Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: Mike2909 on February 24, 2014, 12:08:53 PM

Title: Diff Build Question
Post by: Mike2909 on February 24, 2014, 12:08:53 PM
When I bought the Wrangler TJ  it was advertised with a Detroit TrueTrac LSD in the rear diff.

According to the gen info I received on Birtys this LSD does not need the Mopar LSD friction modifier.
I received the build sheet for the TJ from Chrysler and it has my rear diff down as
DRKS Heavy Duty Dana 44 Rear Axle
DSAP Trac-Lok Differential Rear Axle

How (if possible) do I identify which LSD I have in the diff. The PO I bought the TJ from told me one of the POs that competed with the TJ told him he had the Detroit LSD fitted when modifying the rear axle ( disc brakes) Jeep to compete with the TJ.

Or should I just add friction mod or could that do any damage to the Detroit ( if that is fitted)?
He changed the front axle to Dana 30 from a Cherokee when he fitted the lift kit etc.

Title: Re: Diff Build Question
Post by: bigjeepzj on February 24, 2014, 01:30:51 PM
When you take the diff cover off
the diff will look more like this

(https://birtydastards.com/frm/proxy.php?request=http%3A%2F%2Fwww.off-road.com%2Fimages%2Fcontent%2F22a-Silicone-Jeep-Wrangler-Axle-Gear-Differntial-12-7-11.jpg&hash=46089054f57787c68fe98bc796a7389797632971)

not

(https://birtydastards.com/frm/proxy.php?request=http%3A%2F%2Fwww.off-road.com%2Fimages%2Fcontent%2F6-Rear-Differental-Removed-Jeep-Wrangler-Axle-Gear-Differntial-12-7-11.jpg&hash=902ca9160292a5dc6ced70a35974f7a912fa31d6)
info at http://www.off-road.com/jeep/project/jeep-wrangler-tj-build-g2-gears-detroit-truetrac-mit-drivetrain-work-53362.html
Title: Re: Diff Build Question
Post by: Mike2909 on May 19, 2014, 04:58:53 PM
It looks like this-- minus two teeth  :010: :010:

Changes ahead I reckon.
Title: Re: Diff Build Question
Post by: georgen on May 19, 2014, 05:06:31 PM
That pics a Standard LSD trac loc
Title: Re: Diff Build Question
Post by: Wildfire on May 19, 2014, 05:16:13 PM
Mike
that's an 'Open' diff not an LSD by any type.

If it is jacked up - with both wheels off the ground - turn one wheel and watch the other;

if it rotates the opposite direction - Open Diff
if it rotates the same direction - locker or LSD.

Sorry Bud!
Title: Re: Diff Build Question
Post by: Mike2909 on May 19, 2014, 05:26:25 PM
Mike
that's an 'Open' diff not an LSD by any type.

If it is jacked up - with both wheels off the ground - turn one wheel and watch the other;

if it rotates the opposite direction - Open Diff
if it rotates the same direction - locker or LSD.
Sorry Bud!

No worries , it's too late to complain now and I who checks inside the diff when you buy?
You are correct though, when jacked up it rotates opposite way. I couldn't understand why someone would replace the original Dana 44 with a  Dana 35 just for the disc brakes seemed a stupid decision.
I was only going to change the fluids and when I took the cover off the 2 teeth were laid in the bottom, it was still driving OK but I kept hearing a clunk from the rear.
The metal tag on the diff does say LSD though.

Title: Re: Diff Build Question
Post by: Mike2909 on May 19, 2014, 05:40:24 PM
Considering my options now as to what to replace/change on the diffs /axles. :017:
 I can't afford Willos axles  :jpshakehead: and don't have the required knowledge to fit them anyway.

I am thinking  :017:, go back to a 44 on the rear and then try and find a 44 for the front, add lockers and then hopefully that will survive the 35s.
I have a 5 speed manual with a NV231J transfer case with 272 ratio. The diffs presently have 3 73 ratios so I need to do some homework to find out what that all means  :003:

Title: Re: Diff Build Question
Post by: georgen on May 19, 2014, 05:46:29 PM
The Trac loc looks like an open diff, but has clutch packs on each side out of view, now ive opened the pic to full size you can see end of shafts so as you say its been swapped for a 35, normally have rubber bung for oil fill not threaded plug like 44. also 44 has a large strengthen rib running down passenger front side of  diff housing plus does not have C clip shafts.
Title: Re: Diff Build Question
Post by: gazjeep on May 19, 2014, 06:03:25 PM
When we had to re-gear our Auto TJ, went for 4.10 gearing & true trac LSD's front & rear. Young Bryn will testify to their effectiveness yesterday at Harptree comapred to open diffs

Parts from Randys Ring & Pinion ordered by me & fitted by Bubba (Kev aka MJS) on here. He has all the bearing pulling gear & you wont find a better or cheaper job ...... he's done loads.

Good £ / $ rate at the moment too 
Title: Re: Diff Build Question
Post by: Mike2909 on May 19, 2014, 06:38:32 PM
Why did you go for 4.10 gearing ?
Title: Re: Diff Build Question
Post by: Mike Pavelin on May 19, 2014, 06:59:41 PM
Mike
that's an 'Open' diff not an LSD by any type.

If it is jacked up - with both wheels off the ground - turn one wheel and watch the other;

if it rotates the opposite direction - Open Diff
if it rotates the same direction - locker or LSD.

Sorry Bud!



Nope, that's definitely a trac-Loc.
Title: Re: Diff Build Question
Post by: isle of man on May 19, 2014, 07:03:09 PM
and find a 44 for the front, add lockers and then hopefully that will


Good luck finding one that won't cost £££ to get it under the TJ !!
Title: Re: Diff Build Question
Post by: Mike2909 on May 19, 2014, 07:37:32 PM
and find a 44 for the front, add lockers and then hopefully that will


Good luck finding one that won't cost £££ to get it under the TJ !!

Good Luck is something I am in short supply of.
What is the next best option for the front 30 or 35?
Title: Re: Diff Build Question
Post by: isle of man on May 19, 2014, 07:58:17 PM
and find a 44 for the front, add lockers and then hopefully that will


Good luck finding one that won't cost £££ to get it under the TJ !!

Good Luck is something I am in short supply of.
What is the next best option for the front 30 or 35?

What is your current tyre size? And current lift ?
Title: Re: Diff Build Question
Post by: Mike2909 on May 19, 2014, 08:12:33 PM
and find a 44 for the front, add lockers and then hopefully that will


Good luck finding one that won't cost £££ to get it under the TJ !!

Good Luck is something I am in short supply of.
What is the next best option for the front 30 or 35?

What is your current tyre size? And current lift ?
Tyres 35x10.5x16  with 6" lift.
Title: Re: Diff Build Question
Post by: isle of man on May 19, 2014, 08:23:14 PM
For a 35" tyre you're asking much of a 44, you need to truss if the wall tube is cheese, also the shafts need to be RCV to be safe, and thats some lift you have !!
Title: Re: Diff Build Question
Post by: Mike2909 on May 19, 2014, 09:38:04 PM
For a 35" tyre you're asking much of a 44, you need to truss if the wall tube is cheese, also the shafts need to be RCV to be safe, and thats some lift you have !!
Bought it as such with 4" suspension and 2" body lift.
Title: Re: Diff Build Question
Post by: Mike2909 on May 19, 2014, 09:52:27 PM
Picture before I bought her and before PO spent all his £s on her/

http://www.nl4x4.co.uk/newphotos/displayimage.php?pid=63&fullsize=1
Title: Re: Diff Build Question
Post by: Ezz on May 19, 2014, 11:36:37 PM
I'm running a standard TJ 30 up front apart from an ARB locker and 4:88, perfect for 35" tyres and stock 44 rear, also with an ARB, in the almost 2 years of froading I've only bust 2 front uj's, I was going to upgrade the front shafts, but I've just got a pair of JK rubicon 44's, it'll be a while before they go on my TJ, but when they do my current axles will be up for sale..
Title: Re: Diff Build Question
Post by: Ezz on May 19, 2014, 11:41:08 PM
I can't afford Willos axles  :jpshakehead:

Nobody can :017:
Title: Re: Diff Build Question
Post by: gazjeep on May 20, 2014, 12:06:54 AM
Why did you go for 4.10 gearing ?

Its a 3 speed auto ........Only running 31's & a 2" OME lift
Title: Re: Diff Build Question
Post by: Bulldog67 on May 20, 2014, 04:49:17 AM
I can't afford Willos axles  :jpshakehead:

Nobody can :017:

 :098: :lol_hitting:
Title: Re: Diff Build Question
Post by: Mike2909 on May 20, 2014, 10:31:58 AM
I'm running a standard TJ 30 up front apart from an ARB locker and 4:88, perfect for 35" tyres and stock 44 rear, also with an ARB, in the almost 2 years of froading I've only bust 2 front uj's, I was going to upgrade the front shafts, but I've just got a pair of JK rubicon 44's, it'll be a while before they go on my TJ, but when they do my current axles will be up for sale..
There was  JK Rubicon breaking on ebay but the axles had already been sold.
Did the stock rear come with LSD originally and you changed to ARB locker or is that not possible?
I have found a 44 rear at a scrappy near me ( U pull it) I am going down today to check the ratio see if it matches my front. They are only asking £80 but have to remove myself- worth taking a risk on it I think.
Title: Re: Diff Build Question
Post by: Mike2909 on May 20, 2014, 12:06:12 PM
Would a Chrysler 8.25 rear axle with disc brakes, out of a 2003 Cherokee fit in the Wrangler and is that a strong axle. The 44 at U pull it is bent as in rear end smash. There is however a 2003 Cherokee CRD with the Chrysler axle.
Title: Re: Diff Build Question
Post by: Ezz on May 20, 2014, 12:17:39 PM
I'm running a standard TJ 30 up front apart from an ARB locker and 4:88, perfect for 35" tyres and stock 44 rear, also with an ARB, in the almost 2 years of froading I've only bust 2 front uj's, I was going to upgrade the front shafts, but I've just got a pair of JK rubicon 44's, it'll be a while before they go on my TJ, but when they do my current axles will be up for sale..
There was  JK Rubicon breaking on ebay but the axles had already been sold.
Did the stock rear come with LSD originally and you changed to ARB locker or is that not possible?
I have found a 44 rear at a scrappy near me ( U pull it) I am going down today to check the ratio see if it matches my front. They are only asking £80 but have to remove myself- worth taking a risk on it I think.

That's the JK, axles where sold because I bought them :hysterical:
jk axles are 5 inches wider than a TJ.
My TJ had ARBs in it when I bought it..
Title: Re: Diff Build Question
Post by: Mike2909 on May 20, 2014, 12:28:04 PM
I'm running a standard TJ 30 up front apart from an ARB locker and 4:88, perfect for 35" tyres and stock 44 rear, also with an ARB, in the almost 2 years of froading I've only bust 2 front uj's, I was going to upgrade the front shafts, but I've just got a pair of JK rubicon 44's, it'll be a while before they go on my TJ, but when they do my current axles will be up for sale..
There was  JK Rubicon breaking on ebay but the axles had already been sold.
Did the stock rear come with LSD originally and you changed to ARB locker or is that not possible?
I have found a 44 rear at a scrappy near me ( U pull it) I am going down today to check the ratio see if it matches my front. They are only asking £80 but have to remove myself- worth taking a risk on it I think.

That's the JK, axles where sold because I bought them :hysterical:
jk axles are 5 inches wider than a TJ.
My TJ had ARBs in it when I bought it..

Somehow I knew that  :violence:
Title: Re: Diff Build Question
Post by: Mike2909 on May 20, 2014, 01:35:36 PM
The more research I do about rear axles and diffs  the more I realise I know fook all  :jpshakehead:

It gets even more frustrating when I see what a friend of mine in the US can do for a quarter of what I have to pay.

Good job I am on holiday this week - I think .





Title: Re: Diff Build Question
Post by: JamesH on May 20, 2014, 02:01:09 PM
The C8.25 is a strong axle and will come with disc brakes form a KJ Cherokee so would be a good upgrade.

ARB lockers replace the whole carrier and spider gears so can be installed in any axle regardless of LSD or not.
Title: Re: Diff Build Question
Post by: Dave69 on May 20, 2014, 05:53:20 PM
ford explorer rear axle
Title: Re: Diff Build Question
Post by: Mike2909 on May 20, 2014, 08:26:04 PM
ford explorer rear axle
I checked that on the US forums as there is an Explorer at the scrappy disc brakes and all and they only want £80 for it.
It seems it is not a straightforward swap and requires welding and some fabrication that is beyond me.


Title: Re: Diff Build Question
Post by: Mike Pavelin on May 22, 2014, 07:24:09 AM
This may sound stupid, but what are you trying to achieve? What do you intend using your Jeep for?
Title: Re: Diff Build Question
Post by: Mike2909 on May 23, 2014, 09:23:28 AM
This may sound stupid, but what are you trying to achieve? What do you intend using your Jeep for?

Long answer is too long winded , short answer is best off road capability I can afford. Not used on road except for driving to off road sites  but kept road legal.
Title: Re: Diff Build Question
Post by: Mike Pavelin on May 23, 2014, 11:00:54 AM
In that case the answers to your questions depend a lot on how much money you have to spend on it.
Title: Re: Diff Build Question
Post by: Ezz on May 23, 2014, 11:50:28 AM
What gearing are you running?

My current axles sound ideal for you..
Title: Re: Diff Build Question
Post by: Mike2909 on May 23, 2014, 11:57:47 AM
What gearing are you running?

My current axles sound ideal for you..
3.73 on 35" with 5 speed manual gearbox.
Title: Re: Diff Build Question
Post by: isle of man on May 23, 2014, 01:23:53 PM
For 35" it's 5:13 R&P with stick shift.
Title: Re: Diff Build Question
Post by: Delk on May 23, 2014, 02:37:15 PM
I am running 5.13's with 36's and its to much. 4.88 would be a better option.
Title: Re: Diff Build Question
Post by: Ezz on May 23, 2014, 04:27:44 PM
What gearing are you running?

My current axles sound ideal for you..
3.73 on 35" with 5 speed manual gearbox.

Bloody hell, I hated mine on 4:10 on 35s both on road and off..
Title: Re: Diff Build Question
Post by: isle of man on May 23, 2014, 04:30:08 PM
I am running 5.13's with 36's and its to much. 4.88 would be a better option.

But you have a stroker torque monster engine.

For me, I have 5:13 with 37" tyres through an Atlas 3:8 and stick shift NV3500 with supercharged 4.0, for me this is not deep enough, I guess we are all different.
Title: Re: Diff Build Question
Post by: Ezz on May 23, 2014, 04:30:54 PM
For 35" it's 5:13 R&P with stick shift.

4:88 is the lowest a D30 can go
Title: Re: Diff Build Question
Post by: JamesH on May 23, 2014, 04:34:50 PM
4.88 with 35s and an auto is fine but I'd go lower if it could be done cheaper
Title: Re: Diff Build Question
Post by: Ezz on May 23, 2014, 07:13:49 PM
4.88 with 35s and an auto is fine but I'd go lower if it could be done cheaper


I have to agree James, I'll be regearing the Rubi axles to 5:38, but I'll be going to 37s
Title: Re: Diff Build Question
Post by: Delk on May 23, 2014, 07:41:57 PM
Mine are okay ish on the road but the revs on the motorway are higher then I like. Could slow down but what's the fine in that.

My issue is since I have a 4 to 1 kit in the transfer case I am to low for muddy stuff and don't get the wheel speed until I am in fourth or fifth. It was fine when I did a lot of really technical driving.
Title: Re: Diff Build Question
Post by: wildwood on May 23, 2014, 10:59:12 PM
Have to say that 5.38s and 40's have the right feel at road speed........

BUT by that time you are pushing soooo much weight down the road that you know that the next step is a V8 shaped step and 400 hp.

Not that I have taken the 1 Tonne on the road.......

Much :icon_twisted:
Title: Re: Diff Build Question
Post by: Mike Pavelin on May 24, 2014, 11:55:15 AM
Blimey. 3.73 is no good for 35s. You cheapest option is going to be to hold out until someone has a pair of suitable re geared axles for sale that you can just bolt on. Otherwise you ain't gonna get much change out of 3 grand to upgrade and regear to a basic standard on a 30 and 44 unless you can do all the work yourself. You could also consider going down to 33s and running 4.10 or 4,56, it'd take some strain off the driveline.
Title: Re: Diff Build Question
Post by: wildwood on May 24, 2014, 01:44:18 PM
Amazing we all have such different takes on this.
I started off with 4.56 on a Dana30 and 44 I was running 33s and it was good. It would go to 30 in top gear and pull away  and was happy to shoot past 70 on the Motorway......

I then went 35s and it was a slug that needed to be changed into 4th if you dropped below 50 and forget trying to sit at 70. Yeah it would, but your foot was in the carpet and you knew you were just blowing your wallet out the tailpipe. Reality check by satnav said 60 was a happy speed.

Fuel was 18 average on trips up the A1 to Tong with 33s
12 or 13 on 35s.......
Thank god I was running LPG...... :icon_twisted:
Title: Re: Diff Build Question
Post by: Dave The Sparky on May 24, 2014, 02:40:22 PM
There is a 4.27 ratio as well. :icon_winkle:
Title: Re: Diff Build Question
Post by: bigjeepzj on May 24, 2014, 02:53:45 PM
4.56 on my zj run sweet on 33's
if your going the bigger that 33's go ford 8.8 and D44 but then go 37's,
cos the diff is bigger by 1" so 35's wont make a different in ground clearance of 33's
it will cost you a lot for a re-gear  so go as big as you can and get lockers fitted at the same time. I would go ARB others will say no but it's up to up.

Title: Re: Diff Build Question
Post by: Delk on May 24, 2014, 03:36:32 PM
It makes a big difference in what tires you are running also. When I went from 35x16 boggers to 35x12.5 Goodyear Mtr's my jeep turned into a rocket.