TheSamba.com :: View topic - 1st

Sat Jan 10, 2015 6:30 am

I am going to upgrade my trans this year and after looking through the mags and resources like the DKPIII members cars, I am a little unsure what 1st - 3rd gear ratios would be a good choice.

I have asked a few well know trans ships and get different suggestion so, thought I would ask for suggestion from those using in real life.

I am drag racing occasionally in Nostalgia events and still run on the highway so.
I want a 4.12 r/p and a stock 4th gear ( I only run 1/8ths)
1600lb sedan (no driver) 26" DOT Racemasters.
2276cc, fk10, CB Perf. Super Pro heads 44 x 37, Dual IDAs with 40 vents, 1 3/4" exhaust.

Thanks for the help

Sat Jan 10, 2015 6:34 am

My original idea was Weddle:
1st - 3.75
2nd - 2.25
3rd - 1.36 ( compromise for decent race and highway)
4th - .89 ( for highway )

The RPM drops are almost the same 1st - 3rd. and should be inside powerband.

do these make sense? I was offered a suggestion to go with much Higher ratios I think would lower my ETs.

Sat Jan 10, 2015 9:19 am

What's your trap speed in 3rd?

A 26" tall tire and 6500rpm will get you 77mph with a 1.58 3rd. A 1.48 gear will get you 82mph.

The 1.58 will pull like a freight train to redline. I ran this combo with a 1.04 4th on the street and the 3-4 gap was noticeable but livable.

Sat Jan 10, 2015 9:42 am

I would go 3.78-2.06-1.39 and .89

A good engine has no problem pulling the stock second with a 4.12 but has a problem if you use a 3.88

The third choosen keeps the gaps with in reason.

Dan

Sat Jan 10, 2015 9:59 am

I don't think you're going to gain much e.t. over the 3.78/2.06 stock VW ratio for the $1000 spent on the Weddle Mainshaft. I have a buddy with a similar engine, and a 4.12 r&p 3.78/2.06/1.48/1.04 combo with the 26 inch M&H Dots. With 65mph being around 3600rpm, it wasn't real fun on the interstate, but do able. The high 1.30's, or very low 1.40's is about as high of a 3rd gear I would run with a .89/.93 4th, or you'll be tearing your hair out with the rpm drop. Unfortunately you'll be leaving some on the table at the track with that low of a 3rd gear. What's your current combo, and how does it perform now?

Sat Jan 10, 2015 10:19 am

I just went through this....talking to everyone under the sun about gearing. Finally went with 3.88/3.78/2.06/1.48/1.04 and it pulls great. Not a freeway car but the gears are close and the car never falls out of "power".

Sat Jan 10, 2015 1:57 pm

'Dougy"
My best time and speed last year using same engine with fk8 and 42 x 37 "bill Fisher" style port/polish & 3 angle job.
8.04 @ 82.57mph. my average speed seems to be +/- 81mph
RPM was around 5500.

I am launching 6000 + rpm and shift at 7500rpm three gear. I have to shift to 3rd before the end of 1/8th

Consider The gear ratio I proposed have a RPM drop from 7500 to 4500 give or take. That keeps in in my power band.

to those suggesting stock 2nd: I shift into 2nd at around 100' pull the lions length of 1/8th and shift to 3rd within the last 100' or so, 2nd gear is doing almost all the work.

Also, I have a raped 2nd gear in another trans because all stock gears are worn out and have the larger drive teeth removed now we are all driving on the smaller alignment teeth. Must go to stronger Weddle gears.
I plan to use a .89 4th for the street.

One suggested I go higher 1st - 3.33, 2nd - 1.93, 3rd - 1.22 ?

Sat Jan 10, 2015 2:26 pm

If second gear is doing all the work then you sure don't want to raise it!

Closing the gap between first and second is GREAT for general use, street, dirt, ect. it even lets you shift faster since the syncros don't have to work as hard! If we leave second alone then have to raise first, BUT, I know for drag a high first can cause some BOG off the line depending on traction and you don't want that at all.

I think the 2.25 second would suit you well! Especially with a 3.88 r&p(which you should use, it is stronger), make fourth 1.04 or 1.00,
third 1.42 or 1.48, 1.48 is perfect split for acceleration but 1.42 for better street cruising.
Your 1.36 is 40% rpm drop, just a hare too extreme IMO

I just swapped my rail trans from2.06, 1.58, 1.12
to 2.25/1.42/1.04 and WOW the acceleration 0-60 was so much faster!!

You can do the math yourself but the 1.04 fourth IS same as stock with a 3.88 and your taller tire :D

ALSO raising second hits reverse, so you have to use I think 091 reverse gear. It is doable but PITA, the higher second is only WORTh it for for the hillclimb and roadrace guys IMO

Sat Jan 10, 2015 3:30 pm

Thank you Modok! again you come through.
That is exactly the way I thought but this guy suggested the higher ratios and swears he never built a drag race box with the ratio like you suggest.
Kind of stopped me in my tracks to think.
Yes, 1.36 is a compromise ( 4.12 r/p) was originally think 1.46 / 1.48 'ish.
I know 3.88 is the way but I keep shying on it because of higher ratio. Like those wheelies! also stock .89 cost helps overall price of box.
can I PM you about trans builder?

Sat Jan 10, 2015 3:50 pm

I was looking at compromise for street/ strip gears and something maybe to consider would be smaller tires at the drag strip. I want to run 4.12RP 3.78/2.06/1.31/ and I forget 4th, but it's the stock 4th for a 3.88 trans. Basically take a late model and replace the ring and pinion along with 3rd gear and put smaller than stock tires on the car.

Might be a cheaper alternative to buying a new mainshaft if you're in a money crunch.

Sat Jan 10, 2015 5:33 pm

Here's a link (https://www.youtube.com/watchv=OcCPTDvmAHE&feature=youtu.be ) to Youtube vid of my car going down the strip. You can hear the shift splits. 3rd gear I actually ran a bit past the finish line full power for some reason.
This is a 4.12 r/p stock ratios = 1st 3.78, 2nd 2.06, 3rd 1.26.
[youthttps://www.youtube.com/watch?v=OcCPTDvmAHE&feature=youtu.beube][/youtube]

Sat Jan 10, 2015 7:29 pm

Never built one?? the 2.25 second and 1.48 thrird are probbly the oldest and most common gears to change to.
2.25 was adapted from autostick by welding it onto a bug mainshaft, and 1.48 just happens to be a prefect match for it. Isn't that what the berg's ran??

I see what your sayin about 4.12 with stock fourth, but you can find 1.04 gearsets for as low as 100$ so it's not a huge difference in price all things considered. Could go 3.88 and the stock .93 fourth as it works out the same BUT the "sportsman" manshafts are for key'd gears and I expect all the stock .93 fourths are splined........but you could ask, maybe there is a way.
The mainshaft is not so easy to find a deal on, I waited for years and never found one for sale cheap except for odd ratios.
Sportsman manshafts are I think about 650$ and you won't find lower.
Scat or maybe bugpack has a 3.55/2.21 mainshaft, possibly even better ratios, and lower price than weddle's really nice ones.

my 3.78/2.25/1.42/1.04 with 3.88 is supposed to be for my street car that will run 26" or 27" tall tires for street, and for drag go down to smaller diameter 14" sticky tires that are only 22 or 23" tall. Racked my brain forever to try to find best compromise and that's what I ended up with.

Rancho! I would have them build me one but the shipping is too high.

Sat Jan 10, 2015 8:05 pm

All good info, I didn't know about the .93 stock gear, good call.
I have a Rancho now, and there full out drag box is pricey compared to others.
Do you know about Transworks in El Cajon CA. He has good prices and info on the website.
Also what about KCR?

Sat Jan 10, 2015 11:30 pm

I have no idea, around here it's locals or rancho, and whilst some of the local guys are pretty good I don't think think they do a lot of mail order.

Sun Jan 11, 2015 9:47 am

Mike at PEP VW was highly recommended when I was looking. Nice guy... All the east coast racers use him.
http://www.thesamba.com/vw/forum/viewtopic.php?t=577457&start=0

Sun Jan 11, 2015 10:39 am

1. Off hand I´d say that your shift point is on the high side. I would think early 7´s would give you better time slips. I doubt the engine pulls positive that high. That´s FF87 land :wink:

Good numbers on the 1/8´s and decent on the freeway.
This comes to mind: 4,125 R/P. 3,78/2,06/ 1,35/0,89. Almost like earlier suggested.
Lowering the rpms further on the freeway. (Not a lot, but it all counts): 3,88 R/P. 3,78, 2,06, 1,44, 0,93
This may cause the engine to struggle a bit on the line, as the 1st gear is faster. But the engine oughta have enough torque to overcome it.

T

Sun Jan 11, 2015 10:48 am

I agree with Alstrup. 7500 RPM's is a little too high. I have a 2165 with FK-10. I shift at 6800 RPM's

Sun Jan 11, 2015 12:50 pm

Racer Dave,
Nice vids
Shift point not as important to this as RPM spreads/drops. I did TnT and that produced the best times for that engine/trans combo. New engine will need new testing.
I do not understand this predilection for a stock second gear. I already have this. the fact that all stock second gears have been raped of the original large engagement teeth making them weak.
Lower gear keeps the engine's rpm in the powerband.
The original idea was a drag trans that could be driven on the street.
I might see the stock first ratio with a 3.88 R/P with a more powerful engine.
Beside the strength benefit of the r/p the slightly higher ratio might allow 1st to pull a bit longer with a slightly less savage launch. (?)

Thanks for the Tip on the PEPVW, I could use someone closer to home. If anyone knows a dependable shop that makes quality race boxes near KY please let me know.
Thanks

Sun Jan 11, 2015 2:23 pm

If we keep the 4.12 and stock fourth as constants then your initial idea is Best.

If fourth and first are the same then you can re-arrange the gears ARE, but overall they will still be spaced far apart.

But if you drop fourth then they can actually get closer together, which is why I try to talk you into the 3.88 final and fourth 1.00 or 1.04, then you have 33% RPM drops which is perfect. 40% rpm drop is about the most you ever want, 40% is not downshiftable if you know what I mean. I think you'll have a bit of a gap around 45-55 mph with your idea, but other than that should be ok

Sun Jan 11, 2015 4:17 pm

You can't have a compromise between a street gearbox and a race box. You must pick which is more important to you. The only real compromise is a $5000 Berg 5-speed.

my opinion is a 4.12 R&P with 3.78/2.06/1.48/1.04 for a street /strip gearbox. I would not run a 3.88 unless you get a close ratio 1/2 mainshaft, and they are now $1000.

To get the best ET's you must get the car moving quickly in the first 60'. For drag racing I would not run a 3.88 with a stock 1/2 gear. What it all boils down to is do you want to race a $1200 street transaxle or drive a $3500 racing gearbox at 60 MPH down the highway.