Upgrading 15 inch brakes.

Just a thought about all this.
it is my understanding that Roger Parker is a well respected name in the land of MG and in particular MGTF.
In one of his books he addresses the issue of balance between front and rear and as far as I can understand it writes that the designers upgraded the front without doing anything to the rear to promote more braking on the front (I think that must suggest that the original design pre AP 4 pots must have been biased to the rear). 
Can anyone tell if and when the balance valve was introduced and whether it was to overcome that potential imbalance?
And whether the balance was adjusted between models to match braking systems?

It would seem that upgrading to 280 diameter for both front and rear and removing the balance valve in the experience of TA22GT was beneficial, a success, and without introducing tail end problem.

Can anyone put forward reasons or theory as to why?

The 4pot callipers were not introduced because the braking was biased to the rear.
No manufacture could ever release a car with such a potentially dangerous braking system.

The 4 pot callipers were introduced purely to stop the car.

The std brakes were woefully inadequate for a sports car.

I am led to believe the 4pots were brought in for the Club cars and rightfully made their way in to the production line and the first to get them was the Trophy which does not have a proportioning valve as per the factory.
The 280mm upgrade for the rears was because with 4pots up front the 240 rears are way, way underpowered.

I hope others will join in to perhaps comment on their findings of brake bias good or bad. It all adds to our knowledge.

From memory I dont think the brake bias valve was fitted to cars with ABS. Id presume nearly all the later cars that were sold with AP 4 pots and 16" wheels would have had ABS which is why we dont read a lot more about this being seen as a problem

That makes sense about ABS cars.

My 03 TF was fitted from factory with ABS,16” wheels and standard brakes and braking was pitiful. Don’t know whether it has a proportioning valve or not.
Now with AP’s 4-pots in front and M S 280’s in the rear, plus servo brace and braided hoses and braking is very good.

I think there’s more than one way to skin a cat, but certainly every owner should consider a brake upgrading, at least a servo brace and better pads.
 

My 1998 VVC car has ABS & the bulkhead mounting proportioning valve. It remain in situ for now as I haven’t managed to get a good seal with an adapter. I will find an original one on a scraper, remove the gizzards & braze up those holes not required. That should do it.
M

Maybe just removing the spring would be sufficient?
The spring is forcing the valve to seat and brake pressure lifts it to allow flow.

 

 
 

Re#221046
I wasn’t trying to suggest that the manufacturers had deliberately arranged for more rear bias, more that it had turned out that way due to the natural weight distribution of the car compared to others with the engine over the front wheels.

With all these potential kits and modifications there are risks. Who for example has evaluated the design of the rear hub and assessed the additional load on the bolts that hold the adapter to the hub due to the increased moment caused by positioning the clamping force further from the hub than original. Clearly Rover/MG did for the front and you can probably say that the same people did (VHS) when fitting the 260mm adapter kit to the rear. But for 280?
Retaining ABS is probably a good option but for those without ABS ?

Sound thinking, and if owners start communicating issues we'd have to re-evaluate the "upgrades", but in all honesty I think poor braking poses a higher and real danger, at least for the moment.

The larger brakes for our cars have been around quite a long time now..........I've not heard of any structural failures attributed to them in all his time.

Upgrading brakes is not for everyone.

As Pedro says if there were problems over the years we would have heard about them.
MS is coming from a sound engineering background and has deemed his kits roadworthy and I have never read a single complaint.
I doubt any of the kit suppliers have had them tested for bias figures or sheering strength.
Nobody can mortgage their house for those figures when the recoup from sales is so low.
So it comes down to do you trust the process and the opinion of those that have upgraded or do you leave well alone...
It is just personal choice and neither decision is wrong and there is no criticism meant in this post.
It is what it is.
 

  Just to stimulate discussion, try this:-