Topic

Hi everyone, another question:
At the beginning of March this year I had my brakes changed. New stainless flexibles, TT performance Hi carbon 304 front and 280 rear disks (from Neil), new 4 pots at the front and new standard calipers at the rear. So far, so good, but the brakes just don’t bite, there’s no air in the system but it seems like I need a ton of pressure to get the car to stop.
However, I just used standard brake pads that came with the calipers, and they should have bedded in by now. To be honest the car doesn’t seem to brake any better than with the original standard disks all round.
My last TF also was a bit iffy on braking, so is it down to crap pads, or crap design? When I drive my wife’s Twingo I nearly go through the windscreen at first after driving the TF.
EBC Geenstuff?

Keith

When you say "New four pots" what do you really mean?

Brand new, refurbished, or used?

Sounds like used, with used pads.

In which case, what condition were the calipers, and pads, did you clean up the calipers, so the pads are free, and are all the pistons free?

Then were the disks new? If so, you should never use old pads on new disks, as the pads will have worn to the wear patterns on the old disks.

MG TF brakes are never "sharp" like a modern small hatch, but they should certainly be good, but will need a firm application.

Should give more progressive action, and more feel, than the modern small hatch ON/OFF brakes!

These were all brand spanking new, never been fitted, came with pads never used, http://www.mgfntfbitz.co.uk/shop/mg-mgf-mg-tf-front-4-pot-ap-calipers-seb000340-seb000350-free-pads. Same with the rears http://www.mgfntfbitz.co.uk/shop/mgf-mg-tf-le500-rear-calipers-carriers-smc000470-smc000460/. Disks, pads, calipers, were all new.

Keith

Keith, when I changed to 4 pots on the front, the difference was startling!.The brakes were tons better but the fronts locked too easily when under hard braking...

I replaced the standard proportioning valve with an adjustable valve and got the balance between front and rear correct. This minimised front locking and improved the brakes again! I believe that cars with the bigger front brakes as standard don't have the proportioning valve.

Do you have a servo support bracket fitted? This improves the feel of the brake pedal really noticeably...

Hi David,

Thanks for the feedback, I'm going to have to test the front calipers to see if all the pistons actually work because as I wrote before, fitting them made very little if any difference to the braking. Maybe the abs unit is faulty, but the brakes just do not even try to lock.
Possibly my right leg is too weak these days (I'm old) to really apply a strong enough pressure to the brake pedal. Perhaps I should look for a bigger master cylinder, if one exists that will fit the car.
These 4 pots were incredibly expensive as well and I'm very disappointed....

I will get a servo support bracket to see if this helps.

Thanks

Keith

I'm following this because my '04 TF has the 4 pot front brakes and I also find them pretty feeble.



When I bought the car 4 years ago, the brakes were terrible. The rear discs were badly corroded. I was advised to replace all of the discs and pads. I bought Mintex pads and discs.

Once they were replaced, I was spectacularly disappointed by the improvement but the car passed its MOT OK. Over time they must have bedded in because they definitely improved although the MOT figures the following year suggested otherwise.

To operate the brakes, it seems to me that I have to press very hard. I cannot lock the wheels (although I never drive in the wet). The car does have ABS but I have never felt it cut in the way I have in other cars.

I fitted a servo brace. It improves the feel of the brakes significantly (firmer and less spongy) but I am not convinced that it actually improves the braking.

Apart from the MOT, how does one determine the effective operation of the calipers?

Hi Bruce,

Some relief for me that I'm not alone, and not imagining the problems. Your post echoes exactly my feelings about the brakes. I have back ordered a servo brace from Rimmer that might make a tiny difference I hear, but not to the actual braking power - my brakes are firm but they just don't seem to do the job they are supposed to. .

I hope someone can come on here and tell us if it's possible to fit a larger master cylinder / servo to the TF to reduce the pressure needed to get the car to stop.

As far as I can tell, the ABS is useless, we also have a Skoda Fabia, and on braking in the wet, and snow you can feel the pulsing to stop the skid. Nothing like that with the lovely TF, because the braking is so poor.

I heard that Mintex are quite good but they eat disks, I would be quite happy to shell out for a set of Greenstuff / Yellowstuff, if anyone could convince me that they really work with the TF, or suggest a real alternative that does make a difference to the standard pads.

But I still love her despite all of this.

just a "by the by" note!

You actually would be looking for a SMALLER master cylinder.

To increase the brake pressure you would have to apply the same foot pressure over a smaller surface area piston.

Down side is you need the peddle to travel further, to move the caliper pistons the same distance, so it is possible to run out of peddle travel.

Rover MG calculated the optimum master cylinder size.

Brake servo effort might be your issue, so worth servicing/replacing it. Have heard of some rusting through. However too much servo, and you loose the feel of the brakes, much like a modern small hatch (ON/OFF brakes).

I no longer have a TF, but brake performance was never a concern. You could lock the brakes, and ABS kick in in the dry (only ever felt one or two pulses as brakes stopped car quickly), but it did take a firm application of the brake peddle.

I would suggest that there is a problem somewhere in your braking system, as the 4pots and abs should give you a pretty good braking effect. It'll never be quite as sharp as a modern car but should feel more than adequate.
Have you renewed the fluid in the system?
Is there anyone near you who could demonstrate the braking of a properly functioning 4pot setup?

David,

Sadly I'm one of the very few people in CZ who have a TF, there are probably more F's here. I have to say though that braking in my last TF was similar.
Just disappointed that the new 4 pots, new rears, new disks all round, braided hoses, and new fluid made such a small difference.

I wonder of the ABS pump is faulty, but the car has only done 50k Km.

Keith

I'm just about to fit four pot calipers to my F (its not a TF) and this is not the first time I've read a poor report on the performance of this upgrade. Surely the brakes could not get any worse on an F than they are already?
Thinking about it, it can only be a poor friction match or a possible fault with the servo. Maybe a lack of vacuum? When I was competing in stage rallies in the 60/70s in an Escort T/C we tried a few different pad sets and found that P16 discs in conjunction with DS11 pads was the ultimate combination but it took a bit of trial and error before we found out. If the servo is working try some softer pads and see what you get. Check that one way valve and any leaks on the servo circuit, plus the servo itself for a leaky diaphragm.

I was only speaking with my partner today about how good my AP brakes are on my TF. They bite really good and are solid to the feel on the pedal. To be honest they seem far to good for just 160 bhp to me.