Street strip Gear ratios

[CR MAD MAX BUGGY]

Hello everyone.

Im figuring out what could be the ideal gear ratios for my street buggy transmission.

Straight to the point..
- I know that a street and strip tranny is almost imposible to achieve in a 4 speed gearbox.
- I dont want to consider a 5 speed gearbox.
- I have a swing axle 4 speed 4:12 R&P gear box with the following gears.
1: 3.80
2: 2.06
3: 1.26
4: 0.89
- I run a set of street tires Radial TA 27" inches tall on the street but would like to get a set of Slicks for weekend drag racing 26" tall.
- The engine will max out a 7000RPM (86B camshaft)
- 2442cc engine

I was planning on doing the following.
- Putting a 1.44 third and 1.04 fourth in order to get better drag times and also change my street tires to a 29" tall to compensate a little the short gears.
I would be very happy cruising at 65MPH on the highway and I think 3200RPM is good enough in a street buggy as the engine is all exposed with an oil sump and an external oil cooler.

I would like to know your drag racing street gears plus any suggestion are welcomed.

Thank you.

[Casting Timmy]

I like to look at 2500 and 3500 rpm's for street gears and make sure that you get about the same speed in 2nd at 3500 as 3rd at 2500....not exact, but you don't want the gearing too spread apart as you'll get dead spots.

I would suggest changing to a 3.78 first, you can get it modified on the back half to be just like your keyed 3.80 first. That way it will drop right into place with the correct idler as well.

Or if you need an idler and 1-2 slider as well you might just upgrade to the 091 idler option which is a little stronger. Probably also going to be easier to find soon as 002 idlers dry up. Just make sure the 091 idler gets machined for using with the 002 mainshaft. Then it installs pretty easy with an 091 synchro and 091 1-2 slider.
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Choose whether the street, or the strip is more important, and live with the less than desirable results for the lesser important one.

Depending on how hard you plan on running at the strip, and what your 2442 makes, I would consider an aftermarket main shaft. A 3.75/2.25/1.58/1.22 with a 3.88 would give you a little tighter spacing, but get you 65mph at 3600 with a 29 inch tire. Regardless, you’ll need to look into the higher end swing axles.

[EVfun]

[Ohio Tom]

29" tire is going to change gearing in a big way.
More than your 1.44/1.04 is gonna change.
29" tires are not going to work well with your stock ratio mainshaft either.

I'd stick with 26" tires.

I really like the 3.78/2.06/1.44/1.04 combo with either the 3.88 or the 4.125 RP.

Very evenly spaced gears.

Also, I agree with the 091 1st gear idler upgrade to the 3.78 mainshaft. It will make it lots stronger.

[CR MAD MAX BUGGY]

Thank you guys, looks like Ive oing my home work .

I called the wright gear box and he recommended the 3.78 mainshaft to make it stronger so yes, I think I will be going that route.

The thing about the wheels is just to compensate the short gears on the street.

Right now I have a 27 inch for the street and the stock gears works well but with the new setup which I think will be 3.78/2.06/1.44/1.04 on a 4.12 R&P, Im planing on having a 29 inch set of tyres for the rear and a 26 inch set of tyres for the strip. This way I can stip cruise on the highway at a good speed and I can also have fun drag racing the buggy on the 1/4.

I didnt mention the rest of the components because they will be the standard upgrades.... super diff, steel forks, aluminum side plates etc etc etc.

[Dauz]

I have this swing collecting dust. It was okay in the 1/4, horrible in the 1/8th, awesome on the street. 12 volt case, 4 spider superdiff, h.d. aluminum side cover, welded gears, hard keys, steel forks, superbeetle 1st gear upgrade, 3.88 ring and pinion 3.78x2.06x1.26x0.89. Has less than 10k miles on it.. barely broken in.


said gearbox

I'm currently building an 002 Pyramid with an 091 gear stack

[buguy]

That's pretty much the same box i have in my turbo car. Holding 250hp just fine so far.

[EVfun]

[CR MAD MAX BUGGY]

[buguy]

The build and ratios. I should point out i haven't had mine in very long though. Just enough for a few burnouts, some hard runs and driving, and 8 back to back dyno pulls.
KCR built mine.

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If you are planning around 150hp, a VW mainshaft with the 3.78 first would be adequate enough.

Treaded tire spinning burnouts on dry pavement, and rolling starts are completely different than 4K+ launches with slicks on a prepped track. 250hp is a tall order for a VW gearset for the latter.

[CR MAD MAX BUGGY]

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[Teeroy]

Put a shorter tire on it, or switch to 4.37 R&P, car will be mu h more responsive! How much time do you expect driving 60 mph where you live? My autocross car only has 23 inch tall rear tires and had a 4.12, 1.48 3rd, 1.04 4th and would cruise 60, now has a 3.88 to get me more mph in 2nd to better match our length courses. Could cruise all day now if needed (not what this car is set up for though)
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[clonebug]

A stock trans will take a lot of power if you respect it a little bit.

My stock trans with 4.12 diff lasted 3 years with about 150 hp before the 3rd and 4th gear syncro hubs needed to be welded. It was a used trans that had a lot of miles on it.

The stock diff finally let go last spring so it held for another 7 yrs. i put in a 4 spyder super diff but it's not good for long distance travel and left me in a pinch 1100 miles from home.
I had it replaced with a 10 tooth stock diff and I have over 500 miles on it now.

If you plan on driving long distances...keep a stock diff in it if you run a swingaxle.

Anything over 120-150 hp/tq will slip the sycro hubs.....maybe not right away but if you are putting decent torque to the ground especially with a turbo you will have them fail. It will be quite obvious because all of a sudden you won't be able to shift 3rd and 4th gears.

A swing superdiff has poor oiling to the fulcrums and spades and will heat up the transaxle pretty quick. Mine heated up in 30 miles while pulling a 6% grade for about 4-5 miles.
Even if the builder does oiling mods they will start to seize when they get hot.....not good when a 1000 miles from home.

I run 275/60-15 tires and have since probably 2006. They give me the best drive I feel.....I have the power to pull them though.
I can cruise all day at 55-75 mph...My 70 mph cruise is at 3100 rpm and the tires are 28 inches tall.

If you haven't run the big engine yet with the stock trans...you should put at least a 1000 miles on it to see how you like it.
Welding the 3rd and 4th gear sycro hubs will give you a nice robust trans if you don't absolutely abuse it with smokey burnouts.
I rarely if ever launch that hard......spinning tires in a short wheelbase buggy is not the smartest thing to do especially at speed. You can get swapped around quicker than you can react and it could easily be fatal.

I'm old enough to know better and once is enough.....hitting second gear and the tires breaking loose instantly put me in the oncoming lane before I could react......I won't be doing that again........
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[Teeroy]

Our old glass buggy had 28 inch tall tires on it with a stock 40hp box (4.37 R&P, .89 4th) it drove great, gearing for stoplight to spotlight or freeway was good. It would've needed some mods to holdup to you big cc engine, mine held up fine to my 1776, no clutch drops though
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[Ohio Tom]

4.37 R/P are weaker than 4.125, and 4.125 is weaker than a 3.88.

Just an FYI..

Your idea to run 3.78/2.06/1.44/1.04 with a 4.125 with 26" for drag and 29" for street will work OK.

The only thing you will notice is that the drop on the 1/2 shift will be pretty big with the 29" tires.

Gonna bog when you hit 2nd gear on the street. (ask me how I know).

If you really want to drag race it, look for a Klinkenberg, or Oettinger 4.125 RP.
The common, "G" Gleason is the weakest. the "K" and "O" are lots stronger.

[CR MAD MAX BUGGY]

[Ohio Tom]