, so I thought I'd see what the consensus is.
Hi Fergus - haven't tried disconnecting the rear and corner weights sound like a good idea. Won't have a chance to do anything until into next month, but I'll come and harass you at some point! By the way, December's out now and very good it is too - will see what I can arrange.
allen l said:
Change your tires first before you try anything. That's like safe sex with a 12 year old condom... 
I suspect therein lies the answer. I'm too stingy to change them until they look vaguely worn though, so maybe I'll get a few car control days booked in over the winter to finish them off.
BTW I meant to stop by the garage this morning and check the ARBs, but forgot again. Will have a look and report back.
Chris, I changed the tires immediately for new ones after I bought my car. Avon ZV3. Scared the hell out of me on my way to my first trackday in Belgium. Lost the rear twice on a damp motorway when I was cruising around at 50-60 mph. I soon changed for 021-r tyres of which I can happily report I'm not afraid to toy around with the car in the wet. The only downside is that they wear quite fast. As they are only 75 pounds per corner it's not too bad though.
Try to look for the dot code on your sidewall. You should be able to see the year and week of production. If the tyres are over 4 years, I'd change them, even if they still look good. You'd better be spending 300 pounds on tyres then 10k for a new Caterham.
PS, if your car has been setup really stiff and it doesn't roll at all in corners, than that could be part of your problem in the wet.
Try to look for the dot code on your sidewall. You should be able to see the year and week of production. If the tyres are over 4 years, I'd change them, even if they still look good. You'd better be spending 300 pounds on tyres then 10k for a new Caterham.
PS, if your car has been setup really stiff and it doesn't roll at all in corners, than that could be part of your problem in the wet.
Finally got down to the garage and the front ARB bushes are yellow-ish, a bit hard to tell if they're a mucky yellow or a faded orange, but I'd say yellow (there's also a spare front ARB which is red, both have the markings DMc).
On the rear the ARB is connected to the second hole from the front.
Just to reiterate the springs/dampers are the softer (factory supplied, fixed-rate) road spec units, not the firmer fixed-rate RSA racing ones any more.
On the rear the ARB is connected to the second hole from the front.
Just to reiterate the springs/dampers are the softer (factory supplied, fixed-rate) road spec units, not the firmer fixed-rate RSA racing ones any more.
Red Seven said:
Yellow bushed ARB is 3/4" and VERY stiff.
Orange is 1/2" and quite soft.
I'd fit the red front ARB, and disconnect the rear ARB.
Thanks. That makes sense - when I was trying to improve the ride (back when it had the original race suspension on) it felt particularly stiff on the front end. It's not so obvious now there are some more suitable springs and dampers on there, but that still makes sense. And although it's quite neutral and comes smartly back into line it did seem to let go a bit faster than the other Sevens I've driven on a track, which again suggests its a little stiff.Orange is 1/2" and quite soft.
I'd fit the red front ARB, and disconnect the rear ARB.
Lastly - numpty question - what's the best way to swap the front and disconnect the back? Are they genuinely unloaded when the car's off the ground or do you need to jack the suspension or something?
ETA: Couldn't find my inspection lamp and the lighting was horrendous in the garage last night so I ended up using the flash on my camera phone to try and identify the ARB bushes, which wasn't great, hence the confusion on the colour. Just noticed the photo and it is indeed very yellow...
Edited by Chris71 on Wednesday 16th December 10:40
Chris71 said:
Red Seven said:
Yellow bushed ARB is 3/4" and VERY stiff.
Orange is 1/2" and quite soft.
I'd fit the red front ARB, and disconnect the rear ARB.
Thanks. That makes sense - when I was trying to improve the ride (back when it had the original race suspension on) it felt particularly stiff on the front end. Orange is 1/2" and quite soft.
I'd fit the red front ARB, and disconnect the rear ARB.
Lastly - numpty question - what's the best way to swap the front and disconnect the back? Are they genuinely unloaded when the car's off the ground or do you need to jack the suspension or something?
Disconnecting the back is a case of getting under the back of the car and using a thin walled 12mm open ended spanner on the 'ball joint' end of the drop link connected to the ARB, and a 13mm spanner on the (probably) nyloc nut attaching it to the ARB. Get it loosely zip ties out of the way. For the front, as long as the car is on level ground, i.e. has no roll, the front ARB should not be preloaded and you can just remove the nose cone and undo the 4 bolts which hold the nylon mounts. However, as the ends of the ARB on the caterham are not parallel, but taper out at about 30 degrees and have ball ends fitted to each end, you'll need to exert a little force to 'pop' the ball out of the socket. (It's not so much a socket, more a captive bore for the ball to locate in.
Give me a bell if you need any help. 15 min job max!
Red Seven said:
Yellow bushed ARB is 3/4" and VERY stiff.
Orange is 1/2" and quite soft.
I'd fit the red front ARB, and disconnect the rear ARB.
I don't think the yellow bar was available in widetrack, and I'm buggered if I know why you'd ever want one. Most likely orange, which is 1/2" in widetrack form, and the softest available. Orange is 1/2" and quite soft.
I'd fit the red front ARB, and disconnect the rear ARB.
The rear's fairly stiff though, but if it's nuetral handling as is, I'd be wary of disconnecting it and inducing roll-oversteer/power-on understeer.
sfaulds said:
fergus said:
Disconnecting the back is a case of getting under the back of the car and using a thin walled 12mm open ended spanner on the 'ball joint'
If we're going to be pedantic today, it's 7/16" or 11mm.
Failing that you could use a 4-500 micron digital nail terminal release the retaining clip on either end and pop the ball joint off, repeat the procedure on the other end using the same 4-500 micron digital nail terminal and remove the whole drop link from one side. The ARB now doesnt serve its purpose so you can, after crawling around underneath the car, wait for the clouds to miraculously part and the sun to come out.
Just about managed to squash the rubber washer aside and get a regular 12mm spanner onto the flats on the ball joint for the rear ARB. The two ends of the front popped out surprisingly easily once the clamps were removed.
Even though I'm not strictly supposed to at the moment, I couldn't quite resist the urge to take it out for a quick blat. It hasn't been out since October (maybe early November at a pinch) and to my surprise it started first time. Despite running no anti-roll bars at all the car still wasn't exactly wallowy - the extra roll was noticeable, but not excessive for a wet road.
It was the most fun I've had in the car I reckon. Removing the ARBs has made it more progressive and I found myself going round the local roundabout more times than was strictly necessary. After nearly three months and the onset of the slimey winter road conditions it's hard to tell how much the grip has changed, but there's no doubt it's improved.
So much fun though. I'd forgotten what I was missing.
Even though I'm not strictly supposed to at the moment, I couldn't quite resist the urge to take it out for a quick blat. It hasn't been out since October (maybe early November at a pinch) and to my surprise it started first time. Despite running no anti-roll bars at all the car still wasn't exactly wallowy - the extra roll was noticeable, but not excessive for a wet road.
It was the most fun I've had in the car I reckon. Removing the ARBs has made it more progressive and I found myself going round the local roundabout more times than was strictly necessary. After nearly three months and the onset of the slimey winter road conditions it's hard to tell how much the grip has changed, but there's no doubt it's improved.
So much fun though. I'd forgotten what I was missing.
Chris71 said:
Despite running no anti-roll bars at all the car still wasn't exactly wallowy - the extra roll was noticeable, but not excessive for a wet road.
Chris, It should not be a suprise that the car wasn't "wallowy".
"wallowing" is when the springs are oscilating because of inadquate damping. ARB's, are, in effect, additional springs, that, ideally, require additional damping to control them.
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