Board logo

Sierra and Cortina geo differences - what are they?
james h - 13/11/16 at 03:15 PM

I'm on a quest to find out how much unsprung weight I can save - a swap to alloy Cortina uprights and hubs would be preferable to the heavy cast iron Sierra items.

What are the differences in geometry? Would I be able to just lengthen the top wishbone and steering arm, or are there other issues to consider?

Cheers

James

Sam_68 - 13/11/16 at 04:03 PM

Comprehensive, is the short answer: they are not directly interchangeable in any way.

phelpsa - 13/11/16 at 05:03 PM

quote:
Originally posted by Sam_68
Comprehensive, is the short answer: they are not directly interchangeable in any way.


However on a lot of kits that can take either the only difference appears to be the top wishbone length....

Doctor Derek Doctors - 13/11/16 at 06:31 PM

I sold my old Cortina uprights to a guy with an MK Indy R with Sierra uprights and all he had to do was get some slightly longer top wishbones.

What it did to the geo I don't know, but the actual change was pretty straightforward.

james h - 13/11/16 at 07:39 PM

Sounds like it could be feasible. I'd be interested to hear from anyone has actually done this directly. And then work out if it is actually worth it of course!

kingster996 - 13/11/16 at 08:27 PM

I've gone from Sierra to cortina on my Westy. So Sierra SDV front end to Westfield alloy uprights and hubs and as well as that I also went widetrack at the same time.

Handling feels much sharper, precise and more immediate. Sierra uprights felt slow but solid in comparison. Definitely prefer The Cortina geometry.

james h - 14/11/16 at 12:11 AM

Looking at this more, since the disc bolts onto the back of the hub for a cortina upright, I'll need new front discs.

Will the wheel offset change?

kingster996 - 14/11/16 at 04:41 PM

Yes, you need discs and possibly different brakes too - I managed to get adapters for my Wilwoods.

Wheel offset was no problem (ET38 worked for me on both even though most Westies use et24 ish on Cortina uprights) - but of course, that might be different for different makes of kit?

loggyboy - 14/11/16 at 04:47 PM

Also worth looking at Escort Rs2000/Capri uprights, which are broadly similar to cortina but very common due to continued Mk1/2 escorts for rally use.