Newb Trans Gear Ratio Question.

Discussion in '1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-' started by 90lxwhite, Jul 9, 2014.

  1. Can one change out 5th on the t5 to run lower rpm's on the highway? If so by doing so will it affect the rest of the gear ratios in a negative manner? Is something feasible or am I thinking crazy?
    I have a t5 and a 3.73 gear and I think 5th gear ratio is .67 (.68?) I'm not real sure but it's 95 gt that came with the 2.73 rearend. If this is something that can be reasonably done. What 5th gear do I want and where does one find it?

  2. There are different gearsets available. My g force t5 and my old z spec t5 both have .63 overdrive gears. I can't tell you what's involved to change the gears. I would imagine your best bet would be to sell your current trans and look for a z spec T5. It also has the 2.95 1st gear.

  3. A Tremec 3550/TKO/TKO 500/TKO 600 is a completely different transmission from a T5. Strong and almost bulletproof unless you run them without proper lubricant or full throttle shift without the clutch.

    A Tremec T5 is still the same T5 that is prone to self destruction when used in a street/strip or racing environment

    T5, all versions used in 5.0 Mustangs

    Tremec 3550/TKO /TKO500/TKO600 AFTERMARKET replacement for T5 - handles racing environments with ease

    See for more information - check out the "Light Duty" group, since TTC makes monster transmissions for big trucks as well as passenger cars.

    T5 identifier information.

    On the tail shaft of the transmission, there will be a stamped aluminum tag. The tag will have a number on it that you can cross reference to the chart below. There is no other way to find out what type of T5 it is without disassembling it. All the rest of the numbers on the outside of the T5 case are part numbers which are not unique to any particular T5 model.

    Remember that 94 - 97 T5's have a longer input shaft (about 11/16” longer) and can only be used with a 94-95 bell housing unless you modify or replace the input shaft.

    T5's used with a 4 cylinder have a 3.93 first gear, reduced torque ratings and an input shaft pilot diameter that is smaller that the T5 used for V6 & V8 engines. The pilot diameter is .59" compared to the .668" used on V6 & V8 T5's. It requires a different pilot bearing to be used with a V6 or V8. The pilot bearing you need is for a Ford Ranger diesel from AutoZone part #14672


    I don't know how you feel about the DYI thing when it comes to gears, some people don't like the idea of working on transmissions. If the DYI transmission fix idea isn't something that you would rather leave to someone else, here are some resources:

    See to download a FREE service manual for T5 or Tremec 3550/TKO
    You will need the Adobe Acrobat viewer which is also a free download –

    See or for parts

    A T5 rebuild kit with syncros, bearings and other small parts costs about $160. It does not include any gears or shafts. also has a video on how to rebuild your T5 or Tremec. It costs about $20, and is worth every penny of it.

    I did a Tremec 3550 rebuild, and it wasn't that difficult. The video was an immense help, and I would recommend viewing it. At $20, it will give you an opportunity to look and decide for yourself if you think that it is something you want to try to do.

    T5 Shim kits – best product I have seen in a while…
    “The Peel ‘n Place T5 World Class shim kit makes shimming T5 counter gear and main drive gears very easy.”
    #3 jrichker, Jul 11, 2014
    Last edited: Jul 11, 2014
    A5literMan likes this.
  4. The Astro hardened gear set will bring it up to .62 instead of .68. It's a good bit of cash for the gear set though.

  5. I like their A5GK-PKG1 kit. Jacks up the torque capacity to 485lbs/ft and when you using it with your existing overdrive, it drops the OD ratio down to .59:1

    2.95 first, huge torque capacity, nice low cruise RPM.....Win...Win...Win :nice:
  6. According to the rpm calculator the .59 od will drop the rpm's 316 rpm's @ 70 mph. Not sure it's worth it and for sure going to a .63 from a .68 isn't. I'm not needing any more power holding capability, I was just hopping against hope there was a solution to lower highway rpm's other than a t56 or 2.73 gears.
  7. Well, unless you get a Viper Spec T56 (.50:1), you're not gonna get any lower 6th gear ratio than the ones outlined above anyway. Then you run into another issue. Will a your primarily stock 5.0L pull a .50 gear ratio? Yes, it's making a lot more power with the blower....but you need to make the torque without the blower in order to utilize the ratio. Otherwise, you start seeing boost on the gauge when you get bogged down at low cruise, or steep which point the system is going to add fuel to compensate and negate any benefit that the lower O/D ratio provides.

    One big reason GM was able to get away with the .50 O/D ratio with their cars for so many years was because they utilized engines displacing nearly 50cid (or more) displacement than our 302's that produced a broader, higher torque curve than began lower in the rev range.....and thus gave them the ability to pull a longer overdrive gear.

    That being said, swapping out to the above .59:1 O/D ratio would be similar to you swapping rear gears from your current 3.73's to a set of 3.27's on the top end....but with all of the acceleration advantages of the 3.73's in the first four forward gears.

    ...or, you could swap out your 3.73's for a set of 3.27's, get the mileage break and live with the slight loss in acceleration. I don't imagine you'll notice it much under daily driving conditions with your blower on there.....but that highway fuel mileage will start to add up quick over the course of a year if you do a lot of highway travel?
  8. I disagree to a degree. Bringing the top gear ratio up to .62 or .59, or even .50 is just bringing the final ratio back to what it was when the car had a stock 2.73 or 3.08 axle ratio.

    The most expensive gear set in the T5 is 5th gear. Retail on that set is $273. One other thing. If you have your original T5, then you should have a 8 tooth drive gear on the speedo set, which means you have a 23 tooth driven gear to correct the speedo for 3.73 gears. The 23 tooth is an aftermarket hack to correct the speedo, and it is almost sure to be torn up. Swap to a 7 tooth, 21 tooth combo instead.

  9. That's a fair point. I still had the stock gearset in mind.
  10. It sucks there's no .5 5th
  11. No, there is no .5 5th gear ratio. You can get close but not quite there. It's cheaper to change your rear end ratio than to get a 6 speed though.

  12. there's something better out there than a .63? Would it be a tranny swap deal or just changing out 5th? I was originally thinking maybe I'd try 3.27's but after playing w a gear/rpm calc it seems that it would only lower the rpm's @ 70 300 and some odd. I dont think it would make enough of a difference on the highway to justify the cost and low end loss. I'd have to go all the way down to a 3.08 to get below 2k. I guess I'll just ride it out w the 3.73. I probably should've went with a 3.55 originally.
  13. Nothing really makes a whole lot of difference cruising down the highway. It's all perception anyway.

  14. Half empty