With regards to a project I'm building up to at the moment, I've come across a stumbling block.......the transmission.
Basically I understand that the TH350 is the general 3 speed auto to use with an SBC - but I can't help feeling I'd prefer a 4 speed at least, if not a manual.
So, what's the most cost effective way to get a 4 speed auto, or manual box (even more clueless about those) to withstand a street-driven 600BHP small block?
It's gotta be reliable and withstand abuse, I'd also like the moon on a stick, please...
Any info appreciated
I'm shooting for something a little like this:
If it makes any difference, the car will weigh less than 1000kg hopefully. I suspect traction may be 'interesting' too......
The answer in manual box - at reaosnable money - has to be a Tremec TKO 500 (500ftlb) or TKO 600 (600ftlb).
Those ratings are generous - Tremec bought over the T5s from BW and only rate them at about 250ftlb, so you know the TKOs are tuff as nails.
Have a shop around before you buy - they are listed at around £1750 by most people. I bought my TKO500 from Roadcraft (Brian 01903 522900) at £999+vat a couple of years ago - couldn't buy a new R380 for that!! Can't comment personally on the box as the project is not up and running yet, but they have a hell of a reputation stateside. they really look nice and have multiple locations for the gear lever, so you can fit them into just about anything, and depite having strong wide gears they're not too big (A T6 is a much bigger box which can be a swine to fit in many cars but only rated at between 400 and 450lbft).
Here's some general stuff I cut'n'pasted:
RPM CRUISING 5th GEAR – Overdriven 5th Gear Ratios of 0.68 (TKO-500) and 0.64/0.82 (TKO-600) provide comfortable highway driving, improved fuel economy, reduced wear and tear on engine and accessories.
FAST ACCELERATION 1st GEAR – Lower 3.27 1st Gear (2.87 TKO-600) vs 2.52 Muncie or BW T10 4-spd. Produces excellent acceleration from a standstill, possibly eliminating the need for a low differential gear.
KEISLER CUSTOM TAILHOUSING – Retooled with new internal shifter rails, true internal offset, correct shifter geometry, permanent lubrication, smaller profile for correct driveline angle and tunnel clearance.
BOLT IN REPLACEMENT – NO CUTTING or ALTERATION of the car body or frame; attaches directly to GM bellhousing and works with mechanical clutch linkage.
CORRECT SHIFTER LOCATION – Keisler mini billet shifter with true offset for factory location & appearance for console and bench applications.*
FULLY SYNCHRONIZED FORWARD GEARS
TKO-500 Ratios: 3.27, 1.98, 1.34, 1.0, 0.68
TKO-600 Ratios: 2.87, 1.89, 1.28, 1.0, 0.64 (0.82 optional)
LIGHTWEIGHT & HIGH STRENGTH MODERN TECHNOLOGY– Only 99 LB weight, tapered roller bearings, chromoloy steel shafts and gears, one piece countershaft.
You can get them with either a Ford or Chevy spline input shaft, and get the output yoke to suit your prop.
Transmissions are dictated by lots of variables Weight of car wheel size, tire size, general intention of useage, 600hp wont break anything, but the amount of torque will do plenty of damage, Torque makes the car accellerate and the HP will get you speed,
As for gearboxes, a cheap option would be the Toyota W156? Turbo box, that will handle sensible amount of torque,
Have a Look here, http://www.jegs.com/webapp/wcs/stores/s ... 2_10529_-1
Note they do not quote max HP or Torque figures the boxes can handle,
but it may give you an Idea as to what is out there.
THE SMOKING GNU
12.604 with an old boiler of a RV8 and no gas
WHY are there so many IANS on this site???????
Ask Eliot, he has broken most transmissions out there on his turboSBC and is currently playing with 4l80E boxes. Fora light car unless you are running drag radials I don't see why a TH350 with all the usual upgrades shouldn't handle it, TH400 is beefier but A LOT heavier.
bill shurvinton wrote:Ask Eliot, he has broken most transmissions out there on his turboSBC and is currently playing with 4l80E boxes. Fora light car unless you are running drag radials I don't see why a TH350 with all the usual upgrades shouldn't handle it, TH400 is beefier but A LOT heavier.
Indeed.
TH350 nice box, but only three speed - killed that without turbos. TH700r4 is a straight swap nearly, just slightly longer.
The 3/4 clutch pack is the weak point on those boxes - ive tried must setups. Avoid the 9plate alto, consider the 8 plate alto with full thickness steels - despite that Ive killed one of them too. Currently using a raybestos Z pack. But I think my 2/4 band is slipping now.
I spent a fortune upgrading parts in 700's, they are reasonable boxes if you put money into them - on 2wd car it should last longer due to lack of traction.
My problem is 4wd, big tyres, weight and lots of torque. I'm only running 6/7Lbs of boost.
As Bill says, I'm now slowly working on a new adapter to fit a 4l80e box - which an electronicly controlled 4 speed version of the venerable TH400 - but be warned they weigh nearly 100kilos.
I know where you can score 4l80e's in the uk also, which are uber rare.
Wow! Didn't expect quite as much information so quickly! Great stuff...
The aim is to break the 200MPH barrier and whilst I'll probably hoon about in it a lot, I won't be doing rolling burnouts from every light I'll have to look at the various ratios and check what my rear end will be before going further....
I'll have to re-read this all in a bit and take it all in! Much appreciated!
Eliot wrote:For you application / aims, i think a manual box would be better.
I think you are right for top end especially if you dont have a lockup, I would think the losses get progressive the faster you go, then the fluid starts to cook and you end up going in ever deceasing circles, needing more power to eliminate more and more losses, , a few years ago, my maye balloned his torque converter and caused loads of damage,
Something that used to be popular was clutched Autos, have a Auto box, but do away with the Torque converter and use a normal mechanical clutch, means you have to use the clutch pedal to start off and when you stop but apart from this it works like an auto but without the associated losses, obviously the fluid has to be stopped traveling along to where the converter used to be but its not to difficult.
THE SMOKING GNU
12.604 with an old boiler of a RV8 and no gas
WHY are there so many IANS on this site???????
Sounds intresting, that clutched autobox. I think if I was going to do the work to have the clutch hydraulics in place that I'd probably stick with an all manual.
I'll have a look at the W156 and T56 ratios, see what works. I guess I could always run one, see what happens and see what issues appear.....
>bang<
I hadn't thought about the oil cooling issues in the autobox - especially important seeing as it might be sat flat out for some time - probably only so much heat you can remove from it on each pass through the cooler and so on....like you say, around and around in circles trying to fix new issues.
Lewis wrote:I'll have a look at the W156 and T56 ratios, see what works. I guess I could always run one, see what happens and see what issues appear.....
I'm aiming for the 200mph thing as well, with 400ish bhp normally aspirated and 400bhp nitrous on top.
I looked at T56, TKO500 and TKO600, and the one which best matched my gearing needs was the 500.
If you have your car's power or torque curve, and can give my your wheel and tyre sizes and diff ratio, I can run it through a package I have and send you back graphs of what your optimum gearing should be - what's the car? (I'd need that too for drag reference point).
A powerglide is a direct swap for a TH350. Its a bolt in application. You can even keep the converter as it is possible to get a 'glide input shaft with the appropriate splines.
Even the mounts line up and the prop is re-used depending on which tailshaft you've got fitted to the 350.
You can stick 2000bhp+ through a glide
Downside is its 2 speed. however, gearing is all about leverage. If you don't NEED 4 gears then have less!
Think 'housebrick' and you're not far off.... An -urk, don't laugh - Dolomite......So 70's saloon, albeit slightly smaller than usual.
Don't know what the power or torque will be like. I'm guessing it'll be like my previous L98, just amplified across the range. Say 400ft.lb at 3800RPM maybe?
Rear end would most likely be a 3.07:1 I think....
I'd be trying to get the engine to rev safely to about 6000RPM, maybe more, I think, a lot higher than the standard L98. It'll have a fair bit of internal work done (i.e. all forged) so should withstand a little more, too.
I'd like a nice big safety margin though
Basic spec would be a twin-turbo (or single SC) 383 smallblock, ally heads, forged crank/rod/pistons, suitable cam, all fuel injected....
Last edited by Lewis on Sat Dec 22, 2007 4:23 pm, edited 1 time in total.
Forgot to say - there'll be fairly extensive aero development done on the car - so whilst seeming totally ridiculous, it will be a considerable improvement over the standard offering
Things like a flat undertray, smoothed trim, ducted cooling packs, etc etc....
Don't know what the power or torque will be like. I'm guessing it'll be like my previous L98, just amplified across the range. Say 400ft.lb at 3800RPM maybe?
Rear end would most likely be a 3.07:1 I think....
I'd need your actual power or torque curve from the engine you'd be using, or a very similar engine, to feed into the programme, because it's a matter of optimising gearing to match the peak of the power curve to drag at a specific speed.
Also would need wheel sizes, and tyres (width/profile) as this all significantly determines overall gearing.
Reference drag can be obtained 'close enough' from known top speed vs power for a standard car, so that's easy enough to find.
-JC.
