Gearbox ratios

[chateau la fete]

Hi

I'm trying to work out the best options for gear ratios, as my gearbox needs stripping.
The current set up seems pretty good for acceleration, but 4th is to close to 3rd and no good for the motorway.
I want to be able to drive at 70 without ringing its neck, but also want to accelerate as quick as possible for occasional strip use.

Current set up in car is as follows:

Super beetle main shaft
1st stock
2nd stock
3rd 1.48
4th 1.04
4.12 ring and pinion
Welded syncros
HD super shift/steel shift forks/HD side thrust plates
Race axial's

Motor:
2332
C55 cam
8:9:1 compression
48 IDA's

205/70 15 tyres

Thanks for any input

[chateau la fete]

IRS box

[Zach Gomulka]

Can't have it all unless you go to a 5 speed. Simple options are to either swap the 4.12 out for a 3.88 or swap the close 3/4 out for stock 1.26/.89. Personally, I hate the 1.48/1.04 combo. The 2/3 drop is shorter than the 3/4. To balance out your gear splits and still have slightly more aggressive gearing than stock you can use a 3.78/2.21 mainshaft with your 1.48/1.04, and run them with a 3.88. That's a lot of money though.

[chateau la fete]

I do understand about not having it all, just trying to get as good a balance as possible.
I did think about 5 speed, but the amount of time the car gets used it would probably not warrant the cost of a 5 speed

Thanks

[richie]

According to my calculations that should equate to 3850rpm at 70mph, that sounds ok to me, do you think that's to high? stock VW for 4.12/0.89 would be 4100rpm in 4th at 70mph, also it has nice fan speed to keep heads cool at that rpm, much slower rpm than that and engine will run hot I feel, a 0.93 4th slows it down to 3450rpm, and more than that and drop from 3rd to 4th will make it hard work


cheers Richie

[spanners]

The C55 isn't the maddest cam in the world but it may become hard work and drop right off the range with wide spread ratios, I run your ratios on the 3.86 rp so I can use 2nd at hairpins, the motors a torque monster and pulls that top all day, it's a bad problem in circuit racing and most VW's with 4.12 have effectively only a two speed box, useless,  and we get all excited at 5 speed boxes when we need to think 6 speed along the lines of Peters, at least for lower torque aspirated motors, Ritchie's advice is about there.

[Andy]

What times does your car run at the strip.

I run a 4.12 gearbox with stock ratios, on the motorway the 0.89 fourth gives 70mph at about 3300 rpm, with 195/70 tyres.
On the drag strip running low 14s I keep it in third and cross the finish line at 6500rpm/ 96mph. I think if I ran much quicker I would need to get a close ratio box to use fourth.
For the moment I drive to the strip, run it down the track and then drive home, in relative comfort.

[modnrod]

I've come around to a happy compromise that works for me, lots of highway involved but still with a closer 3rd/4th for noticeably better acceleration, and a better rev drop on each change. Like you I like the 1.04 4th at the track but dislike the revs on the highway.

 3.78      2.06      1.35      0.93

6500     3540      4260     4480
            6500      6500     6500

Highway rpm around 3500.

[chateau la fete]

Car was running around 13, with the current work, was hoping to get mid to high 12

Richie are your calculations on my current set up or with a 3.88?

Car runs around 3200 at 55 mph

[richie]

Car was running around 13, with the current work, was hoping to get mid to high 12

Richie are your calculations on my current set up or with a 3.88?

Car runs around 3200 at 55 mph

Current set up as you described it with 4.12, says 55mph should be 3050rpm with 1.04 4th and 205/70/15 tyre, I am guessing you run a shorter than stock front tyre? so then speedo is out

this is what I used for calcs if you want to input info and see what changes to ratios do

http://johnmaherracing.com/calculators/gear-ratio-calculator/

cheers Richie

[chateau la fete]

Cheers Richie

Yes, running 135's up front.
I calculate the mph via gps

[dangerous]

1.318 40hp 3rd and 0.93 SSC 4th is a good economy set up.

If you want even less rpm on the highway,
and spend some $ on an after market main shaft
you can go slightly taller in 1st and 2nd and use the factory 1.26 and 0.89
which ends up closer ratio(than above) between each, and better gaps than any stock ratio.
(except the 1.26 to 0.93 SSC)

[chateau la fete]

I have removed the gearbox and will now get it sorted.
Originally Cogbox built the box (late '90's), it's done well!!
Do I go their or bears, or.........??!! To get it rebuilt, there are some diff issues as well by the sound of it

[chateau la fete]

Ring and pinion are toast!!

Anyone used ranch a pro street/pro comp plus box before??!!