Bus 4 spd trans, Anybody done this Options

[jwalters]

(IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

Thought of an interesting topic---has anybody put a beefed up bus or t1 trans in the teener----

I loved the gear spacing on my old superbug--and first gear for my car,,well,,,sucks ass--and second is too tall for a good start off--

Would rather spend 650 bucks on a pro-streeter WITH a rhino case and super diff than thousands upgrading my 901--

Sand rail mid engine cable shifter should be able to be adapted rather easily and the trans install is a non-event...

What you think???? (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

[jwalters]

QUOTE (andys @ Jan 22 2005, 01:29 AM)

QUOTE (jwalters @ Jan 21 2005, 10:13 PM) (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)  yea thats easy--go to CB's website--they do tranny's too and list all the gearsets and final drives-----basically if you want a 3.88 R&P AND a stockish .85 fourth--you can have 1500 rpms at 70 mph--the ratios are mind boggling--the T1 guys have something close to 200+ different combos and each gear is about 35-75 bucks!!! You simply tell them your tire diameter and what kind of driving you do and what you expect and all the T1 tanny people take it from there.... Also look at rancho transaxles--they are one of the T1 industries leaders---there is another one made called a Mendeola 4 spd--this is good for 800 hp $$$$ About 3 years ago hot vws mag came out with an issue listing all the T1 hipo trannies and the makers--ungodly!!! Whatever you want--you can have...... That 3.88 R&P and 0.85 4th is not nearly tall enough for the tires you'd run on a 914. I know there's a ton of ratio's for sure, but I don't recall seeing anything in a suitable range for a 914. The beauty of this trans, are the incredibly cheap prices. Parts are everywhere!! Andy

(IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) well the bugs run 15 inchers as stock also-put a bug and teener side by side with stock ratios and stock 165-15's and the bug will be at 2800 rpm at 70 mph--my teener is at 3350 rpm and my tires are only 1 inch smaller than stock , so not really allot of diameter reduction to fudge the numbers--something like only 2.5%, again , not allot.-also the bug standard R&P is 4.88:1, I believe--I know it is more than 4.12:1--and what is the 901?? Something like 4.42:1??? Now for the guys putting 16's 17's and 18's on their cars--the rubber will be in most cases of a larger diameter with a inverse reduction in rpms--that is just for high gear analysis--Now take that same bug tranny and gear the lower cogs to match the torque curve--and voila--you have insane acceleration thru torque multiplication in 1-3 and because of the high ( numerically low) R&P when you do shift out of third to fourth, you are already smoking at close to 120 mph--In my superbug--stock engine, stock tranny, 1600--100 mph was all it could muster on a cold dense day--but at only 5500 rpm and in third gear, I was doing 80 mph. Now most hotted teeners will easily pull another 1000 rpms, and with optimized ratios coupled with careful tire selection--you have a beast.

The stock 4th ratio of a bug is .84:1 and the 5th gear of the 901 is 1.40:1--it is allot higher ( numerically smaller, the input shaft to output shaft is 22:31, meaning the engine is turning faster than output) ) Wheras on the bug the engine is turning less than once per revolution of the tire, the 914 engine is turning 1.4 times per revolution of the wheel--plug a 4.12:1 or a 3.88:1 R&P ( which already is taller than the 901 ) in to the bug tranny and you have a much more efficient combo with which to play with gear sets, much more latitude....and a higher top speed if the power is there. but again, it all depends on tire selection. So in fact this combo is MUCH taller than the 901 trans.

I always laugh at those guys that put 22 inch wheels on their cadillacs!!! Even in my teener they are no match----they take away so much torque multiplication with those large diameter tire combos, that 0-60 they suck ass--and inversely--they have a much higher top speed potential if the POWER is there--which it kinda is----

point is -whatever you gear your box to for a specific tire diameter, and then later change the diameter for whatever reason--you will no longer have the same speed / rpm shift points or top speed.

This is how many crotch rocket dudes set their top speeds--it is prohibitively expensive to change internal gear ratios--so they go to a larger diameter tire which gives more available rpms for a given top speed than at which previously they were redlined--again-they have the power to do this--and their 0-60 times slip only a little due to high power output. this is the poor mans way to change the final gearing w/o going into the boxes.

With my tire combo-I will be looking for a max of 45 mph in first, 70 mph in second, and at least 105 in third--kinda tall first, but I am turboing--so I will have available more torque in the lower rpm range to power thru the ratio deficit--then coupled with a close 2-3, because as speed increases the power required to maintain that speed is squared, you need close coupled gear sets to relieve the motor and take up all the air / drivetrain drag which is induced and robbing HP, hence, a better torque multiplication rule. Then a nice long tall 4th gear to maximize trap speeds--

What is sooo cool, that say an engine makes 200 hp on a direct drive dyno and 200 TQ. When you plug in the numbers, lets say, 3.25:1 first gear, the tranny is multiplying this 200 TQ by 3.25:1 or 650 ftlbs of torque is making its way to the final drive--the final drive is 3.88:1 so we plug these numbers in and get 2522 ftlbs of torque--not MEASURED tq--purely mathematical---but then factor in a diameter of say 32 inches, which is inverse to final drive, and you are back down to about 145 measured tq-at the wheels-or say a 28 inch tire, that tq is now about 180--so it is crucially important to finalize the tire choice first---too many people do not even think about factoring in tire size FIRST--and they never see the real potential of their car.

With this in mind it IS possible for the wheels to develope more tq than the engine actually makes--this is where cog and final drive selection comes in---

Another thing to think about--nascar engines put out about 650 hp in a 3000# ?? car, and they go upwards of 200 mph, with phone booth aerodynamics---Ferrari has to make 550 hp to touch 200 and with the very best aerodynamics possible--but the nascar one is not very street friendly..........this is a good case of gear ratios making more power available than the engine produces. And the 4 spd can trounce a five--the 930 did it--it had the power to power thru the deficit coupled with a high 4th--had an eyeball snapping 0-60 and an astounding top speed for its time.