Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - DIY SPRIDGET REAR DISCS - SORTED

Dear gents (and ladies):

After months of research, design and engineering, testing, and a little website building, the DIY rear disc brake conversion is finally ready. Here is the link to step-by-step photos, parts list, the works.

Here is the link to the conversion procedure, which is located under the 'projects' drop-down menu:


JM Young

Interesting conversion Joel, and nicely presented!

The only problem for the UK (and Europe ?) markets is that the Nissan was fairly rare over here, so those parts are not going to be readily available. Unless the components were fitted to different European Nissan models, or another brand's callipers are of equivalent dimensions.

Nice clear instructions though.
Guy W


A quick wiki and the Nissan Sentra might have been sold here (UK) as the Nissan Sunny.

Probably need a trip to a breakers yard (see, didn't call it a junkyard or salvage yard !!) to confirm that.

I think I'd be looking for a machine shop or a mate with a lathe to open up the centre bore of the disc, but otherwise very tempted, likely more so when I get my souped up cylinder head back from Peter Burgess !!!


Malc Gilliver

Long time since l saw a Nissan Sunny in a pre-loved car dismantling emporium. Although l think Hyundai may have inherited the mechanical designs ?
Guy W

I think this is definitely a US-centric idea. I'm glad he sorted the details and presented it well. I would likely do mine a bit different, but that is the beauty to his approach. He is providing the difficult bit (the adapters) at a reasonable price for the guys that like to DIY, but are not quite capable of machining/making the adapter portion.

Joel, you should post this in the buy/sell/trade section of the MGExperience and on the Britishcarforum

Trevor Jessie

Guy & Malc -

First, thank you for the comments. Very helpful. Guy, 'pre-loved car dismantling emporium' may find itself onto the website. I love it.

As for parts availability, I did not mean to leave out folks in the UK, Australia, New Zealand, Germany, France (and elsewhere). My thought was that you chaps (and people who don't frequent pre-loved car dismantling emporiums) could order rebuilt Sentra/200SX calipers, rotors, hoses, and pads from on-line parts houses. Of course, that pushes the cost to around 50% of the cheapest UK-centered alternative, which requires welding.

Also, the calipers and rotors won't need service for at least a decade (I have a car with 250,000 miles whose calipers don't leak), so I rationalized that the difficulty of quickly obtaining, say, a rebuild kit wouldn't be a huge obstacle.

That said, I will research cross-referenced part numbers, as you suggest. I would like to enable the lowest-possible conversion cost for folks on your side of the pond, too. A quick look at a couple of Sunny model calipers, like the 1990-95 GTI, look similar but not identical. I may order one and bolt it on to see what's what.

Malc, absolutely you can take the rotors to a shop, which should only add a few dollars to the cost. As Trevor noted, my aim was to enable people to rely on their own elbow grease and stuff they likely have lying around. FYI, machining with a Dremel takes about the same amount of time as driving to a shop, having them do the machining, and driving back.

Trevor -

Thanks for the great suggestions. I will post on those locations as well.

Well, off to the salt mines...

JM Young


The product looks great, you put alot of work into this project, and you have done an exceptional job

BUT... will you allow me to be a prick for just a moment, im sorry buddy, I want you to succeed with this, and I see a blairing problem.

Your website is going to be your undoing, I fear it will shot you down before the landing gear is retracted and flight begins

1st.. it may just be me, but the menu dosnt work, im on sprint with samsung note 2 phone

2nd... Brevity !!!, think more "winnie the poo" and less "war and peace" doing websites is like writing a book, edit edit edit, and when you think your done edit 5 more times

3rd think of the website as a book, a book is devided into chapters and each chapter is devived into pharagraphs... your website is alot of paragraphs with no chapters except for a few headings

Id put all the technical info into a downloadable PDF file that would really clean up the sight alot...

The big problem I see is your combining sales with the how to technical

As a model as to how to lay out a good website for one product ...look at rivergate 5speed conversions and berry king wishbones

The most serious of all unpardonable sins you have commited is your lack of purchasing links. You shoud have a sale link to purchase on every page ... even 2or 3 times listed per page, it should be no effort to find a link to purchase the product at any time without ever leaving the page... at the end of the day, its about sales, sales sales... if you dont close sales, your screwed

On a positive not, so im not a total prick...I loved how you over came one of the most important objections right off the bat in the 1st 15 seconds... WHY YOU NEED REAR DISC BRAKES,... that is huge and your response was great... most will ask that as there 1st objection because the brakes are only 10 to 15% of the braking system...well done luke skywalker jr

I wish you the best of success

Prop and the Blackhole Midget

Here is a little tid bit I came across about 3 years ago ... I cant remember where but I just loved it at the time and it will help you to see your new business from a new perspective and can plane according

The 3 P's of Why a business fails...

1. Product... something is wrong with the product or service

2. People.. the wrong people are in the wrong postions

3. P ??? I cant remember but its about the day to day performance and exacution of of the companies operations, ... book keeping, product placement, advertising,.pricing,.competion ect.ect

Give it some thought... a good business plan is a incrediable investment that pays in spades and can guild you though the lows and highs

Prop and the Blackhole Midget

Interesting project.

Looks like Nissan 200SX parts may be available in the UK:

Rear brake calipers:

See also repair kit for caliper on same website.

Also discs:

Also liked the look of the extended combined clutch and brake reservoir for MkI and II Sprites.


M Wood

That's a good link Mike.
I see there is a 60 surcharge "refundable on return of your old units" So one would need to add that to the cost. Would bring it up to 340 for a pair. And it doesn't include the mounting brackets, which I think are needed. I wonder if the distance between the bolt mounting centres matches any other brand? VW or Peugeot parts are cheap and plentiful in the UK
Guy W

The issue is more than bolt centers. There are three other dimensions to concern yourself with. Not saying that there is nothing on that side of the pond that would work, but it seems unlikely.
Trevor Jessie

I noticed another manifestation of the mythical 140 lb/ft torque on the rear axle hub retaining nut.

If you look in almost every Sprite and midget manual including official publications there is no mention of this torque except for the rear differential pinion nut, and no mention of a torque for the hub retaining nut.

On Mini's a large torque is necessary because they only use RH threaded nuts and the large torque is to prevent rotational forces loosening the nut.

Midgets and Sprites Have LH and RH threads to prevent this. I would use 40 to 60 lb/ft not 140.

Unless you are into auto testing where rapid acceleration and deceleration in both forward and reverse directions is experienced and the 140 figure might be necessary.

Rob aka MG Moneypit

Alex G Matla


A question on the wheels that are being used. Many of us have rims that aren't stock or Rostyle so would it be possible to get a dimension say from the center of the axle to the outer most part of the caliper so that someone could measure their rim to see if it will fit without having to go through the whole process and cost just to find out that it won't work.

I've got some 6 inch wide four spoke Shelbys on my frogeye so I'd be interested when you get that version ready.
Martin Washington


Thank you for the feedback and questions. I have added some hyperlinked purchase points and renamed the 'products' navigation button at the top of each page 'purchase.' I am trying to add product 'buying blocks' to the pages, but the interface gets wonky at night when lots of people are modifying their sites.

Here are some individual Q&A responses:

Martin, I will do this measurement tomorrow or Saturday for you, and will also add a few other measurements that may help. Happy to do this, as I certainly don't want you to buy anything you can't use. Feel free to email me directly if I'm not getting you the info you need to determine if the adapters will meet your needs. I can shoot you higher-quality images directly that way, too.

Rob, I appreciate your careful attention to that detail. I have always wondered about the right figure and seen debates about it here. I defaulted to 140 because of what I took to be a well-informed website to which I link on my own site, authored by Norm Kerr, who seems to know what he's talking about: Norm recommends that torque. Also, as a lawyer who has litigated lots of tort cases, including wrongful death, dismemberment, etc., I am paranoid about specifying too low of a figure. Perhaps I should simply say 'reinstall per your shop manual, but as you suggest, I guess that's not very helpful. Quite the conundrum. I just want people to be safe.

Mike and Guy, this is really odd, but that's the same year Nissan 200SX but the caliper is completely different from the one I list. Well, I say 'completely' different, although certain aspects appear similar. Trevor is right, this is a very specific location over the rotor in 3D space, and also the diameter of the rotor dictates the arched profile of the pads, etc., etc. That said, if I can snag one of these calipers cheap on eBay, I will gladly mount it and give you a report.

In the interim, Rock has the Sentra calipers I list with guide brackets for $101.89 U.S, including core charge, so that's, what, 67.83 pounds a piece?

JM Young


Is this the correct caliper?

Really need someone with Nissan knowledge, 200SX model numbers and part numbers.

The matching rear brake caliper for the S13 - in the does not seem to visually match the pictures you show on your website:

Whereas the S14 caliper seems to look similar (in my earlier email), but is not. Perhaps the S13 one will work? And maybe I was drawn to the S14 caliper as it had the handbrake cable mount on it in your website and the Camskill pic.

Nissan part numbers would help the detective work, and would probably highlight parts shared across car model numbers.

The brake discs looks like Nissan 200SX 'S13' model, which have 4 stud holes.

Are these the correct brake discs (note seem to be shared with Nissan Skyline R33 model series):


M Wood

Martin - I just took the measurements that I believe you need to determine fitment for your custom/racing wheels. Here is the link to the page that discusses fitment, to which I added photos of what I was measuring, and listed your requested measurements. Please let me know if this answers your questions, or if you need additional measurements.

Mike - I will talk to Nissan, and/or look at a cross-reference chart later today or tomorrow at the outside, and confirm the part numbers for you. I will also add the corresponding information to the website's parts list.

Thanks for the questions,

JM Young


Thanks, that's exactly what I needed. Now all I have to do is measure the car.

By the way, you've got the site down pretty good for first try. We all know how we never make mistakes or overlook things so a second pair of eyes always helps and from the reaction here it looks like you've succeeded. So if this doesn't work out you can always go into web page design ;-)
Martin Washington


Nope, sorry - all of the links you provided above are to parts that won't work. The 'hat' height of the rotors is wrong, and the S13 calipers will not work, either.

Here are some caliper and rotor numbers from on-line suppliers in order of increasing price. Rock is the cheapest, without a doubt, but you need to browse by vehicle rather than part number, as they have closeouts and various manufacturers, sometimes VERY cheap.

Calipers: 6816-05001203, 6816-05001202 (Parts Geek); C9330, 9331 (Autozone); CAL SE2352, CAL SE2351 (NAPA).

Rotors: 6816-05052725 (Parts Geek); 31148 (Autozone); NB4886154 (NAPA)

I will talk to Nissan tomorrow, if the parts department is open.

JM Young


Glad I could help, and thanks for the kind words. I hope you'll submit photos of your installation for posting on the website. I'm going to make a gallery page for people's race and road cars.

JM Young

A good product and a very nice website. Thanks for sharing it Joel.
Nick Nakorn

Mike (and others),

I have now posted the Nissan OEM part numbers and some aftermarket alternatives, with sources. I will have a free downloadable PDF parts list and instruction sheet soon. The website is now optimized for smart phones and tablets, as well as laptop/desktops.


Thanks for your kind words. Hope they'll be of use to you. Now, to finish the EFI kit...

JM Young

Dear All:

I have updated and corrected the parts list. Someone had pointed out that I'd transposed some digits in the proportioning valve part number (thank you). I also took out thumbnails of the parts, which people don't seem to find useful, and will be adding a downloadable PDF when I get the chance.

This weekend or sooner if I can manage it, I'll be returning to the 'pre-loved car dismantling emporium' (sorry Guy - I think I misquoted your hilarious term on the website, which I'll fix). The goal will be to capture some photos of a likely location for the proportioning valve on cars with a single-line master cylinder. If memory serves, that would be near the union that also houses the brake light pressure switch, mounted inside the R/H wing. On my '67 Midget, which is retro-fitted with a later-model dual-circuit master cylinder, the obvious location is right next to the master cylinder.

That said, I would greatly appreciate learning about people's experiences with and advice about their particular hydraulic configurations. That is, where they have mounted proportioning valves and what type was used, which master cylinders have worked or been inadequate with big brake setups, four wheel disc systems, etc.

I will be adding a page to post photos and data from people's experiences installing and using the DIY setup, but I gather from visitors' questions that data and/or photos from the experienced people frequenting this site would be appreciated as they contemplate their own, unique setups. If people post photos on this string, please indicate whether it's okay to post them on the DIY website.

Also, I have had questions from Australians about obtaining high-quality proportioning valves at less-than-obscene prices. Are there any Aussie Spridget owners who have found good brick-and-mortar stores on the island, or on-line vendors who ship to Australia at reasonable rates?

Finally, I'm negotiating with a local airstrip (for light planes--don't worry if you're flying into Albuquerque on a commercial carrier for a fly-fishing trip anytime soon) for a block of time to conduct some before-and-after tests. Before and after installation of a proportioning valve, that is.

I'm going to post data and some videos of 'hard stops' from 35 mph, 60, and perhaps 85, to inform people's decision whether to mount a proportioning valve--which I would recommend. The '67 Midget has a 3.9:1 rear end and a 5-speed, so I might be able to log a 100 mph stop if there's a tail wind, and I have time to draft a will. I intend to ask a traffic officer to stop by with her radar gun, so we get accurate data (no offense intended to Mr. Smith). Should be fun.

JM Young

Hello joel,

Here is a couple photos of my braking system

Its a tilton, 3 masters / 2 peddle system....the brake has an adjustable proportioning valve and uses 2 masters and the clutch is by its self

The masters come in a wide range of sizes , I got a brake light switch from them also and plumbed it in on the backside, I also used stainless steel hoses on AN ,fittings instead of brake to deciding what size master to us, I called there customer service phone... told them the various spec. And an hour later I got an email from there on sight engineer suggesting what sizes I needed....its been a great modification scence day one and would recommend them in a beat

I used a bread baking pan and some door seal to make a cover that goes over the proportioning valves as well as seal the hole that the peddles protrude thur

The masters are (were) fairy inexpensive a decade ago when I did this $35 to $40 a
pop ...but its been trouble free, no issues, and a very solid feel scence day one

To get the braking bias set up, I just took about 20 runs at around 60mph and slamed on the brakes as well a some normal braking runs and kept adjusting till I liked it

Your welcome to my photos


Prop and the Blackhole Midget



Prop and the Blackhole Midget


Will this kit fit if you have Frontline's RTL fitted?

Nick P

Prop - Thank you for the photos and description (I will try to figure out a place to fit in your photos). Any way you could send a photo that shows more the pedal box? My email is hot linked.

You mention a bread pan as the cover (very ingenious!), but does that also form the mounting for the cylinders, or is there an underlying steel frame?

Also, could you provide a photo of where you mounted the proportioning valve? I have been getting LOTS of queries about where to mount the valves (just added some photos with arrows).

Nick - Another person asked that and after looking at Frontline's page, I TENTATIVELY wrote on the FAQs page I added that it may not. This is due to the R/H linkage near the leaf spring.

That said, if you have a Frontline RTL and want to do a test-fit, I will provide a full refund with postage (both ways) in exchange for photos showing the interference. My email is hot linked here and you can contact me through the Creative Spridgets website, if you'd like to discuss further.

JM Young

Sure joel,

It will be a few days before I can get onto the car for what your asking,,,

im currently stuck on a large house to finish painting and trim replacement with a tight deadline before play :-/

Prop and the Blackhole Midget


Thanks, and please take your time. I fully understand how work gets in the way of art!

JM Young

Er....why? Most of the energy is dissipated by the front, and rear drums are more than capable to take the rest......
Mark O

He mentions some reasons on his website why people may want to do it. I do not think he implies that they will make a spridget stop any faster under normal conditions. For me ... I guess the attraction would be ease of service and no need to adjust the brakes.

I do not know if the stock handbrake can exert enough leverage to make the calipers grip better than the drums, but that might be another advantage. I've had to do a few emergency stops after failed hydraulics and the stopping distance with nothing but hand operated rear drums is not very good.
Trevor Jessie


'Why rear discs?' is a years-long debate on this forum (and elsewhere), but I've synopsized the standard reasons as I understand them here:

Interestingly, experienced mechanics--who are *least* likely to be daunted by R&Ring shoes--are *most* likely to mention the adjustment-free operation and ease of serviceability that the disc setup offers.

That was actually a big motivating factor for me in designing this conversion. Look at this image, which shows a caliper neatly hinged out of the way and resting on the leaf spring after removing two bolts, and compare in your mind the process of replacing shoes or pulling a stubborn drum to service a hub or half-shaft on OEM brakes:

I also didn't include in the list on the website the factor that seems to motivate lots of people: they look really cool.

Then there's the more intangible stuff, what I like to call 'the hot-rodder factor.' Where I grew up in the U.S. (and I suspect without knowing that people like Prop fall into this category), there was a whole generation who enjoyed modifications done for the sake of being unique, and also just for the fun of diving into them. These guys were the original DIY'ers. I'd imagine this is also true in the UK, though I don't know.

Not that many of those hot-rodder, DIY modifications weren't inspired by their efficacy for racing; they were, at least in part. I'm talking about chopped roofs (aerodynamics), lowered axles (lowered roll center), IRS, etc. But there's a connection between how people feel about their rides, how the car looks and sits on the black top, and an almost visceral feeling one gets driving (or even just sitting in) a car whose guts one has altered with one's own hands, that is immensely satisfying to a certain breed of driver, and which can't be reduced to the net effectiveness of a particular modification.

In a nutshell, having discs at all four corners is a cool modification for lots of reasons, and for no particular reason at all.

JM Young

Sorry, Trevor - I was evidently typing at the same time you were.

I will say that the disc parking brake *is* more effective than the original setup. Once adjusted, it's two clicks and the car holds firm.

Moreover, the e-brake function actually works now, unlike the original drum arrangement. You actually *can* lock up the rear wheels by pulling on the hand-lever, which has enough feel to let you modulate the rear brakes and stop the car using just the rear wheels.

Note in this regard that this is one reason I chose the Sentra calipers: the parking/e-brake is mechanically actuated, *not* hydraulically actuated as with some rear disc calipers. So, even with total hydraulic system failure, you have *both* a parking brake *and* an e-brake that actually works.

JM Young

Hmmm...Hammer and nut springs to mind, even assuming there is a nut to crack in the first place.

A very complex solution to a very small problem - is maintenance of the rear drums so very difficult?

You're not some sort of engineering consultant by any chance?
Mark O

Well, there's your answer Mark. These are not for you.
Trevor Jessie

Hey, Prop. I used one of the photos you offered, and it looks great (thanks):

No rush on the bias valve photo, but I am curious about where you mounted it, so I can educate people about alternative locations. Mine is right next to the dual-circuit late Spridget master cylinder.

P.S. See the knob? Do NOT leave your brand new bias valve lying around within reach of your Labrador Retriever!


JM Young

I prefer mine to be accessible from the drivers seat to make adjustments, but I guess on a street car the need for anything beyond initial setup is not needed.
Trevor Jessie

This thread was discussed between 23/04/2015 and 27/05/2015

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.