Author |
Message |
Gil-bug Samba Member
Joined: February 17, 2015 Posts: 90 Location: Luxembourg
|
Posted: Mon Aug 01, 2022 6:38 pm Post subject: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
Hi i have a 1965 split bus with rgbs and a stockish looking 1776. (Stock 4.375 tranny and big nut rgb)
Aa performance cyl. and heads
278 novak cam
123 ignition
9:1 compression ratio
37 pict 3 carb
Stock air filter and exhaust
The engine runs great and serms strong but don't know how much hp. Could anyone know approx. how much horse power this could be
With the stock 4.375 tranny, It's quite high on rpms in 4th gear. I want to be able to drive 60 mph with less rpms. and beeing able to drive some hills without effort.
Which tranny would you recommand knowing that i want to keep my big nut rgbs?
3.88? 4.125? 4th gear 0.82 or 0.89 ? |
|
Back to top |
|
|
AS350driver Samba Member
Joined: April 17, 2016 Posts: 1340 Location: Tucson
|
Posted: Mon Aug 01, 2022 7:04 pm Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
When I had my 65 Westy transaxle rebuilt, I went with 4:12 instead of 3:88
It has a fairly high performance 1776 dp. I retained the .82 4th gear.
If the bus isn’t a camper with the associated extra weight, a 3:88 and .82 is nice. I had a 64 standard microbus with 3:88 and a unusually stout 1641 in it; and loved the combo. 65 mph and still good acceleration and good in the hills. |
|
Back to top |
|
|
Lind Samba Member
Joined: November 06, 2000 Posts: 9915 Location: idaho
|
Posted: Mon Aug 01, 2022 7:53 pm Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
A 1965 bus with a 1500 would have come with a 4.12 ring gear. You should have no problem driving 65 with a 4.12x.82x1.26 and stock sized tires. I can easily drive 65 on flat roads with no wind with my stock 1965 bus which has a 1600 engine, 4.12x.82x1.26 and stock sized tires. If you put a higher geared transmission in your bus, it will rob you of your power and put you into third gear on less steep hills. _________________ .
Wanted:
Idaho VW license plate frames or other dealership items.
VWoA literature and early dealership or distributor literature/pictures/information
. |
|
Back to top |
|
|
pyrOman Fire Master
Joined: July 21, 2003 Posts: 12408 Location: Over 2002 posts deleted!
|
Posted: Tue Aug 02, 2022 8:43 am Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
Run taller tires! For years I ran an 1835 with RGBs and taller tires. It did just fine. Once I installed the IRS, I had to go with smaller diameter tires. _________________ Some people are so busy being clever they don't have time enough to be wise. |
|
Back to top |
|
|
AS350driver Samba Member
Joined: April 17, 2016 Posts: 1340 Location: Tucson
|
Posted: Tue Aug 02, 2022 9:45 am Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
Lind wrote: |
A 1965 bus with a 1500 would have come with a 4.12 ring gear. You should have no problem driving 65 with a 4.12x.82x1.26 and stock sized tires. I can easily drive 65 on flat roads with no wind with my stock 1965 bus which has a 1600 engine, 4.12x.82x1.26 and stock sized tires. If you put a higher geared transmission in your bus, it will rob you of your power and put you into third gear on less steep hills. |
The hills. If you live near, or plan to travel to mountainous areas, it’s pretty much agreed that you’ll have to downshift to third on most grades. Maybe even second. Even a strong “built” vw motor is probably not even 100 hp, especially on a hot day at altitude. With a 3:88, you’ll probably have to downshift a little sooner than with a 4:12 or 4:37 Once you’re in third though, with the 3:88, you’re going faster in third than if you had 4:XX gearing. I have one bus still with the original 4:37 gearing, and a strong dual carb built 1835. Still end up having to downshift to third on steep grades, but then have to let off the gas and slow down further to keep from over revving the engine. Then you’re climbing at ~40 mph while with a 3:88 you might climb at something closer to ~50. All depending on the temperature, steepness, weight, tire size, wind, moon phase, octane of fuel, coriolis effect, magnetic variance, and health of your engine of course. |
|
Back to top |
|
|
iamdonquixote Samba Member
Joined: January 28, 2003 Posts: 2041 Location: M*ssholia
|
Posted: Tue Aug 02, 2022 11:11 am Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
with that configuration of your engine, I wouldn't bother upgrading the transmission.
if you decide to get a built transmission, get an engine to match it. what you have doesn't appear ( on paper ) to be much more than stock. |
|
Back to top |
|
|
Alan Brase Samba Member
Joined: March 28, 2004 Posts: 4532 Location: Cedar Falls, Iowa
|
Posted: Thu Aug 04, 2022 7:44 pm Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
One can certainly change a lot of things to get different performance. Displacement changes by itself changes hp hardly at all. Air flow through the engine is what make horsepower. HP is what determines your top speed and cruising speed.
I have had great fun driving a near stock 1640 engine (slip in 87's) single port.
(I also had a 1978 with about 100 hp)
The further you go from stock, the more you will have to learn from your own mistakes. _________________ Al Brase
Projects: 67 sunroof bug, 67 Porsche 912 Targa, 70 Westy
Dec 1955 Single Cab pickup WANT 15" BUS RIMS dated 8/55, thru 12/55
To New owners: 1969 doublecab, 1971 Dormobile
Vanagons:
80 P27 Westy JUL 1979, 3rd oldest known US
83 1.6TD Vanagon, 87 Wolfie Westy daily driver, swap meet home |
|
Back to top |
|
|
Clara Samba Member
Joined: June 14, 2003 Posts: 12400
|
Posted: Sat Aug 06, 2022 6:03 pm Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
Gil-bug wrote: |
Hi i have a 1965 split bus with rgbs and a stockish looking 1776. (Stock 4.375 tranny and big nut rgb)
Aa performance cyl. and heads
278 novak cam
123 ignition
9:1 compression ratio
37 pict 3 carb
Stock air filter and exhaust
The engine runs great and serms strong but don't know how much hp. Could anyone know approx. how much horse power this could be
With the stock 4.375 tranny, It's quite high on rpms in 4th gear. I want to be able to drive 60 mph with less rpms. and beeing able to drive some hills without effort.
Which tranny would you recommand knowing that i want to keep my big nut rgbs?
3.88? 4.125? 4th gear 0.82 or 0.89 ? |
Please what is the"quite high rpms" you are finding at 60mph with this set up?
What tires are you using?
My 61 with 1.26 boxes, 4.375 r/p .82 4th and 205 /75R15 tires drove the flat nicely at 60- 65 mph. (until recently when the engine seems to have worn out, but that was ~60Kmiles later) It also pulled hills nicely (still dropped to 3rd over the siskiyoos etc mountains with ~6% grade)
I have the numbers in my book from when I had a tach on it. _________________ The Obsolete Air-Cooled Documentation Project http://oacdp.org/ |
|
Back to top |
|
|
Gil-bug Samba Member
Joined: February 17, 2015 Posts: 90 Location: Luxembourg
|
Posted: Mon Aug 08, 2022 5:42 am Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
Clara wrote: |
Gil-bug wrote: |
Hi i have a 1965 split bus with rgbs and a stockish looking 1776. (Stock 4.375 tranny and big nut rgb)
Aa performance cyl. and heads
278 novak cam
123 ignition
9:1 compression ratio
37 pict 3 carb
Stock air filter and exhaust
The engine runs great and serms strong but don't know how much hp. Could anyone know approx. how much horse power this could be
With the stock 4.375 tranny, It's quite high on rpms in 4th gear. I want to be able to drive 60 mph with less rpms. and beeing able to drive some hills without effort.
Which tranny would you recommand knowing that i want to keep my big nut rgbs?
3.88? 4.125? 4th gear 0.82 or 0.89 ? |
Please what is the"quite high rpms" you are finding at 60mph with this set up?
What tires are you using?
My 61 with 1.26 boxes, 4.375 r/p .82 4th and 205 /75R15 tires drove the flat nicely at 60- 65 mph. (until recently when the engine seems to have worn out, but that was ~60Kmiles later) It also pulled hills nicely (still dropped to 3rd over the siskiyoos etc mountains with ~6% grade)
I have the numbers in my book from when I had a tach on it. |
I have 195 75 r 14 tires. I didn't yet have a tach on it but it just seems too high in my ears on my opinion. I'll try to have a tach to know exactly . I can keep hills in 4th with my actual configuration, so i guess it's not so bad.
Anyway thanks to everyone for the interesting answers that make me understand that this is kind of trial and error.
Gilles |
|
Back to top |
|
|
sled Samba Member
Joined: February 16, 2005 Posts: 6179
|
Posted: Mon Aug 08, 2022 7:20 am Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
with your tires and transaxle gearing (assuming its all stock ratios for a late big-nut box) you're spinning around 3572 rpms at 60, and 3870 rpms at 65.
thats a bit higher rpms than I would want to be cruising. Would you entertain larger tires? this would of course lower your rpms.
if you went to a 4.12 ring and pinion, this would drop your rpms at 60 to 3365, and at 65 to 3645 _________________ drive your split. |
|
Back to top |
|
|
srfndoc Samba Member
Joined: August 21, 2010 Posts: 3275 Location: SoCal
|
Posted: Mon Aug 08, 2022 8:07 am Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
The exact reason I run 15" bus rims with 195R15LT tires. Overall dimension is about 27" which helps keep the rpm's down. You can use the formula in my signature to figure out your rpm's based on tire dimension/rgb/R&P/4th. _________________ RPM=(MPH*336* (R&P*4th*1.26))/Tire Diameter in inches |
|
Back to top |
|
|
ted698 Samba Member
Joined: June 17, 2016 Posts: 104 Location: Shropshire, UK
|
Posted: Tue Aug 09, 2022 8:29 am Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
I have a '67 with stock RGB's (1.26), stock gearing (.82) fitted with 205/80R14 tyres - big! - 27.2" dia - very slightly bigger than original crossplies.
Speedo is bob on according to GPS
I have a Tacho fitted and my RPM's are about 3,900 at 65 mph, around 4100 rpms at 70
I have a 1904 SP with dual Kads and a CSP Python exhaust etc - I worked out out using the handy calculations for RPM's that changing to a 4.12 R&P would drop 200rpm off, changing to a 3.88 would take about 500rpms off.
However it does drive nicely currently, with plenty of poke, just motorway/highway crusing at high speed is a bit wearing (in both senses! hahaha) - I have a friend with a early Late Bay with a 3 rib box - and I can leave him for dead pretty much anywhere, as that seems to have a fairly long 4th. |
|
Back to top |
|
|
srfndoc Samba Member
Joined: August 21, 2010 Posts: 3275 Location: SoCal
|
Posted: Tue Aug 09, 2022 8:59 am Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
ted698 wrote: |
I have a '67 with stock RGB's (1.26), stock gearing (.82) fitted with 205/80R14 tyres - big! - 27.2" dia - very slightly bigger than original crossplies.
Speedo is bob on according to GPS
I have a Tacho fitted and my RPM's are about 3,900 at 65 mph, around 4100 rpms at 70
I have a 1904 SP with dual Kads and a CSP Python exhaust etc - I worked out out using the handy calculations for RPM's that changing to a 4.12 R&P would drop 200rpm off, changing to a 3.88 would take about 500rpms off.
However it does drive nicely currently, with plenty of poke, just motorway/highway crusing at high speed is a bit wearing (in both senses! hahaha) - I have a friend with a early Late Bay with a 3 rib box - and I can leave him for dead pretty much anywhere, as that seems to have a fairly long 4th. |
Your rpm's seem high if you're running a stock R&P (4.375):
.82 x 1.26 x 4.375 = 4.52
65 x 336 = 21840
4.52 x 21840 = 98716.8
98716.8 / 27.2" = 3629rpm _________________ RPM=(MPH*336* (R&P*4th*1.26))/Tire Diameter in inches |
|
Back to top |
|
|
audiman72 Samba Member
Joined: January 19, 2007 Posts: 47 Location: Salinas Ca 93906
|
Posted: Fri Aug 19, 2022 4:18 pm Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
ted698 wrote: |
I have a '67 with stock RGB's (1.26), stock gearing (.82) fitted with 205/80R14 tyres - big! - 27.2" dia - very slightly bigger than original crossplies.
Speedo is bob on according to GPS
I have a Tacho fitted and my RPM's are about 3,900 at 65 mph, around 4100 rpms at 70
I have a 1904 SP with dual Kads and a CSP Python exhaust etc - I worked out out using the handy calculations for RPM's that changing to a 4.12 R&P would drop 200rpm off, changing to a 3.88 would take about 500rpms off.
However it does drive nicely currently, with plenty of poke, just motorway/highway crusing at high speed is a bit wearing (in both senses! hahaha) - I have a friend with a early Late Bay with a 3 rib box - and I can leave him for dead pretty much anywhere, as that seems to have a fairly long 4th. |
Ted,
what kind of cam is in your 1904?
Brian _________________ There are those who have, those who will, and those who will lie about it. |
|
Back to top |
|
|
Alan Brase Samba Member
Joined: March 28, 2004 Posts: 4532 Location: Cedar Falls, Iowa
|
Posted: Fri Aug 19, 2022 8:25 pm Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
Just from memory, I kinda think the 185R14C tires used on T2's and T3's (Vanagons) from about 1970 to 1992 are all about the same height as the old 6.40 x 15 bias ply tires originally fitted since 1955. 25.5 inches or so.
Fitting taller tires will certainly bump up your final drive ratio quite a bit (lower numerical) and it is so easy to do without the major commitment of gearbox changes.
Not sure what sizes will fit, especially the non flared early rear quarters before 1963.
I'll be looking for the tallest skinny tires I can find for my 1956 single cab. Sticking with stock gearbox for now. I assume that would be 195/75 or /80? who sells them? _________________ Al Brase
Projects: 67 sunroof bug, 67 Porsche 912 Targa, 70 Westy
Dec 1955 Single Cab pickup WANT 15" BUS RIMS dated 8/55, thru 12/55
To New owners: 1969 doublecab, 1971 Dormobile
Vanagons:
80 P27 Westy JUL 1979, 3rd oldest known US
83 1.6TD Vanagon, 87 Wolfie Westy daily driver, swap meet home |
|
Back to top |
|
|
ted698 Samba Member
Joined: June 17, 2016 Posts: 104 Location: Shropshire, UK
|
Posted: Mon Aug 22, 2022 5:00 am Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
audiman72 wrote: |
ted698 wrote: |
I have a '67 with stock RGB's (1.26), stock gearing (.82) fitted with 205/80R14 tyres - big! - 27.2" dia - very slightly bigger than original crossplies.
Speedo is bob on according to GPS
I have a Tacho fitted and my RPM's are about 3,900 at 65 mph, around 4100 rpms at 70
I have a 1904 SP with dual Kads and a CSP Python exhaust etc - I worked out out using the handy calculations for RPM's that changing to a 4.12 R&P would drop 200rpm off, changing to a 3.88 would take about 500rpms off.
However it does drive nicely currently, with plenty of poke, just motorway/highway crusing at high speed is a bit wearing (in both senses! hahaha) - I have a friend with a early Late Bay with a 3 rib box - and I can leave him for dead pretty much anywhere, as that seems to have a fairly long 4th. |
Ted,
what kind of cam is in your 1904?
Brian |
Hi Brian,
It has a SCAT C25 cam kit - so Cam, HD Springs, had to replace the Scat followers as they spalled (material too hard, common scat complaint) so it has stock followers in now. had to fit HD Aluminium pushrods too as I have 1:1.25 solid rockers in. For a SP it flies! and its ultra reliable. Cheers |
|
Back to top |
|
|
Blue Baron VW Aficionado
Joined: June 16, 2006 Posts: 24103 Location: Southeast USA
|
Posted: Mon Aug 22, 2022 12:31 pm Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
Gil-bug wrote: |
1776 with rgbs 4.12 or 3.88 tranny? |
Didn't it already have a 4:12? At any rate, we have a 3:88 in ours with a similar combo, and it delivers performance comparable to our 40hp Beetle. This would be my choice if you live in a relatively flat area. _________________ We are striving for perfection, to make our cars run forever, if possible.
Heinz Nordhoff |
|
Back to top |
|
|
storm Samba Member
Joined: April 28, 2008 Posts: 299 Location: Juneau, Wisconsin
|
Posted: Sun Aug 28, 2022 4:02 pm Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
Have a’66 bus with a 2027 Scat engine. 3.88/82 4th gear, reduction gear boxes 195x70 x15 inch tires.
I had use this combo in a area of flat land. Cool running and low rpms.
Now living in an area of 6 to 10% hills. 4 th gear hardly used. Even tho my 4 gear can work sometimes head temps raises up. Going down hills temps go down to 290-325 degrees.
If I do it again would go to a 4.125 r&p or use a smaller diameter tire.
Ok for the Vw people that want to go up hill faster, my area where I live people pass me going up hills. I just put on my flashers. _________________ always ready to learn and give advice |
|
Back to top |
|
|
Gil-bug Samba Member
Joined: February 17, 2015 Posts: 90 Location: Luxembourg
|
Posted: Wed Oct 12, 2022 3:13 pm Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
Blue Baron wrote: |
Gil-bug wrote: |
1776 with rgbs 4.12 or 3.88 tranny? |
Didn't it already have a 4:12? At any rate, we have a 3:88 in ours with a similar combo, and it delivers performance comparable to our 40hp Beetle. This would be my choice if you live in a relatively flat area. |
No, it did't. 64 to 67 they had 4.375 trannies with 1.26 rgbs. |
|
Back to top |
|
|
Gil-bug Samba Member
Joined: February 17, 2015 Posts: 90 Location: Luxembourg
|
Posted: Fri Jan 06, 2023 2:22 pm Post subject: Re: 1776 with rgbs 4.12 or 3.88 tranny? |
|
|
Hi
I had a rebuild in a tranny shop. It is 3.88 now and is just great. Lower rpms and more quiet.
Gilles |
|
Back to top |
|
|
|