Car diving to front N/S on hard braking

[MilesA]

Just woken up the 6 after a long lay up. My 17 point plan (including new fuel and plugs) got her going and I took her for a run.

Car is ‘fluffing’ at low revs. From previous experience, I think this is a plug issue which I will look at separately.

However, it’s the brakes that I am concerned about. On hard braking the car dived front N/S. Fine at low speeds and being driven generally. Tyres had just been pumped back up to 24 front and 26 back.

So first thought is that it’s a brake problem on the front O/S. Either a pinched / blocked hose or a sticking piston in the caliper.

In my doll’s house size lock up I propose to get the front wheels off and see if either of the wheels rotate whist ‘A N Other’ presses the brake pedal.

Assuming the O/S wheel keeps spinning, I was going to look for any hose kinks, leaks and also remove the caliper with a view seeing if the pistons are stuck and if so, trying force the pistons back and then retesting.

Anything else I need to have in mind chaps before I have a go at this?

My intention is to nurse the car to my local TR Workshop for them to resolve definitively in addition to other outstanding service work that’s needed.

I've read that  worn bush / ball joints can produce similar effects but the car was fine when stored and the N/S dive is quite pronounced.

Thanks.

Miles

[trchris]

Hi Miles my guess would sticking pads in calliper/ piston slightly seized 

Chris

[Tim 72TR6]

I would second that opinion , in all probability its caliper  sticking.  (I would expect it to be unlikely to be the suspension if it was fine when previously used).

Tim 

[MilesA]

Thanks. 
Assuming the piston is seized in the retracted position, any ideas on how to free it off so that it will slide out and back in use?

Thanks

Miles

[TR NIALL]

5 hours ago, MilesA said:

Thanks. 
Assuming the piston is seized in the retracted position, any ideas on how to free it off so that it will slide out and back in use?

Thanks

Miles

Take out one of the Pads and stick in something slimmer, press the pedal and piston should come out part way then repeat same with the other.

You may be better taking the Calliper off the Car and working on the Bench with an Air Compressor to push out the Piston and a G Clamp to retract it,WD40 will also come in handy.

Edited May 1 by TR NIALL

[MilesA]

Thanks Niall. Good to hear from you. 

This morning the O/S was not braking at all when pedal pressed. No leaks or kinks in fluid line. Wheel off, pads and shims removed. Both pistons just touching shims so got a G clamp on each in turn and both moved. So not obviously seized. Pads a shims back in. My wife came by, so bled that caliper in case there was a local air lock. A couple of tiny bubbles only. Pads and shims back in. Brake works when presse - Hurrah….BUT…now stays locked when pedal lifted and only gradually eases off after about 20 seconds. So a slightly worse position.

Going back this afternoon and will remove pad and shims again to press pistons out further using pedal as you suggest and clean in situ. Cannot get caliper off as fluid line connector nuts are solid. 

We will see! 

Miles 

[TR NIALL]

5 minutes ago, MilesA said:

Thanks Niall. Good to hear from you. 

This morning the O/S was not braking at all when pedal pressed. No leaks or kinks in fluid line. Wheel off, pads and shims removed. Both pistons just touching shims so got a G clamp on each in turn and both moved. So not obviously seized. Pads a shims back in. My wife came by, so bled that caliper in case there was a local air lock. A couple of tiny bubbles only. Pads and shims back in. Brake works when presse - Hurrah….BUT…now stays locked when pedal lifted and only gradually eases off after about 20 seconds. So a slightly worse position.

Going back this afternoon and will remove pad and shims again to press pistons out further using pedal as you suggest and clean in situ. Cannot get caliper off as fluid line connector nuts are solid. 

We will see! 

Miles 

Brake Cleaner or WD40 will help along with a Pry Bar and block of wood.

[MilesA]

👍

[Hamish]

Sounds like a collapsed rubber pipe. Had this on a Daimler with the same calipers as our TR’s 

acted as a one way valve locked on. Took ages to release to give a false sense of security 

[MilesA]

Well, I am beginning to wonder. 

Started with no braking on the front O/S. Now have braking but very slow release despite adopting Niall’s suggestion and copious amounts of WD40 and some Plusgas on such of the pistons that I could expose. Very hard to push them back in unless I released the bleed nipple or reservoir top. Having said that, the hose is protected by a metal spring covering and I can’t see any kinks or depressions in the rubber. 

Anyway, will leave it now for a few days. Will then run it round the block to see if it’s capable of being driven gently to the workshop. 

Thanks all for the input.

Miles

[TR NIALL]

2 hours ago, MilesA said:

Well, I am beginning to wonder. 

Started with no braking on the front O/S. Now have braking but very slow release despite adopting Niall’s suggestion and copious amounts of WD40 and some Plusgas on such of the pistons that I could expose. Very hard to push them back in unless I released the bleed nipple or reservoir top. Having said that, the hose is protected by a metal spring covering and I can’t see any kinks or depressions in the rubber. 

Anyway, will leave it now for a few days. Will then run it round the block to see if it’s capable of being driven gently to the workshop. 

Thanks all for the input.

Miles

The Brake Hoses normally fail from the inside out if your considering replacements go the Goodridge Braided Hoses available from the usual suppliers. 

[MilesA]

Thanks Niall. 
Catch up in Malvern?

Miles

[Trev Good]

I'm with the collapsed flexible brake hose group, had this on my Scimitar with TR6 suspension, new caliper, new disks and I eventually found it!

[MilesA]

Thanks Trev. Next port of call although absolutely zero external evidence of kink or collapse. All looks full and smooth but who knows what happening inside.

Miles

[Drewmotty]

I've had my TR3 dive for the kerb under hard braking when a leaking rear wheel cylinder lubricated the offside rear drum.

[Trev Good]

Miles, that's why I spent a fortune changing everything else! When I took the flexible pipe off, I realised the interior core had swollen, blocking the flow of brake fluid, the outside looked fine!