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Sierra uprights vs brake sizes?
falcor75 - 26/3/19 at 05:07 AM

I'm in the parts sourcing phase and I'm looking at Sierra uprights.
I want to run vented brakes in the front, due to the engine weight and hp but will any Sierra upright take a vented disc
or do I need the upright from a car that orgiginally had vented discs such as a DOHC or Cosworth?

jps - 26/3/19 at 07:32 AM

I think the uprights are all the same and caliperscaliper brackets varied to allow different discs.

I think most Sierras did run vented front discs, solid front discs only on the early lower powered cars I think (1.3 and 1.6)

Bluemoon - 26/3/19 at 08:32 AM

Originally posted by jps
I think the uprights are all the same and caliper brackets varied to allow different discs.

I think most Sierras did run vented front discs, solid front discs only on the early lower powered cars I think (1.3 and 1.6)

Have vented on ours with std pads. The consensus seems to be solids as you can't get the disks warm in a 7 even with a heavy engine.

falcor75 - 26/3/19 at 09:24 AM

Its more of a MoT demand over here. To get approved with the 170 hp engine the car needs to achieve a retardation of 8 m/s2 which the inspector said I'd have a good chance of doing with 280 mm discs.

COREdevelopments - 26/3/19 at 10:14 AM

You say you are in the parts sourcing phase? Have you found any sierra uprights? If not I can help you there. I have a set of recon uprights which I had done while back, been in storage and never been on a car since recon. Let me know if you're interested.



[Edited on 26/3/19 by COREdevelopments]

nick205 - 26/3/19 at 10:14 AM

My donor Sierra 2.0 Pinto had vented discs at the front. Replaced the calipers, discs and pads during the build.

mcerd1 - 26/3/19 at 12:49 PM

^^as above the standard sierra uprights are all basically the same and will fit the 240mm solid discs, 240mm vented or 260mm vented discs (with a different matching caliper for each)

but Cosworth 2wd cars used 283mm discs, these have a different offset and a massive 4pot iron caliper that has a totally different mounting and doesn't fit without alot of work (and its still not a great solution )

Cosworth 4x4 sierra and escorts both used 278mm discs with a different offset again and a larger single pot caliper - again this is not a strait fit on the standard upright...

you could use these larger cossie discs - but they'd probably be best with aftermarket calipers

also the XR4x4 discs are also 260mm vented (with the same caliper as the other 260 ones), but 4x4 discs have a different offset

I've got the measurements for most of these discs if you need them and a spare set of the 260mm discs calipers and the cossie 2wd 4pot calipers too

[Edited on 26/3/2019 by mcerd1]

falcor75 - 26/3/19 at 01:53 PM

Thank you everyone for the replies.

I was looking at getting Hi Spec Ultralite 4 calipers from the UK and planned to spec them for a 24 mm disc + trailing edge mounting.
Not sure if they mount directly to the upright or if I need the caliper mounts?

I have a lead on a pair of front uprights from a DOHC car here in Sweden but if that falls thru I'll let you know.

I've ordered all the tubing and some other stuff so I'll be back with a build thread once the madness starts.

mcerd1 - 26/3/19 at 07:51 PM

The later cars (like the DOHC) are more likely to have ABS

It's no big deal, just a hole that needs plugged if you dont leave the sensor fitted

se7ensport - 26/3/19 at 08:27 PM

If you are planning on competing in the car consider different uprights as the geometry of Sierra uprights are set to be “safe” and will understeer when pushed (cortina / escort / Westfield / Caterham all have a more aggressive geometry more suited to competition).

If for road use and an occasional trackday this won’t make any difference to you.

falcor75 - 27/3/19 at 05:08 AM

It will be 95% roadcar with one or two autocross events thrown in just for fun so the Sierra parts should be ok.
The concept is more "fun and smiles" rather than outright speed.

Nickp - 27/3/19 at 06:43 AM

My 230bhp/630kg Haynes runs 260mm vented discs and std Sierra calipers. These are more than enough at Blyton Park, which is notoriously hard on brakes, even with fairly crappy EBC Greenstuff pads. TBH I think I could get away with a decent road pad

rdodger - 27/3/19 at 10:42 AM

Rally design do Wilwood kits for Sierra. p;x=0&y=0

hughpinder - 27/3/19 at 01:11 PM

You would definitely have a good chance of achieving 8m/s2 with 280 disks - the Caterham R500 only has 254mm vented front disks as standard and does 100-0 in 3.6 sec (11.85 m/s2). These are the same size as on a standard mx5 1.6 I believe.

If you can lock the wheels without undue effort you don't need bigger disks to slow faster - you need better tyres and/or suspension. Obviously bigger diameter disks are effectively bigger levers so you will achieve lock up at lower pedal effort (or you could use a smaller brake master cylinder for the same effect assuming they are big enough to hold the amount of fluid to move your calipers and this does not add undesirable unsprung weight). In a real race situation bigger disks can absorb more heat for those continuous maximum braking effort with short gaps parts, so bigger disks may be better. Just looked up the 'big brake kit' dor the R500 - only goes up to 260mm disks.