AT gearbox maximum torque

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TZepeSH
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AT gearbox maximum torque

Post by TZepeSH » Fri Jan 31, 2014 6:39 am

Hello, I have an AT gearbox in my superbeetle and have in plan (for some time now) to build a 2056 type 4. I expect the maximum power to be somewhere between 100-120HP and the torque shall be 105-125 lb ft (140-170Nm). I also want to replace the 4th gears to 0.82 and weld 3rd and 4th (I know, big gap between 3rd and 4th, but it is the easiest modification). Maybe 1.21 3rd if I can find a set.

What is the maximum torque that an AT gearbox can withstand?
Would the above engine/gearbox combination still be reliable for a decent number of kilometers (~100 000).

Where in Europe can I buy gear sets?

riseabove
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Re: AT gearbox maximum torque

Post by riseabove » Sat Mar 08, 2014 9:37 am

if you want top quality i would go finnish gears.... http://kuplapaja.blogspot.fi/

the highest quality there is around these neck of the world i think...... hold up easily to rallycross abuse and so on.....

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Pablo2
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Re: AT gearbox maximum torque

Post by Pablo2 » Sun Mar 09, 2014 8:26 am

Those are rally gears (noisy and clunky) .. great for quick shifts, but not suitable for 100K street miles.
aka Pablo, gears, Geary
9.36 @ 146 in '86

riseabove
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Re: AT gearbox maximum torque

Post by riseabove » Sat Mar 15, 2014 3:32 am

Pablo2 wrote:Those are rally gears (noisy and clunky) .. great for quick shifts, but not suitable for 100K street miles.
Noisy and clunky..... its all in what you percieve as annoying .... this was the route i went and cant wait to drive it. How may of you guys are really truly running your bugs as daily drivers anyways ? :)

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Pablo2
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Re: AT gearbox maximum torque

Post by Pablo2 » Sat Mar 15, 2014 7:46 am

I lasted about 6 months with a Hewland 5-spd in my daily driver ('67 bug). It gets old. The unseen issue is faster wear of engagement dogs, when a rally box is used on the street.
aka Pablo, gears, Geary
9.36 @ 146 in '86

Bruce2
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Re: AT gearbox maximum torque

Post by Bruce2 » Wed Mar 26, 2014 8:32 pm

riseabove wrote:
Pablo2 wrote:Those are rally gears (noisy and clunky) .. great for quick shifts, but not suitable for 100K street miles.
Noisy and clunky..... its all in what you percieve as annoying .... this was the route i went and cant wait to drive it. How may of you guys are really truly running your bugs as daily drivers anyways ? :)
While those gears are probably pretty nice for a race car, I gotta go with Paul. They're a huge mistake for a street car.
The only car I drive is my Beetle. Snow tires are still on it!

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Fiatdude
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Re: AT gearbox maximum torque

Post by Fiatdude » Wed Mar 26, 2014 9:37 pm

I want your Hewland trans!!!!!!!!!!!!

TZepeSH
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Re: AT gearbox maximum torque

Post by TZepeSH » Mon Jul 03, 2017 2:32 am

Re-starting discussion on this topic.
I am working now on a 2056 type4 for my 1303S. I expect ~130-140HP. I will have to work a bit on the transmission too to make it "live" with the engine.
The purpose of the car is daily driver, long stretches of highway and mountain climbing. I now have a stock AT gearbox: 3.78, 2.06, 1.26, 0.93, 3.88 R&P.

My questions are:
1. what ratios would you recommend with 3.88 R&P?
I also have a '72 Bus gearbox I bougth for taking 3rd and 4th out. But many people say having 0.82 4th make a too big gap between 3rd and 4th (they seem to be 1.26 and 0.82), and the drivability will suffer.
For this change it is clear I will have to send the gearbox to a builder, I do not have the tools or experience to change the gears myself. Do you know of any gearbox rebuilder here in Europe? Sending to Germany or UK for example will be much easier than sending to the US.
2. I think that a super diff and a HD side cover are a must. Is this something that can be done at home?

What would be the ballpark cost such a rebuild (also changing 3rd and 4th to bus gears)? I have no idea what the rates are, and it would be useful to know what budget to plan. Maybe in the end it is easier to adapt a Subaru 5 speed - that will be ~2000Euros. I see Rancho gearboxes in UK for ~1500Euros. I don't know if it is better to buy a new gearbox or to rebuild mine, if I don't know even rough estimations for a rebuild cost.

Slow 1200
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Re: AT gearbox maximum torque

Post by Slow 1200 » Mon Jul 03, 2017 3:45 am

I say run your stock box as is and see how you like the ratios in there

TZepeSH
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Re: AT gearbox maximum torque

Post by TZepeSH » Mon Jul 03, 2017 5:10 am

That would be the first option. BUT, I want to buy an Eriba camping trailer in the near future. That combined with more torque, and I can already feel the gears spinning. I totally trust myself not to kill the transmission with acceleration, racing is not on my priority list.
It's clear that welded gears would be the best, but I am reading that 002 bus gears already came welded from factory, and if they were ok for a heavy bus, they shall be also ok for a light bug and a 500kg trailer. So, of course I can get whatever gears welded from reputable suppliers, but at what cost, when I already have something available?
Same with super diff, I feel it is needed, and seems something that can be done at home, not necessary to send the trans to a builder. I would at least add the super diff on the stock gearbox, if it can be done at home.
And if the cost of a rebuild is too high (meaning ~1500 euros), I would rather put 500 more and get a Subaru 5 speed, which will definitely work with the torquey engine and trailer behind: it was designed for a heavier and more powerful car from the beginning.
If the rebuild with my gears and a super diff is ~500-700 euros, I would do it in no time.

Slow 1200
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Re: AT gearbox maximum torque

Post by Slow 1200 » Mon Jul 03, 2017 5:59 am

to pull a trailer I would definitely stay away from that 0,82 4th

I also doubt that a superdiff will be any better than the stock differential in that AT box

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Marc
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Re: AT gearbox maximum torque

Post by Marc » Mon Jul 03, 2017 1:02 pm

For fourth there's also the option of replacing the .93 with a .88 instead of the .82 (that's the stock setup in the late `Ghia AN transaxles w/3.88 R&P)

TZepeSH
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Re: AT gearbox maximum torque

Post by TZepeSH » Mon Jul 03, 2017 2:40 pm

I know about the Ghia 4th, but I don't think it is much stronger than the current 0.93. I wouldn't split the gearbox to put 0.89 in. The point here is not more speed (although I don't mind more speed at 3000-3500 rpm), but strength. I am looking at bus gears becaise they are welded from factory and coarse teeth, and if there weren't any issues pulling a heavy bus, it would be the same for a Bug and trailer.
I would like 0.82 more as a 5th gear, but that means serious money.
Having the bus gears 3.78, 2.06, 1.26 and 0.82 (this is what i found on several sites), means that the gap between 3rd and 4th already existed. Of course, combined with the 5.4 R&P made it much less significant, but again heavy bus vs light bug.
And again to price: i have no idea how much a rebuild with welded gears (don,t care what ratios, either stock or bus) and a super diff. This could change the game completely.
As you can find on another topic from Jan72, he had 0.82 4th with a 1.8 type4, 90hp, and was ok on flat surface, but dissatisfied on hills
And another example, a friend has a bus with 136hp subaru engine and 091 gearbox and managed to kill the box having a boat after the bus...

Casting Timmy
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Re: AT gearbox maximum torque

Post by Casting Timmy » Mon Jul 03, 2017 7:37 pm

The 93 fourth would have been factory brazed just like the Ghia of that time.

3 ribs had a 82 fourth and the 5 rib had a 89 fourth, but of those are coarse tooth and factory welded.

You can also get some floating hub gears and no welding is required.

I'd probably think more about the 5 rib 3rd and 4th (1.26 and .89) if you want to gear up. The super diff you will need some extra shims to reset the ring and pinion backlash. You can search IRS transaxle rebuild on thesamba to see about what it takes to rebuild a transaxle. There are transaxle rebuilders over there in Europe, I think JDM racing in England and T????? in Denmark. You might post on VW Aircooled Drag Race parts for sale or Flat 4 Racers on Facebook as I see more European guys on Facebook.

Clonebug
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Re: AT gearbox maximum torque

Post by Clonebug » Tue Jul 04, 2017 12:01 am

You should be fine with a stock transmission to 150 plus hp unless you do "Mario" style launches. Just the extra torque shouldn't hurt it.

My transmission with a 4.12 R/P held up to 15 lbs boost when the 3rd and 4th gear hubs slipped and it wouldn't shift anymore.
I got the hubs welded and it's been fine all stock except the hubs and I am now at 23 lbs boost.

We just beat on it for 50 miles of full boost runs tuning the EBC. It took everything we gave it and then took me home on a 100 mile drive at 75-80 mph.
Stripped66 wrote:The point wasn't to argue air temps with the current world record holder, but to dispel the claim that the K03 is wrapped up at 150 HP. It's not.

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