Scorp Diff into Sigma

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Scorp Diff into Sigma

Postby C_Fernance » Mon Jun 14, 2010 2:16 pm

The old Borg-Warner diff in my GH Sigma is on it's last legs. It's leaking oil and has heaps of play in it. It needs to be replaced asap. If i'm going to do this i may as well go to a stronger diff and disc brakes. A Scorpion diff would be perfect, and lucky me i have a couple spare.

For a long time i have said that the Sigma and Scorp diffs are a straight swap, as long as you use the right diff. GE and GH sigmas need a GH Scorp diff (can use a GE Scorp diff but these are smaller), and GJ and later Sigmas need to use a GJ and later Scorp diff. However i'm now finding out there are a few small issues.

For my GH Sigma i've used a GH Scorp diff. The diff housing itself does indeed bolt straight in. Lower control arms are exactly the same. Upper control arms are different where they bolt to the diff. Use the Scorp upper control arms and there is no problem. Unfortunately this means no more sway bar unless you want to get the welder out. Springs are interchangeable, and for shocks you can use Scorp ones (mine were the same as the Sigma anyway). The Scorp lower shock mounts use a different thread size on the nut so make sure you get the nut, etc with the donor diff or you will have to try and find some.

The flexible brake hose from the body to the diff are slightly different lengths - the Sigma is a couple of centimeters longer. I used the Scorp hose as the difference seems to be where it attaches to the diff. Not sure how the master cylinder will handle disc brakes instead of drums long term, but seems reasonable after a quick drive - will update it the next couple of days. I do have a master cylinder from a disc brake sigma i could use though.

Hand brake cable is a straight swap, but you need to use the Scorp cable to suit the disc brakes. Attached fine and works better than the old one.

Biggest issue has been the tailshaft. The flange that bolts to the diff is different between the Borg-Warner and Jap diff. A Scorpion 1 piece tailshaft may work but i didn't have one handy to try. Managed to find an easy enough solution - use a flange from a Galant. I've got one here out of a GD Wagon. It uses a Jap diff, and the flange bolts straight onto the GH Scorp diff. It also uses the same universal joints as the Sigma tailshaft - RUJ1786. Just swap the rear flange on the tailshaft with a new universal joint and it should be good to go. Later Scorp diffs use larger diameter bolts, you may be able to drill the galant flange out to suit, get some bolts made up with a step in them, or swap the flange on the diff itself.

Got it all in and working with a weekends worth of work. It could be done in one day if you had all the tools, universal joints, etc ready so you didn't have to organise parts. Overall it's a lot better than the old diff - but a lot of that could be due to going from a worn out diff to a good one. No more funny noises, no more jerking on gear changes as it takes up the play in the diff, etc. The only part that wasn't 'bolt-in' was the tailshaft flange, it should be done with a press, but I managed to make do with a hammer and a couple of sockets.
Last edited by C_Fernance on Mon Jun 14, 2010 5:12 pm, edited 2 times in total.
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Re: Scorp Diff into Sigma

Postby rob020 » Mon Jun 14, 2010 4:55 pm

:thumpsup: this should be stickied or put in some kind of "knowledge base" section or something
"launching missiles? who do they think i am? iraq? where would i get a missile from?" "that means rocks too dumbaass" "oh"
conversation recently overheard at police station after big night out
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Re: Scorp Diff into Sigma

Postby Cipher124 » Mon Jun 14, 2010 5:15 pm

^^^ I strongly agree, good write-up!
1980 GH Chrysler Sigma SE - Project - Now with 4G54 wideblock and 5spd BW. Getting it back on the road!
2008 Volkswagen Golf 2.0 TDI Pacific - The daily

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Re: Scorp Diff into Sigma

Postby cheaterparts » Mon Jun 14, 2010 7:15 pm

C_Fernance wrote:
For my GH Sigma i've used a GH Scorp diff. The diff housing itself does indeed bolt straight in. Lower control arms are exactly the same. Upper control arms are different where they bolt to the diff. Use the Scorp upper control arms and there is no problem. Unfortunately this means no more sway bar unless you want to get the welder out.



from memory chris the links that go from the lower control arms towards the diff for lat support are also different use the scorp ones

as for the rear sway bar sigmas steer better with out them
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Re: Scorp Diff into Sigma

Postby C_Fernance » Mon Jun 14, 2010 7:34 pm

The lower control arms + the smaller lateral arms look the same, but there may be a difference as i never actually checked if the Sigma ones fit the Scorp diff. I left all the control arms on the Scorp diff, so it's now got all Scorpion arms in it.
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Re: Scorp Diff into Sigma

Postby Sigmaproject » Mon Jun 14, 2010 11:18 pm

I have read that before. If you are after a scorp diff for your Sigma, make sure you get the control arms as well as the diff housing and brake cable.

I have been using a disc/drum master cylinder for years with my disc/disc setup. Every year my rego inspection include a drive onto a Platetronic brake tester.

Perfect brake balance 8-)
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Re: Scorp Diff into Sigma

Postby Billsy » Tue Jun 15, 2010 10:03 am

i swapped a scorp diff into a gk with the sigma arms, they are interchangeable.
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Re: Scorp Diff into Sigma

Postby GC75 » Tue Dec 14, 2010 7:34 am

moved :thumpsup:
Previous owner of a GC Coupe, a few GSRS and random Sigmas.
Converted to the Ultimate Driving Machines
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Re: Scorp Diff into Sigma

Postby C_Fernance » Sun Jun 05, 2011 12:47 pm

Seen other people having issues with the flange so I thought I'd post up some pics.

[IMG]http://i58.photobucket.com/albums/g275/c_fernance/WP_000150.jpg[/IMG]

[IMG]http://i58.photobucket.com/albums/g275/c_fernance/WP_000152.jpg[/IMG]

On the left is the original Sigma flange. On the right is the Galant flange. As you can see they both use the same universal joint - RUJ1786. The Galant flange has the bolt pattern to suit a Jap diff as that is what the Galants use, and by using the same uni joint means it is a straight swap onto the Sigma tailshaft.

Didn't get to take a pic of a Scorp flange. They look similar to the Galant, but use a differnt uni joint which means they don't fit the Sigma shaft.
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Re: Scorp Diff into Sigma

Postby Shifta » Mon Jul 25, 2011 2:04 pm

Good read that! Anyone know if the flexible hose being shorter is the same issue with GK to GK conversions? I'm thinking it might be one of those little things that holds up my progress as I didn't get the hose out of a Scorp with my diff. Good tips with the Galant flange - I was lucky enough to have a GB wagon tail shaft in the shed and it looks like that uses 12mm bolts whereas the Scorpion Diff takes 14mm. I'll look at either drilling them out or trying offset bolts.
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Re: Scorp Diff into Sigma

Postby C_Fernance » Mon Jul 25, 2011 7:25 pm

The later Scorp diffs do use larger diameter bolts. The GE and GH Scorp diffs had the same size as the early Sigma's and Galants.
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