Hi Guys,

Just a question, looking to change over my diff to a 3.45.

Doesnt need to be LSD yet just want to see the difference.

There is a guy on ebay saying that they should go straight in, maybe just need a shim.

My Question is, how hard is it to change?

I have put an XR6 head on my car so I am not too mechanically illiterate.

I suppose I would just like to know, can i purchase gears off ebay and are these relatively simple to put in?

Do i need any special tools? Can I just take of the back cover when its cold, unbolt the old one with standard tools and put another gears in and bolt it all back up?

Or am i dreamin...

Hiya,

Sorry 3.45's will not fit into a 3.08 diff housing, you need to have 3.23 or above,

If you really wanna get 3.45's in your car, go to a wreckers and buy a 3.23 diff, you can prob pick one up really cheap, if you ask for just the housing, (thats if the wreckers have any) most come with the gears in them, but no axels. Then once you have that, you can fit your 3.45's if you have a LSD or just open wheeler, you can still use your center thats in your car at the moment (without the 3.08gear) you will prob need diff shims, new spacer, and new seal on the front, if i remember right, the LSD Vs Non LSD have a different main seal .. But thats if you changing the diff gears.

If your 3.45 came out of a ford BW diff, it should have the right size bearing on the pinion shaft.
But remember, because you have changed the ratio, you might need a few different shims each side of the center (where crown wheel bolts on) so you don't get lash back or heel or tow on your diff gears.

Good luck! Laticia.!

thanks laticia, I will give that a try.

I might have 3.23's not sure, will proably have to get under and to the wheel turn trick.

The manual says either 3.08s or 3.23s, (im hoping they are 3.23's)

Thanks for all your help!

3.45's and 3.08's are interchangeable, its the 2.77 that is an orphan diff

try and fit 3.45's into a 3.08 diff

i have to agree with sommers if you can fit 3:45 into a 3:08 diff with out having to machine bearing cups etc i would be mighty surprised

speak to the guys at Mal Wood auto, they should be able to give you a straight answer

theyve corrected me on a few bits of info regarding diffs that ive gathered from various places

my two cents worth, i just picked up a 3.45 diff complete from fellow fordmods member for 200 bucks, then just swapped the whole thing over, only took a few hours (took longer to remove than to replace - bloody factory blue loctite everybloodywhere) if you buy the gears it's a pain unless you know what to do (i don't) and diff mobs will always want to rebuild the whole thing when fitting gears.
I reckon you should keep your eyes and ears open for a complete diff, ps diff gears are addictive! i like the 3.45's , but know i wonder what 3.89's would be like, as the revs have only changed about 200 revs at 110 now 2200 was 2000 with auto in NF 5.0, anyone know what 3.89's rev at?

so does there seem to be a noticeable difference on take off?

Indeed, and i only went from 3.23 to 3.45 if you go from 3.08's you will notice even more and if you change the speedo drive use the grey one.

If you do ahve a 3.08 diff in there now, it would pay to get a complete diff with 3.45 in it (out of an XR or Ghia) like Fairlane6970 stated. Would save you having to modify the 3.08 housing or whatever else has to be modified to make it fit. Have seen them floating around on ebay in the past for reasonable prices.

You should feel a noticeable difference too i would think. I have a Fairmont with 3.23's with full exhaust and intake mods and higher comp and compared to my old man's XR6 its nothing. The XR6 is completely stock apart from a full exhaust and it revs out quite a bit faster than mine. I know its not the best comparison seeing as the XR6 does have other higher performance gear from factory over the fairmont but its just a rough guide. I reckon if the 3.45's were in my Fairmont, it would be almost as quick as the XR6. Ive got a set of 3.45's going in hopefully this year if i can save up the funds lol so i'll know for sure how much of a difference they make after they are in.

Oh and by the way Fairlane6970, how are the shift points with the auto in your fairlane after the 3.45 diff went in? Did you change the speedo gear? Have heard of cars hitting the rev limiter under full throttle and not changing gear under until the accelerator is let go after changing diffs/ratios and changing the speedo gear.

Shift points are the same as before the 5.0lt's have a seperate shift module thing for the auto's - my bro-in-laws ex chaser XR8 changes at 5,800 full throttle my NF still changes at 4,800! (buggar) he has different ecu as well!, i changed the speedo gear it cost $15 from ford i used the grey one the original with 3.23's was green - all good

Much easier to just get a whole diff and swap it, all you've got to worry about then is about a dozen nuts and bolts.
And get LSD while you're at it.
If you're going to go to the trouble, may as well make a job of it.