Brake Upgrade – Elan S2.

Its exhilarating to drive a fast sports car, but its also important to be able to stop that fast sports car with excellent brakes.

The disc brakes on the S2 elan were OK, but not brilliant, and with an increase in power and other go faster upgrades, they were found to be wanting.

Throughout the many decades of the writers ownership of the S2, the first initial brake upgrade was to remove the original elan two pot calipers and orig disc rotors, and replace them with larger discs and larger two pot calipers.

These items were sourced from a Triumph 2500TC, and probably the same type as those used on the Plus Two Elan, they were almost a direct fit to the S2 with little work required, they did work better, but the brake pedal always felt quite firm, and required a hefty push to get the required braking response.
The long term wish has always been for a better braking experience.

It should be pointed out that the writers S2, being a former race car, has a legacy from its former competition life, that legacy is a pedal box with bias bar brake adjustment. This feature alone is the key to fine tuning the brake set up, having the ability to be able to adjust the front to rear brake ratio settings. Of course it is also possible to fit a brake proportioning valve in the brake line, but nothing can really equal the almost endless variations made possible with the pedal box bias bar adjustment.

One of the major drawbacks of the larger/heavier Girlock cast iron calipers was the dramatic increase in unsprung weight, each caliper alone weighed just over four kilograms, while it didn’t seem to affect the handling, the extra unsprung weight could be felt via pronounced jolts in the steering wheel when the front wheels hit big bumps in the road… maybe it was just my imagination, but it was there… I swear.

But the ultimate dream was to one day, purchase and install some mickey mouse four pot, light weight brake calipers. But there is always the question, which brand does one buy? Which ones will fit correctly with out fouling on the inside of the wheel rims? And which ones will provide the best braking action? As is always the case, there are plenty of unknowns.

As you would expect, research on the internet is the place to gather information, but better still, is to talk to someone who has walked this path before.

The forums and blogs can be a good place to glean information and guidance, but there is also the element of misinformation and the odd put down from people who dislike any form of Elan upgrade mod.

Luckily, through the Aussie Lotus grapevine, I was able to speak with another S2 owner. Rod K who is based in NSW, and after a couple of emails were exchanged, thanks to Rod, I had all of the info I needed to move forward with the brake upgrade project.

The recommendation was to install the Hi Spec Ultralite UL4 M16.

So now it was time to communicate with the UK Company, (This was just prior to Christmas 2021) only to be told they were far too busy for trivial inquires, and to get back to them in late January 2022!! Well, so much for customer service from them, their response put my upgrade plans on the back burner for awhile.

The decision was then made to look at other options such as Brembo, Wilwood, etc, both of which are high quality products, but the cost was above the budget range, so then we went cold on the bigger brake idea for a while.

But It’s quite strange how wheels can turn within wheels.

At an organised January lunch meeting one Friday with some other petrol head sports car mates, saw a box of imported brake parts dumped into the boot of the elan…“Take them home and trial fit them… look them over”, said Peter K, and so, on arrival back home, I was like a kid opening Christmas pressies… Lo and behold, there were two brand new, unwrapped, Hi spec UL4 M16 front brake calipers, plus all of the hardware required to install…

Maybe all of my Christmas’s had arrived at once??

As with any new product, there is always the lingering thought, “Will they actually fit Ok”, how much work is involved, and how much of an improvement will they make? But after a bit of a look and see, plus a rough trial fitment, it was clear to see that these Hi Spec calipers will indeed fit the elan…. with room to spare, and then some.

So a deal was done with Peter K, I then had my brand new Hispec calipers, and I didn’t have to wait any longer for the HS blokes in the UK to pull their fingers out and supply me with the info and product I required.

This is (Photo above) the very heavy Aussie Girlock (Same design as Girling) brake caliper. The existing 240mm Dia cross drilled rotors were retained to mate with the Hi Spec calipers. The original idea was to fit ventilated disc rotors, but then decided not to at a later date. (The cross drilled rotors are not standard fair either, this mod was carried out many years ago with the first Triumph brake caliper install. You may not agree with cross drilled solid rotors, but all I can say is that the idea does work, there has been zero issues, including considerable hard driving punishment, NO cracking of the discs, and they are subject to regular visual inspections.)

The fit up and install begins with a trial install just to see where things are sitting in relation to each other. The Hi spec caliper unit was purposely separated to do this. Note that there are two “O” rings per caliper between the body and each side of the upper spacers. DO NOT LOSE these… but on saying that, the “O” rings are a nice firm fit in the machined recess in the caliper body. And if they were lost, a trip to the local industrial or hydraulic shop will have you walk out with the exact size “O” ring required.

The inner caliper body half mounts directly onto the existing elan brake caliper mount, but we found, due to the spacers required, there was a need to change the existing 7/16″ HT threaded bolts for slightly longer items… a couple of bucks worth at the local bolt shop. (You DON’T have to use Lotus supplied bolts… any normal grade High Tensile bolt, with correct spring washers, tensioned up correctly will hold the calipers firmly in place, use thread loktite if you have to, lock wired bolt heads are not required on the road.

The process of mounting and setting up of the caliper body and the disc rotor.
Comparison measurements are made between the face of the rotor and the inside of each side of the caliper body. The caliper body can be shimmed in or out laterally with the stainless shim collars that are supplied with the kit. If the shims need to be thinner, they MUST be machined on the lathe so as to make sure the faces are dead true to each other.

In the photo above, the caliper bodies have been spaced/held in place with dummy aluminium spacers machined up for the purpose. The brake pads are an old set acting as dummy pads, were previously used in the cast iron Girlock two pot calipers, but inserted into the new caliper body to fill the gaps, simply to get an idea of the spacing, helping to make sure the disc rotor is central to the caliper.

It is also important to make sure that the inside face of the caliper body is parallel with the outer face of the disc rotor.

The Hi Spec calipers are amazingly light weight, and to be honest, there were initial concerns if they had enough strength across the bridges (Spacers) to prevent the caliper body from expanding or springing outwards under brake pressure. But to be honest, they are quite well designed, and work brilliantly on the writers S2 elan, which weighs 700KG laden. (Don’t be fooled by the factory unladen DRY Weight figure of 680KG)… (But it is also possible to shave the weight of the elan down to 580KG racing trim).

Because we retained the larger original Triumph disc rotor, the OD was a little too large to be accommodated by the Hi spec calipers, that problem could have been fixed with a larger type of mounting bracket that is bolted to the suspension upright, and in reality, the caliper body only needed to be moved outwards radially by 1.5 mm and everything would have been OK.

The alternative was to machine the OD of the disc, which we did, and it didn’t take much to make it all fit and work correctly, it is a great advantage to be able to machine components in house rather than send it off to “the machine shop specialist”.

After trial fitting of the calipers, it was noted that a small amount needed to be machined from the outside diameter (OD) of the disc rotor to prevent fouling on the inside surface of the caliper spacers or bridges.

You might look aghast at the caliper above which has been split. I don’t why people get their knickers in knots over this because they are just two machined billets of metal held together with four hex drive bolts, the only drama anyone will have is if they lose, or forget to insert the “O” rings, or they don’t understand how to re-torque the bolts after the dismantling… you DO NEED to use a torque wrench… and the torque setting is 20 lbs foot in the old money on each bolt. DON’T try to guess it.

The clearance between the OD of the rotor and the inner surface of the bridges of the caliper is between 0.25″- 0.30″ thou. The photo above is purely for illustration purposes, taken while the trial fitting and machining operation was being carried out. The bearings/hubs were dry, with just a light film of oil…the final assembly required a thorough clean, blow dry clean with compressed air, and repacked with correct bearing grease, yes, its a lot of work, and yes, its a messy job… but just get in and do it.

The shot above illustrates the amount of room available within a fourteen inch Dia wheel. So much so, that a 260mm Dia brake disc rotor could easily be employed, but for a road car, not really worth the expense, because the set up as described in this article is excellent.

Note: The S2 brake system is none servo assisted, is operated via a pedal box with twin master cylinders, which makes it easy to adjust front to rear brake ratio with the bias bar. The brake lines front and rear are braided lines, which totally eliminate any expansion as would be experienced with older reinforced rubber lines, which accentuates pedal softness under hard braking.

The UL4 Hispec calipers can also be employed with vented brake rotors, the requirement of course is that wider bridges or spacers are required, and also longer caliper body bolts.

It is also possible to go all out with braking systems, semi floating discs on aluminium bells, incorporated with the four pot calipers, but there is quite a bit of engineering and expense involved, and unless you track your car on a regular basis and you are chasing quicker lap times, there is probably little point with that exercise.

Among’st the hardware and brake parts supplied, were a set of anti rattle clips. After an attempt to install these, they were put back in the box, and now after some road miles, they are totally not required, and they are a pain in the butt to fit.

The Summary.
While the initial inquiry with Hispec UK was not all that productive, it was just pure luck that the UL4 calipers became available from a friend who had ordered them in, but then decided not to use them on another project.

The final results after several hundred kilometres of pretty hard driving have proved that there is now a much improved braking performance with the S2 elan, providing improved driving pleasure, and greater confidence (Read, really late braking) with the stopping power.

The conversion was definitely a worthwhile upgrade. The brake pads are EBC Red Stuff (Ceramic) The Master cylinder is 5/8″ bore. Producing the perfect pedal feel, perfect pedal travel.
And really amazing brakes.
Note: Peter k, and Rod K are not related.