anti roll bar

[higgins]

I am thinking of upgrading my standard anti-roll bar from 5/8" to 7/8". According to my parts manual, "this will increase the handling of the car significantly".

As I want to understand more about how things work, I have the following questions?

1) what is the purpose of the anti-roll bar?
2) how does the strength and size of the anti-roll bar
improve the handling?
3) Besides needing different brackets, are any specific
adjustments needed to have the optimal settings/trim?

While awaiting your responses, I think I'll have a /ubbthreads/images/graemlins/thirsty.gif or two.

regards----Higgins

 

[JamesWilson]

[ QUOTE ]
1) what is the purpose of the anti-roll bar?
2) how does the strength and size of the anti-roll bar
improve the handling?


[/ QUOTE ]

Some answers to these general questions can be found at:

https://www.advanceautoparts.com/english/youcan/html/dsm/dsm20021001hs.html

[ QUOTE ]
3) Besides needing different brackets, are any specific adjustments needed to have the optimal settings/trim?


[/ QUOTE ]

is much more challenging. Chris Dimmock in a series of exchanges on the Healey list provides some useful comments- and you might look at what the others in that thread also had to say:

https://www.team.net/html_arc/healeys/200310/msg00764.html

getting to "optimal" can be pretty interesting....

 

[piman]

Hello Higgins,

in general terms I would be surprised if a thicker anti roll bar would "increase the handling of the car significantly."

The trouble is that handling is a very subjective subject so it will be interesting to hear from someone who has one. Normally increasing your front roll stiffness creates more understeer, and if that is to your liking it may be worth while.

Alec

 

[bighly]

It keeps the car slightly flatter in tight turns on mine. No "significant" change just slightly less body roll. No noticable increase in understeer. On a street car I would not recommend going up more than the one size. When you do uprate give your original bar to a 100 owner as it is an uprate for them. Trivia, the original stock size rubber bush is the same as an MGB stock bush.

 

[JamesWilson]

[ QUOTE ]
...in general terms I would be surprised if a thicker anti roll bar would "increase the handling of the car significantly."

The trouble is that handling is a very subjective subject so it will be interesting to hear from someone who has one. Normally increasing your front roll stiffness creates more understeer, and if that is to your liking it may be worth while.

[/ QUOTE ]

Please see Dimmock's posting I cited, he says:

[ QUOTE ]
And thats why a bigger (7/8in) front rollbar - on its own - will 'improve' a road going standard suspension Healey - because it removes some of the body roll on cornering - but doesn't affect the ride - and actually gets the car 'closer' to the ballpark (but still in the next suburb).

[/ QUOTE ]

There are a number of factors- spring rates, ride heights, camber, etc. that may be tinkered with in looking to make handling improvements. The anti-sway bar is probably the easiest and seems to offer the greatest benefit for the cost and effort involved. But my car is still in bits, with all my hypothesized improvements yet to prove themselves ... and others may offer their own experiences....

 

[zblu]

I had the 1/2"? original in, and went to the 3/4"? whilst doing the car up, the brackets fit the original holes in the chassis, so maybe the rubber bush is slightly thinner

 

[piman]

Hello James,

the one word in the original claim for the thicker bar was 'significantly' and I still do not believe that some extra front roll stiffness wil achieve a 'significant' gain. Noticeable or useful I would not quibble with but significant is, to me, misleading.

Alec

 

[Johnny]

I can only say that when "stress" is relieved somewhere, it's generally increased somewhere else. So if you relieve stress in the front of the car it'll increase stress in the rear of the car, possibly to where the car may have a tendency to "come a round" more easily. Sometimes this is desirable, such as on a oval race track, but for general driving I believe in leaving the enginering to the professionals. Just my opinion.

 

[JamesWilson]

[ QUOTE ]
...and I still do not believe that some extra front roll stiffness wil achieve a 'significant' gain. Noticeable or useful I would not quibble with but significant is, to me, misleading.

[/ QUOTE ]

Hi Alec:

From the cited:

https://www.team.net/html_arc/healeys/200310/msg00764.html


> > I promise you, i can take turns a million times faster
> > in my BJ8 because of my rose jointed anti-roll bar.
> > Much less tire squeal, quicker turning - a tad less
> > understeer but not going fast enough to throw out the
> > back. The ride is bit tougher but I can take turns
> > now +20 mph from before without having to back off the
> > pedal.

And:

https://www.team.net/html_arc/healeys/200310/msg00840.html

"...my BJ8 with standard springs & standard suspension,
makes the car handle in tight curves significantly
better that with the stock bar.

....

I am not racing the car, so I cannot speak for pushing
the car to the edge in every turn, but indications are
that it would perform better here also.... as the car
holds even when my gut tells me that if the car had
the old set up I would have lost it."

I'll leave you and the other readers to judge whether +20 MPH is "significant"; or whether the other comments in that thread are worthy of note or not....

The are the admittedly subjective views of people who've installed them... have you evidence otherwise from people who done so?

I've done a fair search of archives considering a great variety of suspension enhancements and I do not recall any comments to the contrary, but I'm open to hearing them. After all, my car's still in bits and I'd like to put it back together in the best and most cost-effective manner....

James.

 

[Keoke]

-- /ubbthreads/images/graemlins/savewave.gif

HI piman,how about we say "expressive" gain!, you buy that??.---Keoke-- /ubbthreads/images/graemlins/grin.gif

 

[piman]

Hello James,

it's your choice as to what you believe, and yes 20mph is significant but forgive me if I reach for the salt!
Hello Keoke, expressive or poetic licence?

Alec

P.S. The cheapest handling upgrade is to put more air pressure in your tyres.

 

[JamesWilson]

[ QUOTE ]
...it's your choice as to what you believe, and yes 20mph is significant but forgive me if I reach for the salt!

[/ QUOTE ]

Yes, the 20 mph seems overstated... but I suppose we could e-mail and ask them for the details of which corner/curve it was and whether there were witnesses....

But there are several reports from different people that anti-roll bars do make a real difference to the car's performance. The second commentator's views, where the bar was the only change, for instance.

An inspection of cars in our local club showed that the ones that performed best in a slalom had uprated anti-roll bars. There were usually other modifications too, so that proof is not absolute, but there's more than enough empirical evidence to support their use. Either that, or the drivers of cars that made these modifications were more inclined to drive them like bats out of h*** than those who made no modifications.... (A real possibility, based on knowing them)

There's also Chris Dimmock's technical explanation of the contribution they make. Mr. Dimmock has contributed for several years to the Healey list and his expertise can be readily judged in those messages and on his web site.

Both theory and practical experience support the idea that these do help a Healey's performance.


What am I and the others to believe-

The several reports of people's real experience?

Chris Dimmock's technical explanation?

Or your entirely unsupported opinion, and quibbles about the subjectivity of "significant" improvement?

I can assure you that I've approached the subject with an open mind, and have considered a range of handling improvement possibilities. My considered opinion is that a moderately up-rated (7/8") anti-roll bar (along with a good set of tyres) is one of the easier and more basic improvements that may be made to a stock Healey.

Other things- like uprated springs, tubular shocks or up-rated standard ones, off-set trunnion bushings, poly bushings, Lowering kits, etc. might also improve things.

But my opinion based on a fair review of what people have reported over the past few years on the Healey list and elsewhere is that the anti-roll bar is the easiest, most cost-effective and useful one.

Putting air in the tyres works too.

I don't think I'm going to change your beliefs; nor you, mine... and that we may agree to disagree....

It would be more useful if others reading this could contribute their own assessments of whether uprated anti-roll bars made an improvement to their car's handling and whether they consider it to be worthwhile....

 

[bighly]

[ QUOTE ]
20mph is significant


[/ QUOTE ]
This was 20MPH delta or "faster"
So was that 40MPH verses 60MPH???
Was that on the ragged edge + 20 or 5MPH plus 20? /ubbthreads/images/graemlins/devilgrin.gif

 

[zblu]

Cant say that I have noticed any difference, altho I dont drive to the cars limits!

 

[Johnny]

Yes James, 20 mph faster around turns is significant, but is it really what you want? I would think that if you had a "Jule" frame installed you would need minimal "anti-roll". But consider this, the centrifugal weight of the car going through a turn exerts a certain amount of stress on the wheels (L or R depending on which direction your turning) by not allowing any of the weight of the car to be dispersed through the body that "stress" is going to be increased somewhere, probably on the wire wheel. IMHO without also adding different wheels, springs and shocks your asking for trouble. As I said thats just my opinion.

 

[Dave Russell]

[ QUOTE ]

I can assure you that I've approached the subject with an open mind, and have considered a range of handling improvement possibilities. My considered opinion is that a moderately up-rated (7/8") anti-roll bar (along with a good set of tyres) is one of the easier and more basic improvements that may be made to a stock Healey.


[/ QUOTE ]
Hi James,
I'm trying to stay out of this discussion where it appears that apples, oranges, & pears are being compared, & subjectively compared at that.

I would hardly consider the change from a 5/8 bar to a 7/8 bar moderate. Because the torsional resistance of a bar varies with the fourth power of the diameter change, the 7/8 bar is 7 times as stiff as the 5/8 bar.

From a 1/2" bar;
5/8" = 2.4 times as stiff
3/4" = 5 times as stiff
7/8" = 9.4 times as stiff
1.0" = 16 times as stiff
D

 

[JamesWilson]

Johnny:

While a Jule frame may be considerably stiffer than the stock Healey one I cannot imagine anyone using one simply to take adavantage of a heavier anti-roll bar.

As I noted when discussing the slalom the cars that were most successful had other modifications besides these bars and the overall performance was due to their working together as a package.

The initial question was very basic and asked how they worked and whether there would be any advantage in moving from 5/8 to 7/8; my reply provided a basic background and an opinion that it would. Perhaps the better answer would have been to say, yes it'll make an improvement but you'll only be able to take the full advantage of it if you also use heavier springs, off set trunnion and poly bushings, alloy wheels and uprated shocks. The question was kind of like asking how a cam works and whether a different cam would be better. I'll grant Yes, but.... is a better answer than Yes....

Again the technical aspects were well addressed in Chris Dimmock's contribution and the other contributions within that thread, that I directed people to read. Suspensions are complex systems and changing one element may or may not be beneficial; and its full exploitation may depend on other complementary upgrades.

If you dislike my answer, what then would you say to the initial question? Please note that my initial response also qualified this by recognizing the challenging nature of the problem and that getting to optimal would be "interesting"....

 

[Keoke]

Well James Wilson, I will give you a little support.I did not even go to a larger roll bar.I purchased "Energy Suspension's sway bar end link kit # 98105GC" from PEP BOYS and then installed PolyFlex polyurethane bushes in them and the sway bar mounts.Result; flatter turns at speed.---Keoke

 

[JamesWilson]

Hi Dave:

All I can say is to look back at what Chris Dimmock had to say about the upgrade to a 7/8 bar. There are larger ones than that available so it is in a sense moderate in not going to those extremes. I'll grant its the largest size generally used on road cars, so maybe I am being a little immoderate in doing so.

Moderate vs not moderate; significant vs not significant- it seems this is more about judgements of effect or scale rather than the underlying change....

I think I've tried in each of my responses to indicate that a variety of elements are involved and work together along with the anti-sway bar.

And I directed people to other sources that also reinforce that point. As I've said in my initial response the issues are challenging and getting to the best set up can be "interesting"... its interesting that my mention of this complexity gets overlooked in considering the simple opinion expressed about the bar....

 

[JamesWilson]

Hi Keoke:

I appreciate your contribution, and it does bring things back to the latter part of Higgin's message- the other things/adjustements that may be desirable.

Johnny has pointed out that the wheels will come under greater demands from faster cornering. I would suggest that whether the upgrade is made or not that the wheels should be in good condition: no damage to the rims, or hubs, good splines in the hubs, no broken, bent, missing, loose ot over-tight spokes and the whole balanced and true. These original wheels have endured 40+ years of wear and tear, probable neglect and possible abuse (hitting curbs, etc.) so an inspection and check up would be a good idea regardless. The original cars ran on these wheels in competition in the '50s and ‘60s so they should be good for the sorts of lesser demands you propose making on them. As an aside: I'd initially intended to keep and use the wire wheels from my car. But I discovered that the splines on the hubs and wheels were badly worn and that two needed replacing; of the other two one was a 60 spoke and probably the spare and the other a 72 spoke as were the bad ones- and there was no spare/wheel. I was stuck with having to get 4 wheeels. I got a good deal on a set of 4 alloys- basically for the same price as a set of wires. Had the wires been healthy and a set I'd have kept with them.

Tires- As Piman has remarked keeping them properly inflated is important, and having a good set of tires is fundamental. Some people go to wider tires- 185/15 and larger. Others try to maintain more of an original look with taller tires. Mine came with ancient Michelin ZX 175s. I've no idea what I'll use when that time comes- there seems no consensus about what current tires are best for a fast road Healey... I might be wrong about that... and if I am, I hope people would be so kind as to point me in the right direction....

The Anti-Roll Bar: This has been covered in previous postings, but as I saw it: you could go for a minor improvement 5/8s to 3/4s, a moderate improvement to 7/8s, or to more extreme improvements of 1” or more. Most of the comment I’d seen focused on the 7/8s bar and was invariably favourable. I provided the sources so you could see them for yourself.

I presume you’ll be getting a kit consisting of the bar and everything needed to mount it:

Bushings- the bar mounts to the chassis with brackets (most probably you’ll have new, wider ones) and bushes. The bushes are generally either rubber (softer) or poly (harder). The harder ones will compress less under cornering loads and allow the bar’s effect to be more stiff. Note too that the bushings may be wider for the thicker bar- thus not only will the material be denser but there will also be more of it to compress.

Links- the links from the bar to the A frame bracket may be heavier for a thicker bar. These transmit the load to the bar. Besides the metal link there are also bushes here at both ends. These too may be rubber or poly; again with the harder material providing a stiffer effect. The most rigid link is provided by “rose jointed” links- no bushes are used but instead a hard pivot is provided for the stiffest connection.

The A Frame Bracket- is the original one unless a rose-jointed bar is used. This is the one component where I’m inclined to think Johnny’s concerns are potentially valid. With a heavier bar this bracket will endure greater stresses. It may be more likely then to develop faults. I’ve not seen any written reports of problems with this but I’ve heard people speak of them- without any specifics of the size of bar, how long it took, how roughly the car was used, etc. This component should then be inspected regularly, or perhaps a heavier replacement fabricated or some reinforcement fabricated to strengthen it. I’m inclined to go that route….

I’d presumed Higgins was interested in a “bolt-on” performance upgrade and didn’t want the whole discussion of stronger springs, uprated shocks, altered camber, etc. that a more thorough performance improvement would invite….

Improving handling with a thicker bar can also involve choosing bushings and links that also affect its stiffness. With a kit this is done for the buyer and presumably the supplier will provide a compatible set of components- so I didn’t think it particularly necessary to discuss these.

I hope he enjyed his beer... I think I'll similarly rest... /ubbthreads/images/graemlins/cheers.gif