Renovation of front discs and calipers, replacing pads

I should mention here that most of the front end jobs were actually performed concurrently. Sorting the brakes meant I had to strip the hubs to get the discs off... and that showed  ball joint problem which led to servicing the upper wishbone. At the same time the rack has always needed renovation so that was done too. I've tried to give the jobs some structure with separate entries but this is really s bit artificial! A word of warning- many pad sets don't come with clips or anti-squeal plates so save your bits unless they are obviously unusable.


I started the front strip by removing the wheel... Horrorshow! Why does this car keep kicking me in the balls! It has clearly been a very long time since anyone has ventured in here - cobwebs, dust dirt and rust!

Initial view of front disc/caliper-looks way better in the pic than in reality!

Top ball joint boot split

I had hoped to leave all the suspension items for the time being as they "might" pass the MOT- however the boot was split on the top  balljoint which is an obvious failure so I will have to do this- since I am stripping the hub to get the disc out I guess now is a good time to do this as well...?

Stripping the caliper was the same as at the rear, unscrew the pipe unions, remove the pivot bolt and swing caliper up and push off. The Torque bracket comes off with two bolts behind... but

This was all incredibly difficult- the flexible pipes fitted at the front were a different design and had very slim flats making them almost impossible to grip in a spanner - they were also rusted solid so in the end I was forced to cut the pipes. Dont like doing this as its a bodge but then I'm not refitting these so what the hell.! The caliper then pulled off easily.

Caliper- single large (57mm) piston- not what I had expected. Rubbers all very poor and perished.

Caliper is one rusty lump!

Caliper- stub of pipe still attached. I couldn't unscrew this even when out of the car! 

I cleaned up the threads of the pipe union with a wire brush and left it to soak in penetrating oil overnight. I was able to unscrew it by clamping the metal part of the pipe in the vice and putting a spanner on the locknut.

The Torque bracket was very VERY tight on the wheel- it was a pig to unscrew the bolts despite penetrating oil and there isn't really much room to use a breaker bar. In the end I had to hammer the ring spanners and eventually they shifted and the bracket came off easily once they were out.
The pads were very worn but were fixed well in the bracket and were still sliding nicely. Anti squeal shim dropped out as it was rusty.

Pads very worn, torque bracket very rusty

Whether these were salvageable or not really comes down to whether I can remove the piston without damage. In fact and to my amazement, the piston pumped out easily using the grease gun on my modified nipple (that's not something you hear every day!). The piston wasn't damaged and as these are the  larger 57mm pistons they are more expensive than the smaller ones at the rear- its good to save a little money so I will try refitting the originals with new seals and boots. I may be jumping the gun and taking the other side on faith but I ordered a caliper repair kit w/o pistons from Bigg Red.

In the meantime I started the caliper on the degrease, derust and repaint process I had used for the rears. I  brushed the bracket and caliper in paraffin before spraying that off with carb cleaner and then sonicating at 60 deg for 2 hrs. I then soaked both components in DeoxC overnight before rinsing them well, and treating them with Jenolite and a wire brush.

As usual the DeoxC worked wonders. Jenolite treatment immediately after rinsing (without drying) has prevented flash rust. The calipers were then sprayed in alloy effect UHT paint.

The left side was then stripped

Left side front caliper- even worse!

Pads were very worn- and in this case incorrectly fitted as the spring clips have been left against the edge of the pad instead of under the recess- which causes the clips to stand away from the torque bracket- as in the rear calipers.

Loads of cobwebby detritus needed to be removed.

 Once more I gave up on unscrewing all the pipes and cut the hose in order to dismantle it on the bench.

I pumped out the piston with grease and then started the process of degreasing and de-rusting. The piston on this side did appear slightly scored. The markings aren't really detectable with the fingernail test so may not actually matter, but to be on the safe side I ordered one new piston. Its actually possible that some of this marking was done by the top boot circlip and I would suggest that in all cases the boot and its circlip should be removed before pumping the piston out.

I also needed to treat the discs with de-ruster this meant removing the hubs. I got a bit side tracked with them because of needing to renew oil seals and bearings. I have described the hub strip in another post and the disc clean up is in that one too.

I fitted the Bigg-red kit to the calipers exactly as before, lubricating the seal with brake fluid before inserting the piston.

Caliper renovation kit installed

I ordered new disc pads from Delphi. Their catalogue suggests pack LP17 is right- but they are not! Once out of the box it was clear that they are a completely different size and shape. The pack needed is LP0456 which doesn't seem to be listed on their web site at all? Perhaps its obsolete? I got mine as NOS at a a bargain price on eBay. The pads look pretty much the same as the rears but I can't compare them directly as I've fitted the rear ones already.  Anyway the pack says  for the Lotus Esprit, Excel and Toyota Celica and Supra- which all sounds very promising. Warning though- the Delphi pack doesn't come with clips or anti-squeal shims. There is a school of thought that says that new coatings on the rear of the pads make the anti-squeal shims unnecessary. I would still fit them but (stupidly) I have thrown the old ones away. The clip patterns and distributions are the same as for the rears- pics below.

Anyway- for the inner pad there are clips top and bottom that locate on lugs on the pad. The one nearest the caliper pivot shaft at the top of the torque bracket is the "strong stop" clip. This provides a firm base to take any rotational strain- at the opposite end is the "complex clip"- basically a spring clip with and external spring projecting away from the bracket and disc. The "wavy clip" is  a pad support clip and is installed between the strong stop and complex clips. It has three tabs on one side and two on the othjer. The tree tabbed side faces away from the disc and there is a cutout in the torqure bracket to locate the central tab.

On the opposite side, the outer pad is fixed by two "Vee" clips, their tangs face away from the disc position and their spring clips (the vee part) should rest inside the torque bracket facing down towards the disc when the caliper is on the car. this acts to spring the pad into the recess.  (see rear pad description for an explanation of the terms I'm using here)

overview of clips and pads installed, caliper assembled in torque bracket. Note Vee clip springs are located such that their projecting tangs face awat from the disc (toward the viewer in this pic) and that the Vee clips are located inside the cutouts in the pad springing the pad into the torque bracket. 

 However the pads were a really tight fit. I am reusing the clips here so perhaps a real "Delphi" fitting kit would make everything fit better; however as the pads aren't listed, the appropriate fitting kit isn't mentioned either. The pads did eventually go in and I was able to assemble both calipers to their torque brackets and set them aside until hub renovation is complete.*

I would add that if just changing the pads then these clips can be the work of the Devil. The lugs on the inner pads should be a smooth sliding fit inside the two inner pad top and bottom clips, mine weren't and I needed to bend them to fit more closely around the pad lugs. These two lug clips should also grip the torque bracket so they stay in place while you are trying to fit the pad- if you are reusing the clips like me then they probably wont so bend the bracket clipping tabs so that they do. The inner pad has a lower pad rest/support spring. This also needs to grip the torque bracket and stay there or you will have no chance so bend the small lipped tabs until it grips. Note that the side of the pad support with the three tabs faces inwards (ie towards the same face as the caliper slider spigot and there is a small cut out in the torque bracket to locate the central tab. I managed to get all three clips for the inner plate to stay in place on the bracket but even so I found it virtually impossible to fit the inner pad while the torque bracket was bolted to the hub. I  had to remove the two 19mm bolts to release it and fit the inner pad to it before fitting the torque bracket/inner pad assembly back into place. I could then fit the outer pad which is much easier owing to better access, visibility and simpler mounting clips- and then finally sliding the caliper back onto its sliding spigot- Hold it well up as you re-slide it on or it will knock the inner pad out of place again! You can then swing the caliper back over the pads and refit the swing bolt. NB its always wise to retract the piston using a spreader before swinging the caliper back down EVEN if you haven't changed the pads or disc as I found that the piston tends to move out once the caliper is removed.

Renovated calipers awaiting refit.

Dust shield reinstalled along with the renovated upper suspension arm (see separate entry)

Hubs installed (see separate entry)

Finally calipers reinstalled simply as reverse of disassembly.

Hoses now hooked up so next step is bleeding the system in the hope that there is nothing wrong with my master cylinder and I finally get brakes!

Front Hub Strip, bearings, oil seal and discs.

Before starting the strip and with caliper removed I tested the bearings and rotational resistance. The bearings seemed fine and turned smoothly without noise. I measured the rotational resistance using a spring balance- the hub rotated at well less than 10g of force.
***

First step is to remove the caliper- this pic taken before just to show the caliper and metal hub end cap. The metal cap is the primary exterior oil seal so its a really tight fit.

I found that I couldn't get a screwdriver blade in to dislodge it, but it moved easily enough using a old screwdriver ground to a point that would fit between hub and the metal cap.

Cap off- castellated cap nut visible

Close up of the way the split pin is bent

Remove the pin and the castellated cap just lifts off. To my surprise the nut below was only hand tight and unscrewed easily. There is a tab washer beneath which has to be removed and then the hub just pulled off with hand pressure

 I had a hub puller on order but it wasn't needed. The Hub did bind on the stub axle put was pulled off fairly easily with firm hand pressure. I think this locking onto the stub is probably a sign of wear in the bearing cage (see on) but its also possible that this firm pull actually did some damage? Surely wheel bearings cant be that fragile...?

Brake back plate dust shield on stub axle. The brake plate is retained by two fastening- an upper bolt from behind...

Bolt removed- its locating hole is visible in the back plate and the spigot/spcaer into which it screws is behind the plate in this view.

Brake dust shield back plate from behind. Note bracket which fastens behind to a bolt in the vertical linksteering arm. Note the spigot/spacer that the small bolt screws into (top). This has to locate into a hole in the vertical link side arm... I had problems because I didn't check this when refitting (see on)

This bolt passes through the back plate bracket which is then held on by a nyloc nut on this stud. Once the back plate was off I could see that there is quite a lot of grease on the vertical link- possibly therefore the seal has been failing and I should renew this.

Lower ball joint looks OK and the rubber is intact

On this side the upper ball joint also looks undamaged but if I am changing one side, then I will change both.

Rear of hub/disc assembly, oil seal centre- all very dirty and I think I got quite a lot of grit in the hub grease as I took it apart. I think if doing this again I would make cleaning the hub an essential step before trying to dismantle anything. The four bolt heads here fix the disc onto the hub.

It was hard to unscrew these bolts with a spanner as I could get no purchase on them. I couldn't find a way of holding the hub/disc part securely enough, so I used an electric impact wrench which shifted all four easily.

The disc remained stuck fast on the hub so I supported the disc on wooden blocks, hub downwards.

I could then fit a punch through the cut outs in the disc to contact the back of the wheel studs beneath. A few taps and...

The hub dropped out of the disc- again its very dirty. I couldn't find any problem with the bearing but I think I will have to clean it out completely and re-grease to make sure it continues to last.

The bearings seemed to be fine but the oils seal was dodgy and as I may have got grit into the hub during disassembly its probably as well to change them anyway.  The bearings are sets 2 and 6 consisting  of parts LM67048/LM67010 and LM11949/LM11910.  I bought the Koyo-made bearings. The oil seal is nitrile 48x62x8 (metric) or 2.445 x 1.89 x 0.315 (imperial). Its available as double  (R23) or single lip seals (R21) both with garter spring. I went for single but this will lead to a tighter bearing when setting preload than a double lip which would drag more itself.

Disc cleaned up nicely in DeoxC overnight followed by a brass wire polish

Similarly the dust shield came out well...

And was painted in Aldi metal protection paint.

 I then set about dismantling the hub to clean out the bearings. Removing the oil seal is done by putting a wooden block on the disc and levering against it- in my case of course the disc was already off. It was a bit more awkward but it came out in the end. When you lever the seal out like this make sure your lever is engaged with the underside of the seal and not the top of the bearing.

Using a block and a lever to pry out the seal- you will need all three hands. I recommend doing this before you remove the disc (see on) its much easier.

Seal came out. It as a metal cased seal which is obviously superior to the all nitrile seal I will replace it with- but it is 40 odd years old and it is leaking...

There is no nice way to say this- any further dismantling of the hub is the work of the devil. The whole thing is covered externally with grit and rust and internally with sticky disgusting grease. It is impossible to keep the two separate so I did what I should have done in the first place and refitted the seal and hub loosely back on the car so I could use Gunk (green) to clean everything thoroughly on the outside, all of the hub and the vertical link- wishbones. I waited, scrubbed and hosed everything off to achieve some measure of cleanliness- but its a disgusting job (see steering rack which was removed at the same time).

I then removed the hub again- picked out the seal and lifted out the bearings. I then set about spooning the grease out of the hub. There are times, and this is one of them, when I truly wished I hadn't started this job! After all the bearings did seem fine and if I had cleaned the hub and vertical link before disassembly I might have got away with keeping it clean enough just to fit a new oil seal.

Anyway- got new bearings... I went for KOYO Japanese which are OEM quality but were obtained at about half the price from Wychbearings.  I was then able to compare the old and new bearings. When under load there wasn't much difference in smoothness of rotation but the tapered nature of these bearings does allow a certain amount of "in out" movement of the inner bearing in its race. Here there was a difference. If you hold the bearing such that you are trying to press the balls out of the cage there is a small gap visible at the bottom. I have tried to show this below...

New bearing- pressing the ball cage backwards (gentle hand pressure), small gap between ball cage and  race- RHS

Old bearing- the same process opens a bigger gap

This clearance allowed the bearing to twist slightly on the shaft and this tended to lock the bearing on the shaft as I tried to withdraw the hub. Its possible therefore that some of this wear was actually made by me when I pulled the hub off! Was it hard to remove because it was worn- or is it now worn because it was pulled against being hard to remove?? In any event I am feeling that changing this bearing would be a very good idea.  Looking through the hub (past the outer race uppermost in this picture) towards the inner bearing there is a slot in the casting through which the rear of the race is visible

Slot inside hub gives access to back of race

Support hub on blocks

Using a punch tap downwards on the back of the race alternately on each side.

 The race can be tapped out from behind. Its important to use a tool with a plain flat end, it mustn't be sharp and you need to keep it as near to vertical as possible because the idea is not to scratch the inner surface of the hub. The ideal tool appears to be something called a soft chisel... I have no idea what this is or whether I have one so I used an ordinary punch. I checked that its end was flat and square and tapped carefully until the race dropped out. I could then turn the hub over and tap the smaller front race out in the same way

Tapping out front race on alternate sides of race to drive it downwards

 And front race removed

Until it drops out

 Fitting the new races is effectively the reverse, but make sure you fit them the right way round- the bearing has to be removable so the widest part of the taper in the race must point outwards.

The easiest way to ensure this is to place the whole bearing in position and then lift out the cage.

Offering up the whole bearing to make sure its the right way up and the cage is removable

Push the race down into the hub with firm hand pressure until it locks. When its down as far as it can go with hand pressure gently tap it down on the edges using your "soft" chisel. Take care not to slip or mark the inner surface of the race.

Race fitted with hand pressure- widest side of taper facing out

Tap it down carefully- I used a 12, 6, 3 and 9 O'clock pattern but keep an eye on it and if one side looks high then tap it down there.

Race fully home. 

 You can tell when the race is fully home as the sound changes- becoming more metallic. Also, because its hard on the hub shoulder, any tapping isnt absorbed and tends to bounce the hub upwards.

Front race installed in the same way

Test fit bearing- just to make sure I've got it the right way round!

 I will wait to grease the hub and bearings until I am ready to install them as once the grease is in the things become grit magnets. I stored the hub carefully with the ball cages that matched these races until I was ready to fit.

Store hub  with the ball cages matching the races installed.

 I was then able to remove the other hub and repeat the process. The following pictures are simply for my reference- they might be useful, but the method is exactly as already discussed.

 This side I left the brake disc on whilst I removed the oil seal. Put a supporting wooden block under the disc (not visible here as its below disc)  and a second above it on top so you can lever up the seal without rocking the hub/disc... much easier!

 I then detached the disc and placed it and the back plate in DeoxC whilst I cleaned the mucky grease out of the hub and fitted new races to this one too.

Cleaning the hub.

I put this into store until I'm ready to continue with the assembly, grease up and refit.
I reassembled the discs onto the hubs, cleaning the threads of the mounting bolts and using Loctite threadseal... then I did it again but the right way round!

OOps Discs mounted backwards!

Ahh better- discs reversed to correct orientation. using the cordless impact wrench

Attached with Loctite 2701 threadseal 

Refitting the Hubs
"The best laid plans of mice and men...." Who'd have known Robbie Burns had a Lotus???

Well dear reader- I hadn't expected any problems with this process- and therefore came horribly unstuck! I pushed grease into the bearings- no pictures because its a horrible messy job and I didn't want to get my camera filthy! Its easy enough- I usually wear 2 pairs of gloves and peel off the outer greasy pair once the bearing is greased so I can handle the hub without contaminating it. If you have any bubble wrap then you can make a hole in it and use this as a quick mask to protect the rest of the hub/disc from the flying grease!

Bubble wrap used as protection

Anyway greased bearing laid into hub...

Oil seal...

placed in position...

tapped in with Draper  seal press...

... and pressed home.

I then  greased the second (outer) bearing and loaded up the inside of the hub with grease before...

Loading up inside of hub with grease

bearing with grease worked in and...

dropped into hub.

...offering up the assembly up to the stub axle. Problems! The hub wouldn't slide back enough for the threads on the stub to emerge from the front bearing! This turned out to be due to an incorrectly positioned dust shield. The smaller of the back plate fastenings (which has a small spigot) hadn't entered its socket properly. I didn't think this was a problem at this stage and it was fairly simple to loosen this bolt, slip it into the socket and re-tighten. Problem was that fastening it in this incorrect position had unfortunately distorted the dust shield as I later found out! I went ahead and fitted the hub but it still wouldn't go back because it fouled the back plate. It turned out the central hole in the dust shield was no longer concentric with the axle. I did eventually fit the hub by tugging on the shield, but it fouled the edges of this hole making a terrible grating sound when the wheel was turned. I tried hard to re-position the shield with the hub in position but to no avail- the mounting bracket is I think bent out of shape by the misfitting event and I will need to re-bend it! This meant removing the hub again- and here I hit a snag because the inner bearing simply wouldn't pull off the stub axle. The outer was easily removed but nothing I did would shift the inner which was bound up on the taper on the stub axle. I had found this tended to happen during the strip and attributed it to wear- however that can't be the problem in this case  as the bearings are new so it must simply be a problem with taper bearings in general. I had no choice but to pull on the hub and of course this simply meant that the oil seal was pressing on the bearing trying to push it backwards and off the taper. Its not designed for this and so eventually the inevitable happened and the oil seal popped out. This allowed the hub to slide off, but it meant leaving the seal behind with the ball cage and inner race still attached to the axle... bugger!

Inner race and ball cage left on stub axle- oil seal still there behind! Dust shield hole is closer on left than right in this pic.

I now cannot refit the hub because the oil seal wont engage again and so I will need to use a puller to get the ball cage off- hopefully without damaging it. I can then re-bend the dust shield mounting bracket to get the hole concentric with the axle, reinstall the bearing and oil seal in the hub and repeat the attempt to fit the hub to the axle!!!.

In the meantime a thundery shower has drenched everything and sloppy wet grease- now grit encrusted- and greasy marks all over the brake disc are all things I was trying so hard to avoid. There ain't no justice! If I sound miffed- well its because I am!

Lesson: Test fit the hub before greasing or adding oil seal to make sure it will fit without fouling this shield!

Anyway... that sorted it with relatively little fuss- puller shifted the bearing- taking care to pull on the inner race not the ball cage- I don't think its damaged. A few attempts got the shield obviously more central and a test fit showed it wasn't binding. I re-seated the oil seal and refitted the hub which now turns without grating! I will seat the bearings and adjust preload before I fit a new split pin. With new oil seals the range works out at 3.4- 8.6 Newtons so a 10 newton balance should be fine.

I managed to set the hub to 6 Newtons. In fact the range is so wide that I don't think you would miss it just by doing it until it feels snug but smooth.

Installing new split pin (note this is a split pin...NOT as many call it, a cotter pin!)

... and finally tapping on the dust cap

I then refitted the caliper- no problems

Caliper fitted- hose is now connected!

... and the other hub- only slight event here was that the outer bearing (the small one) needed to be tapped gently before it would slip onto the stub axle, but it went OK and the hub seated without fouling the dust shield. Still to fit the second caliper but don't expect problems... famous last words I wonder...?