Lotus Elan

Has Anyone Done An AR, NR Caliper Or Other Brake Conversion?

PostPost by: bill308 » Thu Apr 29, 2010 12:31 am

I should probably have my head examined but I've been thinking about replacing my S2 Elan calipers with 26R type calipers and associated equipment. Has anyone done this?

There appears to be several ways to do this, the full 26R route, a partial route, and 2-more possibilities.

The full 26R route replaces the front calipers with AR's along with the hubs, discs, mounting brackets, wheels, and spinners.

The rears apparently replace the calipers with NR's along with the hubs, wheels and spinners.

The benefits are less weight, less unsprung weight, and larger piston bore and disc diameter for more clamping power. The down side is high cost.

The partial route replaces the front calipers and brackets, but uses GT6 (+2 Elan) front discs that must be reduced in thickness. It retains the OEM hub, wheels, and spinners. The rear just replaces the calipers and retains the hubs and spinners.

The benefits are less weight (not as much), less unsprung weight (not as much), and larger piston bores and disc diameters (front only) for more clamping power, just not as much. The down side is high cost, but significantly less than the full route.

My car is an S2 SE which came with a brake servo, which I removed. The potential increase clamping power and choice of brake pads (Ferrodo DS-11's) I think is improved with either of the above options. AR's and NR's are used on a lot of vintage racers so parts are likely to be available for a long time. These brake system options might be considered period correct.

A third option is to replace the front 14LF calipers with +2 calipers the 16PB and appropriate mounting brackets, which I have on the shelf. This option enables the GT6 (+2) front disc. Benefits are increased clamping force due to larger piston diameters and larger diameter discx and lower cost. The down side is increased weight and increased unsprung weight. Also only the fronts are affected.

The forth option is to go with something like a Wilwood setup. I haven't looked at this closely but one might expect increased clamping power and reduced sprung and unsprung weight.

Has anyone done any of these changes and what were your conclusions?

Bill
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PostPost by: GrUmPyBoDgEr » Thu Apr 29, 2010 9:48 am

Bill,
here's my experience, for what it's worth.
The Mk14 Elite that I once owned had AR's & NR's fitted & I used DS11 pads with them.
They worked very well, strong progressive braking.
You will know that those brakes have no "Dust" Seals on them, so need looking after.
On my Elan S4SE Zetec conversion I needed to put the larger Radiator where the Brake Servo was previously located.
The resulting Brake Pedal effort was very high & the Braking unsatisfactory when compared to modern Cars.
A change of Pad material (very expensive stuff) only brought a marginal improvement.
The next step was to fit +2 Front Disks & Calipers, they are very much heavier than the Elan components but being only used on the Road I've not been aware of the effects of increased unsprung weight.
Initially I was disappointed with the performance of these Brakes & bought a Pair of Wilwood 4 Pot Calipers together with slotted/cross drilled Disks.
The Wilwood Calipers, like the AR/NR Calipers also have no Dust Seals but they are very light, lighter than the AR's going on memory.
Those Brakes are still in their original packing sitting in my Workshop.
Why? Well those +2 Brakes took a long time to bed in & provide the Braking performance that I was searching for so they're still on the Car.
I have a number of small jobs to do on my S4 & one of them is to fit & try the Wilwoods; they're bought & paid for anyway; oh & they look "the Dog's dangly's" :lol:
Was that too little or too much information.
No doubt the "what's wrong with the standard Brakes" debate will re-emerge now. :roll:
I just like my Toys :wink:

Cheers
John
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PostPost by: TomR » Thu Apr 29, 2010 12:37 pm

I was looking for a period performance appearance and light weight, so my route was the AR calipers and bracket, modified stock disc, and aluminum bolt-on hubs at the front, NR calipers (from Chequered Flag specially made to bolt on the stock Elan uprights rather than "real" NRs) and TTR steel bolt-on hubs in the rear. Actually lighter than the 26R I think. Bolt-on Minilights aren't as pretty as the knock-ons but the hubs and wheels end up being a huge unsprung weight savings even without the brakes.

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PostPost by: rgh0 » Thu Apr 29, 2010 12:49 pm

bill308 wrote:I should probably have my head examined....... The potential increase clamping power and choice of brake pads (Ferrodo DS-11's) .......
Bill



DS-11's had to get hot to work when I used them on my Elan many years ago and they were never really suitable for road use becasue of this. They originally contained asbestos and you cant get them today because of this, if some one sells something called DS-11s they are just trading on the brand name and they will not be the same as the original compound. In any case a lot of better race and road pad compounds are available these days

cheers
Rohan
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PostPost by: bcmc33 » Thu Apr 29, 2010 1:21 pm

To show an embarrassing level of ignorance on this subject – I have to ask for some informed information.

I have been advised on numerous occasions by numerous people that I need to remove the brake servo from my car to get better “driveability”. But as I see it, the lower pedal effort from a 2:1 servo has to give better braking performance from a driving point of view.

Do I read it correctly that Bill has removed the servo from his S2 to increase the clamping power? This is what I don’t understand. Perhaps the ‘feel’ may be percieved as better, but the clamping power is directly proportional to the right foot effort, and with a servo the clamping power is double for the same pedal effort.

So what is it that I don’t understand???

I have fitted a new 0.625” brake master cylinder ILO the standard 0.7”, I have no idea how effective this is until the busted servo comes back from Classicar.
Brian Clarke
(1972 Sprint 5 EFI)

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PostPost by: GrUmPyBoDgEr » Thu Apr 29, 2010 2:45 pm

The problem I had when I started driving my freshly rebuilt S4 was that I'd not driven any type of old Lotus for more than 20 Years & for those 20 Years I'd been driving sporty new BMW's.
Driving the Elan on Weekends etc. was a massive changeover. The Brakes just did not match the Car's acceleration capabilities & due to the amount of Pedal pressure required I was finding myself braking very early when going into fast empty Roundabouts & that spoiled the fun.
At one time I was thinking of plumbing in a Brake Servo but couldn't find a suitable location that wouldn't turn the Car's Engine Bay into something that looked like a Junk heap.
Since then I've read on here of the many problems that other Owners have had with their Servo's & feel happy that my Car no longer has one because of that.

Brian,
I'm in agreement with you on the "clamping power" front, the more you have available, so much the better IMHO.
A quick dab on the Brakes then back on to the loud Pedal is fun driving.
Regardless of posh Brake lines etc. etc. & "good feel"; breaking out in a sweat hoping that you're going to slow down enough on time to get around the next corner belongs in the past & can be overcome via a good Brake Servo. i.e. minimum effort for maximum effect.
Many may say that, that is what the original Elan does so well; well it's eluded me so far.

Cheers
John
Last edited by GrUmPyBoDgEr on Thu Apr 29, 2010 5:58 pm, edited 1 time in total.
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PostPost by: bigvalvehead » Thu Apr 29, 2010 5:31 pm

Hi Guys
Pegasus Auto Racing supplies in the USA supply an ally 4 pot caliper that mounts directly to the std Elan caliper bracket.
This gives a larger brake pad area and better balance with improved braking on the front. The 26R uses smaller discs on the rear to get the balance right.

Hispec racing in the Uk also do a similar caliper.

My friend Steve Smith from Sarasota runs the Pegasus calipers on his G12 Ginetta which has Elan front uprights.

Cheers
Dave Hughes

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PostPost by: bill308 » Fri Apr 30, 2010 1:09 am

There's a lot of good information here. Thanks guys.

John,

I didn't know the AR's, NR's, and Wilwoods didn't have a dust seal. Please report back when and if you fit the Wilwoods. The more information the better.

Tom,

Are saying that the real NR's will not bolt up directly to the rear uprights but the Checkered Flag version does? Any idea what's different? My understanding was that the AR's required the larger +2 discs but had to be thinned. Did you use the standard Elan (Spitfire) front disc? I'd hate to give up the knock ons because they do look pretty cool and I do have Panasports for this system. I do appreciate the weight reduction you've attained using the light weight hubs, wheels and calipers. Is your Elan back on the road?

Rohan,

I was looking at Dave Beans catalog in which he shows a plot of coefficient of friction vs temperature. The DS11's show a nearly straight line (0.33) from about 100 F-1800 F. I was not aware that these pads are no longer available in their original formulation.

Brian,

Sorry, but you did not read my post correctly. Shortly after I purchased my car, almost 30 years ago, I removed the servo because it had problems, not to increase clamping force. At this time I'd like to recapture some of the braking force I gave up. Hence, I'd more piston area and larger discs. If I could obtain a good replacement servo and be assured that I could maintain it long term, I think I might go for it. Real estate un in the front is limited however and there is the weight issue.

Dave,

Do you have a part number for the Pegasus caliper? I also didn't know the 26R's used a smaller rear disc for brake balance purposes. Not too long ago I seriously considered purchasing a set of spinners from you. Were these for the standard knock off hubs or the 26r knock off hubs? I thought they were for the standard knock off hubs.

Thanks again guy for all the info. If there is anything else you'd like to share I'd appreciate it.

I think at this point I'm beginning to lean toward a Wilwood or other aftermarket setup. I'd like lower pedal force in my old age. Having said this, Crostwaithe and Gardiner in the UK recently quoted me pretty good prices on AR's and NR's. The NR's are also available with a parking brake option at extra cost. I don't know if this will work with the Elan hand brake system though.

Thanks again guys.
Bill
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PostPost by: GrUmPyBoDgEr » Fri Apr 30, 2010 8:24 am

May be of interest; some Photos of the Wilwood Alloy 4 Pot Calipers that I'll fit to my S4 one Day.
You will note that there are 4 Bleed Nipples per Caliper meaning that they can be fitted to LH or RH side.
However both upper Nipples will need to be bled which should be fun :roll:
I suppose that start with the furthest from the Source rule will also apply here.
Cheers
John
Attachments
Wilwood 4 Pot5.jpg and
Wilwood 4 Pot4.jpg and
Wilwood 4 Pot3.jpg and
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PostPost by: dlbutler » Fri Apr 30, 2010 12:37 pm

Hello All,

I use Ferodo DS-2500 compound pads on the front - the part number I have is FCP809H. On the rear I have Ferodo FD.524.G.(M) pads that I bought in 1982 from r.d. enterprises and installed in 1996. Unfortunatly the matching front pads (GD 533 M) were ruined by a leaking seal between the caliper halfs. I tried several different pads to replace the front Ferodos, but untill I tried the DS-2500 pads the braking was weak. Now I can lock a wheel without much effort and maximum braking will cause a passenger to be thrown forward into the seat belt and complain about it being painful.

Other than the brake pads, I use 175/70-13 tires, DOT-5 fluid and NO SERVOS (dual circuit system). The rest of the braking system is as original.

Don
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1700 cc, Dave Bean #112 cams.
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PostPost by: rgh0 » Fri Apr 30, 2010 1:12 pm

On an Elan with modern tyres of good grip levels you have to much rear braking due to the levels of weight transfer to the front that can be achieved before the fronts loose grip and lock. The result is premature rear lock up making control hard.

The easiest way to rebalance the brakes is to use a modern high coefficent road pad such as the DS2500 which I have used with good success at the front and a "standard' lower coefficent rear pad.

The high coefficent front pad will also give good brake pedal effort levels without boosters or changing to larger calipers.

"Pedal load" are not the only brake performance parameter -- "initial bite" and "brake level modulation" are also important considerations and the right system performance addresses all these issues. The DS 2500 perform well on these 2 parameters also. While their cost is high their life is good and they do not generate the same level of corrosive dust as the EBC greenstuff do which are much cheaper and perform similarly but do not last as long and their dust casues corrosion in my experience.

"High temperature fade" is not normally an issue in terms of brake performance in an Elan except in heavy full race use on a demanding track if you use a odern high performance road pad such as the DS2500.

regards
Rohan
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PostPost by: cabc26b » Fri Apr 30, 2010 1:27 pm

Hi Bill,

In the past I have run most of the period type combination of brakes, hubs. disks. caliper brackets, and a few master cylinder combos ( never ran a servo, never owned an elan made after 65 )

My observation has been that all of your period caliper options will give you plenty of braking power. Others observations on these period combos - " When you went by me into 4 your rear wheel was in the air and not moving"

Opinions on specifics

AR/NR - Great set up. look period, limited choice on brake pads ( race only & $$$) and you have keep em clean. NR on the rear is IMO over kill and expensive - you find this caliper on the back of a lot of mid engine formula and sports racers caring more weight on the axle (than an elan) and with a balance bar to keep the pressure down on them.

Big iron calipers - great brakes, every bit as good at stopping as the AR , cheap to buy, you have a choice of street pads for them etc , depending on the wheel you use you might have to grind on em a little bit. The weight a lot

Hubs - yes the 26R peg drive fronts can weigh more than the alloy bolt on fronts ( not so sure about iron fronts ) On the rear , the peg drive rears weight a lot more and the bolt on (steel or iron) rears.

Hydraulics
Duel master cylinder is best set up for tuning and pedal feel
tandem is very good and can be made to work,


Can't help with the 4 pot calipers.

For my latest build I tried to get as much weight out as possible - so - Used Girling D14R ( alloy versions of the 14LF and weigh less than the AR's ) Alloy versions of the stock rear calipers with handbrake, .75 alloy tandem with proportion valve to keep the rears in check - Alloy front hubs and billet steel rears for bolt ons. I have not used them yet so no real data .


George
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PostPost by: GrUmPyBoDgEr » Fri Apr 30, 2010 2:09 pm

Rohan & Don,

that Ferodo DS2500 sounds like good stuff & your recommendations tempt me to give it a try.
Does anybody know who can Supply these Pads in GB & how much they would cost?
Although I have the original Elan Calipers in excellent reconditioned state & Disks in almost new state in another box next to the Wilwood 4 Pots, I would like to try the DS2500 Pads in the +2 Calipers that are presently fitted to my S4.
I agree with you entirely on the Brake modulation Rohan, I said something similar when I mentioned the braking on my Mk14 Elite, but isn't it easier to modulate the braking when the pedal pressure is reduced & therefore providing more "feel"

Thanks
John
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PostPost by: TomR » Fri Apr 30, 2010 2:32 pm

The standard NRs have a different hole spacing than the stock Elan. The CF NRs are cast with different spacing. Otherwise they are identical. I plan to use a 2 MCs and a balance bar to get them to work. The alloy 14lf sound cool but I haven't seen any. The ARs do require a new bracket and modified disk, NRs bolt right up.

I have a pair of the Pegasus (actually ICP Citation) lightwight LD20 calipers with the bracket supplied to directly replace the 14LFs. I decided they didn't look right and I would just lose my excess money in the market so I got the AR/NR and the never used LD20s are now surplus. I'd sell them at a reasonable discount (10-20%) to Pegasus' price if anybody wants them. Bolt right up, very light, very strong - better answer than Wilwoods IMHO.

Knock-ons still work fine with any of the calipers mentioned, bolt-ons are just lighter. The engineer in me wants a 1200 lb period racer that runs like a Civic when I'm in traffic :-)
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PostPost by: bill308 » Tue Jun 08, 2010 2:27 am

cabc26b,

George, can you hare any sources for the alloy verisons of the 14LF's and rears?

Bill
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