Lotus Elan

7/8" Front Anti-Sway Bar

PostPost by: Davidb » Wed Nov 23, 2016 12:05 am

Having searched the forum fairly thoroughly re sway bars I have decided to get a 7/8" unit-they seem to be the recommended size for fast road use. They used to be available from Addco but they are not making them at present. If six of us got together and ordered I am sure they would! The price I have seen advertised previously is $164 which seems very reasonable.

So, are there another five Elan owners out there (in North America) who would like to get a 7/8" sway bar?
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PostPost by: Elan45 » Wed Nov 23, 2016 1:36 pm

I could be interested in your offer. I don't have a stock one handy to measure and compare w/ your increased diameter, since both my Elans are 900 miles away and will be for a couple of weeks yet.

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PostPost by: prezoom » Wed Nov 23, 2016 4:43 pm

I would be interested. It is that or purchasing a bar of stress proof and making my own.
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PostPost by: Bill » Wed Nov 23, 2016 8:54 pm

David

You can count me in - I could pay tou and pick it up when I am over.

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PostPost by: Davidb » Wed Nov 23, 2016 10:00 pm

This is starting to look do-able. Now I am waiting to hear back from Addco...
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PostPost by: mbell » Wed Nov 23, 2016 11:28 pm

I might also be interested, on my future to-do list...

Never checked but was hoping these would be available from usual suppliers. Guessing that isn't the case?
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PostPost by: nomad » Thu Nov 24, 2016 1:47 pm

I think I would as well. What is stock size again???

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PostPost by: Davidb » Thu Nov 24, 2016 4:43 pm

Stock size is 5/8th".
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PostPost by: bitsobrits » Thu Nov 24, 2016 5:40 pm

Do keep in mind that in a torsion spring (which an anti roll bar is) stiffness increases with the 4th power of the diameter-so 7/8" would be a huge increase (like >380%!) over the stock 5/8" bar. On an otherwise standard car with no rear ARB, you would likely get loads of understeer, which you may not find desirable.

Roll stiffness needs be balanced front to rear for happy motoring. So an increase in front roll stiffness needs to be balanced by a proportional increase in rear roll stiffness.

And of course there's the issue of compliance when encountering bumps mid corner. Increased roll stiffness will reduce compliance. Lotus really did get the road holding thing right with their moderate roll, soft spring, but firmly damped suspension design.

Now if your running a fat sticky tire and lowered suspension, then bring on the stiffer springs and ARBs....
Steve

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PostPost by: Davidb » Thu Nov 24, 2016 6:21 pm

Thanks for the info B of B. I think (hope?) that the people who responded are all aware of that-I have seen their input on various threads re suspension/handling/modifications.

However, I think it is fair to say that fitting a 7/8th bar without other modifications would produce the effects B of B suggests.

Interesting discussion here:
elan-racing-f12/anti-roll-bars-t30365.html
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PostPost by: rgh0 » Fri Nov 25, 2016 8:49 am

bitsobrits wrote:Do keep in mind that in a torsion spring (which an anti roll bar is) stiffness increases with the 4th power of the diameter-so 7/8" would be a huge increase (like >380%!) over the stock 5/8" bar. On an otherwise standard car with no rear ARB, you would likely get loads of understeer, which you may not find desirable.

Roll stiffness needs be balanced front to rear for happy motoring. So an increase in front roll stiffness needs to be balanced by a proportional increase in rear roll stiffness.

And of course there's the issue of compliance when encountering bumps mid corner. Increased roll stiffness will reduce compliance. Lotus really did get the road holding thing right with their moderate roll, soft spring, but firmly damped suspension design.

Now if your running a fat sticky tire and lowered suspension, then bring on the stiffer springs and ARBs....



Not my experience

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PostPost by: frearther » Fri Nov 25, 2016 9:00 pm

I found that Rohan is quite right, as usual. When I changed to a 7/8" bar, the understeer became quite pronounced - too much so for autocross use.

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PostPost by: Davidb » Sat Nov 26, 2016 1:01 am

Still waiting to hear back from Addco...
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PostPost by: el-saturn » Sun Nov 27, 2016 4:33 pm

my punk got his xmas present this autumn: a 1inch sway bar: one mustn't tighten the shocks' lower bolt as much as you may: more movement will keep the bottom bolt attached or unbent. the ride is much better, you can feel the front much better and much better grip. the rear is ttr with the "race" konis + the 539 yoko: not a semi slick but MUCH better than most of the other rubbish! sandy 4982
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PostPost by: Davidb » Mon Nov 28, 2016 12:35 am

I remember going to Sears Point raceway (Northern California) with Nino Epifani and the "Gold Bug" 26R, then owned by Don Orosco, back in the mid eighties. The purpose of the visit was to decide which size sway bar was best. The test driver was Dan Marvin, current Formula Atlantic champion and also a neighbour of Nino. Orosco could afford to have the best...

Dan did a session with the 15/16th bar fitted and then came in and Nino's guys changed the sway bar for a 1". Dan went out again and from the trackside you couldn't tell the difference-I don't recall the lap times but when Dan came back in he said "refit the 15/16th bar it is much more controllable with that fitted".
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