Chim/Griff rear anti-roll bar...er, what's it s'posed to do?
Discussion
Apart from rattle and clang that is? The flimsy drop-link mounting plates welded to the top of the lower wishbones on mine have finally sheared so I have just removed all the ARB gubbins and can't detect any deterioration in handling. Actually feels way nicer and certainly sounds it... should I worry about reinstalling? Is it likely to cause problems come MOT time?
Is that possible?Pupp... The rear anti roll bar does exactly what it says... It helps the rear suspension to deal with body roll.... For example. If hard cornering on a left hander, the n/s rear wheel will try and lift and the body weight will transfer to the o/s therefore making the o/s tyre work very hard. With the anti roll bar in place it helps to keep the car more flat. At this time of year you really do need it. Our cars dont need any help sliding and removing it will cause less trouble at lower speed but at higher speeds it could lead to a terminal c++k up.!!! Lets all make it to the spring ehh?? !!!......... Steve.
If you have uprated and adjustable suspension (springs and shocks), then the rear ARB is pretty much useless in standard form. The uprated suspension will start to control body roll much earlier than the rear ARB. If however you fit Steve's rose jointed drop links and plastic bushes the ARB will start to do what it was designed for.
I removed mine about 2 years ago and noticed I had more grip in the corners but the back end would go much more abruptly, the upside being that it seams to have more feel in the corner so I can tell where the limits are much more easily.
The rear ARB was designed to work with TVRs rather soft suspension setup, if you still have this then I would replace it, if not then unless you up rate the ARB setup its pretty much redundant. IMHO
I removed mine about 2 years ago and noticed I had more grip in the corners but the back end would go much more abruptly, the upside being that it seams to have more feel in the corner so I can tell where the limits are much more easily.
The rear ARB was designed to work with TVRs rather soft suspension setup, if you still have this then I would replace it, if not then unless you up rate the ARB setup its pretty much redundant. IMHO
Of course what most peple don't realise is that the tvr arb is designed to do minimal work at small roll angles anyway .. the way the arb is fitted and it's bushing arrangement means that the drop links are *supposed* to squidge a significant distance before the arb effect comes into play. The rubber bush and threaded rod clamp through the wishbone mount provides a small degree of adjustment to the rear arb, however my preffered route on my upgrade suspension kits is to dispense with the rear arb, however on the tvr set-up it's designed to work with it in place, but as a progressive-with-roll set-up as neill anderson intended.
The amount of force that the bar applies is dependent on the amount of movement and at very low roll is isn't that much anyway. All the squidgyness of the rubber does is make the whole thing a bit of a lottery in that the arb force transfer is not consistant and changes over time. In addition, when the rubber has squished the car is already starting to roll quite appreciably and the amount of force effectively applied is smaller than that available because part of it is taken in deforming the rubber. End result is an arb that is inconsistent on how it applies any roll countering force and also applies it in dollops depending on what state the rubber is in. Not exactly a great recipe for consistent use.
The rubber bush is there primarily to help stop the bolt from ripping out the mounting plate because there is no articulation. I suppose it could be used to adjust the forces by adjusting the amount of squish but the overall effect is very small.
The drop links work better because the ARB force is consistently applied. As the roll starts, the arb starts to apply counteracting force which increases if the roll continues. The ARB forces are progressive anyway - the more the roll the bigger the force - so why make things more difficult by having a squidgy bit of rubber in there?
The rubber bush is there primarily to help stop the bolt from ripping out the mounting plate because there is no articulation. I suppose it could be used to adjust the forces by adjusting the amount of squish but the overall effect is very small.
The drop links work better because the ARB force is consistently applied. As the roll starts, the arb starts to apply counteracting force which increases if the roll continues. The ARB forces are progressive anyway - the more the roll the bigger the force - so why make things more difficult by having a squidgy bit of rubber in there?
I've no doubt that Neill is great at what he does, but I doubt that even he would claim that the standard suspension is right for all car / driver combinations, especially when all the bits are five years old. Having backlash and squidgy rubber in the ARB is fundamentally a bad idea. The ARB doesn't act like a proper ARB it is more like a very soft roll stop, the effective roll stiffness varies substantially with the roll angle. The result is a car with handling characteristics which change as the vehicle rolls into a corner, for example understeer during turn-in followed by oversteer at the apex.
Whether you want an ARB at all is a separate issue, but if you're going to use an ARB it is far better imo to have one which is rigidly connected to the suspension and which has a constant rate.
Whether you want an ARB at all is a separate issue, but if you're going to use an ARB it is far better imo to have one which is rigidly connected to the suspension and which has a constant rate.
greenv8s said:
I've no doubt that Neill is great at what he does, but I doubt that even he would claim that the standard suspension is right for all car / driver combinations, especially when all the bits are five years old. Having backlash and squidgy rubber in the ARB is fundamentally a bad idea. The ARB doesn't act like a proper ARB it is more like a very soft roll stop, the effective roll stiffness varies substantially with the roll angle. The result is a car with handling characteristics which change as the vehicle rolls into a corner, for example understeer during turn-in followed by oversteer at the apex.
Whether you want an ARB at all is a separate issue, but if you're going to use an ARB it is far better imo to have one which is rigidly connected to the suspension and which has a constant rate.
Indeed, the only problem i have is that in the std TVR the rear bar is designed to do little work, it really is a just a handling trimmer.
On the front the arb does much more work and is relatively solidly located with drop links which if in good condition will control roll as intended.
If you then put rose jointed drop links front and rear you're changing the fundamental roll control bias of the car towards the rear, you'll have more load transfer onto the outer rear wheel than on the OE set-up, less load sharing and lower rear grip levels on a like for like basis.
I agree that if things are tired then going rose jointed is a great idea, but I'd also like to see that the roll control is in a similar proportion front to rear as on the std car, if that car is still on std suspension in good working order.
For sure the std suspension isn't all things to all men (and women) .. but I think it's fair to say it's a fair compromise for most drivers given it's non-adjust status.
Go to www.scaredstiff.com Speak to Steve Guglielmi twice winner of the Tuscan Challenge and ask his opinion on the subject.Amongst other things he removed the anti roll bar from my chim and transformed the handling characteristics of the car
Bet he didn't just disconnect it without doing anything else though.
If the shocks and springs can be played with to compensate and provide better roll control then there is a case for removing it. However talk to 5 different racers and you'll get 10 different opinions. Some disconnect the arb in the wet but increase it in the dry. Some run with no ARB front or rear some do. It all depends on how you want the car to handle and making sure that it complements your driving style. The rear ARB is just one way of tuning the suspension. Having it or not gives a different set of parameters to play with.
What does happen is that removing the rear antiroll bar is usually associated with other mods to help control the roll. I have competed with and without rear ARBs and currently run without one. Before you say "told you so" I also had to redesign the rear suspension and change the springs/shock specs to stop the rear roll that the ARB was doing a good job of preventing. Simply disconnecting it meant that the rear rolled so bad it was untrue. With that roll, the tyre camber went to pot and the contact patch reduced. This also reduces grip so there are a lot of factors involved when looking at suspension. Adding the rear ARB took about 2 s off my time because it stopped the roll, controlled the camber change and increased the tyre patch. Better grip through the corners. Removing it and replacing the shocks/springs gave me another 0.5s on top though. However the ride was a lot harsher as the shocks and springs were stiffer to help the roll control. You get nothing for free but it was a good trade off for me.
I'm not agin dropping the rear ARB but it is part of the suspension design. Do the calc and you can see the level of force that it provides. What I don't like about the Griff/Chimaera implementation is the random nature of its effect. I want something that is consistent. In some cases, the rear drop links are so bad that actually disconnecting the arb will make the handling more consistent because it is not randomly introducing correction.
If the shocks and springs can be played with to compensate and provide better roll control then there is a case for removing it. However talk to 5 different racers and you'll get 10 different opinions. Some disconnect the arb in the wet but increase it in the dry. Some run with no ARB front or rear some do. It all depends on how you want the car to handle and making sure that it complements your driving style. The rear ARB is just one way of tuning the suspension. Having it or not gives a different set of parameters to play with.
What does happen is that removing the rear antiroll bar is usually associated with other mods to help control the roll. I have competed with and without rear ARBs and currently run without one. Before you say "told you so" I also had to redesign the rear suspension and change the springs/shock specs to stop the rear roll that the ARB was doing a good job of preventing. Simply disconnecting it meant that the rear rolled so bad it was untrue. With that roll, the tyre camber went to pot and the contact patch reduced. This also reduces grip so there are a lot of factors involved when looking at suspension. Adding the rear ARB took about 2 s off my time because it stopped the roll, controlled the camber change and increased the tyre patch. Better grip through the corners. Removing it and replacing the shocks/springs gave me another 0.5s on top though. However the ride was a lot harsher as the shocks and springs were stiffer to help the roll control. You get nothing for free but it was a good trade off for me.
I'm not agin dropping the rear ARB but it is part of the suspension design. Do the calc and you can see the level of force that it provides. What I don't like about the Griff/Chimaera implementation is the random nature of its effect. I want something that is consistent. In some cases, the rear drop links are so bad that actually disconnecting the arb will make the handling more consistent because it is not randomly introducing correction.
well yeh it does seem to be the case. All i can offer is my own experience, which is on any suspension upgrade one of the first things we do is lower the rear compression rate of the suspension .. in effect we run close to the spring rate of the full-length progressive spring, and reduce the compression damping (in particular the mid to high speed compression of the damping which is very high on TVR to prevent grounding in quick road compressions) of the rear dampers, this makes the rear of the car *very* grippy.
I can't for the life of me see why anyone would have the relatively high compression rear damping on the std TVR and *add* more roll stiffness. As is said, it's personal preference but it looks like a recipe for very slow lap times and lots of rear-slidies from the experience I have ..
On the front however : different story .. winding that front end stiffness up brings lots of benefits.
Errr the Wedge is not standard... doesn't run TVR spec springs or shocks. Design was simulated to identify and address the particular handling problems I was having. Increasing the spring/shock combination offered a good solution and addressed most of the problems.
It now goes through corners a lot flatter and faster. Is it a solution for a road car? No but that's part of the tradeoff.
My Griiff is standard except for the droplinks and it's fine. The Cerbera will be tweaked a little in readiness just in case I supercharge it....
It now goes through corners a lot flatter and faster. Is it a solution for a road car? No but that's part of the tradeoff.
My Griiff is standard except for the droplinks and it's fine. The Cerbera will be tweaked a little in readiness just in case I supercharge it....
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