TKX or stick with T5

[js65cobra]

Hello,

First, some backstory. A few months back, my engine decided it had 0 oil pressure at idle, and so I pulled the engine and had it rebuilt. At the time I also pulled out the T5 trans and decided to clean it up, I replaced the input shaft seal and buttoned it back up. I did notice at the time that the input shaft had some sideways play in it, figuring that I'd need to have it rebuilt or addressed, but due to time and money (at the time), I decided to just roll with what I got. Fast forward to now and I noticed the T5 is leaking out the bell housing near the flex plate, so trans fluid is coming out the input shaft and then down the bell housing and out. (I'm already upset I didn't take the time and just address it back when I had the engine out as it would have been super easy to do)

Anyway, this trans is from an 89 mustang, and was supposedly rebuilt back in 2001, however I have my doubts, and I'd like to just get rid of it/sell it and buy something new.

So my options are TKX or T5 again. The engine is a Ford 302 (bored over to 306), with a comp cam 35-351-8. The rear end is 4.10 ratio. So in doing some calculations it looks like better gear ratio for my application might be the T5 with the better 5th gear... giving me lower street cruising RPM... But I in some research it seems the TKX is a nicer and smoother shifting transmission. So i'm a bit torn between the two.

Also, I have Mk1 so the trans tunnel is just aluminum with no frame under so it shouldn't be that difficult (i hope) to slide the trans (minus shifter) back enough to then drop it out, i hope. Again, really really wish I did this when I had the engine and trans out a few months ago.

[Jeff Kleiner]

I haven't yet driven a TKX so can't speak to it's shifting vs. a T5 but can say with certainty that a T5 shifts much better than a TKO.

Aside from that let's look at gear ratios; your old 1989 T5 has a 3.35 first gear which when combined with your 4.10 rear end results in a whopping 13.73 overall reduction---great for burnouts or yanking tree stumps but really almost useless in everyday driving. If you go with a T5-z you get a 2.95 first gear which results in a much more reasonable 12.09 overall. A TCET17765 TKX has a 2.87 first that produces 11.76 overall. On the other end T5-z fifth gear is .63 which results in 1,850 RPM @ 55MPH and 2,350 RPM @ 70 MPH. The TCET17765 TKX has a .68 fifth gear which works out to 2,000 RPM @ 55MPH and 2,550RPM @ 70 MPH.

So there's your math...choose wisely!

Jeff

[rich grsc]

You need a proper set of rear axle gears. 4:10 are good for a 3500# or heavier car

[js65cobra]

You need a proper set of rear axle gears. 4:10 are good for a 3500# or heavier car

Oh, I know, just unfortunately not in the budget to switch that out.


And thanks for the math, I didn't realize the 89 T5 had different gears than the current ones out there. So it makes me lean more towards a straight T5 make it simple and easy.