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Post by Zed. on Sept 8, 2019 12:46:43 GMT
interesting view of front anti-roll bar mounts flexing  I'd seen 'heavy-duty' or strengthened mounts advertised but sorta considered them as one of those 'fix-it-when-it-fails' parts  so, can you use the mount as a part of the suspension or do you expect the ARB to do all the work & any flex in the mount to be unwanted? I'm lazy so am leaving the mount as mazda designed (it's a mk1 so there is chassis above it  ) although it's easy to add a strenghtener or two.. edit, one of the available strengthener kits in action Rich. |
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Post by niklas on Sept 8, 2019 14:06:38 GMT
I use the things in the second video. Can't say I notice the difference. However, there is a lot of breaking arb mounts on track cars around here. My mounts are still intact.
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Post by howardb66 on Sept 9, 2019 12:08:08 GMT
No point in fitting updated ARBs if the mounts aren’t beefed up it seems. TBH the ARB is trying to do the job of a higher spring/damper rate.
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Post by Zed. on Sept 9, 2019 13:58:31 GMT
No point in fitting updated ARBs if the mounts aren’t beefed up it seems. TBH the ARB is trying to do the job of a higher spring/damper rate. +1 making a stronger mount is easy, a piece of 'box' section steel & some mount tags & also cheap  another thought, if you lower the car, shouldn't the front arb's mount be raised to keep the bar's static position level / horizontal? as it's end travels in an arc so will constantly be pulling the links foreward (ok with RJ's but will eat rubber?) I prefer softer / thinner arb's & have removed them on some rallycars (mk2 escort, Chrysler Sunbeam / Avengers & Vauxhall Chevettes) as it allows them to lean more & keep wheels on the ground - maybe I'm odd I've also been thinking of removing the rear arb & just running the standard front but I prefer to drive not slide so.... Rich. |
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Post by howardb66 on Sept 9, 2019 15:38:27 GMT
Most of the competitors in the TVR Speed Championships remove the rear ARBs, mind you, the TVR chassis twists badly under high load anyway.
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Post by thruxton on Sept 9, 2019 15:40:12 GMT
The front antiroll bar becomes an issue far more so on a vehicle that uses McPherson style suspension.
It's to do with lowering the "roll centre".
On our MX-5's we do have quite a margin of latitude that for most here is acceptable and leaving the ARB as is is fine.
A far greater "threat" is the steering arm attitude to the road surface.
Loaded and static it neither wants to point up or down.
If we take an extreame example, the arms are pointing up at a large angle say 20 degrees above the horizontal then bump steer will make the car undrivable.
Enter the TVR range of cars, ho ho ho.
As for the anti roll bar and it's "strenght" well what does an antiroll bar set out to do?
It physically joins the N/S and O/S wheels/suspension together.
It is required to arrest horrendous steering and suspension actions.
However, if the ARB is too strong/stiff it will induce lift at the unloaded end. You can not go around corners faster on 3 wheels than you can on 4.
So this is not a good thing.
When having fitted coil over springs and dampers it is most times, if the fitted units are correctly designed, not at all required to change the ARB from standard.
An ARB change would only be required in the most extreame track focused situation.
This is of course a very simplistic overview of the front end situation.
I have studied and designed many applications for various cars during the last 40 years.
Regards.
Rich.
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Post by Zed. on Sept 9, 2019 17:22:59 GMT
The front antiroll bar becomes an issue far more so on a vehicle that uses McPherson style suspension. It's to do with lowering the "roll centre". As for the anti roll bar and it's "strenght" well what does an antiroll bar set out to do? I understand a little about suspension design & setup although I also admit theat a 'little knowledge is dangerous' basic McPherson systems that use an arb as a 'link' can be seriously altered when moving mount-points but those as compression or tension-struts are less affected... my comment re. the arb (on a 5) being horizontal was aimed at a lowered car and refering to clearance during the suspension's travel - if it's already inclined then it has less possible upward travel before maybe interacting with the chassis or even a wheel / tyre on compression? possibly overthinking things here (also, shorter / adjustable arb links can be used to alter this?) as to bump-steer. the add-on rack risers that are available, as the rack mounts are angled so adding raising spacers also moves the rack foreward an ammount, I know the distance is minimal but what does this do the the steering-arm's (track-rod) travel especially at full lock? maybe reduce the hub's turn slightly although this is probably not noticable  ^^ probably talking Sh it Rich. |
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Post by thruxton on Sept 9, 2019 20:07:58 GMT
Hello there.
Ok. Now this is NOT MX-5, as we do NOT have MacPherson struts on the MK1 2 and 3.
Trying to keep things easy here......
As you lower your suspension with MacPherson struts the lower control arms will eventually start to point upwards at the wheel point, that is in relation to the ground level. What this does in reality is drop the roll centre below ground level. This is the calculated roll centre.
Well designed MacPherson strut design has the roll centre at just above ground level. This is what designers go for.
With the roll centre below ground height more weight is transferred via the springs, likewise raising the roll centre reduces weight transfer through the springs and increases weight transfer through sprung mass.
This makes body roll more pronounced and in turn increases the leverage against the lower roll centre, making the instantaneous centre move well outside the vehicle causing even more weight transfer and roll. Eventually the car will transition onto the outside front wheel. The tyres limits of grip have now been exceeded, no more weight transfer can occur. Here comes the kerb!
So what about our cars?
Well. We have a more forgiving suspension system. It's very hard to unbalance our double wishbone suspension.
However moving a steering rack forward in isolation.
Hmmm, now we are into Ackerman angles.
It really is a very hard thing to write and explain easily. Moving a rack forward will mean ... slow steering.
The bottom line is this.
The MX-5 range of cars is very well thought out and there is not a great deal of improvement to be had in the suspension unless we are track, or very, very fast road use focused.
This then usually, not always, upsets other parameters that are desirable. Ride comfort for instance. Or getting a jack under the car.
I would suggest that MeisterR units and standard ARB are optimum for 90% of us track day heroes.
I do not work for MeisterR
Regards.
Rich.
Sent from my iPad
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jimb
New Here
Posts: 27 
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Post by jimb on Sept 10, 2019 7:26:40 GMT
If you are running stiffer springs and dampers, a car should roll less, and hence twist the anti-roll bar less. Therefore with a standard anti roll bar, you will be putting less force into the bracketry. (assuming everything else is equal - this includes assuming that if you're running sticky tyres, you do have stiffer springs etc so roll is still less than a std car on road tyres)
Using a stiffer roll bar will of course increase the load going into the brackets, so at some stage you will be getting diminishing returns from the stiffer bar, if the bracket is flexing.
Also, the upper wishbone bolt is removed through this gap, so anything added needs to be removable. |
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) although it's easy to add a strenghtener or two..
le sigh