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  •  » Need advice on T5 rebuild/upgrade

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    5/13/2019 4:50 PM  #1

    jkordzi
    I FYI 24-7

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    From: Sequim, WA
    Registered: 12/28/2013
    Posts: 927

    Need advice on T5 rebuild/upgrade

    I'm rebuilding the WC T5 in my 65 FB and was thinking of changing from the usual 3.35 gear set to the 2.95 gear set.  Seems like the best deal is with Astro: https://astroperformance.com/product/t-5-gear-kit-super-alloy/.  If anyone has a better idea, pls let me know.  I'm also installing the improved counter gear stabilizer.

    While I'm at it, I was also wanting to overdrive it a bit more, as I'm running 3.70 gears in the rear and the rpms on the highway seem a bit high.  My current overdrive is 0.68.  I understand that if I transfer my current 5th gears to the new gear set, the overdrive ratio will be 0.59.  So I'm wondering about also installing the 5th gears from a T5Z spec (25/51 tooth counts), which by my calcs would give me a 0.63 overdrive ratio.  Below are my calcs: 

     My tires are about 25" tall and I'm calculating rpms as RPMs = (MPH x final drive ratio x 336)/tire diameter). Thanks for any advice.

                                                                                                                                                                  

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    5/13/2019 9:20 PM  #2

    Bullet Bob
    Senior 24-7 FYI Addict

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    From: Montrose, Colorado
    Registered: 4/01/2013
    Posts: 4,891

    Re: Need advice on T5 rebuild/upgrade

    I had a Fox with a T5Z (.63 OD) and 3.73 gears.  I was just about perfect IMO.  Plenty of giddyup and It seemed about perfect on the highway...just over 2200 at 70.

    BB

    "you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
     

    5/13/2019 9:52 PM  #3

    jkordzi
    I FYI 24-7

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    From: Sequim, WA
    Registered: 12/28/2013
    Posts: 927

    Re: Need advice on T5 rebuild/upgrade

    Well, I'm finding out that apparently there is a shortage of 2.95 first gears.  Astro got back to me and said that gear is not being produced by the aftermarket and has been on back order since last year, so their kit is not actually available.  Other sources seem to have gears 2-5 but not the 2.95 first gear, or if they have it, that one gear is $200 or more. 

    Last edited by jkordzi (5/13/2019 10:16 PM)

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       •Thread Starter
     

    5/14/2019 9:10 AM  #4

    TKOPerformance
    Hyper FYIFORD ADDICT

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    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,524

    Re: Need advice on T5 rebuild/upgrade

    Its been a problem for years now.  I used to be able to buy 1-4 and the countergear in superalloy for $450 to build my own Z-spec boxes for either Fords or Chevys, but the demand ebbed and the supply went with it.  Now the only 2.95 first gears available are actual Borg/Warner/Tremec made parts that are commanding a hefty premium.  You could try Hanlon, or possibly eBay.  Might get lucky, but unfortunately $200 is about the going rate for one if the guy knows what he has.  Maybe one day the companies based in India will start making the 2.95s, but until then no real low cost option. 

     

    5/15/2019 7:51 AM  #5

    boss347convertible
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    Registered: 4/22/2013
    Posts: 159

    Re: Need advice on T5 rebuild/upgrade

    Years ago, I built a cobra replica with a tremec behind a 427, 3.70 rear end. The 427 made plenty of torque off idle, so the 3.35 first gear was so short as to be useless most of the time. Calculating gears for my mustang, I ended up with the 2.95 first gear, .63 fifth gear, about 12.8 inch dynamic tire height and a 3.55 rear end. I find this combination very good around town and on the open road, anywhere from 65 mph to 75 mph is the sweet spot. I don't have a tachometer, but rpm for that speed range is about 1950-2150 rpm. This works perfect for me on longer drives. Of course, your engine build, driving habits and type of driving will dictate what gears are best for you.

     

    5/15/2019 7:52 AM  #6

    boss347convertible
    FYI Addict

    Offline

    Registered: 4/22/2013
    Posts: 159

    Re: Need advice on T5 rebuild/upgrade

    Years ago, I built a cobra replica with a tremec behind a 427, 3.70 rear end. The 427 made plenty of torque off idle, so the 3.35 first gear was so short as to be useless most of the time. Calculating gears for my mustang, I ended up with the 2.95 first gear, .63 fifth gear, about 12.8 inch dynamic tire height and a 3.55 rear end. I find this combination very good around town and on the open road, anywhere from 65 mph to 75 mph is the sweet spot. I don't have a tachometer, but rpm for that speed range is about 1950-2150 rpm. This works perfect for me on longer drives. Of course, your engine build, driving habits and type of driving will dictate what gears are best for you.

     

     

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