Brakes Upgraded

The plan is to upgrade the rear brakes to discs and the front to multi pot callipers. The front of the car has a Mk5 Cortina sub frame and suspension with 5 stud Granada hubs fitted. The rear end is an Atlas axle with the addition of a slick LSD, most likely of the Capri origin. The rear hubs will also be modified to a 5 stud set up.

So the major upgrade work will be at the rear of the car. The disc brake upgrade is planed to be to standard sierra 253mm discs and callipers. This should supply ample rear end stopping power along with handbrake.  

Rear drum brakes stripped out.

Half Shaft & Hub removed.

Once the half shafts have been removed the they can be cleaned checked then prepared for the 5 stud adaptor and disc brake upgrade.

First job is to remove the wheel studs ready for the adaptation bolts and long main stud.

Half Shaft inspection.

While the floor pans are out the  brake pipes are secured to the chassis. The entire pipe and clips are then painted for ultimate protection and longevity.

Rear 5 Stud Adaptor & Disc

Front 5 Stud Adaptor & Disc

Once the 5 stud adaptor had been manufactured (click here to see the adaptor) the new rear disc can be fitted to the existing 4 stud hub. The adaptor bolts on from the rear with three 12 x 1.5 x 30mm cap head high tensile bolts. The fourth bolt is a long stud that replaces one of the existing studs. This stud also acts as one of the new 5 studs on the adaptor. Once disc is clamped between the original hub and stud adaptor the half shaft can be replaced in the axle.

Completed with 5 Stud Adaptor & Disc

Next job is to mount the the calliper. This will require the manufacture of a calliper bracket that can bolt to the Atlas axle. The the calliper carrier will bolt to this and the sliders will then centralise the calliper to the disc. Well that’s the theory, but as there will be some serious forces at work here the axle bracket will have to be designed with a little bit of clever mechanical anti rotational strength as well as just good old plane robust strength.

Drum Brake Spacer

To replace the space taken where the drum brake back plate use to fit, between the axle flange and the bearing bolting plate, a spacer has been manufactured. This enable all the bolting surfaces and distances to be maintained, as the new calliper will bolt from the very back of the axle flange.

So a rethink is required to make sure the required strengths can be archived without excessive weight. Have looked at a large recessed disc (Saab Vigen) and felt the weight of it the idea has been scrapped in favour of a standard Ford Sierra 252mm thin recess disc. This will be used with Sierra Cosworth Callipers and will require mods to the calliper brackets that were planed as the bracket will need to have spacers of over 20mm. This will result if high torsion twist because of the length of the spacers and bolts from the static mounting bracket.

So fist job is to manufacture the rear bracket, this will bolt onto the rear of the axle flange. To archive this socket head 10mm x 40mm bolts will have their head diameter reduced by 2mm and then used as studs from the rear of the axle flange. This reduction in head diameter is not necessary on the top to flange mounts but required on the lower 2. Dear Mr. Ford please machine your parts accurately... idiots! Actually they even messed up the machining front to back as well as top to bottom. Don’t think they have come across the term centre line.   

Rear Bracket Complete

Rear Axle Bracket Manufacture

The recessed section of the rear bracket mounts flush to the rear of the axle flange whilst the overhang section fits above the axle flange preventing any possibility of rotation. Using just three mounting points and a cut away arc allows the bracket to be fitted to the axle without the need for a major strip down.

Front Bracket Complete

Front Axle Bracket Manufacture

The recessed section of the front calliper bracket is used as the spacer that replaces the old drum brake back plate. This bolts into place using the new studs. The top portion of this bracket is then used as a spacer which is now tethered to the axle.

Front Axle Bracket Manufacture

Finally a spacer is manufactured to fill in the distance between the rear calliper bracket and the front. Again this spacer sits on top of the axle flange so that once the calliper bolts pass through the rear, spacer and front calliper assembly and into the calliper itself the whole assembly become incredibly strong and extremely stable, even before the half shaft is bolted into place.

Next it’s time to paint and protect the calliper brackets and then bolt the whole assembly together and set up / test the calliper position on the nice light weight disc. So that should be bye bye heavy cumbersome drum brakes hello nice efficiently, lightweight easily maintained disc brakes.  Well once we complete the set up and get a new handbrake cable that is.

With the rear and front brackets in place and the spacer between them the four  high tensile cap headed bolts are passed through the brackets, axle flange and bearing retaining plate. Once the cap head bolts are tightened they are used as studs and nuts then secure the retaining plate. Now the calliper can be bolted to the ears on top of each bracket.

Cap head bolts used as studs

Calliper in position

Calliper with handbrake

With the calliper installed, the hydraulic pipe work and handbrake cables can be tested for position. The existing pipes and cables will be replaced for new once the opposite side of the axle has been upgraded to 5 stud and disc brake. There has been a lot of talk about Atlas axles not being able to be 5 stud with disc brakes. Happily this was all wrong and is relatively straight forward despite the total

inaccuracy of Ford mass production during the 1980’s. Today +/- 0.1mm is bad practice, apparently back then if it fitted with a hammer blow that was good enough.  

Top of Page

Click for the Rear End Rebuild

Complete Brake bracket Assembly

Only two things left to do with the brake upgrade. One is to fit a flexible pipe from the callipers to the axle. Even though the callipers move with the “live axle”, brake pad changes need to be fast and bleeding the brakes because of fixed brake lines is a just not on. So a T will be fitted in the centre of the axle and solid pipes will run to each axle end. From here flexible hoses will run to each calliper.

The last thin to fit is the new handbrake cable. This will be shortened and joined and to be honest the original set up is so way OTT it’s a laugh.

Original plates OMG!

The original handbrake lever mounting plate was made from 2x6mm thick solid steel plates with a space between for the cable lever. 6MM Good Grief! Lets try 2mm steel with milled slot and nicely drilled positioning holes. Much better.....

With the new cable hooked up to the callipers and and the cable holders slotted to allow quick cable changes the cable length is adjusted to suite the handbrake lever position. This involves splicing the cable and using a joiner to reassemble.

New Machined Mount

Cable on calliper

New Mount, Cable Splice  & Lever

Final touches to the handbrake

The rear brake upgrade is now complete all we need now is some cylinders and pedals to make it all work

Flexible Brake Hoses