I am looking at learning a bit about gearboxes.

I currently know little or nothing, so can someone give me some links or tips as to where I can find some basic info.

Internals, mechanical works are a bit of a mystery ATM but I have worked out that the CR&P is like a multiplying factor which affects how tall all the other gears are.

I am looking at a gearbox to suit a big torque engine, and run low rpm in top gear at speed, so likely will go with a 5 speed.

I am most interested in know what ratios people are running so that I can plug them into Baja Wes's awesome spread sheet.

Please let me know what you guys are running out there.

I have also discovered albins gears who are often referred to on here as the best.

Any comments on them?
good/pricey/worth it.....

Wow that could take a whole book to answer!

I will get some discussion going with my train of thought,
and "ask away" with specifics.

Some will be 'my opinion' and may change over time.

I like to convert ratios back to the stock 1500 beetle ratios,
since they are a good comprimise for most applications.

4.125 CW&P
first: 3.8
Second:2.0588
Third: 1.2609
Fourth: 0.889 (or 0.883 in fine tooth)

It is well known that the stock 2nd to 3rd shift is a pretty big rev drop,
and 1200 bugs had a closer 1.3182 third.
This can be used but then creates a bigger step into 4th.
But then you can use the lower 0.931 fourth(fine tooth) that comes from AT trannys.

With the 5 speed you have planned, these can be improved greatly.

Engines with big torque can benefit from a 4 speed tranny that has taller 1 through 3 gears and retain the stock ratio 4th.

When ever I convert ratios to something better suited, or stronger,
I like to keep the gaps between the ratios BETTER than stock.

Also a taller first gear CAN some times be tolerated if the engine has more torque than stock, at the same rpm as stock.

hi dave, i know you are talking about beetles there but is there a similar way to lower 4th in a 091 box in a kombi? i have tall tyres on the back and love 1st 2nd and 3rd but 4th is a tad high...got a 2.2 subaru behind it btw

Hi Rob,
if you are refering to a gear ratio that has less rpm at high way speeds?

Yes, Albins and Weddle in the US have a taller 4th of various ratios.
It requires a full rebuild to change,
but the gears them selves are around $400 by the time you pay freight.

Stock 091 ratio is 0.883 but there is a stock ratio that is 0.82.
....but I have never seen on in Australia (Weddle lists them in their calalogue).

The most common aftermaket ratios for what you want are 0.77, 0.74 and 0.696.
I would never recommend the 0.696 unless you have 8 cylinders,
and this is all that Albins ever seems to have in stock.

Weddle should have the 0.77 and the 0.74.

try ringing them because they dont answer emails much.

To convert your current RPM, divide by your old ratio(.883) and multiply by the new proposed ratio.

So if you are doing, say 4000 rpm, divide by 0.883 = 4530,

then multiply by , say 0.74 =3352 rpm.

Only problem is that this will make a bigger rev drop when you shift up from the stock third gear.

If you want more rpm(perhaps you have tall off road tyres?),
then the maths is the same,
and there are plenty of lower ratios available for the 091 box.

They are all coarser tooth too, and made from stronger material.

Try Albins first, and then ring Weddle if they have no stock.

yeah thanks dave...i meant lower as in more revs but same deal

OK, first things first, this is likely to wind up infront of a big cc t4, and if you beleive what they say it will make 200+ hp and 200+ ftpd of torque. peak 6k rpm. flat torq

I am thinking of the bus5 which is recently available by bergs.
Have also thought about a bug5 aswell, but the 091 has the best reputation for strenghth, and I am likely to keep improving the engine (its an addiction)

First question is about the cw&p.
What are my options there? Do I have the same options for the bug and bus, or will this choice limit things?

I have done some calculations using the 3.88 and also the 4.57 which I have seen on the albins site. I wasnt aware that they were offering a 4.125.
I will plug that into my spreadsheet and check the shift points.

As for the ratio of fifth, I like the idea of having a big drop from 4th to 5th, so I can cruise using the torque at 110kmph and keep the revs low. I have calculated using a 3.88 and 0.7 5th which is a bit extreme, so I will make some changes on the spreadsheets and see what it gets me.

ok have been spending way too much time playing with this spreadsheet - thanks again to Baja Wes.

I have got a bit of a theory that I will build something with closer ratios than stock, but all tend to be a bit taller, starting with first.
3, 2.25, 1.6, 1, 0.7 using a 4.125

Comparing to a VW T1 IRS tranny, this gives me a taller first, closer 2nd (sitting about 2/3rds of the way between the T1s 1st and 2nd), closer third and fourth (both sitting between the t1s ratios) and a very tall 5th, which sits on 2778 at 110kmph

I know that 5 th is pretty tall, and might pull it back to 0.77 or 0.74, but am curious to know your thoughts on this.

Also, am I better of sticking as much as possible to the stock ratios or going to the aftermarket gears such as albins for better quality?

When working out your "gaps" between gears,
divide the upper ratio by the lower one.
This will give you a number you can multiply the rpm by,
to work out the new revs.
eg a 2.0 second and 3.0 first is .66667.

As you up shift the gaps should be less, and thus the multiplyer a larger one.
5th gear can be a bit bigger gap, since it is normally not used in a race situation.

Try these...gotta rush to be somewhere!

4.57 diff
3.0
2.0(0.66667)
1.4(0.7)
1.04(0.7429)
0.77(0.740)

I did some more sums and being that your engine plan has a lot of torque(or so Jake says),
you might get away with a taller 4th gear.
you might like this:
4.57 diff,
3.1
1.93
1.40
1.04
0.74

The Berg style 5speed kits used 4th and 5th gears that are the key style, rather than the splined ones in the later models.
You can custom order anything you might want from Albins or Weddle.

Being he key style you CAN use VW gears if you want,
but 0.82 is the tallest fourth stock, so may not suit a Bus diff ratio.

The factory Bus 4.57 diff is more than ample for nearly anything strength wise.
Berg includes the lengthening of these and the mainshaft within the price of their kit.

A call to Rancho may be in order because I heard some gossip that they have a new 5 speed kit available also.

Another little calculation trick I found through trial and error,
is if you have , say, a 2nd gear you are happy with,
and a 4th you are happy with,
you can multiply the two numbers together,
square root the answer,
and it will give you a third gear ratio that is exactly MID WAY between them.

The final choice of the result should always be equal, or a little taller than your answer,
so that the percentage REV DROP reduces with each up shift.

Kim, Dave helped talked me through ratio selection for my s/a box (to be mated to turbo engine). Albins 1 through 4 gears, plus OG 3.88r&p. The

3.333
2.08 (0.624)
1.40 (0.673)
1.04 (0.743)

To get the ideal "gaps" as Dave mentions, I tried to get a 1.44 3rd, however Albins didn't have any in stock and it would have been 6-8 weeks wait...so if you do end up going with weddle/albins, give yourself some time to wait if they don't have your ideal ratios on the shelf.
Al

no hurry for me on any counts, so its all research for the time being.

I will read in some more detail when I get home tonight and see what the calcs get me.

Any comments on the extreme 5th gear? Too tall or possible with the right engine?

0.7(0.696) is too ectreme unless you have 8 cylinders.

If the engine has the torque that Jake claims then 0.74 is as far as I would go with 4.57 diff ratio.

If it was my own personal STREET one, I would choose 0.77 even if I had 200 ft lbs(and I only have 170 in my race car so...).

Thanks for starting up this thread Kim, its very topical for me at the moment as I am wanting to build a new box for the T34. Was going with a Supabeetle box with the 3.88 / 1 R & P to get the open road revs down to about 2600 at 100kph. One thing to consider is heating if the revs drop too low in top at cruising speed.

The other thing is not all Porsche 5 speeds drop the revs down in 5th. The 901 5 speed 3000prm @ 100kph. 901 4 speed 3000rpm @ 100 kph. 5 speed porsche boxes are about keeping the revs in a band. High HP turbo Porsches all had 4 speeds from the factory as the 5 speeds would not handle the power.

Heres a link to a Porsche box ratio calulator 901 & 915 ==> http://www.pelicanparts.com/techarticles/mult_tranny_ratios/mult_tranny_ratio...

Dangerous, given that I have a 2.4 flat 6 with 160hp and tons of torque what gear ratios would you recomend for general driving not racing. Was thinking that the standard 4th would be fine, but I am aware of the big gap from 2nd to 3rd. Was thinking of higher 1st & higher 2nd to close the gap. With my current Type 3 box I can let out the clutch at idle and not always stall the motor. (Great for pulling tree stumps) Perfer to use VW standard gears if I can too.

Lastly is there a good gearbox guy in Melb that anyone can recomend?

Hi Dean

It is a good idea to share the info on the black art of gearboxes, as I need some lessons.
I have found this usefull, as previously mentioned, for getting a numerical feel for the combos http://forums.aussieveedubbers.com/viewtopic.php?tid=18037 

As for the porsche boxes, I am leaning towards the bus 5 speed as it is tough and cheaper than the porsche boxes to build/repair/replace. Also, when mating with a t4 the compatability makes for another level of complexity that I dont need.
For you it would be a good option.

I have heard that the 901 is perhaps a lesser cousin to the 915 and have been recommended on other forums and also here that I should stay away from it.

As for gearbox guy in Melbourne, I know that Sash knows someone, so give him a ring and I m sure he will pass on the details. I know of some shops in Melbourne who charge you for the box, and it ends up getting done by this bloke, for less than what they charge you.
Go straight to the source.
Sash will know the guy, I dont know his name.

I better get back to work.

I have plotted the lines onto the speed vs rpm graph, and it is interesting, your 1 2 3 are almost identical to mine with the different diff ratio.
your 4th is a bit past half way between my 3rd and 4th, and your 5th is about the same space between my 4th and 5th.

Maybe I ve got my gears too tall at the top

This is fun, and its encouraging to see that I m on the right track

What about the diff ratio - 4.57. I can get the same final ratios by changing the gears, but I read somewhere that some gear combos will be stronger with different r and p's. Should I be focusing on the 4.57?
Is this the strongest out there.

I dont mind going to all non stock if I have to, I just want to build this to be tough, cos in 5-10 years the engine behind it might a forced induction or twin plugs or both... who knows, but I want to build this box once!

Can someone give me a bit of a lesson on what the diff ratios mean to overall strength?

bump

The taller the ratio,
the less number of teeth on each gear,
and so the more strength.

On the Beetle the G3.875 is supposedly the strongest,
and on the Bus box the K4.57 is the strongest.

There are some different tooth shapes in each type and ratio, some stronger than others,
but the K4.57 is meant to be VERY strong.

Albins does make a K4.57 (among others) in a better material than stock,
but not in 5 speed length (custom order perhaps).

There is an even thicker tooth form from 5 speed bus that is G4.833, and while the tooth is thicker,
word is it is troublesome.

I think in later years, VW reduced the hard layer so they may fail earlier.

Hi guys

resurrecting an old post.

things have changed. budget and location constraints meant that I had to go with a simpler option - 4 speed t1 IRS

Im gonna run a quaife, so that limits the R and P, gonna set that at 3.88

I would really like some feedback on the following combo (using the 3.88):
3.78
2.06
1.21
0.82

this is as recommended to me

I was thinking that I would go with some that was overall a little taller, as the car will be pushing only around 700kg.
What do you guys think?

I was thinking a taller option along the lines of
3.5
1.95
1.21
0.82

or maybe even going to a 0.77

Can anyone guide me to a source of weddle gears on the net? I would like to see if I can get anything near to these.....

The link I had for weddle was just a home page with phone. email and fax details,
but no longer exists. They wont answer emails until you make an order with them, or are known to them.
Ring them and they will send you a catalogue with all their stock listed.

Long Enterprises has a list of ratios in their site.

http://www.longenterprises.com/high_performance_parts.htm 

Using the stock 2.0588 (2.06) second,
and a 1.2174 third will be a huge step in revs.

The 1.217 is a rare early bus third, but can be purchased second hand or new in aftermarket.

Albins will make you a 3.556 and 1.93 which is closest to what you have asked.

If you have a low profile tyre, then a 0.82 with 3.875 diff may work well, but otherwise go no taller than 0.889.

If it were me, and you want the 0.82 I would go for: 0.821, 1.2174.
or using 0.889, and 1.26.

The custom order an Albins 3.333 x 1.857 for use with the 0.82 and 1.217,
or custom order 3.444 and 1.93 for use with 1.26 and 0.889.

The 'Long Ent.' list only has 3.444x 2.077 which will have a big step to the 1.26, and horrible to the 1.2174.
You could use it with 1.3182 third from 40hp bug, and 0.89 fourth.

They do list a 3.333 x 1.93 which has OK step to 1.26, but this would assume the use of 0.89 for 4th.
But that is as tall as I would ever go in first unless your engine has massive torque, or very low profile tyre.

The other option for yours is a 3.111 x 1.857 with 1.2174 and 0.821 fourth.
But not sure if you will have the torque to pull that first gear.

I think I will go with a taller first to try and get 1-2-3 closer, and then have a 0.89 4 th. Will likely be running 17s or at the least 16s, so am working on around 25 inches of rear wheel.

Have bounced an email off to the good ol us of a, so I will see what they say.

thanks for the help.