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Thread: Hilux G series Diff Conversion

  1. #1
    Toymods Club Member Backyard Mechanic auto351's Avatar
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    Default Hilux G series Diff Conversion

    Hi, Can anyone help out with info so I can try and complete my Hilux diff conversion into RA28.
    I now have a G series diff housing; itís a RN25 1410 Unit (housing only).

    First I have been informed that any Hilux diff center will fit the housing.
    I have located a Hilux 4runner but Iím not sure it will fit as it has 6 wheel studs.

    What should I be looking for or asking for to fit my housing, center, brakes, axles etc?

    Un-shortened I can fit 205 rubber, which I think is the largest size for the 1410 diff, do I have to bend the guards to prevent the rubber rubbing?

    I may look at cutting the diff down to 1370 , but I was told that some axles cant be used for cutting due to the size, is there a type of axle which is recommended for cutting down, may be a long axle so the spline can be cut off then re-pressed?

    If I perform the supra disc brake conversion, will this reduce the 1410 drum to drum measurement?

    And one final question, which is best solid tail shaft or standard?

  2. #2
    Hopefully soon a 5S-GTE Chief Engine Builder MWP's Avatar
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    Default Re: Hilux G series Diff Conversion

    Quote Originally Posted by auto351
    First I have been informed that any Hilux diff center will fit the housing.
    I have located a Hilux 4runner but Iím not sure it will fit as it has 6 wheel studs.
    Hilux's have F and/or G series centers depending on the model and front/back diff.
    Any G series hilux center will fit it.

    How many studs the axle has does not effect the center type.

    What should I be looking for or asking for to fit my housing, center, brakes, axles etc?
    Erm, depends on what you want.

    A
    Un-shortened I can fit 205 rubber, which I think is the largest size for the 1410 diff, do I have to bend the guards to prevent the rubber rubbing?
    Thats bollocks.
    You can fit 225 or 235 tyres fine if you find the correct offset wheel to make em fit.

    I may look at cutting the diff down to 1370 , but I was told that some axles cant be used for cutting due to the size, is there a type of axle which is recommended for cutting down, may be a long axle so the spline can be cut off then re-pressed?
    Going that short means any G series axel you do use will need to be cut to the new length, resplined and heat treated.
    I was quoted ~$1000 to have this done.

    If I perform the supra disc brake conversion, will this reduce the 1410 drum to drum measurement?
    No.

    And one final question, which is best solid tail shaft or standard?
    A solid tailshaft? Didnt know there was such a thing.

  3. #3
    Hopefully soon a 5S-GTE Chief Engine Builder MWP's Avatar
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    Default Re: Hilux G series Diff Conversion

    Oh, see the 3rd page of my worklog (in my sig) for photos of my RN25 diff.

  4. #4
    Junior Member Grease Monkey
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    Default Re: Hilux G series Diff Conversion

    Auto 351,
    Diff upgrades can be fairly comlpicated. Make sure you do your homework on ratio's and tyre size before you start. These forums have a lot of useful info, Norbie's Toyota transaxle database is a good place to start.Ther are also tyre,diff and gearbox ratio calulators available on the net
    I recently upgraded my Hilux diffs and found out some info that may help.
    Some model Hiace diffs have 5 stud axles that slot straight into the Hilux housings.
    The 3.9:1 and 3.7:1 ratio's are getting hard to find so I found it easier to base my conversion around a 4.1:1 which are common in the later model two wheel drive Hilux utes,I can get you one if you like not sure on price though.Then there is the mounting of the diff which in your case would involve changing mounting brackets etc. I did not get into this because all I had to do was change centres.
    There are companies that specialise in doing these conversions OzDiff in Brisbane is one such company but I am sure that there is someone closer to you that could do the whole thing,brakes and all for a price.Do your research first don't go in to them knowing nothing otherwise they will rip you off.
    Cheers,
    Wheelie

  5. #5
    Toymods Club Member Backyard Mechanic auto351's Avatar
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    Default Re: Hilux G series Diff Conversion

    Thank you for the advice guys,

    Sorry when I said a solid tail shaft I was think of the one-piece tail shaft.
    So which is the better option one piece or standard?

    I was originally going to re-drill the axles to 4 stud to fit the original wheels & these would take 205 max (Classic hot wires), I was Quoted $650.00 to shorten & re-drill, but this didnít include re-splined and heat treating so I would need to find an axle that had a large spline ( I donít think these exist).

    So Will putting an offset on the wheels cause the bearings to fail sooner than they otherwise would?

    If not; one good option would be to keep the 5 stud on the back And switch the front to crown hubs Like MWP's and go to 5 stud all round, use the money saved from not shortening the diff to get rims with the correct offset, thank you MWP.

    The Diff housing I have has the mounts already fitted for RA28, So I will start track down a 2WD Hilux Diff or a G series unit.

    Do I re-use the brake lines from the donor 2WD Hilux Ute dive or run new ones?
    If new ones are run, where do I shop for these parts?

    I will check what my diff ratio is and try for a match or close to.

    Thanks again


    Manny

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    Default Re: Hilux G series Diff Conversion

    Quote Originally Posted by auto351
    Sorry when I said a solid tail shaft I was think of the one-piece tail shaft.
    So which is the better option one piece or standard?
    2 piece are better... reduces unsprung weight.

    So Will putting an offset on the wheels cause the bearings to fail sooner than they otherwise would?
    On a G series diff with only the weight of a Celica, very unlikley.

    If not; one good option would be to keep the 5 stud on the back And switch the front to crown hubs Like MWP's and go to 5 stud all round, use the money saved from not shortening the diff to get rims with the correct offset, thank you MWP.
    Its the best way to do it.
    Good luck finding MS65 hubs though, people have hoarded them.

    Do I re-use the brake lines from the donor 2WD Hilux Ute dive or run new ones?
    If new ones are run, where do I shop for these parts?
    For what brakes?
    Either way, youll probably have to run new lines.
    As for where to get the stuff... a brake shop.

  7. #7
    Roadhouse Automotive Encyclopaedia emp?'s Avatar
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    Default Re: Hilux G series Diff Conversion

    if its an RN25 diff it should be 1370mm already
    JZA80 - 2jzgte
    MS65 - 1uzfe

  8. #8
    Toymods Club Member Backyard Mechanic auto351's Avatar
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    Default Re: Hilux G series Diff Conversion

    Emp, I think its the RN10 &RN15 which are 1370mm, I just measured my housing and came up with 1248mm Bolt face to bolt face.

    MWP, is it only the MS65 hubs which can be used?

    I have been caught out before with RT132 hubs which turned out to be XT130
    How do i check I have the right crown hubs or will Cressida ones work?

    Im thinking I can take my struts and see if they fit the hubs?
    The hubs I've see have a Disc width of 25mm, depth to wheel stud base 43mm, wheel stud height 27mm does this sound correct?

    manny

  9. #9
    Roadhouse Automotive Encyclopaedia emp?'s Avatar
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    Default Re: Hilux G series Diff Conversion

    i have an rn 25 in my corolla that is 1370mm, also have 2 other 1370mm diffs that are rn 25/27
    JZA80 - 2jzgte
    MS65 - 1uzfe

  10. #10
    Toymods Club Member Backyard Mechanic auto351's Avatar
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    Default Re: Hilux G series Diff Conversion

    Ill will have to ask ask again were I bought this from!.
    What is the housing mesurent from bolt to bolt, not counting the brake assemby?
    I dont think im that lucky to have the 1370 unit.

    Manuel

  11. #11
    Forum Sponsor Conversion King
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    Default Re: Hilux G series Diff Conversion

    you can also modify and redrill early 4wd axles to 5stud but it requires more work ie welding the flange face.

    if you want 4 stud the 4wd axles are easy to mod.

    cheers
    linden
    Quote Originally Posted by WHITCHY
    Prefer someone around the Sydney area but will travel a few hours for a good box!

  12. #12
    Junior Member Conversion King TheStitt's Avatar
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    Default Re: Hilux G series Diff Conversion

    the measurment is from mounting face to mounting face
    ST177 UZS131 Crown Royal 'G' the pimping limo like daily 1UZFE 144rwkw

    DST17T MS53 68 Crown Custom Wagon 7MGTE 266rwkw

  13. #13
    Toymods Club Member Backyard Mechanic auto351's Avatar
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    Default Re: Hilux G series Diff Conversion

    Thank you guys for your input.

    I will go down the road of 5 Stud all round with crown hubs.
    Have found a 3.9:1 centre just need to confirm if LSD.

    All good things take time.

  14. #14
    70s Tragic Grease Monkey RA28tragic's Avatar
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    Default Re: Hilux G series Diff Conversion

    Very interested in this thread. Are there other similar threads in the archives??
    Living in the 70s

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    Default Re: Hilux G series Diff Conversion

    Quote Originally Posted by RA28tragic
    Very interested in this thread. Are there other similar threads in the archives??
    Has been discussed many times before, so yeah, there should be.

  16. #16
    Junior Member Conversion King TheStitt's Avatar
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    Default Re: Hilux G series Diff Conversion

    what do you want to know
    ST177 UZS131 Crown Royal 'G' the pimping limo like daily 1UZFE 144rwkw

    DST17T MS53 68 Crown Custom Wagon 7MGTE 266rwkw

  17. #17
    Toymods Club Member Backyard Mechanic auto351's Avatar
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    Default Re: Hilux G series Diff Conversion

    I would just like to point out while the information is on toymods; getting the information is easier said than done.
    E.g.: when I did a search on "Hilux diff conversion ra28" the results don’t jump out, you have to do other searches from those search result and read what others have found.
    Some topics like this need a product guide which details all the frequently asked questions and technical data plus options.
    So how would someone start such a product guide? Does someone just produce the product guide and post it on toymods or do they have to get authorization, maybe this can be a group effort?

  18. #18
    Hopefully soon a 5S-GTE Chief Engine Builder MWP's Avatar
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    Default Re: Hilux G series Diff Conversion

    Search for "RN25 RA28" and youll get plenty of matches...
    Just need to know what to search for.

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