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Discussion in 'The Garage' started by 1998cobrasvt, Jun 5, 2015.
T45 or T56.
t56 is better for track no?
What kind of track?
This and street use primarily
Its not a major concern, but when i do the trans refresh in near future im wondering which route to take. benefits vs negatives etc etc.
Is it more street, or more track?
1) More street: go with the T45. Less overall shifting required, and depending on your gearing, you will most likely never use 6th gear, even on the highways. And for the track use you do get, depending on your seat time/experience/hours spent you will have many other things to worry about before the gearing becomes an issue. Again, depending on gearing, 5th gear will be useless on the track. Whether this is an issue or not depends on how long the straights are and how quickly you get up to speed. As you get faster and faster (if you aren't already) you will probably run out of gear, which leads to....
2) More track: go with the T56 hands down. The additional shifts can be annoying, but the whole point of more gears is that it allows the gear ratios to be closer to each other (close-ratio) which is ideal for racing. It allows the driver more options for gear selection to keep the car in the powerband whether you are on a straight or a hairpin. For a straight dedicated track car, 6th gear should be close to 5th as opposed to an "overdrive" gear. However, for a car that also sees street time, the extra 6th gear lets you have a close-ratio trans (1st through 5th) for the track, with an overdrive 6th for the highway (better mpgs, maybe). The 5 speed, because it has one less gear, by default must have a wider gear spacing to be as useful in the different street/track scenarios.
My recommendation is to go with the T56, assuming you can get a close-ratio 1st through 5th (I don't see why you wouldn't be able to). Even if you drive it on the street mostly, the minor inconveniences are just that - minor. Things I think you'd forget about pretty quickly. FWIW, my daily driver is a 6 speed and I have no issues with it.
Edit: If I had the money I'd drop a T56 into my Mustang in a heartbeat.
Oh, to clarify a little more - the 5th gear on the T45 will be useless on a track assuming it's an overdrive 5th gear (meant for cruising on the highway). You can get T45's with a close ratio 5th gear that will work great on a track, but then of course kiss any kind of decent mileage on the street goodbye.
My thoughts as well. Thank-you for your detailed response!
Car will be driven to events and elsewhere so id say about 60-70% street for now.
Have 373's currently. Close ratio shifting benefits are what is leaning me towards the t56. If the only negative is extra shifting i'm perfectly ok with that. Will keep an eye out for one, hopefully it will be going in this winter along with a few other goodies :grin:
Sure thing man! There really aren't any other negatives for the T56 other than a bit more shifting and cost of course. The T56, like the T45 and the T5 can be built to varying degrees to handle torque. So I certainly don't think it will grenade on you.
Yeah see that i couldnt do need my 5th for highway! lol. Not sure how short of a gear were talking but (Before newest dyno tune) If i shifted at 6,500 in fourth it entered the powerband at about 4,800-5,000 in 5th. But if i enter 5th at say 2.5 on the highway to save gas it will go to 1.5-1.8 just chilling. Looking forward to getting all my tests in this summer with new setup.
T56 or go home
Good choice! - I just did the T56 swap this spring.
BTW the only con that I didn't like was the weight gain, but at least its in the center of the car.
People are soooooo eager to spend someone else's money. Judging by your mods, I'd say keep it a T45. I've got a stock T5 in my car and I make almost 100 whp more than you, and road race the shit out of my car. If the shifts are nice and easy, you will never break anything. Mine has been refreshed at around 200k miles, right now has about 42k since than, and 4k of track time since the motor build, 0 problems. With 3.73s, and 32v motor, you should still have a LOT of range without needing to go into 5th. So, let's see... spend like 2500 bucks on a T56 swap with nearly 0 performance gain, or spend 300 bucks to rebuild your transmissions, IF YOU NEED IT... seems like a really tough choice
T56 easy imo just for overall enjoyment. I like mine so much more than my T5 it's not even close. You may not NEED it, but the gearing is much more usable for racing and cruising.
No way im stopping at 289rw . Plans on doing something in the neighborhood of H/C S/C build hopefully within the next season or two. While blocks apart im going to rebuild t45 or replace with t56. mcglsr2 and you both made a good point by saying the track length will most likely not even require 5th. I will get to use the new setup at multiple tracks this summer and mostly just having fun and testing i will find out before the tare down. Will post results over the summer. This is only the start of the build! But thankyou for pointing that out, def do not want to throw out on anything thats not needed
Nice, i have used the t56 in an 03 terminator before but never have used a t45 holding down 540 rw to compare with
Its finally ready for the season now. Will be posting an intro to the car this weekend when i have the free time
I wasn't saying go with the T56 because it holds more power - as I said in my previous post both the T56 and the T45 can be made to hold pretty much any torque you want.
The reason I said T56 over the T45 is because you get more gears. Period. Will the T45 work? Sure. I road race my Mustang with a 5 speed (T5). Does it work? Sure. The whole purpose of gears, and where I was going with the T56, is that engines have a range in which they operate best. The sole purpose of the transmission is to attempt to keep that engine in that efficient range as much as possible (via managing RPMS).
On the track, a Mustang typically has gobs of torque, over a range of RPMs. This allows more flexibility in number of gears for the transmission, meaning the driver doesn't necessarily always have to select the best gear to keep torque up (as they might in say a Honda, for example). Depending on the range of the torque provided (say, max torque made between 2900-3400 RPM) means that if your current gear box, when shifting, always drops you in this range, then you are fine. You don't necessarily need more gears. If your range is shorter, or specifics of the track require it (hairpins or really slow sections, etc.), then more gears means that the driver has more opportunity to be in an optimal gear (think coming out of a turn).
If I personally have the option of a 5sp vs a 6sp and the cost of the transmission is not an option, why wouldn't I go with a 6 speed? Will a 5 speed work? Sure. Will a 6 speed work better assuming I have the skill and experience to make use of it? Sure.
If the goal was to not spend money, then yes, go with the T45 and get seat time. But the question was: T45 or T56. In which case, T56. Also, FWIW, F1 cars, rally cars, etc. all have more than 5 gears. Could they make 5 gears work for them? Perhaps. But they have specifically chosen more gears for a reason. Again, my point being: will 5 gears work? Absolutely, and if money is an issue (as it is with me), they will work fine. Should you go with more gears if money allows it? Absolutely. Especially if one drives different tracks and doesn't want to actually swap gears between events (like pro teams do) - the 6 speed will allow one to have a better chance of having more optimal gears for different tracks.