And so it begins -- picked up 2017 Mustang GT IRS yesterday!

[richtersand]

Ordered my complete kit a couple weeks ago (ship date October 10). Called around to local salvage lots and found a complete rear suspension with 3.73 ratio about 10 miles away. Picked it up yesterday and dropped it in my garage. This is the first non-forum "work" I've done for the car, so it's gettin' real! Hung a ceiling hoist in the garage to drop this from the truck and hope to use it to drop the engine/transmission in when the time comes.

Any suggestions/advice for breaking this rear end apart??

132658

132659

[Railroad]

Nice score. You might want to start planning around the 3.73 gears if you keep them. Do you know if you got a Traction Lock or a Torsen carrier. There are some threads on what will work off your purchase.

[edwardb]

Get out your wrenches and have at it. Pretty straightforward. Did the same thing with my Roadster build. 99% certain all 3.73's are Torsen. That's a premium piece (at least based on price :p) but as already mentioned, at 3.73 make sure it fits into your overall plan.

[richtersand]

Thanks guys. I'll do a little digging on the Torsen vs. Traction Lock.

Can you please elaborate what you mean by "make sure it fits into my overall plan"? Do you mean that I should make sure that the transmission ratios play nice with the differential ratio? I am planning TKO 600 2.87 (1st) 1.89 (2nd) 1.28 (3rd) 1.00 (4th) .64 (5th).

Thanks much!

[frd2]

but equally as important - what engine / cam shaft / rpm range etc.

Greg

[richtersand]

Sorry, should have included more detail... planning the Coyote 5.0 power plant...

[Fixit]

Did the same with #9365... a 1000 mile takeout.
Take a look here (https://thefactoryfiveforum.com/showthread.php?27544-The-40-Watt-Garage-9365-Annoying-Rattle-Resolved&p=317059&viewfull=1#post317059)

[richtersand]

Did the same with #9365... a 1000 mile takeout.
Take a look here (https://thefactoryfiveforum.com/showthread.php?27544-The-40-Watt-Garage-9365-Annoying-Rattle-Resolved&p=317059&viewfull=1#post317059)

Wow, sounds exciting. Thanks for the link. I'll let you know how it goes for me...

[CraigS]

Thanks guys. I'll do a little digging on the Torsen vs. Traction Lock.

Can you please elaborate what you mean by "make sure it fits into my overall plan"? Do you mean that I should make sure that the transmission ratios play nice with the differential ratio? I am planning TKO 600 2.87 (1st) 1.89 (2nd) 1.28 (3rd) 1.00 (4th) .64 (5th).

Thanks much!
Exactly. My guess is you will be fine w/ that gear and trans. A more standard trans has a shorter 1st gear which might be a bit much w/ a 373 rear but your's I 'think' will be fine. Your 5th looks good also. It is the taller of the two commonly in use so will be good w/ the 373. Either type lim slip works fine w/ the Torsen probably the most desirable for high performance use.

[Hacksaw84]

Ordered my complete kit a couple weeks ago (ship date October 10). Called around to local salvage lots and found a complete rear suspension with 3.73 ratio about 10 miles away. Picked it up yesterday and dropped it in my garage. This is the first non-forum "work" I've done for the car, so it's gettin' real! Hung a ceiling hoist in the garage to drop this from the truck and hope to use it to drop the engine/transmission in when the time comes.

Any suggestions/advice for breaking this rear end apart??

132658

132659

If it came with the 3.73 from the factory its probably a Torsen. You can check the tag on the diff to confirm. The 3.73 Torsen is what came in the performance pack cars. That is what I have.

[edwardb]

If it came with the 3.73 from the factory its probably a Torsen. You can check the tag on the diff to confirm. The 3.73 Torsen is what came in the performance pack cars. That is what I have.

There's an echo in here. Post #3 :)

To the OP, the caution wasn't about the Torsen. It's fine. I have one in my new Coupe build and other than hearing it clacking around a bit (a common observation from the Mustang crowd as well) I like it. The question was about the 3.73 ratio. 3.55 and even 3.27 are probably a little more common for these builds. Especially if you have plenty of power, which your planned Coyote has. But you need to look at the whole picture. That's what several of us meant by asking about your plan. Engine + transmission + diff ratio + tire size + planned use all factor into the decision. Based on what you've said so far, the .64 5th TKO is the right choice. With the .82 version you'd be north of 2800 at 70 mph, which just isn't necessary especially with a Coyote. Worst case, build it with what you have and the ratio can be changed. Still keeping the Torsen limited slip piece.

[Hoooper]

Just out of curiosity, how much did that full takeout run, and are you planning on keeping the mustang brakes?

[richtersand]

Thanks all, really appreciate the feedback. I am learning A TON on this forum. You guys are going to keep me out of trouble on my build :D


Just out of curiosity, how much did that full takeout run, and are you planning on keeping the mustang brakes?

Full takeout set me back $1280 from local SoCal salvage yard. Yes, planning to keep the stock brakes (no power brakes). My current plan is if there's not enough stopping power stock then I can always upgrade front brake setup down the road to Wilwoods...

[richtersand]

PS -- I found this calculator on FixIt's thread and it helps with the calcs. Thought I would repost here if it's helpful to anyone else...

Tremec Gear Ratio Calculator: http://www.tremec.com/calculadora.php

[Hoooper]

Full takeout set me back $1280 from local SoCal salvage yard. Yes, planning to keep the stock brakes (no power brakes). My current plan is if there's not enough stopping power stock then I can always upgrade front brake setup down the road to Wilwoods...

Makes sense, I figured the brakes are what makes the takeout make sense. My diff and knuckles set me back about $400 but that doesnt include any brakes and also is the much cheaper clutch type LSD.

[Hacksaw84]

There's an echo in here. Post #3 :)

To the OP, the caution wasn't about the Torsen. It's fine. I have one in my new Coupe build and other than hearing it clacking around a bit (a common observation from the Mustang crowd as well) I like it. The question was about the 3.73 ratio. 3.55 and even 3.27 are probably a little more common for these builds. Especially if you have plenty of power, which your planned Coyote has. But you need to look at the whole picture. That's what several of us meant by asking about your plan. Engine + transmission + diff ratio + tire size + planned use all factor into the decision. Based on what you've said so far, the .64 5th TKO is the right choice. With the .82 version you'd be north of 2800 at 70 mph, which just isn't necessary especially with a Coyote. Worst case, build it with what you have and the ratio can be changed. Still keeping the Torsen limited slip piece.

Yeah I was trying to help answer his question on how would he know what locker he has. Not that it matters too much just so he knows. You were first in saying its probably the Torsen ;)