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Author Topic: TJ, Bigger Tyres. 3.06 rear diff.  (Read 2526 times)

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Snowman

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TJ, Bigger Tyres. 3.06 rear diff.
« on: August 09, 2013, 02:45:59 PM »

Hello. This is my first post, and not an obvious one I hope.
I did look for FAQs before posting . . so sorry if this is answered elsewhere.

I have a 97 TJ.
It has a 3.06 Dana 44 axle.

I know I can fit 30 or 31 inch tyres without lifting it.
But will the diff cope with this? Or will it just become a chore to drive?
Can anyone suggest a tyre size that works well with this ratio.

Thanks.

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Nosebolt

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #1 on: August 09, 2013, 03:18:46 PM »

your original 225/75R15 is roughly equal to 28.3" so fitting 31s will be the same as having 3.35 rear axle ratio.


to put it another way if you only changed the tires then with the speedo reading 50mph your JT will be doing 55mph.


look here for a ratio guide
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Mike Pavelin

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #2 on: August 09, 2013, 05:25:21 PM »

Huh? think you've got that the wrong way round.
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MOCAJ

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #3 on: August 09, 2013, 05:49:55 PM »

31's will be fine on standard ratio, your speedo will be out but its not a biggie. You may have to adjust your steering stops to stop rubbing.

If you go taller you got to re-gear tbh although I did run a TJ on 33's with a small lift for a while, just got to accept the lack of 5th gear etc and faster descents in first gear
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wildwood

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #4 on: August 09, 2013, 06:52:27 PM »

And long term they don't like being run in 4th on motorways.......after a year or two will kill the box........




And how do I know that :icon_twisted:
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Delk

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #5 on: August 09, 2013, 07:08:40 PM »

Did the Dana 44's in the Uk come with that ratio? The 44 was an option in the states and I am pretty sure they only came with 3.73's.
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wildwood

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #6 on: August 09, 2013, 07:44:18 PM »

I think all UK bound 4.0 litre TJs came with a 44.....Not so sure about the 2.5 litre ones tho???
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Delk

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #7 on: August 09, 2013, 09:16:59 PM »

I heard all the uk tjs had 44's I was just surprised about the high gears. State side the D35 had 3.07's and the 44's were 3.73's. Doesn't sound like much but the lower gears could still push 33 inch tires without much trouble.
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Jonny Jeep

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #8 on: August 09, 2013, 10:43:32 PM »

In the US 3.73 was available with the 35 and 44. I couldn't tell you what engines or transmissions they were available with though.
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gordy

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #9 on: August 10, 2013, 08:35:06 AM »

My 98 has a 44, stock was 3.07 and with 33"s I waved goodbye to 5th gear, even 4th was lacking power on the motorway under acceleration.  Went to 4.56.  If you intent to re-gear you will need to replace both the carriers if you go 3.73 and up.  Although I did rear somewhere you can fit a ring gear spacer to original carrier as the ring gear thickness is the only difference.  If you do and live in south east I would recommend FTE, Essex, they did mine and did a top job, considering what Steve found.  Before I bought the Jeep the dealer I got it from removed my rear diff and put it into another Jeep, but used my bearing caps in that axle, he put another diff in mine with their bearing caps so the whole thing was out, he thought my brakes were binding it was that tight.  Name and shame?
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Arno

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #10 on: August 11, 2013, 09:08:29 AM »

Manual D44 have 3.07 gears, the Autos have 3.73

I have a '05 TJ with the 6sp box and 3.07 gears, have 31" tyres and it does drain a lot of power, don't  have the get up and go anymore.

 Regear to 4.11 is on my todo list, so trying to find out how much it will be to get it done .. Anyone with an idea re costs.?
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Bubba

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #11 on: August 11, 2013, 10:16:49 AM »

Its not a cheap option parts are not to bad from randys ring and pinion fitting varys wildly
You could have a crack at it yourself but its not for everyone
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wildwood

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Re: TJ, Bigger Tyres. 3.06 rear diff.
« Reply #12 on: August 11, 2013, 11:22:00 AM »

If your going to stay with 33s and its a DD then my money would be on 33x 10.50s cos the narrower tyre will sap less oooomph.

if you want to go cheap and you are handy with the spanners.....

Look for a 2.5 PETROL XJ cos its got 4.10 ratios........ The front will fit your TJ.......the rear you will have to weld on some coil perches and stuff but its all available via the web :icon_twisted:
might only cost you £500 if you hunt around......
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