All the info is very confusing. I spent ages trawling web sites, old manuals
and the outcome is that the diff is either a 3.62 or a 3.67, the estate had
a 3.9 or a 4.1.I've had similar dealings before running Mk11 rally cars and
to be honest, if it didn't pull right I changed the tyres until it did. I
suspect I shall do the same with the Locost and if the worst comes to the
worst, I've only paid £40 for the set up so far and I know where there is a
Chevette stood with a LSD.
All the books show that the gearing is pretty similar between the manta box,
XR4x4 diff and the standard Cavalier set-up. I guess we will have to wait
and see.
I'm going to Stoneleigh on Sunday, and I hope a few of my questions will get
answered there.
Dave
Yep the Fiesta Mk1/2 axles were pretty chunky and would make a good
if narrow base.
I misunderstood I always thought that 3.62 axle was the ratio used
in the standard 1600 and 1800 Sierra and that the bigger models used
taller ratios while the 1300 and 1600 estate used a 3.9.

--- In Locost_Theory@y..., "McHaffie, Aiden" <macdave69@h...> wrote:
> Thanks for the replies,
> As always when deciding on a project, things change. As I couldn't
get good
> power on a budget or get a Ford to fit comfortably, I've gone to
plan Z. So
> I am definitely using a Cavalier SRi 130 unit. This is mated to a
Manta 1800
> 5 speed box and the Ford XR4x4 axle.
> As I have bought the bits, there is no going back.
> I am using a de dion set-up and have read the debate with interest.
As far
> as tube size, I have used a rear axle from a Mk2 Fiesta, I have had
to
> fabricate an adapter (for want of a better word) to join the Sierra
hubs to
> the Fiesta axle as it is 4 1/2 inches shorter, The Fiesta has a
nice bend to
> avoid the diff and appears quite substantial. I have the design for
the
> adapter on AutoCAD, should anyone want it and although it is
obviously
> untested, it doesn't look amiss.
>
> When I read awm's response about the gearing, I recoiled in horror
but after
> 4 hours surfing, I am happy that the advantages of the LSD will
outweigh the
> tall gearing. Incidentally the diff ratio on the Cavalier is 3.55:1
so
> 3.67:1 is actually a slight improvement. I intend to run 15 inch
wheels with
> 50 profile tyres, which should help the gearing a little and I hope
the
> lightweight nature of the 7 will overcome any bogging of the line.
And if it
> doesn't work, I'm sure someone out there will have a solution.
>
> Anyway, the project has started, officially! and it is nice to be
on board.
> Dave (Chesterfield)