Lotus Elan

Bill's 26S

PostPost by: bill308 » Mon Jul 23, 2018 5:43 pm

Hi Sandy,

My cast aluminum wheels likely weigh more that my steel rims, but the aluminum wheels will be stronger, truer, and wider (6 vs 4.5 inches wde) and the aluminum KO spinners will be lighter than the chromed bronze ones. All in all, I think I’m ok with the tradeoffs.

Hi DavidB,
I’m still waiting for my steering rack assembly to be rebuilt using the shortened26R rack. The following photo compares the standard rack with the shortened (-0.5 inch) rack. For a given toe in setting, each track rod will be ¼ inch longer. When rack height is properly adjusted, this additional tie rod length desensitizes the tendency to toe in on bump and droop.

26r-vs-elan-bare-steering-racks.jpg and
26R vs Elan bare steering racks


The following 1965 26R parts list references changes to rack assembly length in the Wiki section.

26r-rack-and-pinion-parts-list.jpg and
Steering parts list


TTR provided the following instructions for minimizing bump steer some time back. I can confirm that rack height adjustment can virtually eliminate bump steer over the indicated 5.5 cm range. Outside this range, my suspension began to toe in. I believe the shorter rack will delay the onset of toe in over a larger range, which could be important for a street car.

bumpsteer-guide.jpg and
TTR Bump steer guide


The diagram below is from Steve Smith’s book, “Advanced Race Car Suspension Development”. My laser measurement system produces a trace as shown below. TTR’s bump steer range is -0.8 (-2 cm) to +1.38 (+3.5 cm) inches, droop to bump. With the rack height properly set, this range shows almost no toe change. Exceed this range, and toe in is apparent. This curve is for the right (starboard) wheel when the tie rod is mounted in front of the spindle. The tie rod is shorter than optimum. A shorter rack paired with a longer tie rod, mitigates toe in change on the Elan. Perfect lengths and angles would yield a straighter, vertical, deflection line.

steve-smith-bump-steer-plot-1.jpg and
Steve Smith bump steer plot 1


The other thing TTR told me was to stick with the standard front anti roll bar for fast street use and if necessary switch to a stiffer one for track days. I believe a stiffer front bar by itself promotes understeer, all else being the same. TTR recommends letting the springs and dampers control roll and weight transfer. I have TTR front and rear fast road dampers and springs on the shelf. TTR says the initial front damper settings should be 5 (10 max) clicks from full soft and the rears should be 1 turn from full soft IIRC. Initial front toe in should be 1/8 inch total and initial rear toe in should be 3/16 inch total. All these setting will have to be done after installation of the new rack and painting of the chassis. For now we are at best close on caster, camber, and toe in at the front. I have not yet be fitted the rear A-arms.
TTR again recommend the Avon CR6ZZ tires in 185/70R13 size for my street application. This is an all-weather tire with a competition compound and I believe a more rounded cross section. The overall diameter is the same as the RA1’s. The problem is cost and availability in the USA.
In addition to the new rack, I am waiting for the new Tilton master cylinder for the clutch master cylinder. The following drawing compares the Tilton with the Girling I currently have. It turns out the master cylinder blister is currently the limiting factor to full left lock. The Tilton should give just enough clearance so that the front anti roll bar becomes the limiting factor for full lock, but in reality the S4-Sprint lock limiter may turn out to be just right.

tilton-vs-girling-clutch-mc-dims.jpg and
Tilton vs Girling clutch master cylinder dimensions compared


The colored volume in the following drawing represents my best guess of the actual 0.625 inch bore. This master cylinder is not only shorter but it appears that the end of the casting can be chamfered for additional tire clearance.

tilton-clutch-mc-dims.jpg and
Tilton clutch master cylinder dimensions


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PostPost by: 1owner69Elan » Mon Jul 23, 2018 6:16 pm

Regarding TTR's ARB's:

When I inquired about fitting one of TTR's larger diameter ARB's they indicated that these don't have barrel bushings, just metal on metal with grease. Strictly for competition and wide sticky tires. Not suitable for street use.

(Of course I kind of have wide/sticky tires: Toyo r888r 185/60). But, very satisfied with (enthusiastic) road going handling with the standard ARB along with TTR fast road springs/dampers front/rear.
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PostPost by: rgh0 » Wed Jul 25, 2018 11:39 am

bill308 wrote:
.....The other thing TTR told me was to stick with the standard front anti roll bar for fast street use and if necessary switch to a stiffer one for track days. I believe a stiffer front bar by itself promotes understeer, all else being the same. TTR recommends letting the springs and dampers control roll and weight transfer. I have TTR front and rear fast road dampers and springs on the shelf......
Bill


Sorry but I disagree with TTR on this. On modern sticky tyres and usable road spring and damper settings the Elan is much to soft in roll with the standard roll bar

TTR is a fan of stiff springs and dampers in all situations from what I see and this compensates for too soft a roll bar to some degree .

What are his "fast road" spring rates recommendation and how do those align with Dave Beans who is more of a "keep it soft" fan.

The most noticeable upgrade I ever did to my Elan when it was still very much a standard road car was sticky tyres ( XAS FF back then 30+ years ago ) and a bigger front bar with everything else standard.

These days for a developed road Elan for someone after performance more than comfort I would go for 150# fronts , 110 # rears, 22mm front bar, adjustable shocks and spaced down rear Aeons by 20mm with no rear bar and Yoko A050R 175/60x13 on 6 inch wheels with suspension height about standard and the car lowered by the smaller diameter tyres. If you want to blow off everything at the lights then a 3.91 diff, if you like highway cruising speeds then a 3.54 diff, but with a well built 8000rpm motor you can live with the lower diff in most circumstances if not doing lots of highway miles and enjoy the acceleration. A 3.77 is a compromise between the two if you cant decide :lol:

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PostPost by: 1owner69Elan » Wed Jul 25, 2018 6:15 pm

What are his "fast road" spring rates recommendation and how do those align with Dave Beans who is more of a "keep it soft" fan.


TTR's fast road springs are: 125 / 100

Bean's Stage 2 (High performance road/slalom) are: 115 / 95

Besn's Stage 3 (Pro Solo/Road Race - Limited or no street use): 160 /125

Standard: 75 / 68

"Rohan's recommendation": 150 / 110

Having the TTR setup, it doesn't seem too harsh for the road. Handling is good but I am still shaking my car out after its recent rebuild after a 14 year hiatus. On the other hand, I wouldn't mind frying a larger ARB on my car from the standard one.

In the rear I am using a cut-down progressive bump stop. I think it is off a VW for Audi or some such. They were obtained from Kelsport. I cut it approximately to the standard Aeon spring length, which I believe is their recommendation. The TTR bump stop provided was useless for me. My rear tires were hitting the upper inside of the wheel arch before engaging the bump stop. With the longer bump-stop things are better.

img_9686.jpg and
Original rubber Aeon spring, TTR bump stop, Kelsport bump stop (before cutting)

img_9693.jpg and
After cutting

img_9687.jpg and
Installed

However, I further decreased the bump travel before engagement by using spacers ("strut packers") that I can insert and fine tune without having to remove the rear unit and spring. They can be readily slipped on the Koni shaft just above the white plastic spacer at the bottom. Much more convenient and allows for easy modification by stacking them- still trying different settings but have eliminated the tire hitting the inner portion of the wheel arch.


img_0253.jpg and

I also considered using a secondary, "helper" spring instead of the longer bumpstop. But, I think this would result in a bi-linear response (effective two step spring rate) instead of the non-linear progressive action of the graduated bumpstop. I would think the progression would be better for predictable handling.

As far as diff ratios, with the low profile 185/60r13 tires (Toyo r888r) which have a smaller radius than the original tires, my 3.77 is effectively 3.944

Acceleration is pretty quick with 181 hp / 143 torque but admittedly it would be nice to have another overdrive gear for the highway.
Last edited by 1owner69Elan on Fri Jul 27, 2018 3:12 pm, edited 1 time in total.
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PostPost by: 661 » Wed Jul 25, 2018 7:51 pm

Those strut packers look interesting.
How do you stop them falling out?
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PostPost by: 1owner69Elan » Wed Jul 25, 2018 9:06 pm

The packers are made of a semi flexible material.

When pushed on they expand a bit and then grip the shaft, enough to keep them from sliding off.

You need to ensure you get the right size for your strut shaft diameter.
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PostPost by: 1owner69Elan » Thu Jul 26, 2018 6:38 pm

Question for Rohan:

You recommended a 22mm ARB. Is this solid or tubular?

I went shopping for a 22mm ARB and found one that is tubular. I don't know the wall thickness (yet) to calculate the effective size but at 22mm it will be less than a solid one, albeit lighter.

I initially ruled out a 1" size as being too big for the road. But since there is one that is available as tubular, its effective size is less. Don't know how much less until I get the wall thickness. If its something like 0.15", the 1" inch tubular is effectively ~23.7 mm. So less than the solid 1" at 25.4mm but a bit more than the 22mm.
Last edited by 1owner69Elan on Fri Jul 27, 2018 8:35 pm, edited 1 time in total.
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PostPost by: Davidb » Thu Jul 26, 2018 8:25 pm

This discussion is timely for me. I have been driving with the original front sway/roll bar for the past year to get a feel for it before changing. I have 115lb front springs and 80lb rear. Wheels are 6 inch and tires moderately sticky Sumitomo 175/70x13.
I have the impression that the front end needs to be stiffer in roll-as I turn at speed the car feels like it is falling off a pinnacle is one way I would describe it--a friend who drove the car felt it and thought I had a toe-in problem- but that is fine at 1/8th front and rear. I would like to experiment with a 13/16th roll bar--anybody got one? :)
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PostPost by: rgh0 » Fri Jul 27, 2018 11:31 am

1owner69Elan wrote:Question for Rohan:

You recommended a 22mm ARB. Is this solid or tubular?

I went shopping for a 22mm ARB and found one that is tubular. I don't know the wall thickness (yet) to calculate the effective size but at 22mm it will be less than a solid one, albeit lighter.

I initially ruled out a 1" size as being too big for the road. But since there is one that is available as tubular, its effective size is less. Don't know how much less until I get the wall thickness. If its something like 0.15", the 1" inch tubular is effectively ~21 mm. Only slightly bigger than the available 13/16" solid (20.6375mm)



solid 22 mm bar that I had custom made many years ago.

I went from standard, to standard with 22 mm bar, to 120/90 with 22 mm bar, to 150/110 with 22 mm bar over the years as i went to stickier tyres. At 150/110 you are on the limit for road use from a comfort perspective in my opinion but the handling is great with sticky Yoko A050R or equivalent. Where you settle on that journey depends on the the tyres your using and your comfort preference. I am now running 200/150 still with the 22 mm front bar and that is getting into the track only except for times when I want a bit of fun on a smooth road.

I suspect my next step may be a 25mm bar for the track but that can break the studs of the bottom of your shocks with the standard installation so you need to modify the set up to have a flexible drop link from suspension to bar.

My personal preference appears to be stiffer than most on the road and softer than most on the track

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PostPost by: 1owner69Elan » Tue Jul 31, 2018 7:20 pm

Thanks Rohan for relating your spring/ARB "journey". Very helpful.

What size tires are you running?

I posted on a separate topic my findings regarding the use of tubular ARB's.

Now leaning toward the following:

Change the stock 11/16 ARB out for a 1" tubular. About 3 x stiffer. I hope this is not too much but it is inline with Rohan's 22mm solid ARB recommendation. Tubular, though substantially stiffer, weighs less than the stock 11/16 bar and is ~5 pounds lighter than a 22mm solid bar. Also, I like the mounting blocks on the drop link to tubular ARB connection as opposed to most of the uprated solid ARB's just having a bare metal collar (metal to metal, with grease).

The rest of the current setup is:

1. Have 125/100 TTR fast road springs. Adjustable front/rear spring perches. Narrow rear springs. TTR valved front shocks, Koni Sports rear (from TTR). Height is adjusted to about .5 inch lower than stock (primarily from tires). Some rear neg camber. Was bottoming my large TTR silencer at 5" height.
2. Progressive rear bumpstops (cut down from Kelvedon ones), same approximate length as stock rubber Aeon's. Added an additional "strut packer" (1/8") to decrease bump travel before engagement. May continue adjusting by stacking more packers.
3. 185/60 VR 13 Toyo R888R, DOT competition tires on 5" 26r wheels, no flares
4. Poly bushes used throughout the suspension
5. Solid rack mounts
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PostPost by: rgh0 » Wed Aug 01, 2018 11:51 am

I currently use 175/60 x 13 Yokohama A050R on my Elan. The rear springs I use are smaller diameter but designed to still fit the original Aeon rubber springs inside the coils. My car has around 110 mm ride height front and rear with driver in the car and 20 litres of fuel in the tank with most of this lowering coming from the smaller diameter tyres. The Aeons have 20mm spacers ( 10 mm top and bottom to bring them in early maybe a little to early for a road car).

I use the spacers to stop the car sitting down on the outside rear wheel in a corner similarly to what a rear roll bar does on the track so i want it to come in early. For a road car for comfort you may need a bit more travel before the rubber springs come into action or use a softer rubber springs that the Kelsport ones may be.

The rest of your setup looks good for a fast road car IMHO and the stiffer roll bar your proposing will benefit the setup I believe

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PostPost by: Davidb » Wed Aug 01, 2018 4:49 pm

1owner: How do you propose bending the tubular bar? I assume it needs to be 1144 Stress Proof steel? Does bending it change the properties?
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PostPost by: 1owner69Elan » Wed Aug 01, 2018 5:08 pm

I'm not fabricating the tubular ARB myself. Buying it already made with the assumption that it is properly constructed.

Here's the ARB ordered:
tubular-1-22-arb.jpg and



I would note that tubular ARB's are quite commonly available from many suppliers for most modern cars, albeit perhaps not for our vintage Elan. Again, presumably these are created properly. I would assume appropriate materials and methods are used. Clearly bending a tube without crimping/buckling and changing of strength would be of concern. The advantage of the tubular bars is substantial weight savings over a solid bar for equivalent stiffness.

For the Elan uprated bars, as noted, I also prefer the mounting blocks instead of a metal to metal collar.

Searching the forum, there are others that have used this tubular bar on their Elan apparently with good result.
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PostPost by: Davidb » Wed Aug 01, 2018 7:19 pm

Thanks for the quick response. May I ask who supplied this bar? I like the idea of weight saving but not sure I want such a stiff bar.
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PostPost by: 1owner69Elan » Wed Aug 01, 2018 7:45 pm

I had started another thread on Tubular Sway Bars, to not potentially hijack this one.

But, to repost from that one:

I received the information from Kelvedon regarding tubular ARB's and thought I would share it for the record:

1. 22mm tubular ARB: wall thickness 2.2 or 2.5mm (probably 2.5)
2. 1 inch tubular ARB: wall thickness 3 mm (~1/8in)

What this yields is:

1. The 22mm tubular is effectively a little less stiff than a 13/16 solid bar, but also ~5 lbs lighter than the 13/16. (22mm tubular is ~1.6 x stiffer than the stock 11/16" Elan)
2. The 1" tubular is effectively a ~23mm solid bar, a little more than the 7/8" (22mm) solid, but ~5 lbs lighter than the 7/8" (1" tubular is ~3 x stiffer than stock 11/16 bar).

Kelvedon is the only source I could find with Elan tubular ARB's. It should be noted that these ARB's are not FIA compatible.
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