Rear brake upgrade for DAX40

[Dave Bilyk]

Hi all,
just mocking up for rear brake upgrade, and looking for any constructive comments.
I am interested in the HiSpec Monster handbrake caliper upgrade. I took the main dimensions from the catalogue as a starting point, and mocked up the caliper in Turbocad, together with the components on my car. The original Ford sliding caliper design is configured to save space, so the wide 4 pot caliper pushes the disc position inward so that there is a conflict of space with the original mounting lugs. The only answer seems to be to weld a lug onto the fabricated upright as in the sketch, drilled and tapped to take the radial mount caliper. The upright is fabricated from 1/4" plate, so should be man enough, maybe with a little bracing to maximise stiffness to avoid judder.
This is just a mock up to see how it all goes together, so not intended to be a final design layout.
Anyone else done anything like this?

Cheers
Dave

[Dave Bilyk]

Hi, I forgot to add that because of the conflict of space between disc and original lugs, I would have to cut them off.
To view picture, click on 'Attachment' just under the title, and click on the icon to see full resolution.

Dave

[Dave Bilyk]

Update on rear brake upgrade.
I finally decided on and ordered a set of components for the rear brakes, not easy because of space limitations, but with some light machining I found a set of components that will do the job.
discs are Wilwood 7705 / 7706 309.6mm diameter 20.6 thick with 35mm universal bells.
Calipers are Hispec Billet 4 Handbrake with adapters to suit, everything was ordered just before Christmas.

The disc diameter is a bit larger than I wanted, but has to be 310 to clear the caliper mounting bolt heads on the ford rear lug. I can adjust front brake specs and master cyl dias if necessary to optimise the balance.
The discs and bells arrived on the 4th of Jan, so I await the calipers and adapters to do some test fitting and confirm the machining I need to do.

Apart from the normal machining of spigot diameters and stud holes in the universal bell, I find that the bore of the bell tapers in, so I will need to decide whether to open that out or reduce the od of the hub flange. Also, I need to machine the bell to bring the wheel further in and increase thread engagement which is not sufficient as it stands. All this I can decide when I have the components in hand and double check everything before I get do any machining done.

A cross section of everything as it stands follows, and a pic of the discs and bells rec'd follows.

[Dave Bilyk]

Finally : received rear calipers and brackets from hispec. Test fitted ok, now machining to get final wheel to caliper, lug bolt to disc bolt, clearances and disc centralisation.

[Ian Anderson]

Dave

Looking good and very neat

What will you do for a handbrake?

Ian

[Dave Bilyk]

Thanks Ian, they are hispec billet handbrake calipers, if you look at the second picture, just above the lower blue nyloc nut, you can just make out the circular hole in the black support where the cable outer sits. Just below the nyloc nut, you can just make out the shiny handbrake operating arm. They are very neat, lets hope they have the holding power!
Concentrating on getting everything else right at the mo, will fit the handbrake cable next week sometime.

btw. Have you been up this way to visit your brother yet? be sure to let me know if you do, be great to meet and see our cars together up here.

[91740Gt]

Dave,

Looking good and well thought through.
May i just suggest that you do not use nyloc nuts on your brake assemblies.
Use non melting lock nuts such as Bink with a drop of thread locker if unsure. I have known of three assemblies vibrating loose under extreme heat build up through the melting of the nylon locking ring.

Graham.

[Dave Bilyk]

Thanks Graham,
your advice is appreciated, nyloc nuts out. I did a search on Bink, but didnt find anything, but I remember seeing nuts with a slotted end or ring and bent in to help grip the bolt thread.

[David Morton]

Dave,
Give Acorn a ring. Their contact info is:

Mail: Unit W4 Lambs Business Park
Tilburstow Hill Road
South Godstone
Surrey RH9 8JL
Telephone: (01342) 893500
Fax:(01342) 892820
EMail:sales@acornfastenersltd.co.uk

regards
Dave M

[Ian Anderson]

Dave
Very neat and presumably all fits neatly inside the 15 Inch rims.

No not been up to Scotland yet but perhaps this year - Car is in for a gearchange mod (I need more than 3rd, 4th and 5th!) Also seems that my front springs are far too soft - get them stiffened a bit with a new set.

So after that time for some miles and shakedown My Daughter normally spends time with "granny" in the August hols so time to collect her in the 40????

Ian

[Dave Bilyk]

David,
thanks for that.

Ian,
yes they fit fine within the 15" rims, just need to position the disc carefully as you end up with about 5mm caliper to wheel spokes, and 2.5mm clearance between the disc and caliper bolts.

My gearchange is ok but slow, because of moving a few kg of steel rod, I have been wondering about using ally tube, but I have a lot to do before I come to that.

If it helps, my springs were F 200lbf/in, R 250lbf/in (about 1.4Hz) which was far too soft and too much adjustment needed to get ground clearance. I went up to 300 / 350 which is still quite soft (about 1.7Hz) but much better for adjustment. I am sure that I could go higher than that, and certainly would if it was for track use alone.

Let me know when you come, and I'll treat you to a beer and a barbecue at my place. Hopefully mine will be back on the road by August!