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mrsntw

Hi Folks,

I am looking to upgrade my differential to a LSD.  Here is the housing...

image1.thumb.jpg.051c3994a2b978b7e20e749a22c2a644.jpg

and here is the tag.

image2.thumb.jpg.0ce6f63aa4b3be44ba2c3e39b916424f.jpg

From what I have gathered so far, this differential is a 3.91:1 open diff from a ford scorpio (I could be wrong!).  Could I please have some advise on the best upgrade method for this as I still feel that I have a lot to learn on this subject and I'm sure many of you have a lot more experience than I do!

The reasons for wanting to upgrade to LSD are:

1) I have a ST170 Zetec engine sat in the garage which will be a nice swap for the 1.8 silvertop that is in the car at the moment.  I'm thinking throttle-bodies...

2) I would quite like to do some track days in the future.

Cheers,

Simon

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RussH

2) you can do a track day and have a great time without an LSD. Indeed, if you’re a novice (apologies for assuming) an open diff is a lot more forgiving, and less likely to spit you into the Armco backwards. 

From a novice trackdayer with an open diff :) 

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mrsntw

Hi Russ,

Thanks for the response.  The open diff that is currently in there has been absolutely brilliant for road use so far and I can only imagine it would be fine up to certain extent on track.  However I really did notice a huge different in corner exiting ability on my old mx5 track car with a quaife diff fitted to it.  I've never driven a kit car on track though so I could be comparing apples to oranges!

It's quite encouraging that your duratec westfield handles itself well with an open diff.

I would still like to have a upgrade route for this diff so I can make a choice as whether to splash the cash or not.

Ta.

Simon

 

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Dave Eastwood (Gadgetman) - Club Secretary

Just on a practical note, the other key thing, is that that's also a 7 1/2" diff, so if you buy internals to swap into it, you'd need to make sure you got 7 1/2", and not 7" versions. The simplest solution, is of course to swap your diff for an LSD version. At the point, you also need to consider if you just look for a diff of identical ratio, or something different. As to type of LSD, that's really down to what comes along, the Ford viscous type will be most common.

Alternatively, you could get your existing diff, rebuilt with LSD internals. This can get complicated depending on the type you want to go for!

How long have you had the car, and has it ever had the suspension geometry set up by a specialist? I would look to optimising the set up of the car itself, if it's not already been done, before starting to spend.

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mrsntw
1 minute ago, Dave Eastwood (Gadgetman) - Club Secretary said:

Just on a practical note, the other key thing, is that that's also a 7 1/2" diff, so if you buy internals to swap into it, you'd need to make sure you got 7 1/2", and not 7" versions.

How long have you had the car, and has it ever had the suspension geometry set up by a specialist? I would look to optimising the set up of the car itself, if it's not already been done, before starting to spend.

Hi Dave,

This may be a stupid question, but what exactly identifies it as a 7 1/2" diff?  

I have a receipt here for a geometry setup etc... at track developments in 2015 after a set of protech suspension was fitted.  

Cheers

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Dave Eastwood (Gadgetman) - Club Secretary

The outward signs are a physically slightly larger casing, and in particular, the top mount goes all the way across between the mounting bushes, whereas with a 7" diff it doesn't quite , so has a spacer at one side. Additionally, the top and bottom mounts on a 7" diff each have one stud that goes all the way across between the metalastic bushes, with a nut at either end*, whereas on the 7 1/2" it has bolts, instead.

*Though some, in particular those competing with their Westfields do like to thread the mounting holes the stud slides into on the diff, with thread repair kits, like Helicoils, so that they can use bolts too - it makes fitting/removal easier.

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CosKev
3 minutes ago, Dave Eastwood (Gadgetman) - Club Secretary said:

 

*Though some, in particular those competing with their Westfields do like to thread the mounting holes the stud slides into on the diff, with thread repair kits, like Helicoils, so that they can use bolts too - it makes fitting/removal easier.

Oh I like the sound of that,something to do next time my diff comes out:sun:

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mrsntw

Thanks Dave, excellent information and just the kind of thing that I was after.  I'll have to have a think about the kind of route that I am going to take and to whether any benefit is to be had from swapping from 3.91:1.  

If people have any recommendations of people who refurbish diffs and replace internals then I'm all ears!

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Dave Eastwood (Gadgetman) - Club Secretary

There are a few different recommendations I’ve heard recently, (I’d have to search out the names), plus the old favorites like SPC, Bara Motorsport etc

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mrsntw

I've had a few people mention Bara Motorsport now.  

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Dave Eastwood (Gadgetman) - Club Secretary

Yeah, if you do decide to go down the Ford Viscous type lsd route, they’re one of a small number of specialists that can actually fine tune and tweak the lsd for use in a car like a Westfield. And even if you don’t want to tweak it, they can still service the actual viscous pack itself, unlike most others, who only deal with the mechanical diff parts.

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CosKev

Dave Rae is another Sierra diff rebuild expert :)

Bara can change the fluid in the viscous LSD to suite a light weight car better than the standard Ford fitted due to the diffs going in cars that were almost double the weight of a Westfield from the factory :)

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mrsntw

Thanks for the responses guys!  

So, out of interest... If I found a 3.92 7.5inch Ford scorpio LSD on a popular internet auction site, would it be a straight swap into my car?  Or am I overlooking some other important aspects?

Cheers,

 

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Davemk1
35 minutes ago, CosKev said:

I've worked with Dave and couldn't be happier. He gave me good solid advice and was then able to provide me with the proper diff to fit my needs and ship it to me in the USA without issue.

Highly recommended.

dave

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