17 replies to this topic

[MiniMadRacer]

Need a fresh set of eyes / brains / opinions....

 

I have a 1981 998 cc A+ engined pickup, standard in every way.

 

It has the dual circuit split front to rear brake master cylinder and the FAM 7821 "limiting" device on the bulk head and drums all round.

 

The brakes have always been sh....te and i have replaced everything bar the FAM unit itself.

 

My problem is I cant lock the front brakes, (forget about the rears), its had new hoses shoes, cylinders, master cylinder the lot, and its still sh...te

 

I had a riley Elf with the same setup but with the single bean can master cylinder and the limiter on the rear subbie and I coudl stop that on a six pence (5p in new money)

 

So..

 

1) Any ideas before I scrap the drums totally (They are all new from mini spares.. now done over 1,000 miles...still sh...te)

2) If I go the S brake route can I keep my standard 3.5 inch by 10 inch steel wheels and not have arches

 

Thanks

[sonscar]

Wild card here but I would make sure the correct master cylinder port was connected to the fronts.I came from an era when discs were so rare cars had stickers on the back warning(disc brakes)and could lock drums on dodgy old bangers OK.Steve..

[Lplus]

Wild card here but I would make sure the correct master cylinder port was connected to the fronts.I came from an era when discs were so rare cars had stickers on the back warning(disc brakes)and could lock drums on dodgy old bangers OK.Steve..

A good point - drums in good condition should lock the fronts.  S discs need far more force to lock the fronts unless a servo is fitted, which really needs the full later servo assembly.  I did wonder about fitting a single line servo to the front discs only of my early 84 car - it would work but might not be legal.  I ended up fitting 4 pot calipers and even then locking the fronts requires effort and a sudden application.

[MiniMadRacer]

Thanks for your input, I will take wild cards, crystal balls anything that makes the damn thing stop.. (it does pass a MOT by the way)

 

Yes correct way round I believe, its a replacement GMC227 from Mini Spares...bottom port goes to the rear top port to the front.. and front pipe goes to the left hand side of the FAM as you look at it from the front of the car.. so they go straigh tthrough the FAM no off set if that makes sense

[MiniMadRacer]

Could the FAM "thing" affect the fronts? (only thing I havent changed)

[absx2]

Just looked under the bonnet of a 1982 mini and the bottom goes to the front but it does say that in the MS description about some early units http://www.minispare...sic/GMC227.aspx

Looking at the picture it would be correct that the top feeds the front as it appears to have a smaller bore size. The smaller the master bore the more braking power but the trade off is more pedal travel.

I`m going to blame it on the limiter valve and I am so glad I don`t personally own a mini with one on http://www.minispare...|Back to search

You can bypass it just to confirm it but here comes the disclaimer. Private road, void insurance Blah Blah Blah. You get the picture but they really are a pain in the ass and adjustable ones are great and safe as you won`t lock the rears and swop ends in an emergency situation www.minispares.com/product/Classic/Brakes/Hydraulics/FAM7821.aspx?0410&ReturnUrl=/search/classic/brake%20limiter.aspx|Back%20to%20search shame you can`t use one.........

A TLS drum braked mini should easily lock up the front wheels at 40 mph, I know as I drive one every day :)

Edited by absx2, 23 August 2021 - 04:14 PM.

[MiniMadRacer]

Thanks, I will look to by pass that FAM thing for now and see if that improves things... and yes I agree drums shoudl be better than this setup.. my 1968 Riley Elf stopped brilliantly...the Pickup will keep up just.... really.. with modern traffic but it sure dont stop with modern traffic

[sonscar]

Another wild card entry,40 years since I had a Mini with drums.My first Mini was an 1960 austin seven which had all new twin leading shoe  brakes and 12month MOT.The person I bought it off told me its full history and added that the MOT tested remarked the brakes met the standard but were much lower than he would expect and said it could be due to needing bedding in.In those honest days I bought it and the brakes quickly became worse.

Upon inspection only about 2inch of the shoe was in contact with the drum due to the pegs in the D shaped holes preventing the shoes from centering properly,might be worth a look,Steve..

[MiniMadRacer]

The shoes should be well bedded in by now, and I did have new drums from MS, but a good shout I will have a look..how did you over come your issue... with the D shaped holes.

[sonscar]

It is possible to have the pegs on the adjuster cams holding the shoes from centering and I seem to remember adjusting was the wrong way round(adjust in direction of wheel travel?)Steve..

[cal844]

I think Retro minis do a FAMwtf valve bypass kit that uses the inertia type rear tee piece

[Ethel]

It shouldn't be the fam valve. As you say, the ports for the front circuit are inline and never interrupted. You could confirm its operation by opening a bleed screw with the pedal pressed hard. The shoes are front shoes and fitted the right way round???

[Spider]

I couldn't say with any certainty if it is the FAM7821, but as you've replaced all other parts, it may not be a bad idea to 'sort' it. I've never liked them and never saw / found that type of limiter was needed on a Tandem system. They have add a bit more rubber in to the system. that doesn't help with pedal feel, they aren't serviceable and in particular, the end under the pressed steel cap breaths to atmosphere in to the bore of them, so they are prone to rusting and somewhere that can't easily be checked. I've also never found any data on them as to what their shut off pressure is.

I'd suggest bypassing it and either moving to the original type of valve (this could be fitted to the bulkhead where the FAM7821 is now) or a better valve is the Inertia one (13H7757). These were originally fitted in the Rear Subframe, though, as long as the angle and orientation is correct it can be mounted anywhere. It can also be tweaked by adjusting its angle. Many of the cars for other markets had these fitted where a Tandem system was fused. They also have no rubber in them, so they don't add to having a softer pedal. Having tried over the years all the various factory valves, these are the types I fit on nearly every build.

[MiniMadRacer]

Thanks Spider I think that may be the way to go.. you say in the correct orientation, any diagrams to show the correct fitment (cant find any onlune) and seems here these items are not plentiful, esp the mounting braket

[MiniMadRacer]

Found the illusive part, now need the braket