germansheperd
New member
I ordered a set of gears today and I'm going to change the differential. I run a Detroit True Trac in my Mustang, what's the set up people like for IRS?
What diff is everyone running in these hi tech irs rear ends?
- Thread starter germansheperd
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driller
El Presidente
Set up? Like gear ratio? Or differential model?
The Detroit TrueTrac is what I have in the Blue Flame with 4.30 gears (it needs 4.56s or 4.88s).
My '96 has a Ford Trac Lok with 4.10s.
The Terminator CE has an Auburn differential with 3.73s.
A NA bolt-on street Mark VIII seems to do well with 4.10s if you can live with the highway revs. Most boosted Mark VIIIs seem to go with 3.73s.
The Detroit TrueTrac is what I have in the Blue Flame with 4.30 gears (it needs 4.56s or 4.88s).
My '96 has a Ford Trac Lok with 4.10s.
The Terminator CE has an Auburn differential with 3.73s.
A NA bolt-on street Mark VIII seems to do well with 4.10s if you can live with the highway revs. Most boosted Mark VIIIs seem to go with 3.73s.
germansheperd
New member
Anything to know or need to put a Truetrac in an IRS carrier? The one in the Mustang has been great and I'd prefer to go this route again.
KStromberg
Vortech kicked in yo
I run an Auburn Pro Series in my car. 1.5 sixty foots which is "above average" for these cars. I pretty much launch just as hard as a P90D tesla electric and those cars are instant torque.
mlschultz
Boost King
410 and trac lok for my 4300 pound with me in it street car. :thumbsup:
https://youtu.be/UNqg9u-D0hw
https://youtu.be/UNqg9u-D0hw
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driller
El Presidente
Installation in the IRS housing is somewhat different than in a solid axle car obviously. While not 100% necessary, a case spreader is utilized to set up the differential with appropriate side shims. You will also want to get new halfshaft bearings and seals since they do not accompany the typical installation kits. Of course you would be looking for 28 spline units.
germansheperd
New member
and that's it to put a true Trac in a Mark IRS?
tonybrooklyn
New member
I run 3.73's, trac loc, Ford Motorsports gears works great.
Set up is very important or noise and vibration is un bearable.
I was lucky as an employee of mine was raised in a shop. Where his grandfather did nothing but rebuild Manual transmissions and rear ends.
Its not as simple as it looks.
Get the shop manual and its possible good luck!
Set up is very important or noise and vibration is un bearable.
I was lucky as an employee of mine was raised in a shop. Where his grandfather did nothing but rebuild Manual transmissions and rear ends.
Its not as simple as it looks.
Get the shop manual and its possible good luck!
germansheperd
New member
I've got 3.73s coming just picking out a diff now.
germansheperd
New member
How has the Auburn held up? I see it accepts the ABS tone ring, if that's anything to consider I don't know.
KStromberg
Vortech kicked in yo
It has about 30k on it with lots of aggressive driving and launches.
tixer
Lincoln Evangelist
Understatement of the year, right here.....
driller
El Presidente
On the IRS, you remove the housing from the car which IMHO makes the installation of the gears and differential an easier job.
In my experience, the Auburn unit is sensitive to friction modifier.
KStromberg
Vortech kicked in yo
I run royal purple 75w140
germansheperd
New member
Royal purple straight with no friction modifier added right?
germansheperd
New member
I believe your right. With my TrueTrac I just run straight Royal Purple.
Ford 4:10, used trac-loc from a non-IRS mustang. Fully rebuilt at home. Made a home made case spreader. The bad Shoe production diff rebuilding video helped tremendously. And some help from Doug(RIP) and Driller.
If you stick with ford gears you can reuse the pinion depth shim from your diff. No need to measure pinion depth.
If you stick with ford gears you can reuse the pinion depth shim from your diff. No need to measure pinion depth.
germansheperd
New member
I bought the Ford 3.73s