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MG Midget and Sprite Technical - Brake mods, rear rubber

If you don't like long strings, please avoid this one.
Any comments on each problem would be appreciated!

BRAKE MODS:
I have a '67 with wire wheels (which I'd like to keep), and am pondering brake mods with my Rivergate 5-speed kit on the way. My car stops fine w/stock discs and braided steel/teflon hoses, but doing the 70~75 mph necessary to avoid getting rear-ended on I-40, I'm guessing I'll want a tad more oomph. Here are my thoughts.

MASTER CYL: Moss now has new casting for OEM-pattern late 1275 dual-line units. I've read the posts on multi-cylinder alternatives, but am assuming the late 1275 setup will be fine for any of the below options. Please straighten me out on this assumption if I'm wrong.

FRONT END: KAD makes four-piston alloy calipers to fit stock dia. rotors.
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Pros: more braking force w/slight increase in bias forward; no radius of upper control arm as w/Peter May's 9" kit (Frontline tube shock conversion already done); simply bolt to existing mount & hyrdaulic line; low unsprung weight.
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Cons: too friggin' expensive for street car (~$700 pair+overseas shipping); stuck with stock dia. solid rotor (unless a spacer would allow slotted/dimpled ones like EBC's GD206 at Auto Parts Warehouse, or could buy Speedwell's drilled rotors--but they're expensive).
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Alternatives: adapt VW GLI or Honda civic (etc.) ventilated disc brakes.
Pros: MUCH cheaper; parts available; rated for 4K lb. vehicle.
Cons: req. fabricating mount/spacer; 260 mm dia. rotor is ~10.25" - so larger than stock or Peter May's 9" kit (autozone's website has photos of rotors one might adapt w/dimensions) and *might* require radius on control arm, unless caliper thinner on outboard surface and could position rotor away from arm; might have to reconsider master cyl piston size and compatibility, though VW/Honda master cyl looks similar to late 1275.

REAR END:
(a) Discs perhaps unnecessary, given that rear brakes don't do as much as front. However, if mounting KAD calipers or larger front rotors...
(b) Moss has a Frontline rear disc setup, but they want WAY too much for essentially fabricating mounts and putting stuff in a box for you, and I'm not clear that you can use it with wire wheels. I can't find any other pay-for-play rear disc setups, so:
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Alternatives: adapt VW GLI or Honda civic (etc.) disc brakes.
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Pros/cons: same as with front end--except for no control-arm clearance issues. Rim i.d.-to-rotor+caliper o.d. only real limitation, and should be workable.

REAR RUBBER: currently - P165 70 R13
My car corners fairy flat w/Moss vertical/tublar shock conversion aft, and Frontline tubular conversion & 340 lb. lowered springs forward. Pondering Speedwell tubular 7/8" chrome moly anti-roll bar forward, but right now the front end stays put, with the rear end drifing nicely--until you hit the gas, and then she wants to wave her hiney around.
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Alternatives: Mounting *slightly* wider rims/tires aft; and/or...?
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Pros: least complex solution; a tad more traction aft would allow more throttle without hiney-waiving, yucky pan-hard rod, or obscenely expensive Frontline RTL setup.
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Cons: can't find wider wire wheels w/offset *inward* toward leaf springs, as it's already tight outward. Can get 'gullwing' leaf springs to allow for this option, but I've only seen one car with wheels offset inboard to retain square wheel wells, and (a) they weren't wire, (b) I can't find the webpage again, (c) the aluminum spoke pattern was ugly; front end might begin to 'push', though we're talking a *slight* increase in rear rubber (5" or 5.5" rim), which I'm hoping would put me in the pink.

Your comments, ladies and gentlemen?
JM Young

you say your midget brakes fine
why change?

the std setup is fine for a street car
if you want to alter anny thing start with better pads
mintex or green stuff is a good start
at the rear you could think about minfin brake drums anny thing other is overkill for a streetcar even doing 100mph

rubber
keep front and back the same
165 is fine
you may want to look in to a stickyer compound
Onno Könemann

Hey JM,


Interesting lay out of ideas and thinking...

My thinking is this on the brake issue, if your going to go the 4 pot calipers and rear disk brakes then definatly go the tilton/wilwood duel master cly with the balance bar, as it will be extreme luck or extreme engienering to get the brakes to work with the OEM BMC original master cly. Now if your not going to do a big brake kit or disk conversion on the rear... then stay stock masters. With the duel master set up it gives you lots of options for differant size masters so you can match them up to the needs of your calipers...a four pot caliper is going to want to dring alot of fluid to stop the car

Check with Bill Young... (related maybe...Nahhh) he has found a good cross/referance caliper to the princies caliper ... the prinices is a vary sought after caliper in the UK and not avialable here in the USA because its lite wieght, has a 4 pot design and massive size pads and is a direct fit to the midget... I want to say its a wilwood, that Bill found not certian

the rear end ...now thats a tricky issue... you can get uprated half shafts, a lower gear ratio, and a phantom grip LSD and disk brakes... but good lord, sell the midget and buy a miaita and us the saving to go on a year long sea cruise...easily $4000... so its an independent decision, Personally Im going to an RX 7 1983 rearend and cutting it down, some have gone to a dana 60, and others to the ford 9 inch rearend...So no ansewer or even advise i can give

Id recommend the frontline front suspension kit, everyone seems to love it. with upgraded barry kign wish bone pans...If not that direction some peter cardwell adjustable high end /vary nice/ never leak agian lever shocks... dont knock them till you see them, thay have beeen borg asimilated right out of star trek

and red polybushes on everything

Prop
Prop

Is the price for the Peter May kit including calipers? If so why not buy it without the calipers and get the calipers stateside (they are only MGB calipers) which will save you shipping costs.
Daniel Thirteen-Twelve

The Peter May kit uses Wilwood calipers.
Deborah Evans

The Peter May kit for 9" discs for wire spoked wheel cars is also for MGB calipers. I believe my car was the first to have this kit having suggested it to him (though the original idea wasn't mine).

Daniel Thirteen-Twelve

I'll respond to each in turn; thanks for your time.

Onno,
Our cars are identical body-wise (my jpeg was too large to upload). Since at 60K my splines are starting to wear and I like the look of your wheels, would you please tell me the brand, width, and offset? What make/size tires have you mounted, and do they rub your square wheel wells with a passenger and the boot full? Also, could you please clarify where one can find the finned drums you mention? Do they simply bolt onto the stock Midget axle? Must one have disc wheels?

Prop,
LSD? I'm not much for mind-altering drugs. Hood down at sunset, a bonnie lass, and a winding road are all I need.
A Miata? No need to insult a new member, is there, old chap?
Joking aside, I have pondered an independent suspension, but at some point the thing ceases to be a Midget. I appreciate that precisely where that happens is open to endless debate. To me, the solid rear axle (together with a bit of sliding around) is part of 'Midgetness' whereas, say, lever shocks are not (I have done tubular conversions fwd and aft; sorry that I wasn't more clear about that). Perhaps as my spine becomes more brittle with old age, I'll reconsider my philosophical position on a more compliant rear axle setup (existentialist view of 'Midgetness' vs. 'sorebuttitis').
Brakes. I appreciate your thoughtful reply. I need to first resolve whether I'm staying with wire wheels, since that apparently limits some options. I really want to stick with a single master cylinder, so may have to go to an adjustable bias valve, perhaps like Bruce Uchida (Google "Bruce Uchida's BMW-powered 1959 Austin Healey").

Daniel,
Are you sure that May's 9" kit will work with wire wheels? I'm loathe to radius the upper control arm of my new Frontline shock conversion, and don't know how else to get rotor clearance without moving everything outboard, and thus creating fender clearance issues. I've got the 340 lb. lowered springs, so don't have a ton of fender clearance up front. Also, I really like the aesthetics of stock track width and sheet metal.

Deborah,
Of course, yours is a race car with lovely, hand-worked haunches for those meaty tires. I, too, noticed Wilwood calipers on the larger May kits. Again, my issue (for now) is whether May's 9" or 10" kits would work with my 13" stock wire wheels. If I switch to 13" minilites, same question. I can't get any responses to my emails to May's company.

You've given me lots to think about. Thank you, again.
JM Young

Of course I'm sure Peter May's type 9 (900) big brake kit works for the wire wheel Spridget. Aside from seeing a photo of it and reading about it in a book you obviously don't have I have his kit on my wire wheel car. I also have the Frontline kit on my wire wheel car as well.

Also re-read my earlier post.

Not least if you like wire spoked wheels you might want to contact Dayton about some very slightly wider wheels.


Daniel Thirteen-Twelve

JM
the wheels are simple minilite type alloys
mine are the original K&N miniators i believe they are not made anny more but there are several repro's still on the market
just search for 13" 5J minilite's for midgets and you will find plenty even with centerlock adapters

the brake drums should fit wire and disc wheel axles
http://www.minispares.com/Product.aspx?ty=pb&pid=37940&title=
this is the type with spacer but that could be turned down.
the ones without spacers are harder to find.

my car is a little low and has a panhard with the 165's on there they rub a little when fully loaded (2 weeks of camping sh*t and 2 people)
but survivable
Onno Könemann

As mentioned above

MGB Calipers with Ferodo DS2500 pads or the Mintex equivalent - Stay away from that EBC guff, unless you like crap brakes and loads of dust eating your wheels.

Rear brakes, go for the Riley or Wolseley 1.5 Rear drums for the OEM look.

Tyres - Yoko A539's or the cheaper a-drives we have found to be absolutely superb for road use. Also sensibly priced, which helps
PeterJMoore

Why not just do it your self


Brad (Sprite IV 1380)

'Rear brakes, go for the Riley or Wolseley 1.5 Rear drums for the OEM look.'

We have Wolseley 1500 drums on the back of the racer.

WRT Riley drums, these are less desirable because the wheel cylinders are NLA.
Deborah Evans

Who supplies Wolseley 1500 backplate, drums, etc?
l snowdon

The going rate on e-bay for Wolseley 1500 rear drums, backplate etc is about £45-£50
Daniel Thirteen-Twelve

If you go to Wolseley 1500 Spares in Surrey, then Andy Bradley will supply (as a package) S/H backplates, reconditioned drums, new wheel cylinders, new shoes and S/H adjusters/hold down springs/handbrake pivots.

I purchesed a rear axle set from him in late '06 when I was building the racer and the whole lot came to about 80 GPB IIRC.

http://www.wolseleyworld.com/1500-services.php

You have to heat the Midget handbrake linkages and twist them through 90 degrees owing to the different position of the wheel cylinder in the Wolseley backplate relative to the Midget backplate.
Deborah Evans

Quick pic:




Deborah Evans

I have to throw down on the rear brakes... Doing the conversion from drum brakes to calipers are not going to give you any real braking power... It might help for ebrake, but you have to remember the balance ration is 85/15, and seriously I think the car does better at 90/10

The whole point of rear disk brakes is Cool factor granted you can do some fun stunt work with them like drive backwards hit the E Brake jam the wheel around while shifting into 2nd and slide into a parrall parking spot... cool yeah, But practical... eeeaaaa?

You seem to be after performance, not gravy,,, there simply not going to give you what your looking for...And I think rear disk brakes takes the car away from being a midget... after all bad brakes on a midget is part of the fun, will it stop or not.


LSD = "Limited Slipe Differintial, Also Known as posi-trak, It make both rear wheels turn at the same time esp. if one wheel is sliding like on mud, ice rain, ect...(see the movie "My cousin vienny") the movie goes into detail about LSD/Posi trak....Its how you lay down 2 black tire marks under hard excelleration instead of 1 line of black tire marks


If your going to drop $1000 minimume for rear disk brakes then Id do the Phantom grip LSD .... I think you will get more bang for the buck... granted not a s sexy or has the same level of cool factor, bbut it will get you around the corners.

Prop
Prop

Do not underestamate the coolfactor! :)

Pro & cons:

- In practice: very low maintanance(no adjusting reardrums anymore).
- In theory: if drumbrakes are used intencively it gets hot and you get fading brakes.
Disc do not get this or it takes much longer/braking to suffer from that.

Why I have them?
Because you can!
and they were part of a good deal. ;)


Arie de Best

Arie are they VW calipers (Aluminium?)
S Deakin

Yep, Volkswagen/Audi.

I got the kit from Frontline which comes complete with discs, brackets and handbrake-cabel(s).

Because Frontline have balanced the kit that it gives enough stoppingpower but cant over-brake.
So this kit doesnt need a biasvelve to adjust
front-rear brakingpower.



Once the wheels are on there is little to be seen of the reardiscs... so there goes the coolfactor. :)


Arie de Best

Arie,

You have to powder coat the calipers bright red to be seen more esialy... "Cool Factor" Back on the menu!

I hadnt thought of those advantaes... Now Im really looking forward to getting my Rx 7 rearend built

Sorry Arie,

"A good deal" does not constitute putting on a live sex show with the sheep for the frontline staffs amusement all for a 5% discount...LOL


Prop
Prop

JM, here's my take on your questions:
Front brakes. To get much more brake action you really need to increase the diameter of the rotors, but with clearance issues to consider about the best solution for the least money would be the standard "big brake" kit which uses Spitfire rotors and MGB calipers. Downside is that you have to move your steering arms in about 5/8" and shorten the tie rods a like amount.
Better pad material will help. With due regard for our posters from the other side of the pond, some of the items you suggest such as the Ferodo or Minitex brake pads and the Riley or Wolsley rear drums aren't easy to find on this side and as a maintenance item I'd tend to stay with items I can replace easily. I'm currently running EBC Greenstuff pads on my car and like the performance. Might not be the ultimate but about the best I can find over here without going through a race shop and paying an exorbitant price.
I did check on the KAD calipers, the US distributor wants almost $900 for a pair plus the cost of the pads. Out of my price range for now. Wilwood has a caliper that would come close to fitting as far as disc diameter and thickness but no mounting bracket available for our application, so you'd have to have those fabricated yourself. Those calipers are $99 each last time I checked. They're listed for a minimum disc diameter of 10.5" which is almost 2" larger than out discs, but I'm pretty sure they would work as the same caliper is used in England as a direct replcament for the Princess caliper on some Minis.
I doubt if the later 1275 style master cylinder would buy you much except the safety of a split system. Changing the pedal ratio would be more of an improvement if you can stand a bit more pedal pressure. That would just require you to weld up the clevis hole on your pedal and redrill another a bit lower on the arm. We're only talking 1/8" to 1/4" at most though, but will help without adding too much pedal travel. Any more movement would require moving the mounting postion of the master cylinder a bit lower to line up. Here's a similar mod on a MGB as an example. http://www.britishv8.org/Articles/Budget-Brake-Mod.htm
Rear brakes. Unless you're racing or really doing a lot of fast road driving on the twisties they're not going to be of much use. Install some quality linings and keep them adjusted to minimize pedal travel and you'll have all the brakes at the rear you need.
Rear rubber. Due to the confines of the wheel well and rim width you're not going to be able to put much larger tires there. Perhaps a 175 would fit. See if you can find someone with a wire wheel Triumph GT6. The wires on those are an extra 1/2" wider rim but the hub is a bit different, splines fit, but the hub is shorter so the knock off probaby won't tighten down properly. Anyway it will give you an idea about the offset and I'm sure that Dayton could lace up a set of those wider rims to a Spridget hub.
That's about all I can think of. As you know combining wires wheels and a SWA body really limits some of your options.
Bill Young

Hawk pads are extremely good, available in road or race compounds and made in the USA.

Dayton don't need to consider triumph rims and spridget hubs as they have a 4.5" wire wheel on the shelf.

Changing the pedal ratio does NOTHING to improve the braking of the car anymore than fitting a servo does. However, if you do want a different pedal ratio the 1500 pedal is the one to get.

Mmmm, there are books with this stuff in...


Daniel Thirteen-Twelve

Wow... okay, I've done lots of research, digested what all of you have suggested (I really appreciate people taking the time to post photos), and this is where I'm at:

Rear-
I'd love 4-wheel discs, because they're neato, give a nice progressive feel, resist fading, and are simple to service. But, the Frontline kit is too rich for my blood (and Moss says it isn't configured for wire wheels).

Indeed, the remanufactured, mid-'90s Audi A6 rear calipers Frontline/Moss uses are less than $150 on the web, including core charge. (Rebuild kits are the price of a large Starbucks drink.) Sourcing some rotors that would work shouldn't be too bad. However, I'd need someone to make up brackets, and perhaps a spacer--though the calipers appear to be floating models. (Deborah, are you here yet?)

Until then, and given the limited portion of the total stopping power contributed by the rear brakes, I think the finned Minispares drums are a good compromise for the rear (I already run decent quality Moss semi-metallic shoes). Also, as Bill and Deborah seem to agree (racers who know better than I ever will), this setup would probably be all I'll need for fast road work.

Front-
The KAD bolt-on four-pots are dreamy, but I'm with Bill--too much bread. (Prop, Bill and I have never met. Maybe that will change, as I'm working with Albuquerque's city planners to rescue one of the original Route 66 motor lodges, and part of my vision is to make it THE spot for local classic car clubs to show their cars, hang out, etc.)

Daniel, I am thrilled to hear that May's 900 kit can be installed with wire wheels and a Frontline kit. But no-one (including Peter) has yet reassured me that I can mount his Big Brake kit without grinding the upper control arm on my Frontline suspension. Sorry that I wasn't clear that this is my concern. If you were able to mount yours without grinding, would you please post a picture? I'd love to learn from your installation experience.

Bill, ideally I'd have Tom Colby (or whoever) drill out some stock diameter Brembos for me, find some alloy calipers that are reasonably priced, and have some brackets made up. I will keep you posted about whether I can come up with something that approximates the braking force of KADs while keeping the cost under $500. Do you recall which Wilwood calipers might fit stock diameter Midget rotors?

Dayton's? Cool. If I can get some rear rims that are slightly wider *inward*, I'm set (even if I need to get gullwing leaf springs). My hubs/wheel splines are clicking, so I may need new wheels aft anyway...

Thanks, again, to all of you for sharing your expertise and valuable time. Whenever I figure out how to shrink an image, I'll post one of my car. She's stock-looking but lovely.

Joel.
JM Young

Update/prologue:

1) Peter May tells me he that is not sure whether I can mount his Big Brake (900) kit without grinding the upper control arm on my Frontline suspension. Alas.

2) Running down an off-ramp two weeks ago, and heard a strange oscillating sound from the front left corner. Moss' brand new wheel bearing kits, properly installed and torqued, were wobbling worse than my original, 40-yr-old jobs.

I believe this may have been making my front brakes drag a bit and heat up--which, of course, would reduce efficiency. Wobbling rotors *might* be less of a problem with floating calipers, but with fixed Lockheed grabbers, seems like the hub needs to be dialed in pretty well before I can discount the capacity of the stock arrangement for my purposes: fast road work, consistent NM highway speeds of 70~75+ mph, and whacky NM drivers slamming on their brakes for no apparent reason. I've read several threads on this, and have decided to eliminate this variable with Tom Colby's tapered bearing setup, which uses shims to retain the internal bearing spacer and maintain the stub axle's rigidity.

Once she's back on the road in a few weeks, I'll find a likely stretch of lonely NM highway, get her up to 80-90 mph, and report some stopping distances. Anybody ever had the time to record stock setup stopping distances? Deborah, Bill, what kind of distances are you getting on your racers, just for comparison?

Joel.
JM Young

We also have stock brakes on our bugeye, but a with two masters and a tilton bias adjust. You most likely won't get any numbers for stopping distances from the racers. Not too often do you have to bring your car to a complete stop from speed. Alsomost racars are a bit lighter. I know of one very fast Sprite that is supposed to weigh 1275 lbs. Less weight = less braking force required. If you really do want to go with different brakes, as Bill says, do the MGB calipers and Spitfire rotors.
Tim Michnay

Thanks, Tim.

I am tempted by the setup you and Bill recommend, but I'm trying to figure out a way around grinding a radius on the upper control arm of my new Frontline kit. It doesn't bother me to have to shorten the tie rods and shim the steering arms; neither of those mods reduces the amount of metal engineered into the respective components. As I point out above, Bruce Uchida did this, as have others, but I'm trying to invent a better mousetrap, if you will.

At any rate, I'll post whenever the thing is done.

Joel
JM Young

Joel,

My cousin had an American spec Frogeye that he rebuilt over there then imported over here (running a Suzuki Swift motor).

I know he had the Frontline set up and he definitely had the Spitfire 9" rotors. He was also running a set of Wilwood calipers. When I see him next (hopefully next week) I'll have a wee chat with him about whether he had any 'issues' and which calipers he used. I don't recall him having to modify the Frontline upper control arms, although his car was running Minilite type wheels.


WRT stopping distances on the racer, well initially it ran the Wolseley 1500 rear drums and modified Austin Allegro front discs (just slightly sub 9") with the (uber heavy) Austin Princess 4-pot calipers. We run in Class B (Modified) and could easily outbrake the Class C (Road-going) cars that are limited to stock brakes. Peter May told me (after going back to Class C, having previously run in Class A) that he'd forgotten (and was shocked by) just how bad the braking is on the stock set up.

As an example, I ran our car at Snetterton which has one of the longest straights in UK Motorsport followed by a tight 'ess' bend. Arriving at what I thought was the normal braking point at around 135 odd mph I hoofed hard on the stopping pedal only to find I shed so much speed that I had to accelerate back to the apex!

Obviously we didn't have a stopping problem then! I have since changed the front set up for a 10" vented rotor, Wilwood lightweight 4-pot calipers and my own alloy front hubs. This was done purely to shed weight (both unsprung as well as overall). The current PR Engines set up weighs less than the stock Midget set up.

Quick pic:


Deborah Evans

This thread was discussed between 08/05/2010 and 31/05/2010

MG Midget and Sprite Technical index

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