Numbah-1

Hi guys, I gotta a question about how the transmissions are rated? I guess it sounds simple until I teally thought about this;

T5's are rated to handle 300ft/lbs. But...
RS's with LO3s make 255 ft/lbs.
Z28's with LB9 rated at 190 and 300. If i remember correctly, thats at the wheels.

Are they rated at the input shaft?

cosmick

Ratings don't mean much. If you drive abusively, any engine can break any stock T5. If you baby it, a V6-spec T5 will survive a 350 forever.
ALL third-gen engines were rated at the crankshaft, not at the rear tires.

sofakingdom

iTrader: (1)

Those "ratings" are UTTERLY MEANINGLESS.

Thimk for a second or 2:

If they DID "mean" something, what would that "meaning" be?

Would it be, that if the "rating" were exceeded by .000001 whatevers (HP or ft-lbs for example) the trans would instantly self-destruct like the matter meeting the anti-matter, maybe even leave a black hole behind to devour the galaxy? (probably not) Would it be that such a thing would only happen on the drag strip? (probably not) Would it be that it might only last 100 miles or 1 hour of use, whichever came first? (probably not) Would it mean that it wouldn't last the mfr's warranty period? (probably not) Would it mean that at that power level, whether "real" or "rated" by whatever weasel-word method, the financial cost of warranty repairs/replacements in a new-car fleet so equipped, would rise to become the equal of the marginal profits in the entire new-car fleet generated by the lower cost of that weeeeeeeeeeenier transmission to the OEM, compared to one with a "higher" "rating"? (NOW I think we're getting closer to the REAL "meaning")

You can tear up a T-5 with a 6-cyl. You can make one live behind a 400. It's all in how you drive it.

Z28s w LB9 were "rated" at the crank, same as any other motor, under the terms of federal law at the time. That "rating" is only slightly less meaningless than the one for the T-5.

Granny

The manufacturer transmission ratings are about constant load, like a hard pull up a mountain pass. Over time the trans heats up and the oil film breaks down, leading to gear failure. I don't think many here are concerned with constant load, we tend more about the load it can withstand for 10-13 seconds at a time

Just make sure the clutch's yield torque does not exceed the transmission's input torque capacity. Ultimate capacity will vary with the gearset used, but most any properly shimmed T5 will survive if clutch capacity is kept below 550ft/lbs. Do this and it won't matter much how you drive it.

cosmick

Never seen a 10.4" 26-spline clutch come with a torque/slip rating. Using the cheapest stock-replacement clutches won't save it if you drive harshly, using a Kevlar clutch won't hurt it if you drive it like you love it.

sofakingdom

iTrader: (1)

Clutch "ratings" would be as MEANINGLESS as any of the others. Never even heard of such a thing. Now granted, I've only been doing this for a bit over 40 yrs or so yet, so I'll FREELY admit I have plenty left to learn and that I haven't seen EVERYTHING there is to see; so maybe some clutch out there somewhere has a "rating" that can be somehow "matched" with those UTTERLY MEANINGLESS ones for a motor or trans. But somehow I doubt that it really matters, since as someone mentioned earlier,

The T-5 is WEEEEEEEEEEEK. It's simply NOT a performance piece. It's a gas mileage piece.

cosmick

But there's no affordable, readily-available alternative. T56s start at $1200 used, TKO600s can only be had new for close to $2k, and there's really nothing else suitable. A T5 isn't a bad match to a mild 350, and I'd rather trust that than hurt yet another 700R-4 / 4L60E. If you don't do high-RPM clutch-drop launches, and don't do powershifts, a T5 will last forever behind a mild 350. You can still use WOT, just not when engaging the clutch, only after the clutch is fully engaged.

Granny

Most clutch manufacturers can give you a torque rating, but many include a 15% safety margin in that rating, basically under rated so that you are less likely to burn up their product. If you ask a manufacturer for a torque rating and they can't give you one or they don't know if it includes a safety factor or not, find another source for your clutch.

Keep in mind the clutch manufacturer's point of view. They would much rather shift your car's failure point to anywhere else besides their clutch. When you break your T5 you blame the T5 for being weak, when the real blame should go to the clutch. They recommend more clutch than you actually need to keep you happy with their product. Given the choice, which would you rather replace- transmission or clutch?

Mustang Cobra clutches have proven over time to be a pretty good match for the oem T5 in terms of overall capacity, they use a 10.5" organic disc and a PP clamp load of around 2124lbs.

For the aftermarket A5 gearsets for the T5, Astro recommends no more than 2600lb pressure plate load with a single organic 10.5" disc. Many performance clutch oriented packages exceed that.

Granny

Lots of Mustangs running in the 10's using a T5, mostly because Ford Racing sells an affordable properly spec'd clutch.

sofakingdom

iTrader: (1)

Ummmm.... no.

Mostly because the Mustang is a lighter car (puts less load on the trans) and usually doesn't hook up as well.

Never seen a clutch with a torque "rating". Not sure even what that would mean. Not sure therefore that it would make the slightest bit of sense to be bothered with it. See discussion about "meaning" of "ratings" above.

Yes I've seen various hack jobs over the years involving things like screen door dampers; pretty ingenious, in its own way, but still a hack job. All it does is force the clutch to slip more than it otherwise would as it engages. Any way you slice it, a hack job.

Yeah I know about clamping force. I also know about area.

The T-5 simply isn't a performance part. Period paragraph end of story. You can still tear it up with a 6-cyl and a stock clutch, as has been demonstrated PLENTY of times. Not worth wasting money on gearsets and whatnot, unless you're racing in a sanctioned class with rules that require it. Otherwise, if power-handling capability is important, it doesn't belong in the car.

jmd

iTrader: (4)

The rating provided by manual trans. manufacturers is something like a continuous torque load rating over a 24 hour period or something like that.

The problem is a 50 lb-ft. difference between an M28 T56 and an M29 T56 isn't accurate (1st, 2nd, 3rd are different ratio / tooth counts, but the main avenue of power transmission is at the headset gears up front.)

Also, a 700 lb-ft rating for a T56 Magnum uses many same gearset parts as a 400+ lb ft rating of a production vehicle TR6060. So aftermarket numbers can be poked and stroked / rated differently than numbers for an OEM application.

I'm not afraid to run a T5 behind a 350, but there are lots of guys who will tell you it will fall into pieces next week. A lot depends on how you drive and if you know how to drive. And I'd rather have a "weak" T5 with the best ratios for the vehicle / engine / rear gear, than a totally built TR6060 with the new Viper ACR 2.26 first gear. Ratios matter a lot.

Granny

True if you have a clutch that's too aggressive. Install a clutch well matched to the transmission's capacity and vehicle weight and how well it hooks become non-issues.

http://clutch101.blogspot.com/2012/0...-capacity.html

http://clutch101.blogspot.com/p/clut...alculator.html

Says the guy that can't figure out how to make a T5 live behind a stock 6 cyl. Meanwhile, the Mustang guys have figured out how to get 400+whp thru basically the same transmission.

sofakingdom

iTrader: (1)

So, some enthusiast posts stuff on the Internet in some "blog" about how to "calculate" some kind of "ratings" for clutches.

Now of course we all know you can't post stuff on the Internet if it's not true. Right? If you see it on the Internet it's GOTTA be true.

OTOH, is that THE SAME THING AS the clutch manufacturers THEMSELVES publishing "ratings"????

I've never had a stock 6-cyl. I've never even SEEN one, let alone HAD one. I didn't say anything about ME figuring out how to make it live behind those things. Don't lie and put words in my mouth I didn't say at the same time.

Meanwhile, the Mustang guys tear em up just as much as we do, once they figure out how to get traction. You know it just as well as I do. Go visit the Mustang forums if you are willing to subject your preconceived notions to the test of REALITY. (which I'm suspecting would be too stiff a test for your ego to survive, so I'm equally suspecting you won't)

As someone said earlier,

cosmick

https://www.thirdgen.org/forums/tran...-t5-t-5-a.html

And Mustangs are the preferred chassis for entry-level drag racing on the cheap, takes almost nothing to get them to 60-foot in the 1.3s.

Granny

Sorry, I thought you were speaking from experience. Probably explains why you are having trouble grasping the value of matching a clutch to the transmission's capabilities.

Here's a link to a manufacturer explaining torque capacity ratings...
http://www.phoenixfriction.com/t-Clu...y-Ratings.aspx

I never said all manufacturers publish torque ratings for their kits, but many do. The ones that don't will generally provide a horsepower rating that can be roughly converted to a torque rating, but they should be able to provide an actual torque rating if you ask them. Note that manufacturers can only provide a torque rating for a complete package of components that they provide, as they have no control over what combination of parts an individual might put together. The calculator link I posted is a useful tool for an individual that wants to mix/match components to come up something in the ballpark to suit their needs.

sofakingdom

iTrader: (1)

All I know about 6-cylinders is what I read on the Internet. Including, how people tear up T-5s with them. (check the S truck boards too just for Ss & Gs)

I know PLENTY about V8s, including 400s; for example the one I had in my 83 T-5 car for acoupla decades. Until I got tired of T-5s tearing up behind it (although the first couple that shredded were when the OE 305 was still in it), at which time I put a transmission with a bit better power-handling capability in the car. (T-56)

Obviously you haven't figured out yet that a better program than dinking with the clutch somehow, is to put a transmission in a car that can handle the power and usage that the car is expected to put it through. Which would pretty much leave the T-5 out of the equation, despite its many good features. But maybe someday when you get some experience doing something besides posting on the Internet you'll learn too.

Granny

With the right clutch, experience has proven the T5 capable handling 400+whp. Below that level a T5 is going to be quicker as it is lighter, shifts quicker, and has less internal drag than a T56. I'm at 700+whp now so a T5 is no longer in my car, but went 4spd over the T56 as i didn't want the added weight/drag slowing me down.

novaderrik

a quick google search found me a few different clutch manufacturer sites that have the torque ratings of their clutch kits listed- pick a nice weak one and a T5 should live thru anything that isn't 6000rpm clutch dumps and WFO powershifts..

think of it like the slipper clutch on a tractor PTO shaft that keeps **** from breaking if something jams it up..

even found a rating for the cheap Luk clutch kit that i picked up for the non WC T5 swap into my Camaro.. it was $69.99 at rockauto and has a 310 lb ft rating, which should maybe theoretically help it live for a little while behind my 350ish hp 355 compared to a fancy aftermarket high performance clutch setup...

cosmick

Some of those ratings are made up based on liability concerns, or based on what the trans is rated for, whatever. The axle ratio and tire radius will affect the actual holding ability, as will the car weight. But if you're easing the clutch out under 2000 or so RPM, part throttle, like you would if a cop was behind you, then you're not feeding all that much torque into a clutch, even if your engine makes 400+ TQ at peak.
The more axle ratio you use, the shorter the tires you use, the less your car weighs, all these reduce the load the trans / clutch sees from any given engine.

Granny

An engine making 400ft/lbs isn't going to break a T5, even if launching from it's torque peak. The clutch is what can take that 400ft/lbs from the engine, then add another 400ft/lbs or so of stored inertia energy that is released from the rotating assy as it loses rpm. If a clutch with less clamp pressure slips enough to spread that same rpm loss over twice the time period, the impact of that additional energy release is cut in half (that additional 400ft/lbs in the example would be cut to 200ft/lbs). Basically the same energy release, spread over twice the time, will have 1/2 the impact intensity.

If you launch that 400ft/lb engine at 5000rpm and the clutch slips just enough that rpm never drops below 5000, no additional inertia energy is released and the input shaft torque never goes above the 400ft/lb output of the engine. Basically vehicle weight/gears/tires will have no effect at all in deciding if the transmission lives or dies during launch. It is key to wrap your head around this if you want to be successful in getting the most out of any manual trans.

sofakingdom

iTrader: (1)

As stated above,

For s street-driven car, nobody in their right mind is going to put in a screen door closer, to make their clutch slip.

There are 2 tricks to making a T-5 last in your car:

1. How you drive it
2. Use some other transmission while it sits on the shelf

All the rest if that crap about "clutch ratings" is just that, crap.

I tore up a handful of them with my original L69. (one of the weeeeeekest motors I have ever owned) Then another dozen or so with a 400. Toward the end of my inability to avoid that transmission model, I realized that I was NEVER going to be able to treat it like I always had treated 4-spds in the decades before I got this 83 car. Quite simply, I had to develop the strange and unnatural distortion of lifting my right foot off the gas pedal at least partway while shifting. Once I overcame that mental stumbling block, I made the last T-5 I had last about 20,000 miles probably, as opposed to 2,000 or less oftentimes before. It still failed from stretching across the front from the torque, that being the weak point of that trans; the case is too lightweight to hold the gears in alignment.

Same clutches as always... ones that HOOKED UP.

I never put a screen door closer in my car to make it sound like those laughable weeeeeeeenie Happy Meal toy Honduhs the little children drive around when they first graduate from skateboards, where the clutch is SOOOO inadequate that even with a motor that makes less than 100 ft-lbs, the clutch still slips going into EVERY gear. I can't begin to imagine how often those people have to keep changing those clutches out. It'll be a cold day in Hell before I ever deliberately force a car to drive like that. That's even worse than lifting the gas to shift.

Granny