Brakes checklist.

[Keith Clements]

Keith

I have a question for you that I am sure you can answer!

Brakes

The brakes in my Jupiter 'pump up' that is to say pressing on the brake pedal followed by a very quick re-press brings the brakes on with a noticeably shorter brake pedal travel for the second press.

Would you say this is a fault of the master cylinder, or maybe something to do with the new rear wheel cylinders and / or newly re-lined rear brake shoes? Both items just been installed. Front brakes untouched.

Edmund Nankivell
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Hi Ed,

Quick test, put handbrake on and see if any difference.

Then adjust all front brakes up tight and try again. That way you eliminate the adjustment possibility. If there was no change, keep the system like this.

Could be soggy hose but most likely air in the system, so bleed the system. If you still cannot get a hard pedal straight away, press the pedal down slowly taking at least 30 secs. Does it go hard or to the floor. If to the floor, it is the master cylinder, but maybe the piston is not returning fully. Check it is by trying to push it in after it has supposed to have returned. Before now I have put a separate spring on the piston rod to help it return. Check there is the 1/4inch of play in the slotted caliper. Make sure the bolt at the back allows the MC to rotate slightly.There could be other reasons for the slow depression causing pedal to go to the floor such as loss of fluid in a line or cylinder. Look for drips on the floor!

If all OK, then it might be the recuperating seal in the MC which is needing the force of a hard push to close its lips. This may be symptomatic of a wrong size or worn seal, worn piston or possibly worn aly ring.

Could be the shoes or springs have not been fitted properly, allowing too much travel, the JG has diagrams on how they should be. Make sure the wheel cylinders are free to move on the backplate.

Come to the Resto show where I am demonstrating a complete brake overhaul.

Regards

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Hi Keith

Many thanks for your fulsome reply, I have printed it out and will take it down the Jup when the rain clears, and see what follows

I used to do every job on the Jupiters but not any more, alas!

I would love to come to the Resto show but sadly, apart from the Dutch rally, I don't get around much any more!

Edmund Nankivell
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Have a look here.

http://jowett.org/jowettnet/dt/tech/bra ... brakes.htm
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Hi Keith

Many thanks again for your helpful reply

Your last point was the right one, my man had fully tightened the rear wheel brake cylinder fixing nuts. I backed them off half a turn as the book says, then re-adjusted the shoes, and now, no pump-up!

Edmund Nankivell

[ian Howell]

Am I right in thinking that the Thakeray washers are used on the brake cylinder fixings so that , although firm, there is a degree of 'slack' to permit the cylinders to move slightly on the backplates for this reason?

[Forumadmin]

Yes, it could be Ed does not have the washers...or his mechanic does not know what they are for. I am not entirely convinced why the housing movement is necessary as I would have thought the opposing pistons compensated for any slight diffrences in wear or position of the shoes. It maybe the movement of the servo housing helps centralise the shoes with respect to the adjuster ramps on the other side, as they are at an angle. But the empirical evidence is clear!

The brake team at the NEC spent a couple of hours pondering over the fitment of the springs and shoes. I gave them the relevant manual pages (or at least the Girling sheets on the matter, see link in first post but particularly here) and let them RTFM. They found they had two of the same shoe on each axle rather than different leading and trailing. Amazing how many faults exist on every Jowett I have ever inspected, especially around the braking area. I always mark each shoe as to which axle and which position they are fitted and mark where each spring and its colour is to be fitted. In quick change situations on rallies this saves a lot of thinking. RearNearsideUpper (RNU) and G Y at the correct holes. It is quite possible to fit the wrong shoe, in the wrong place and the wrong way round with the wrong spring in the wrong hole. All of which I think were tried on Sunday!

You work out how many combinations that is. 2 (perhaps 3) springs, 2 holes (unlikely to stretch the spring to the other two, but who knows), 2 (perhaps three) types of shoe, and 2 ways to fit each. I have also found non Jowett springs and shoes in one car and one drum with a piece of coat hanger to extend a non-Jowett spring.

Also Amy and I had a long discussion on how to fit the front springs but eventually decided the swan neck had to fit into the baseplate and the spring went behind the shoe.

The dimples that hold the shoe off the back plate also become worn and need building up to keep the shoe square with the drum. The early model has adjusters.

[Forumadmin]

And another point.

The PC car had a cross threaded brake pipe into a cylinder. The cylinder was being replaced anyway, but that is now not restorable. I recommended to the fitters (Amy, Jack, Rupert, Robert and Paul) that the pipes are inserted by hand prior to bolting up on the back plate. This allows easier alignment by 'finger feel' and saves replacing a £60 plus component!

If you do have a mechanic do your car why not point them to the relevant pages on this website. You never know they might RTFM.

[ian Howell]

Keith: -

It might be possible to restore the thread with a Helicoil?

Certainly this type of repair should not be regarded as a 'bodge' or of suspect integrity as Helicoils are used in many original equipment applications on aircraft - both military and civil - and they do NOT take chances!

In the case of the brake cylinders, the hydraulic seal between pipe and cylinder is on the 'olive' or bulge in the pipe - not imposing any threat of leakage past the threads, so no worries there.

[Forumadmin]

Must find a source of the requisite helicoil. I have a stock of casings many of which will have that problem, but the majority will also need resleeving. So another task for the winter months.

[Keith Clements]

As reported on the ' Breather hole ' thread our three cars were taken out for their spring clean.
The Javelin still had the clutch problem reported by Peter at Goodwood so it was up on the lift for adjustment. A test run proved that it had been fixed. So thankfully the engine did not have to come out. At the same time I put an extra shim in the the offside track rod as it was showing excessive play.
The brakes were pulling to the right and, with the issue with the rear brakes not stopping the wheels turning on the lift, I took both rear drums off. The shoes seemed to be a matched set and in the right place but a stone had found its way in and embedded itself in the lining, so hopefully that is the cause. But, since after another test drive, the pulling was still the same I will have a look at the front today. A similar problem on the SC last year proved to be mismatched linings.
It maybe there is a distorted shoe, so careful examination of wear is necessary.

[Keith Clements]

Inspection of the Jav front brakes showed oil/grease to have found its way to the shoes. The other side was fitted with sealed for life and hence no grease. I had done this as a test fitting new to both sides but one set sealed and one normal. I suspect the oil may have found its way through the corner spaceras the back of it was filled with oil and there was a dribble down the backplate. If I was going to use grease in the front again I would seal the corner spacer with silicone.

There was also some wear on the stub axle which will need some attention.

I have just ordered
LJ12RS Imperial Rubber Sealed Deep Groove Ball Bearing 1x2-1/4x5/8 inch
MJ3/42RS Imperial Rubber Sealed Deep Groove Ball Bearing 3/4x2x11/16 inch
from Simply Bearings.

The SA meanwhile is waiting for new foam for its Piper X air filters ordered from RamAir.
Air Filter Foam Material Universal Fitment - Size : 600mm x 400mm
This is a two stage filter system that I will also fit in the Javelin airbox where currently there are paper filters. After all the dust of Goodwood they probably need renewing.

Inspection of the keyway on the SC water pump is the next subject of attention.

[Keith Clements]

Well now I am confused. At some stage the drum on front wheel of the Jav must have been changed, as it contains a roller bearing that I have never (knowingly) put on the car. Indeed, on examination, it is a roller and not taper roller so I am worried that all the sideways forces have been taken by the outer bearing. See pictures below. The non standard spacer would bear down on both the inner and outer race, which would cause metal to metal contact with an outwards sideways force. If the sideways force was inwards, the outer race would bear on the oil seal which would then ride over the corner spacer. All the sideways force in both cases being borne by the outer bearing's cage.

I am extremely glad I noticed some lateral movement and chose to investigate. Where did this drum come from?

This also explains why the grease may have got to the shoes because the oil seal was hard. I am fairly sure the oil seals on this car were changed within the last 5 years.

I should have rotated the picture above 180deg so that the items were above each other.
Below the spacer is on the right , the outer race on the left and the inner race and cage of rollers in the centre.

The picture below shows some silver solder applied to the worn shaft, perhaps caused by the roller mod but more likely the 500,000 miles this car has done?

[Keith Clements]

After examination of the drum I am fairly sure this was originally fitted to the car (as it has the same paint on it). So my assertion that the drum had been changed, and that I had fitted new bearings at some stage are both wrong. It must have been a mod that the previous owner, Ben Shaw, was trying out . It cannot have been that bad a mod as it has lasted at least 20 years. But I am still not happy with it, so the drum will be converted back with standard bearings (albeit sealed for life) and a standard spacer.

I would think if we went back through the 1960's Jowetteers we would find details on this mod written by Ben.

Here is the entry in the index for a later mod for a taper roller where I am acknowledged as contributing.
Taper Roller Bearings 2003 Sep Page 22

The scan is perfect, it is the original which is illegible. If anyone has the original technical drawing it would be great to get it into the Gallery.
Double click on image and expand to get great detail.

[Keith Clements]

I have always run on standard bearings on the SA Jup through may thousands of hard driving miles with wide gripping tyres. So I do not think tapered rollers are necessary, but they are a better solution.

However, failure of bearings in the early days was cured by using non-melting grease Addmax B3. I am now using sealed for life bearings which are only about £15 per pair and just carry those in the spares kit. We changed one on top of a Rockie mountain on the Ted Miller commemoration run. But Scott had been hammering the car down the mountain the previous day.

[Srenner]

I'm not positive "hammering" is the correct word. "Spirited" seems a more apt description.

I do agree that sealed are the way to go, as IIRC, I made a bit of a mess trying to pack the spare with grease.

[Keith Clements]

Yesterday I fitted the new sealed bearings. They were pressed into the drum, outer first , then the spacer the correct way around, then the inner , then the seal (although this is now superfluous).
I put cyanocryolate ( Loctite bearing fit) onto them even though they appeared a reasonably tight fit. The bearing holding ring was fitted and the locking pin hole lined up, so the pin bolt was tightened. More Loctite on the stub axle bearing surfaces and the drum was screwed home. The drum was fairly tight to start with, possibly caused by the new seal, but the bearings are not free rolling when out of the packet. The brakes adjusted, centred using the foot pedal and adjusted again. There is now no play.
I was going for a test drive this morning, before taking the Jav to the rugby match against Leicester, but it is pouring with rain.

[ian Howell]

Keith said: -

I would think if we went back through the 1960's Jowetteers we would find details on this mod written by Ben.

I also seem to remember that PJGD produced some spacers so that he could fit tapered roller bearings to his car back in the 60's and also some drawings that MAY have appeared in Jowetteer (no Jowett.net then!).

'You there PJGD?

[Keith Clements]

Anyhow the weather cleared up and so out for a test drive, stopping off to see daughter's new kitchen. The fitters had managed to drill through the electrical cable which might have been excusable except the same guys had installed the cable in the wall! Quite how they will fix that remains to be seen.
Then off to pick up fellow Saracens supporters in the Javelin, make one hell of a noise drumming at the match, and back home to celebrate a good win against our old arch rivals. Major incident on the way back, the sun visor fell off. So that to do today plus try to get rid of a prop or wheel imbalance at 65-70mph. Goes away above 70 to become a smooth motor.