Rear Brakes

SteveWood · Post by **SteveWood** » Sat Feb 11, 2023 5:00 pm

Having finally managed to extend my working space at home its time to start work on my Javelin. First job - sticking rear brake. Having done the usual checks and adjustments its time to get inside the drum. Hints and tips on removal and replacment would be greatly appreciated before I start. replaced and rebuilt brakes on a number of cars but never a Javelin!

cheers Steve

Keith Clements · Post by **Keith Clements** » Sat Feb 11, 2023 6:07 pm

viewtopic.php?p=46816#p46816

SteveWood · Post by **SteveWood** » Sat Feb 11, 2023 11:19 pm

Thanks for the info - I really need advice on removing the brake drum and how tight (is there a torque setting?) for replacing the hub nut. I can't seem to find this info in my workshop manual?

Nick Webster · Post by **Nick Webster** » Sun Feb 12, 2023 1:01 am

I have removed the rear drums using a fabricated puller made of a ring that was held on by all 5 studs and a cross piece with a substantial bolt/pusher to engage the end of the half shaft. I was a bit wary in case the drum should crack, but it did work. A better idea is the proper tool that screws on to the threads on the drum which seems to me to be the strongest part. The club had one of these in a tool library which (l may be wrong) these days is in the custody of Jowett Car Spares. Worth also contacting your local area secretary - some members do have them but they are so precious they likely come with the owner who will assist in usage! Least, that's how I feel about mine.

Tightening the nut is mostly dependent on getting the holes lined up for the split pin. I don't know a torque figure, but I tug mine up with a 2 foot bar. How much you struggle to get the nut off will be a clue. The important thing is not to back the nut off so approach the final few degrees with care. I use a single headed ring spanner and bar so I can see the top of the nut relative to the shaft.

One final point of note is that it is important to maintain the sliding action of the wheel cylinder on the back plate. If it is too tight the shoes will not be able to self centre.

Nick

David Morris · Post by **David Morris** » Mon Feb 13, 2023 9:33 am

Hi Steve,

All the advice above is very useful, so study carefully. I recommend using either a puller on the studs or the screw-on fitting on the threads provided on the centre of the drum. When tightening the screw on whatever type of puller you are using, don't just tighten up and hope for the best. As you are tightening, give the head of the bolt a regular set of heavy thumps with a lump hammer. It's the shock that will unstick the taper.

Beware that when the drum releases, it will fly off! Stand well clear.

If your back axle is fitted with mechanical brakes, do check the condition of the Woodruff key. These early axles are pretty weedy and the key can start 'fretting' and cause a sloppy fit. The later full hydraulic axles are bomb proof, and have a different thread for the extractor.

If you find that when refitting the drum, that the drum just will not go over the shoes, there is a cause that took me quite a long time to discover. The expander at the bottom of the back plate has two sliding pegs. After you have stripped everything down and are reassembling, it's quite easy to get these pegs round the wrong way. It will all look ok by eye, but you need to get the sloping faces on the pegs fitted so that the pegs are set to their minimum insertion depth. Fitted incorrectly, the pegs will stick out too far. They will look right, but they will lift the shoes out too much and make fitting the drum impossible.

Also, as Nick says, make sure the hydraulic cylinder can slide on the backplate. There should be special coil spring washers under the nyloc securing
nuts, to keep the cylinder secure but allow a degree of sliding self-centering action. It's best to give this area some red brake grease upon reassembly, as the back plates will get showered in water from the wheels. Once back on the road, you need to keep this area regularily greased or oiled.

All the best,

David

David Morris · Post by **David Morris** » Mon Feb 13, 2023 9:44 am

Hi again Steve,

Upon reading what I have submitted, I see that I have omitted to answer your question on the torque setting for the hub nuts. I liked the words Jowett's used in the manual for their Stationary two cylinder engine. They said nuts on the engine were to be either 'tight' or in extream cases to be 'blxxdy' tight, or words to that effect. I suggest the latter applies to the hub nuts. They are big nuts on big threads and I doubt you will be able to fracture them by hand. Something like 85ft/lbs should be enough.

All the best,

David

Keith Clements · Post by **Keith Clements** » Mon Feb 13, 2023 10:23 am

There are a few things to check.
1. make sure the taper is not shiny as this means it is not tight. The taper should not be greased.
2. make sure the washer on is contacting the drum. Wear often means it is not. This may be bodge fixed by filing the shoulder on the axle or chamfering the washer.
3. Make sure there is no oil or grease or brake fluid on the shoes or back plate.
4. make sure the shoes are contacting evenly. The pimples on the backplate control this and can be welded or an adjustment screw fitted to get the shoe alignment correct.
5. make sure the drum is not rubbing on the back plate. The drum can be bodge fixed by grinding but the cause may be a worn taper or incorrect shimming.
6. check wear on drums. This will affect the bedding in of new shoes.
7 . Check stretching and threads on hub studs.

SteveWood · Post by **SteveWood** » Mon Feb 13, 2023 5:18 pm

Thanks all. Wonderfull advice as always - just waiting for the hub puller to arrive.

SteveWood · Post by **SteveWood** » Fri Feb 17, 2023 4:55 pm

Quick update on progress: Having purchased a good hub puller, 60cm breaker bar and a socket big enough for the hub nut I finally managed to get some time to start on the rear brakes. With the car still on the ground I removed the split pin in order to try and turn the hub nut a little before jacking the car. Imagine my surprise when the hub nut turned once the split pin was removed as I tried the socket for size, and then once the car was jacked up I removed it by hand and then after attaching the hub puller removed the brake drum by hand as well!!! Result.

One seized cylinder removed and new ones on the way.

Nick Webster · Post by **Nick Webster** » Fri Feb 17, 2023 9:10 pm

My sympathies for your wallet, but you know what kind of a job it would have been if you had not bought all the right gear! Sod's law applies in every case. At least you can put it together properly.

Nick.

Chris Spencer · Post by **Chris Spencer** » Sat Feb 18, 2023 12:08 pm

Steve - If you are fitting a new rear brake cylinder you may well find it next to impossible to refit the brake drum over the shoes so before you rebuild everything strip the new cylinder and remove the white plastic mushroom type plungers from each side of the cylinder then reduce the top face of them by 1mm and reassemble prior to fitting to the backplate and you shouldn't have any issues - The rear cylinders supplied are generic to a few manufactures and are identical with exception of a slightly wider fully retracted / closed tolerance than that of the original cylinders - Its a simple fix that will save you hours of head scratching

SteveWood · Post by **SteveWood** » Thu Feb 23, 2023 9:38 am

That explains the slight binding I can't get rid of!

Keith Clements · Post by **Keith Clements** » Sun Sep 03, 2023 1:48 pm

David suggested 85 lb ft but I would suggest more based on similar axles. At least 100lb ft.

The Yorkshire manual would say 'bloody tight' so you need at least a 15 inch wrench to controllably acheive this torque.

The hub must be tight on the taper otherwise wear will occur quickly. Sometimes the washer needs to be recessed to acheive this. The torque should be at least 100lb ft so DO NOT SLACKEN OFF TO PUT SPLIT PIN IN. If necessary shim to acheive hole alignment.

The socket for the Salisbury/tube axle hub nut is 1 5/16" AF (same as for the crankshaft pulley nut). On wire-wheel cars this has to fit down inside the splined tube, which is about 1.87" ID. Some have reported difficulty in getting one to fit, but my 1/2" drive came off the shelf and is 1.73" OD so fits easily. Maybe the problem is with 3/4" drive or impact sockets. Hub nut torque is 150 ft lb, with a split-pin. Tighten to that then (like front hub nuts) to the next split-pin hole, there should be two at near right-angles in the half-shaft which should mean less than a castelation

From MG forum.

Post by **Forumadmin** » Mon Sep 04, 2023 7:51 am

Or read this thread.
https://forums.jag-lovers.com/t/rear-ax ... c/352867/6

or from the manufacturers service manual page 23
https://www.google.com/url?sa=t&rct=j&q ... i=89978449

Axle Flange to Wheel Hub Nuts J175-S Only 5/8" - 18 8 Steel 160 - 185lb ft 217 - 250 newton metres
OK it may not be the 3HA axle but not much changed.

or here

https://www.winget.co.uk/wp-content/upl ... -AXLES.pdf

RECOMMENDED TORQUE TIGHTNESS
Axle Shaft Nut - 130/140 lbf.ft (175/190 Nm) THE HUB NUT.
Bearing Housing Nuts - 38/43 lbf.ft (51/58Nm)
Brake Cover Nuts - 65/75 lbf.ft (89/102 Nm)
Brake Pressing Cover - 19/22 lbf.ft (26/30 Nm

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