Towing with T56

[CDeeZ]

The point of the thread was just to show what I did. I'm not reccommending anyone do anything other than use common sense.

The 4.88s are perfect for a vehicle with a deep gearspread in the trans (T56) and tall tires 29" or above.

"But who wants to tow with 4.88 gears" Elaboration????

The fact that the T56 was not given a towing rating is kinda irrelevant I think, a simple quick search on google will turn up plenty of people who have towed with a T56, including Mrplow in his 6,000 lb tank.

There is data in the form of real world experience. I have towed a pile of axles, motorcycles, engines, etc. This was the most recent and probably the heaviest tow so I chose to report it. When did real world experience become "not-data"?


Like I said I've been beating on this craigslist T56 for 5 years and have done some occasional towing during that period so I think if towing was going to break this T56 it would have done that in the course of 5 years.


And as far as the oil analysis data and everything else you guys are talking about. Great idea. Do either of you work at Conoco or something because I don't have access to anything like that.


Fullsize trucks did come with the T56 , the SRT10. GM toyed with a concept truck that also used the T56 in a stripped down, vinyl floormat fullsize truck. (Never made full production unfortunately).


The drivetrain combo is a 350 TBI that I screwed together maybe 6 or 7 years ago. ~ 300-350 HP and 400-450 LB/FT est. Elgin cam, ported and polished heads, Ultimate TBI mods, AFPR, TBI and pod spacers, .060 over, HVOP, midlength headers with H pipe and full dual 3" pipes, ported and relieved oil return holes in lifter valley, 7427 PCM swap and DIY tuning. T56 trans obviously. 14 bolt semi floating 9.5" ring gear with 4.88s and Detroit TrueTrac. 3/4 ton brakes all around.

[EagleMark]

Watching trans oil temps while towing in 4th, 5th and 6th gear would at least say a lot of what the trans is doing with the load and if oil is being heated past it's tolerance.

Oil analysis can be mailed in by anyone to various companies for engines, not sure who does trans? Diesel shops regularly use analysis at service intervals to see what is wearing in motor.

[RobertISaar]

im'ma just do some math here, because i'm curious about this myself:

T56(no model specified, so i'll assume a 95ish LT1 F-body unit for gearing purposes):


NV4500(i'll assume another 95 unit, MT8 RPO):


it's too bad the graph function isn't working at the moment.... it's nice to visualize it as well.

but those are with the same 4.88 gears(and 28" tire). as far as the highway(55MPH) is concerned, 5th in both is 2350-2400 RPM, but the T56 has the option of 6th gear when possible, RPM would drop to just over 1600.

to match the same RPM as the T56 6th gear, the NV4500 would need to use 3.35 final gears. i don't know if this is realistic/normal or not.


anyways, from a purely mathematical perspective..... the T56 gear spacing is VERY nice, has fairly consistent ratio changes, which would certainly help keep the engine in its powerband at any time. the NV4500: not so much. shifting at 3000 will land you anywhere from under 1500 to 2200 in the next gear. some gears, you would need to wind it out a lot further than others to keep the engine from dropping to too low of a speed in the next gear.



as far as the hardware holding up, i won't speak of it, neither the T56 or the NV4500 is anything i have experience with nor knowledge of. i'm much more interested in seeing how to stuff a T56 into a 4WD S10 chassis with a heavily boosted V6 in front of it for my personal use.

[CDeeZ]

I would think that any place that analyzes oil should be able to do trans fluid as well, it's still oil after all, just with some hydraulic fluid mixed in as well.
My T56 is the 95+ model with the 2.66 1st. I believe that is the most common gear spread for T56s, not sure on that one though.
As that shows, the NV4500 has that short 1st gear which would be very helpful in getting a very heavy load moving, and as you pointed out, 5th is nearly identical.
"
anyways, from a purely mathematical perspective..... the T56 gear spacing is VERY nice, has fairly consistent ratio changes, which would certainly help keep the engine in its powerband at any time. the NV4500: not so much. shifting at 3000 will land you anywhere from under 1500 to 2200 in the next gear. some gears, you would need to wind it out a lot further than others to keep the engine from dropping to too low of a speed in the next gear."
The same closely spaced gears that are enjoyable to just drive/hot rod around in are also helpful when towing because as you stated, it will help keep the engine in the fat spot of the powerband each and every time you shift.
The NV and T56 are both great gearboxes. Just depends on what you want to do the most. Do you want mainly fun cruising from a brick-shithouse-tough trans that shifts like a sports car and can still do some occasional towing. OR, do you want a true truck trans with that granny 1st gear to really get the load moving. The NV is a wonderful box and certainly has it's place, but it will never have the shift feel and shift throws of a T56 (obviously). Don't anyone misunderstand me, the NV is a great box.
　
There are/have been/will be some companies offering 4wd T56, not sure if it's available yet? Anyways I have thought much about a 4wd T56 myself, and I know there are people out there who have done it; I believe it usually involves running a divorced T case but check this out
http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja &docid=9Wt6w2tujfFoNM&tbnid=Lrp-I4q_SnSRUM:&ved=0CAUQjRw&url=http%3A%2F%2Fgrassroo tsmotorsports.com%2Fforum%2Fgrm%2Fcyclonetyphoon-clone-on-a-budget%2F22144%2Fpage1%2F&ei=LWWvUpqZGfTTsAStp4CgD A&bvm=bv.57967247,d.eW0&psig=AFQjCNHrmxo31kDBz7PBX 5FU3MmghzvSBQ&ust=1387311334351554

[steveo]

i can stab my tire with a knife several times without it failing, does that mean

- it definitely wouldn't fail in short order if i keep doing it?
- someone else with a different knife might puncture it on the first try?
- you were perhaps, even subconsiously, stabbing it like a wuss trying to prove your point?

using the thought process "i've done it a few times and it hasn't broken yet" as a metric for component strength and longevity...... is that good?

just sayin'

[CDeeZ]

via Imgflip Meme Maker

[EagleMark]

Please don't make me delete this thread!

[CDeeZ]

4+ years later..... I finally had to take the T56 out to take it apart. But not for any reason related to towing with it, which many internet "experts" say you simply cannot do. The stock stamped steel 3-4 slider keys finally broke, a common problem with T56s that can happen at any time. When this happens it gets stuck in 4th gear. Everything else inside the gearbox looks perfect, bearings, tooth contact patterns, races, synchros etc.

I bought this used T56 secondhand on CL 8 years ago, beat the shit out if it in this pickup behind a SBC for years. Lately, I have been thrashing it some more behind my S475 turbocharged LQ4 (still in the same heavy AF truck). I also towed with this trans in the truck a few dozen times after the original post, didn't get to run it over a CAT scale every time but it was always around the ballpark of 11,000+ pounds based on the occasions that I did hit a scale.

Since I'm in the gearbox to replace the broken slider keys I'm bulletproofing it at the same time, building a T56 hybrid. Credit for this info goes to this guy here:
https://www.eecis.udel.edu/~davis/z2..._Fbody_T56.pdf

SSR 32 spline mainshaft, solid billet slider keys, bronze fork pads, triple/double cone synchros, TH400 slip yoke. I'm also going to TIG weld a -6AN fitting onto the case for a fluid/sprayer pump. This will eventually get hooked up to a pump which will spray oil directly at the headset gears. Should be a good addition when I start to crank up the boost in this heavy groundpounder.



The trans on the bench ready for teardown



Everything inside looks perfect. It's just the goofy stock stamped steel keys that forced me to take it apart.




The F-body gearset is sticking in the bench. Corvette input in the front cover, F-body laying next to it. Corvette and F-body clutsters laying next to each other.



SSR oil seal, bronze fork pads, and billet keys. Also a 3/16 loose ball bearing for the upgraded 1/2 snychro retainer.



SSR mainshaft, VSS reluctor, 1/2 synchro retainer, small input bearing, TH400 yoke, and steel Viper 3/4 fork.



Not a lick of unusual wear anywhere in the whole thing.



The C5 Corvette donor trans for the hybrid build.



Corvette and Fbody T56 torn down. There is a 3rd T56 floating around the shop somewhere haha.