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MG Midget and Sprite Technical - Spridget Big Brake Conversion

I read here that there is a Wilwood Caliper that works on the big brake conversion that formally had MGB Calipers and the Spitfire rotors. I have that on 13 x 5" Minilites and want the Wilwood calipers. Anyone know the Part # for a direct replacement of an MGB caliper (or close)?

Thnx, John
John B. Carey

Don't know the part number but here is a link to the Peter May conversion using Wilwood calipers. I'm sure they'd supply you with the calipers only.

http://www.petermayengineering.co.uk/specialistProducts.htm#3.1.1
John Payne

id think you would want the MGB replacement wildwood caliper

maybe even the princes caliper

prop
Prop and the Blackhole Midget

I had the Peter May setup with MGB caliper/Spitfire disc and have fitted Hispec 4 pot calipers from a Westfield.Needed to turn the disc down 5mm to fit,but the pads are still on the disc and the total piston area is the same as the B.Weight is down by 2kg each side though.
steve cowling

Hi John,

Where have you been for the last decade? Still have the Red Sprite (wasn'a midget was it?)?

I guess not everyone realises the Wilwood calipers are made in the USA so you don't really want to buy some from the UK and buy double shipping and tax.

I'm not a big fan of Wilwood caliper and have yet to try the Hi-spec caliper.

Regards
Daniel Stapleton

Hey Daniel,

I spent from 2000 to 2008 restoring a 20HP Rolls. See it at:

http://www.rrocncr.net/technical/Gen36Resto/Gen36Resto.htm

The Bugeye gave me no problems during that time... to shows, parts running, and my fun gofer, and back roads zipper.

Now I've done a 3 MC conversion and want better calipers. I didn't find reference on the Wilwood site to an MGB replacement. It seems that one has to measure and give specs for a fit. I had hoped someone had done that and has the part #.

Hope you are getting sufficient road time.

John
John B. Carey

hey john

what 3 MC conversion did you go with...I used the tilton and replaced most.soon to be all brake lines with SS braided on.AN fittings

im also doing the big brake conversion..ive got everything except new hubs which im going to use chrome moly 6061

im using the regular B but I had them powdercoated red and im going.to use ceramic pads for the HD V8 mgb...its almost double the size of the midget pad with only.a.small file off of 2 corners...im using.drilled/sloted rotors...I know I know, but they looked so pretty on the websites and even sexier in real life

I cant post.any photos on my tilton master set up at.the moment... later I can....id love to see yous

prop
Prop and the Blackhole Midget

well... I thiught I had a better photo

but you can see mine in the corner

prop

http://db.tt/PLm0BJIy
Prop and the Blackhole Midget



here is my big brake set up

http://db.tt/kcMW2KRk


Prop and the Blackhole Midget

here is pads I was talking about

http://db.tt/IbwoYvQK
Prop and the Blackhole Midget

John,
Nice RR!

I remember the rather strange braking effect that results from the "servo" clutch taken off the side of the gearbox. Really good brakes at first which then just seem to fade away as the car slows. Makes for nice progressive braking once you get used to it but a bit scary at first, especially going down some steep Scottish passes!
Guy W

John,

That is a magnificent piece of work that you have done on the Rolls, especially given that you have done almost all of it yourself.

I donít have any advice to offer on the Sprite brakes, except to note that I believe some of the conversions had trouble fouling 13-inch wheels, and so required 14s.

Charley
C R Huff

My three MC conversion. I will explain in next post if this Pic goes up.

John B. Carey

Thank you all for the help and comments... Guy and Charlie... my RR (Gen) is no track wonder or high speed braker, but it sure gets attention. This one project has given me inspiration and incentive since 1978. Glad to have it done. I learned a lot that helps with the Bugeye.

The 3 MC conversion for the Bugeye was done personally due to the fact that the conversion I knew about was expensive and required cutting the deck hole larger. Mine has lenghthened peddals that reach up to all the mechanism fully above the deck. I used Tilton MC's and all works out great.

For the front disks, I'm still deciding. Wilwood tech support says any of their MC's would have to have an adaptor plate. Given a min., I hope to find out more about the MG V8 pads and how they fit the calipers. If I do that I will have the existing calipers rebuilt. Have a good place here in San Jose.
John B. Carey

hey john

the V8 HD pads im using on my MGB caliper is ...TRW GDB 340 (wva 20364)

TRW is the manufacture

the pads fit the caliper easily... its the spring retainer that gets caught up on a small edge of.the pad.... ill see if can post a pic of a loaded caliper in a bit

I like your 3 mc set up...very smart looking..it took me a week of just measuring over and over before I made my 1st cut...it is a close fit

one of the big advsntages is the MC are cheap so you can replace them with the best size needed for the brake caliper size your converting to

prop
Prop and the Blackhole Midget

Prop,

Thank you for the info and pix.....good looking setup!

I also got the drilled and sloted TRW rotors. I have determined that my calipers are in need of a rebuild. But your pic of the V8 pads seem to show the increase in area as being a gain across the rotor swept area, and not too much extra width.(longer pads such as would be in a 4 pot caliper.) The stock MGB pads are already sweeping the disk all the way across.

Trouble is, Wilwood 4 pots require an adaptor (not a biggie), but also probably have a different brake hose fitting. I think I will look into it further however.

John
John B. Carey

The Wilwood 4 pot caliper will be a fine fit with all of the larger pad used directly on the spitfire rotor. (see the pic of old and new)..... just have to make an adaptor. I will be posting all the facts, part #'s and an adaptor drawing when it is finished.

John

John B. Carey

hmmm..

Im not sure an adaptor is going to work...2 problems I see

1 . you will need to.make a new hub spacer (between the hub and rotor) longer by the same thickness as the adaptor...3/8 inch minume im guessing

2. just useing known working parts is maxing out all free space inside the wheel....you may end up needing to go 14 inch wheels

I think you might be better of finding the propper wildwood caliper that Is a direct replacement for the MGB caliper...then trying to force fit an odd sized one into the mix


I hate to say this but maybe the best option is to buy a pre-devoloped kit....ive seen them at.around.600 - 800 bucks...but.it.comes with the whole kit and cabootal...just bolt on and go

prop
Prop and the Blackhole Midget

also...make sure the "LOADED" caliper fit over the rotor...the loaded mgb caliper with the HD v8 pad is a close fit..

id also check that this is going to fit inside the
wheel

if you do have to make the spacer longer...you will also need to make a new wheel bearing spacer depending on what bearing you.decide to employ

wow... the more I think about this, the more im liking the idea of it because of all the creative engineering involved

this is going to get hairy fun really fast

any chance the caliper is thinner then the mgb caliper in the rite places by at least 3/8 inch so an adapter can be made

this is going to be a fun.project for certian...expensive, but alot of engineering fun

are you telling the wifey, or do you have a special source of cash she dosnt know about

prop

Prop and the Blackhole Midget

hmmm...now that I think about 14 inch MGB wheels...do they have a deeper back spacing then the midget R. wheels...I just assumed.it did...

hmmm..

another thought... even if this does all work with these mods.... is it going to push the wheels further out and by how much....that could look a little clownish if the adaotor is really thick

prop
Prop and the Blackhole Midget

I have wilwoods fitted on my dads car, will attempt to dig out part numbers. They fit under the 13" wheels. There was a little bit of work needed to get them to work, I had custom brackets made as they mount completely different to the B calipers. Nice light calipers compared to the princess set up. I would also call Peter May direct if you want these. Good to keep business local and he will have already worked out all the spacing etc. if you want hi spec i would go to Frontline. By the time I had machined alloy mounting brackets etc it was no cheaper than buying direct from either supplier. I also had several kits made to save on costs at the time!
WDT Corry

This is my one if it helps.

brian s

that triple cylinder pedal box is gorgeous.

PeterJMoore

Hi Brian, good to hear from you.

Only now noticed that oilpipe on the bottom of your caliper: is that where it gets its brakeoil-feed?
Do you happen to have a picture of the rearside of the caliper?
Arie de Best

OK folks, I have BRAKES! It was not for the faint of heart.... but nowhere near the problems that you anticipated Prop. They fit inside the 13" wheels better than the MGB calipers and the pads sweep ALL of the spitfire surface.... that give max. swept area possible for these calipers... (Willwood 120-6808). What is required is alloy adaptors in a step configuration specifically machined to center and position the pads perfectly. Once that was done, however, the mounting did hit the lower "A" arm at the bottom of the caliper. I had to cut a notch in the "A" arm with my plasma cutter (until all was clear) and then take the "A" arms off and reinforce them. I put them back with new poly bushings, so in my case it was a two for one deal. I used my radial arm saw with carbide blade for many of the rough cuts, my horozontal mill for fine cuts, and metal band saw and sanders for some of the shapes.

NOTE: Willwood does NOT have a direct replacement for the MGB nor any of the cars that we play with. You have to use the drawings and specifications on their website and carfully determine what specs you need. Spitfire rotors require a 3/8" thickness between pads.
After the interference with the "A" arms, I went back to see if any other caliper would have eliminated that glitch... I could not find any better than the 6808..... will post pics in subsequent posts.

John Carey
John B. Carey

This is a shot of the Willwood Caliper (120-6808) and new Spitfire Rotor.

John B. Carey

This is a shot of the old MGB and new Willwood pads and calipers as well as a diagram of how the caliper and pads were going to match the swept area of the rotor perfectly.

Note that on the MGB pad, not all of the material conformed to the shape.... that unused "bump" of friction material was causing rough rub on the non surfaced area of the rotor causing a throbing during hard braking.

All better now.

John B. Carey

This is a shot of the back side of the Willwood showing the adaptor alloy. It is thinner where the caliper bolts on, and thicker where the adaptor bolts to the spindel. !" aluminum was used and the various thickness's must be determined by the application. What is needed is the pads to be equal distance from the rotor surface front and back (pads).

John B. Carey

OK, here is the downside (truth in lending). This shot shows the notch that has to be cut out of the lower "A" arm where the bottom of the adaptor plate was hitting. The notch area is reinforced with a "box" frame and a strap across the whole underside of the "A" arm in that area. (not a bad idea anyway). This didn't take as long as I thought and worked out to my satisfaction. I used a plasma cutter, MIG welder to tack in the parts and a TIG welder to do the detail welding.

Let the questions begin.

John

John B. Carey

john...that.is amazing, it looks the smart part for sure...

faint of heart... yeah I bet more like its friday anurizium day...that took some serious engineering skills to pull that off

prop
Prop and the Blackhole Midget

btw... what.size master cly did you end up going with to power that behemaoth monster brake kit ?

prop
Prop and the Blackhole Midget

Looks good.

Would it have been possible to rotate the caliper up a bit more to clear the a-arm? (obviously requiring a more complicated adapter)
Trevor Jessie

or... could the rotor have been moved closer to the wheel flange and shift the caliper out with it.

I really need to work out some sort of big brakes for my sprite.
Trevor Jessie

what type of pads are you usjng...kevlar, ceramic, asbestos, metalic?

hey trevor... what kind of set up ar you thinking about

so what do you think is more important and offers the most benifit....the tilton 3 master cly set up or the bigger brake caljper and pad set up....I really love my tilton 3 master cly mod...it was worth every cent and minute of time invested

prop
Prop and the Blackhole Midget

If I upgrade to bigger brakes, I will also upgrade my master cylinders.
Trevor Jessie

cool trevor

im planning to.work on the car this wdekend... ill send you lots of pic of my set up

prop
Prop and the Blackhole Midget

Prop,

Thnkx, I am glad it could be done..... I had done the 3 MC setup using 3/4" bores and didn't see the need to change that. Hydrolic theory says that the smaller 3/4" over the larger 7/8" Bugeye bore is better for disk brakes. It gives a harder, more forcefull pressure.

As far as engineering, I do my homework and then sneak up on it. The thickness of the "step" was critical to the position of the front and rear pads relative to the rotor, and the hole placement got it far enough onto the rotor so the pads conform perfectly. Naturally the first one was the most time consuming. The pads are made by Willwood and are called PolyMatrix part # 15E-6096K. They have metallic in them and seem to need to be heated up.
John B. Carey

Trevor,

I could not figure any way to position the caliper differently to eliminate altering the "A" arm. There just isn't any room. Now, if Peter May is doing a setup without "A" arm interferance, I can't see how.
Anyone?

John
John B. Carey

Hi John, looks like I have the same Wilwood calipers on my midget, it was suplied and build on by Frontline-UK.
Mines are in combination with 10 inch vented discs in 14 inch wheels.
they didnt had to adapt the A-frame just grinded off the lower boldhead.
Sadly I have no proper pictures of my set up I now realise.
Will take some pictures next time my wheel is off.

Im not sure of the strenght of your adapted A-frame.
I already had one crack in that same position while on holliday in Scotland.
Did you restrenghten it enough?

Arie de Best

My A-frame was a reconditioned one so maybe in the past already sandblasted 2? and there fore weaker?

I only want Barry King A frames from then, they are very good and have extra strenghtning in the places it needs.

Arie de Best

"they didnt had to adapt the A-frame just grinded off the lower boldhead"

Correction: grinded off a little angel of the bolt-head.
Arie de Best

"Hi Brian, good to hear from you.

Only now noticed that oilpipe on the bottom of your caliper: is that where it gets its brakeoil-feed?
Do you happen to have a picture of the rearside of the caliper?"


Hi Arie,

long time no log on, sadly life gets in the way of having fun. As for the caliper it is a standard 6 pot from KAD (cant fault them or their service/parts and help). That indeed is the oil feed between the two caliper halves, I will see if I can get a pic for you.

Brian
brian s

Arie,

I believe that the A arms are now stronger than before. The notch is totally boxed in and a heavy steel strap crosses inder the A arm. Will see.....I don't baby my baby.
John B. Carey

I purchased a Frontline Big Brake kit several years ago. To source replacement rotors, are all Spitfire rotors the same?

Eventually I will need to source replacement rotors but I don't want to have to order again from overseas. At the time Frontline kits weren't available in the US. Can anyone please point me to the correct replacement rotor for a Frontline big brake kit?

Rotary-MG

you can get the spitfire rotor from.all the USA usual suspects...moss, victoria british and id have to belive car quest, advance, oreillys, and auto zone

and definatly on ebay...no.shortages there

prop
Prop and the Blackhole Midget

Stan,

I got my Spitfire rotors from E-bay sources.... plain, with slots and drills, or finned rotors. I would not think that the finned rotors wouild work, but the others are OK. Spitfire is Spitfire.
John B. Carey

Thanks!
Spitfire is Spitfire,
Good to know that there is no chance of ordering the wrong disks.
Rotary-MG

For information can I draw your attention to this link

http://www.jlhmorrisminors.co.uk/store/index.php?act=viewCat&catId=29
J L HEAP

This thread was discussed between 15/01/2013 and 14/02/2013

MG Midget and Sprite Technical index

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