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Is it LSD or not?

HappyFather - 26/3/18 at 04:43 PM

Hi people!

I have a friend doing some restoration work on a Sierra XR4i he bought recently. He pulled out his diff and we're trying to understand if it is LSD or not.

The tag on the torx bolt is of no help: 88GG JB 392. I looked it over on http://www.super7thheaven.co.uk and I got no match. The only time 88GG matched was to a Granada but there was no code ending in JB. Usually for a diff to be LSD there should be at least one A on the code ending but the 7th heaven states clearly that there are several exceptions to the "A" rule. So...

With the diff out of the car, the following 3 tests were done:
1) rotate input shaft: both outputs rotate on the same direction.
2) hold the input shaft and rotate one output: the other output rotates on the opposing direction.
3) rotate input shaft: both outputs rotate on the same direction; hold down one of the outputs and the other output keeps rotating on the same direction.

So... 1) behaves as LSD but because of the lack of attrition it may be a false positive.
2) is a clear case of open diff.
3) left us baffled as we were expecting that, being open, holding one output should have made the other rotate on the opposing direction.

Maybe we understand nothing of this. So we come for the collective help. Without opening the diff case, can we tell if this is LSD or Open? Any other test we could do to be certain?

Thank you all for looking into this mysterious diff story! Kind regards,
Duarte HappyFather Loreto

theconrodkid - 26/3/18 at 04:48 PM

spin the input and both outputs go in the same direction = LSD..ps , send us some sunshine please

adithorp - 26/3/18 at 05:51 PM

LSD

James24785 - 26/3/18 at 07:12 PM

Sounds like non LSD to me.
A normal diff will send power to the path of least resistance. Hence why if you hold one output, the other spins.

mark chandler - 26/3/18 at 07:50 PM

2) spin opposite ways, a LSD would be fighting you to do this so its open.

ReMan - 26/3/18 at 09:10 PM

You need to look closer to home!
http://www.locostbuilders.co.uk/forum/3/viewthread.php?tid=85080&page=2
JB codes appear to be export.

Either way just open the back cover and look whats in it!

I'd have said 2.0 xr4i were non lsd and only xr4x4 but assail theres anomolys in all of them so open it up!

mcerd1 - 27/3/18 at 08:26 AM

quote:
Originally posted by mark chandler
2) spin opposite ways, a LSD would be fighting you to do this so its open.

^^ what he said - it sounds exactly like an open diff or at least a dead LSD

If the LSD is working properly its actually quite difficult to force the outputs to turn in opposite directions by hand - it will still allow the wheels to turn in opposite directions (it wouldn't be much use as diff if it didn't

) but it should be noticeably more difficult to do this than with an open diff, even with the extra leverage the wheels give you when its still on the car

both outputs rotating the same way when you turn the input just means they have the same amount of resistance to turning at each side (ie. the same as if you drive a car with an open diff on a strait road with plenty of grip

)

Personally I wouldn't trust the tag on the diff all that much - they are quite easily changed after all and who knows what the history of this car really is...

but that said a 2.0 XR4i would be most likely to have a 3.92 (7" ) or 3.91 (7.5" ) open diff - I told the LSD was an expensive option and only the 4x4 models and cossie's are guaranteed to have it as standard

from one of the old threads on here - pics of the inside of a ford LSD

viscous lsd

Ho ho. 3.62 written inside. Ford always did this. Handy!

basically the bit behind the crownwheel is fatter and has the split in the flange - as you can see even with the back off its not that obvious unless you know what your looking for

[Edited on 27/3/2018 by mcerd1]

nick205 - 27/3/18 at 09:39 AM

Were XR4i's not V6 engines?

A neighbour had one when I was a nipper - I recall being impressed with the rear spoiler arrangement

mcerd1 - 27/3/18 at 09:55 AM

quote:
Originally posted by nick205
Were XR4i's not V6 engines?

I think there was a 2.0 DOHC one towards the end

I'm only guessing its a 2.0 as the 2.8 & 2.9 V6's would have had a 3.62 or 3.64 ratio and that tag did suggest its a 3.92 ratio

nick205 - 27/3/18 at 09:57 AM

quote:
Originally posted by mcerd1

quote:
Originally posted by nick205
Were XR4i's not V6 engines?

I think there was a 2.0 DOHC one towards the end

I'm only guessing its a 2.0 as the 2.8 & 2.9 V6's would have had a 3.62 or 3.64 ratio and that tag did suggest its a 3.92 ratio

OK - wasn't aware of that history - just assumed they were all V6.

mcerd1 - 27/3/18 at 11:45 AM

quote:
Originally posted by nick205
OK - wasn't aware of that history - just assumed they were all V6.

you could even get a 2.0 pinto version of the XR4x4, but they are as rare as hens teeth, just like the 4x4 mk3 granada and the 2.3 petrol transit connect....

not sure how many they made, but the V6's are far more common

https://www.howmanyleft.co.uk/vehicle/ford_sierra_xr4_i#!engine
https://www.howmanyleft.co.uk/vehicle/ford_sierra_xr4i#!engine

saying all that the car the OP is talking about could be a V6 thats had the diff swapped to get better acceleration...
or the diff tag could have been taken off another diff and who knows whats really inside....

[Edited on 27/3/2018 by mcerd1]

HappyFather - 1/4/18 at 07:28 AM

Thanks for all the answers!

This Sierra is indeed a 2 litre engine XR4i (2wd) and it was sold originally in Portugal, thus the "88GG" code for "export cars". I didn't know that but it explains why the 7th heaven had no track of that code.

Do note I'm based in Portugal. I bought the kit parts in the UK (2010), had them shipped to Portugal. Built it here, got it in a trailer to the UK for IVA and registration (2015) and I'm now on a over-two-year process trying to import the car (no luck so far and starting to look grim )

Portuguese law at the time penalised enormously "high cc" engines. So, there was even a <1.8cc bracket for which some manufactures made special "portuguese" versions. A V6 here would be too tax-heavy and that is also why the most Sierras in Portugal are 1.6. So, we had many 3,14 diffs around. Harder to get is an LSD version at any ratio.

From the UK I can only get the LSD's at around 500 pounds. From Latvia and the likes I can get around 250 pounds but unseen and I'm afraid I'll be buying a non-LSD stated as LSD. So I'm trying to buy locally.

In this specific case, if the seller doesn't want to open it for the final check, I'll leave it be. The lack of "A"s on the final bit of the code and the behaviour are screaming "open" too loud...

Once again, thank you for all the answers and the images on how to tell if it is an LSD looking inside!
Cheers,
Duarte "HappyFather" Loreto

@theconrodkid This year we've been having rain (or light rain) 3 or 4 days per week. Nonetheless I've sent some sun in the mail. Just can't be sure it will arrive, our post service is going down the drain...

jacko - 1/4/18 at 01:20 PM

no3 the info on the 5 photos came of the internet

No1 and as far as a know are correct

no2