The 'E' Type Forum

Hi all.

I have a problem with the brakes on my '66 car, when driven for some time the brakes are susceptible to slightly holding on when the brake pedal has been released. I have changed the brake fluid (all the brake components are reasonably new) to no avail, I suspect the problem may be down to heat soak and I understand (perhaps incorrectly) that Jaguar fitted heat shielding in an effort to stave off the problem.
Can anyone help - I'm trying to get a definitive answer on when heat shielding was fitted to the front left hand engine frame on Series 1 right hand drive 4.2 cars. Mr Porter states is was from chassis No 1E1545 so I'm assuming from early 1966 ?
If this is the case are the parts the same as the heat shielding fitted to the left hand drive cars to protect the brake reservoirs (C18695) or something else ? - Part numbers and a supplier would be great !!

Thank you in advance for any help.

KR Neil

Neil,

The heat shield fitted from 1E1545 is C26500. It is illustrated in the SC parts catalogue but doesn't show how or to what it is fitted.

Nick

Fosseway have just brought out a stainless steel one, quite expensive but good quality, I got one.

However, the symptoms you state could just as easily be the master cylinder not quite returning, if you put your foot under your brake pedal and lift see if it goes away. Worth a try, not saying a heat shield isnt needed, the original ones used to crumble, you could quite easily make one too.

There must be free play when the pedal is released otherwise the reaction valve doesnt quite return fully and leaves a little pressure. I know, it happened to me.

Hi Nick, Ian.

Thank you for your comments and information. I have tried lifting the brake pedal to no avail. One prevailing school of thought was heat soak into the servo unit which may promote a brake 'hanging on' condition.

It has really only been present when the car has been driven for some distance - i.e. after coming off a distance on motorways and then into heavier traffic conditions.
I would like to try fitting the heat shield to see if this improves and/or eradicates the problem.
I'm assuming that once the heat shield was fitted post 1E1545 this continued on into series 1.5 and 2 cars ?

KR Neil

Yes. The heat shield stayed to the end.

As you suggest, it is a marginal issue and had it been otherwise all 4.2 cars would have it all the time. It also occurs more often these days because there are cars with multi-branch headers that kick out a lot more heat in that area.

Hi Peter.

Thank you for the conformation, I'll have a chat with SNGB (whom I have sourced most of my spares from) to see if they can supply.

With the weather closing in it may be next year before I can test the theory !

KR Neil

Dave Kerr sells a stainless steel version which is very effective: viewtopic.php?t=4300&highlight=servo+heat+shield

Not directly applicable as I have a car with Kelsey Hayes bellows so no brake lines any where near the exhaust but I had a sticky brake issue that was traced to the master cylinder reaction valve not releasing. New master cylinder resolved the issue. Your issue may very well be heat soak but it might be worth making sure there is free play at the pedal allowing the valve to release properly. Just my 2 pence worth. J

Had a similar brake sticking issue on my car. Traced the problem to a collapsed vacuum hose at the slave cylinder. Changed vacuum hoses and the problem was cured.
Mikael

Hi. The problem that you have is not heat soak at all but a sticking release valve in the brake servo. Take the servo apart and apply a little grease to the valve, that should cure the problem, if not then you need a new servo. Alan

Hi. Sorry to confuse I meant brake master cylinder and not servo. Alan