Spacing the Brake Rotar equidistant in the Brake Caliper Center

[Peter Truman]

I've just spent a fruitless day trying to fit Type 14 Calipers onto the daughter Mk2 Spitfire. After dismantling the caliper, front hub, and backplate from the front vertical upright assembly to bend the backplate ends so the backplate cleared the bigger Type 14 caliper I started the reassembly removing the old incorrect mechanical seal between the old rear hub bearing and the vertical upright at the stub axle to be able to fit the correct new felt seals GHS146.

The new felt seal had been oiled well the compressed over 24hrs to get excess oil out it wouldn't fit over the raised annulus the stub axle goes through & is part of the vertical link, nearly fitted but an oversized socket had to be pushed in to get the felt ID larger than the annulus 36mm OD, finally achieving a clearance and after cleaning the front and rear bearings and greasing them I assembled the hub onto on the stub axle and tightened the hub up then slackened off to rotate it.

Then I offered up the caliper to the vertical upright the caliper centre rotar groove wouldn't clear the rotar fouling the outer face of the caliper groove, so I removed the caliper, hub and rotar, the felt hub backing steel disc had collapsed ie pushed in onto the inner bearing virtually seizing the bearing, it appears the inner dia of the felt seal backing plate/washer is also 36mm fouling the vertical upright stub axle mounting annulus, I think there are multiple issues the felt seal doesn't clear the upright annulus, and maybe the rear bearing inner race protrudes too proud of the hub so when the felt seal is compressed it's steel backing is pushed backwards seizing the inner bearing race.

My temporary solution was to cut the felt seal off it's steel backing fit the thinner felt seal over the vertical upright annulus and then fit the hub on sans the locating felt seal backing washer/plate ie now the felt seal runs up to or abuts the inner bearing race, NOT ideal. The bearings I have fitted are Japanese of good quality BUT are they a match for the originals re overall width of the race?? Oh in this arrangement tightening the hub up on the stub axle it won't lock up it still runs free!

The old mechanical ie rubber lip seal I removed showed signs of its outer metal case rubbing on the upright annulus! The car has done over 25k klm like this!

One solution re the caliper fitting is to file off the rear of the caliper mounting lugs so the caliper can move forward, but that's a bridge too far, Oh the Type 14 caliper has exactly the same offset and distance from mounting to the rotar groove as the removed Type 12's.

Any ideas anyone

[Colin Lindsay]

I'm trying to picture the components from memory. New versions of these felt seals are terrible, often too large, so I for the Herald I get the original Unipart GHS110 (I think!) and they're a simple straight slot-in fit. If the stub axle won't even go through the centre then yours is definitely wrong, and more so if it's holding the hub out so that the disc fouls the caliper. That part number of yours, GHS146 is listed by some for both Herald and Spitfire, but I know the Herald is GHS110 or  PAYEN NA988.

Try the assembly with no seal - this will give you an idea of how it all fits, and will confirm that it's all correct, and you can see how the disc fits into the caliper. The original method was to fit without the seal, torque all up, mark where the castellated nut sits then release, fit the seal, and replace to the original marks with no torquing so the seal is expected to cause some distortion, but not as much as you're experiencing. 

[Peter Truman]

I've been thinking overnight about the issue of the felt seal metal retaining ring fouling the upright stub boss/annulus ie it won't fit over it, so I'll machine it down to fit over ie say 38mm ID vs 36mm OD for the boss/annulus, then fit that now separate metal ring into the hub to restrain the rear bearing, with the clearance the inner rebated flat of the ring shouldn't be distorted back onto the bearing which stopped the bearing turning, a job for later today or tomorro!

Only issue then is that the felt seal will be running on it's retaining ring rather than the boss/annulus, I can live with that!

I'll order 2ea new GHS110 and GHS146 from Rimmers as spares or later permanent fix's, and if they are too tight re ID I'll get them enlarged to clear the boss/annulus 36mmOD, the felt can be cut down re thickness provided it's done before oiling, did that on the Sprint, NEVER had any of these issues with the Vitesse, which has a separate caliper mounting bracket.

[Peter Truman]

As above I ground out the ID of the felt seal metal retaining ring to 38.5mm ie larger than the 36mm boss/annulus tapped it up to the rear of the back bearing. I then assembled the hub onto the stub axle tightened it up backed it off a couple of flats, hub spun ok, then undid it all to ensure the rear bearing still span ok and the felt seal retaining ring hadn't collapsed on it, all ok rear bearing held in place and running on felt washer, ALL HAPPY!

Rebuilt Type 14 caliper & pads fitted and all centered to the rotar ok, then new SS and carbon fiber effect poly coated braided hoses fitted, now just to check all bolts are tight and bleed them BLO*DY brakes, then drive the car to my daughters, 350Klm up the coast. 

[Puglet1]

That sounds like a good job!👍

[Jbc562l]

I had the same issue and using a Stanley knife to cut the felt seal in half gave me the correct endfloat and disk/calliper position. See pic for the original seal before surgery.

I used a tiny drill as a guide to cut seal at correct height.

[Colin Lindsay]

That's a good solution and saves a lot of hassle!