Tunnel trans swap W/WW Okrasa expectations

Thomas Pedigo

Just ordered tunnel trans W/type2 nosecone and hockey stick for my`56. I am doing the Okrasa kit as well. I figured I'm gonna get approx. 12 more ponies in my 36h so it made sense to go fully synchronized with taller gears. What would be the ideal gear ratios considering ill now have about 48h and I want to drive 65-70 on I-5? I did the math comparing the original 4.43 in the stock split-case vs/ 4.12 gears in a stock tunnel. Its about a 7% difference which does not sound all that great. Would a 3.88 ratio be too tall? I also have considered how these changes affect the fan speed for cooling and that I do not want to "lug it" on the RPM`s. What do you guys think?
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Defying conventional wisdom since 1970

Snort · Posted: Wed Mar 02, 2011 9:04 am Post subject:

OK, I'll go first. In all honesty I am not an Okrasa person, and my only experience with changes in gear ratios has been reading the threads here and my own general VW driving experiences since the womb. But I encouraged this person to move his question from the Oval forum to Vintage Speed, hoping he would find a better audience.

VW changed their ring and pinion ratio to the 4.12 on the Bug in 1967 with the 1500 single port motor. You might be OK with this, but to go any further seems un-advisable. From what I've read, people are sticking with their early ring and pinion ratios with both supercharged and Okrasa 36hp motors, and they like the way they drive. On the flat, my stock 36hp can make 70mp on the speedometer, with a little more room to go, so you should be comfortable cruising at 65-70 with your Okrasa kit unless climbing steep grades with your 4.43.

I agree that you should be concerned about cooling fan speeds if you move to taller gearing, but you could at least move to a larger crank pulley, and perhaps go with the fresh air fan which has more blades if you go that route.

Thomas Pedigo · Posted: Wed Mar 02, 2011 9:18 am Post subject:

Thanks for your input as this is my official "first build". I like the idea of the fresh air fan blowing more cooling air by the heads. As far as crank pulley goes,I have been eying those aftermarket "OT" pulleys. Ill do more research on these, but since I'm already here,is the diameter larger than stock which would spin the generator faster? Side note; I just ordered the WW "Abarth" repop....GULP!!!
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Defying conventional wisdom since 1970

Erik G · Posted: Wed Mar 02, 2011 9:29 am Post subject:

ouch.

Also, consider the 356 generator pulley. It is smaller than the vw one, therefore spinning the generator faster. It's also cheaper to do, and will not change your crankshaft assembly weight (not that it makes a huge differance on a 36'er)
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Formcar 179 · Posted: Thu Mar 10, 2011 12:39 am Post subject:

I am running a WW kit on my '56 Beetle, with the original split type transmission. It is 77X64 with an 8/1 compression, stock cam. I figure it is dishing out about 48 HP.

I was happy to get some mid range acceleration, rather than higher top end speed. The VW seems geared about right to me. I would not want to cruise it above 60 until I get a better crank in there.

Flavio · Posted: Thu Mar 10, 2011 9:18 am Post subject:

Hi
Also full rebuilding a 36 engine with WW Okrasa Kit.
Regarding the OT pulley I have an iron one (i've been advised not to buy repro aluminium ones) that has 17 cm diameter. The stock 36 Hp has just more 5 mm, so, the OT will spin just a little bit slower. My 6 volts generator has the fan with more blades.

The gearbox is a stock ratio 1963 full synchro and for sure I'll be happy with it.
Learning with more experienced people, here in The Samba, The Rule seems to be that a taller gears gearbox only works good when the engine has more than 100 Hp, which is not our case with the Okrasa. It will "lug" !

The engine will be running maybe in a month or so. Then, I can be more helpfull.

Thomas Pedigo · Posted: Tue Mar 22, 2011 8:04 pm Post subject:

OK...so I already received the aluminum OT pulley and decided to use the smaller diameter Porsche 95mm gen pulley with the fresh air fan. I also ordered a Berg deep sump and Mr Wob oil cooler. Its gonna be a while before the WW Okrasa build is complete and the`67 tunnel swap is installed but I feel as though this all seems to be a good combo for cooling and better hwy drivability. At 48hp,it should be comperable to the performance of the 1500cc that the`67 came with I would imagine.....just way cooler!
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Erik G · Posted: Wed Mar 23, 2011 9:55 am Post subject:

sweet, keep us informed, and you know we like pictures
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pig-pen · Posted: Wed Nov 19, 2014 3:24 am Post subject:

old thread from the dead....

I am expecting about 60hp from my 36hp build so I am toying with the idea of changing transmission... but not sure if it is worth it...

I have 3 options open to me right now...

stay split case (4.43) 3.60 / 1.94 / 1.22 / 0.82
use early 1500 (4.12) 3.80 / 2.06 / 1.26 / 0.89
use GT BEETLE (3.88 ) 3.80 / 2.06 / 1.26 / 0.93

As far as I can make out using this calc... with a 155 / 80 R15 tire

http://www.kabamus.com/garage/gears.html

that the top speed @ 4000 rpm is 81, 80, & 82 mph respectively.

so... just wondering what the point might be... other than the 1500 box available is recon and in great condition... is it worth swapping things about to go 1 mph slower??? Are those speeds above the max I will ever get with these combos?

also, overheating would not be nice.

60ragtop · Posted: Wed Nov 19, 2014 6:28 am Post subject:

I stayed with the stock trans in my 60 went I went with my stroked WW Okrasa kit. It likes to cruise at 75MPH all day long getting 30 MPG and top speeds of over 85 with GPS. no overheating worries either.
_________________
Rick
Certified Mechanic by the State of Michigan in 1977
ASA certified in 1987
Certified Hunter Wheel Alignment Master Technician 1986

pig-pen · Posted: Wed Nov 19, 2014 7:34 am Post subject:

and a '60 was still split case right???

60ragtop · Posted: Wed Nov 19, 2014 8:04 am Post subject:

yes, split case running 165 80 15 radial tires, 16K since I installed it.
_________________
Rick
Certified Mechanic by the State of Michigan in 1977
ASA certified in 1987
Certified Hunter Wheel Alignment Master Technician 1986

pig-pen · Posted: Wed Nov 19, 2014 8:16 am Post subject:

then you have just made my mind up for me! split it stays. thank you very much.

gears · Posted: Wed Nov 19, 2014 11:03 am Post subject:

For whatever reason, I haven't seen the early tunnel trans R&P listed. 4.37 (8:35) seems a pretty decent choice.
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9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
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Kjell Roar · Posted: Wed Nov 19, 2014 12:05 pm Post subject:

One thing against split transmissions and hot engines, I have heard people telling they have broke it with a standard 1600DP. So dont know how much power they take. But it probably have to do with how you drive. A lot of torque from low rews is not good, neither many hp at high rews.
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My car, Aug. 4th, 1955 / an early 56: http://www.thesamba.com/vw/forum/album_page.php?pic_id=610438

pig-pen · Posted: Wed Nov 19, 2014 5:03 pm Post subject:

kjell... I think I will just grab the 1500 box on offer and wait and see... I can always put it in later if I need to.

Mr. Motorhead · Posted: Wed Nov 19, 2014 7:46 pm Post subject:

RichardinNZ · Posted: Tue Jan 27, 2015 2:43 pm Post subject:

I'm about to fit a tunnel trans into my dual carb 36hp '58 bug. It will have a bus nosecone on it. Could someone tell me what front mount I should use?

Many thanks
Richard
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Richard
'58 Beetle; NZ Assembled
Dual Carb 36hp
My Car https://www.thesamba.com/vw/forum/album_page.php?pic_id=1750253

fcampbell356 · Posted: Wed Jan 28, 2015 9:30 am Post subject: Mount

Try to find a mount part # 211 301 265 or 211 301 265A. That is what I used on my 1959. Wolfsburg West list one.

RichardinNZ · Posted: Wed Jan 28, 2015 12:40 pm Post subject:

Many thanks. I'll find one of those.
Richard
_________________
Richard
'58 Beetle; NZ Assembled
Dual Carb 36hp
My Car https://www.thesamba.com/vw/forum/album_page.php?pic_id=1750253


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