31 replies to this topic

[Spider]

 

 Kudos to Mini Spares for offering a kit, however,

 

Spend some more money and bypass it entirely

 

This ^.

They FAM7821 is a terrible valve.

 

What is wrong with it then? 

 

 

It adds more rubber in to the system than is needed, and under that pressed on steel cap the raw cylinder is vented to atmosphere, just inviting them to rust.

There's no published data on them, not even their close off pressure.

The cars that I have bought that have had them, always without exception, when I have removed that valve from the system and fitted a better one, the pedal feels better and the brakes also work better.

[Ethel]

It's a superior fail-safe to the single circuit pressure limiter. I've not had one in bits but I can't see  how the (working bit) of the cylinder can be exposed. Though, obviously, there must be a pushrod for the spring that's exposed to some degree. An inertia valve also has the main advantage of not limiting your rear brakes if your front brakes go awol.

 

Piccy I found of what you'll likely get in the kit.

[Steve_S]

This guys cut one open                  

 

Edited by Steve_S, 07 July 2022 - 04:03 PM.

[Spider]

Steve S - thanks for posting up the clip.

 

It highlights how complicated these are for what they do.

 

It's a superior fail-safe to the single circuit pressure limiter.

Piccy I found of what you'll likely get in the kit.

 

Thanks for finding a Pic of whats in the kit.

 

Just keeping an open mind here, why are these 'superior'?

 

 

 

 

 Kudos to Mini Spares for offering a kit, however,

 

Spend some more money and bypass it entirely

 

This ^.

They FAM7821 is a terrible valve.

 

What is wrong with it then? 

 

 

It adds more rubber in to the system than is needed, and under that pressed on steel cap the raw cylinder is vented to atmosphere, just inviting them to rust.

There's no published data on them, not even their close off pressure.

The cars that I have bought that have had them, always without exception, when I have removed that valve from the system and fitted a better one, the pedal feels better and the brakes also work better.

 

 

Sorry, I did also mean to add that I've had several of these valves leak internally from one circuit to the other, thus negating the safety feature of the tandem circuit arrangement. They are also a difficult item to diagnose if there's a fault in the Brake System. With all other brake components, they can be stripped and inspected, but these are not made to be stripped. They can only be diagnosed by replacing the valve.

[Maccmike8]

Would you replace it with;?

 

0 21A2031 Regulator valve, 850/998 MK3 only except Cooper ‘S’ MK3 1     20 21A1774 Regulator valve, MK1/2 plus Cooper ‘S’ MK3 1
 

[Spider]

 

Would you replace it with;?

 

0 21A2031 Regulator valve, 850/998 MK3 only except Cooper ‘S’ MK3 1     20 21A1774 Regulator valve, MK1/2 plus Cooper ‘S’ MK3 1
 

 

 

My favorite factory valve is the Inertia Valve. I don't think they were fitted on many models in the UK (?) and do tend to be a little thin on the ground. They work very well, I think the best of any factory Valve, and they are extremely simple in their design.

In lieu of that, either of the Valves above, with an appropriate shut off pressure, would be fine.

 

The 21A2031 has a shut off pressure of 390 PSI. This would be best suited to a Drum / Drum set up.

 

The 21A1774 has a shut off pressure of 370 PSI. This is usually best suited to a Disc / Drum arrangement.

 

You may find an adjustable valve better to it can be tweaked to suit your combination though, as much more comes in to play than just the brakes.

If you're unsure which way to go, use the 21A1774.

[Maccmike8]

 

 

Would you replace it with;?

 

0 21A2031 Regulator valve, 850/998 MK3 only except Cooper ‘S’ MK3 1     20 21A1774 Regulator valve, MK1/2 plus Cooper ‘S’ MK3 1
 

 

 

My favorite factory valve is the Inertia Valve. I don't think they were fitted on many models in the UK (?) and do tend to be a little thin on the ground. They work very well, I think the best of any factory Valve, and they are extremely simple in their design.

In lieu of that, either of the Valves above, with an appropriate shut off pressure, would be fine.

 

The 21A2031 has a shut off pressure of 390 PSI. This would be best suited to a Drum / Drum set up.

 

The 21A1774 has a shut off pressure of 370 PSI. This is usually best suited to a Disc / Drum arrangement.

 

You may find an adjustable valve better to it can be tweaked to suit your combination though, as much more comes in to play than just the brakes.

If you're unsure which way to go, use the 21A1774.

 

 

Would you use the 21A1774 as well as an adjustable valve?

[Spider]

 

 

 

Would you replace it with;?

 

0 21A2031 Regulator valve, 850/998 MK3 only except Cooper ‘S’ MK3 1     20 21A1774 Regulator valve, MK1/2 plus Cooper ‘S’ MK3 1
 

 

 

My favorite factory valve is the Inertia Valve. I don't think they were fitted on many models in the UK (?) and do tend to be a little thin on the ground. They work very well, I think the best of any factory Valve, and they are extremely simple in their design.

In lieu of that, either of the Valves above, with an appropriate shut off pressure, would be fine.

 

The 21A2031 has a shut off pressure of 390 PSI. This would be best suited to a Drum / Drum set up.

 

The 21A1774 has a shut off pressure of 370 PSI. This is usually best suited to a Disc / Drum arrangement.

 

You may find an adjustable valve better to it can be tweaked to suit your combination though, as much more comes in to play than just the brakes.

If you're unsure which way to go, use the 21A1774.

 

 

Would you use the 21A1774 as well as an adjustable valve?

 

 

No, just one valve.

Mini Spares do an adjustable version of these valves

 

http://www.minispare...74.aspx|Back to

 

[Ethel]

Steve S - thanks for posting up the clip.

 

It highlights how complicated these are for what they do.

 

It's a superior fail-safe to the single circuit pressure limiter.

Piccy I found of what you'll likely get in the kit.

 

Thanks for finding a Pic of whats in the kit.

 

Just keeping an open mind here, why are these 'superior'?

 

 

 

 

 Kudos to Mini Spares for offering a kit, however,

 

Spend some more money and bypass it entirely

 

This ^.

They FAM7821 is a terrible valve.

 

What is wrong with it then? 

 

 

It adds more rubber in to the system than is needed, and under that pressed on steel cap the raw cylinder is vented to atmosphere, just inviting them to rust.

There's no published data on them, not even their close off pressure.

The cars that I have bought that have had them, always without exception, when I have removed that valve from the system and fitted a better one, the pedal feels better and the brakes also work better.

 

 

Sorry, I did also mean to add that I've had several of these valves leak internally from one circuit to the other, thus negating the safety feature of the tandem circuit arrangement. They are also a difficult item to diagnose if there's a fault in the Brake System. With all other brake components, they can be stripped and inspected, but these are not made to be stripped. They can only be diagnosed by replacing the valve.

 

I'm guessing the Minispares  kit is the same, as far as I know they're all the seals in one.

 

I reckon the whole purpose of using front circuit pressure to operate it is so it won't limit rear pressure if the front circuit fails to make any. Totally accept that's not much benefit if the FAM valve itself is the failure.

[Maccmike8]

Thanks folk.

[Maccmike8]

 

 

 

 

Would you replace it with;?

 

0 21A2031 Regulator valve, 850/998 MK3 only except Cooper ‘S’ MK3 1     20 21A1774 Regulator valve, MK1/2 plus Cooper ‘S’ MK3 1
 

 

 

My favorite factory valve is the Inertia Valve. I don't think they were fitted on many models in the UK (?) and do tend to be a little thin on the ground. They work very well, I think the best of any factory Valve, and they are extremely simple in their design.

In lieu of that, either of the Valves above, with an appropriate shut off pressure, would be fine.

 

The 21A2031 has a shut off pressure of 390 PSI. This would be best suited to a Drum / Drum set up.

 

The 21A1774 has a shut off pressure of 370 PSI. This is usually best suited to a Disc / Drum arrangement.

 

You may find an adjustable valve better to it can be tweaked to suit your combination though, as much more comes in to play than just the brakes.

If you're unsure which way to go, use the 21A1774.

 

 

Would you use the 21A1774 as well as an adjustable valve?

 

 

No, just one valve.

Mini Spares do an adjustable version of these valves

 

http://www.minispare...74.aspx|Back to

 

 

Thank you, you are a great help. Sorry to keep asking questions, so i would do away with the proportioning valve, connect the front lines straight to the master cyl outlet, and on the rear line, put this adjustable valve between the m/cyl and rear line?

[Steve_S]

The kit arrived from mini spares no good at all not even near [see pic]

The issue I had was the rear o/s brake locking up under heavy braking and the rear end stepping out................ It went through the MOT test ok in fact the tested said how good the brakes were, just goes to show the rolling brake tester does not show ever thing up.

Iv striped the valve down its doable its just a faf to get the end covering the spring off turns out the piston at the spring end had sized this is probably due to the car sitting for over 2 years and must have had moisture in the brake fluid which had caused rust in the bore cleaned the rust  out cleaned it all up and re assembled it and the pistons were now moving re fitted bled the brakes and HO RAR no more locking o/s/r

 IMG_6433.jpeg   14.25K   5 downloads

 valve.jpeg   53.5K   4 downloads

[Spider]

 

No, just one valve.

Mini Spares do an adjustable version of these valves

 

http://www.minispare...74.aspx|Back to

 

 

Thank you, you are a great help. Sorry to keep asking questions, so i would do away with the proportioning valve, connect the front lines straight to the master cyl outlet, and on the rear line, put this adjustable valve between the m/cyl and rear line?

 

 

No problem with the Questions as long as you don't mind the delayed offerings of mine here.

 

Yes, the Front Lines are connected directly to the appropriate port of the Master Cylinder and the Rear as you say, via a Valve of your chosen type. The actual physical location of the Valve can be anywhere, just mount it in such a way that an air pocket won't form inside it when bleeding and if you end up using an Inertia Valve (13H7757), it's does have a particular way it does need to mount up.

 

While the FAM7821 was a common valve fitted by the Factory, it wasn't the only Valve used. Here in Australia, in our Local Production, they used the FAM7821 in the early days of Tandem Brakes (we first got them in 1977), they later dropped them in 1979 and went to the 13H7757 Inertia Valve. They also fitted these in the UK to cars destined for Canada and a few other countries.

 

 

 

[Spider]

 

It's a superior fail-safe to the single circuit pressure limiter.

 

Just keeping an open mind here, why are these 'superior'?

 

I reckon the whole purpose of using front circuit pressure to operate it is so it won't limit rear pressure if the front circuit fails to make any. Totally accept that's not much benefit if the FAM valve itself is the failure.

 

OK, yes, fair point here. The 13H7757 will also do similar.
 

[Ethel]

I think the also used the inertia valve on vans pickups for the domestic market.

 

An advantage of inertia valves is that the don't sense pressure & rely on an appropriate load on the rear tyres to avoid skidding, so they aren't as application specific. Any inertia valve could be made to work, but the Mini one is a great design & value if it's available.