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TequilaSunSet
Samba Member
Joined: May 30, 2012
Posts: 2109
Location: Philippines
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 Posted: Mon Oct 20, 2014 10:40 am Post subject: |
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| 1621 wrote: |
I think the reason why guys like Tequila are running hills with no issue are two fold - stock R&P, and low vehicle weight. |
My ears were burning 
Mine is not that light compared to a westy. I have the westy interior crammed into it. Minus the top and fridge, but with dual aux batteries and the storage is full with crap at all times for a moments notice get away. My tire set up is slightly taller than stock, at 65mph (GPS) my speedo reads 62mph... not sure how to quantify that difference into RPM etc.
_________________
Don't harsh my mellow...
1985 Hightower Vanagon 1.8T- Gone
1972 Panel Bus- Gone
1967 Bug- Gone
1964 Euro Sunroof Bug- Gone
1969/72/63 Sunroof Bug- Gone
1975 Brazilian Bug in the Philippines 🇵🇭- New to me |
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Jon_slider
Samba Member
Joined: April 11, 2007
Posts: 5091
Location: Santa Cruz, Crowdifornia
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| Posted: Mon Oct 20, 2014 1:28 pm Post subject: |
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In my opinion, youre having to use 2nd gear too much because your gearing is 14% taller than stock, AND your 1.8t is not chipped.
I would not have recommended a 3.73 ring and pinion.
I think a stock ring and pinion with your 5% oversized tires would be a better match.
fwiw, Stephans gearing is 10% taller than stock IF he still runs 215x75x15, which are 27.8" diameter
Most people I know with 10% tall gearing with a 1.8T are ecstatic! Their gearing change is from the tires only, no ring and pinion change. They do run a stage 1 chip tune, recommended.
your gearing is just 4% taller than those people. So there may be other factors at play.
your low gas mileage seems to be a mountain based measurement. I suggest you find some reasonably level highway to develop some MPG data.
iirc Stephan was getting 17.5Mpg, and I know someone who gets 20mpg with the same motor and tires, and a stage 1 chip. Stephan is chipped to stage 3 I believe. (needs confirmation)
So, to be comparable to other 1.8Ts besides your ring and pinion disadvantage, your lack of a chip tune may be relevant.
| ThankYouJerry wrote: |
| Nokian WRG2 215/65/15… Nokian specs show them at 26.5" |
where do you find that info, can I have a link? I dont know where Nokian specifically lists their tires diameter.
Analysis
a 3.73 is 9% taller than a stock Auto R&P of 4.09
a 26.5" tire is 5% taller than a stock 25.3" diameter tire
add those together and you've got 14% taller than stock gearing.. Not something I would recommend. (I avoid double digit % tall gearing)
Assume a stock auto tranny with stock 25.3" diameter tires goes 70mph@4100rpm
A 3.73 Ring and pinion with stock 25.3" diameter tires would go 70mph@ 3731rpm (9% tall)
A 3.73 Ring and pinion with 26.5" diameter tires would go 70mph@ 3544rpm (5% tall)
references:
http://www.gowesty.com/library_article.php?id=116
At 75 mph, for example, the 4-speed Vanagon will have an engine speed of about 4000 RPM, whereas a AT Vanagon will be closer to 4400 RPM.
http://www.gowesty.com/ec_view_details.php?id=3862&category_id=&category_parent_id=
We are now offering you the option to lower your RPMs across the board by 9%. This is achieved by installing a TALLER RATIO European-only ring & pinion set with a 3.73:1 ratio (instead of the standard 4.09:1 R&P ratio all USA-delivery vehicles got). For example: If you are used to doing 70 mph at 4000 rpm, your new cruising RPM at the same speed (70 mph) would be 9% lower at 3640 rpm
| TequilaSunSet wrote: |
| My tire set up is slightly taller than stock, at 65mph (GPS) my speedo reads 62mph... not sure how to quantify that difference into RPM etc. |
If you tell me the specs for the diameter of your tires, I can tell you how tall your gearing is over stock (not a tape measure of your wheel, I need manufacturer spec for your make model and size).
Since you have not changed your ring and pinion that wont be a factor. Do you have a chipped 1.8t or stock?
Your speedometer error is not relevant. You would need an accurate tachometer, and GPS speed, to calculate how tall your gearing is. But if you just give your tire diameter spec, I can calculate it, even if you have no tachometer.
sample calculations:
26.5" tire, divided by 25.3" stock diameter, -1 = 5%
27.8" tire (215x75x15 BFG AT KO), divided by 25.3" stock diameter, -1 = 10% taller than stock gearing
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My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco |
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TequilaSunSet
Samba Member
Joined: May 30, 2012
Posts: 2109
Location: Philippines
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| Posted: Mon Oct 20, 2014 3:19 pm Post subject: |
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Tha sample you gave is = to mine. So I have 5%
Stock 1.8T
Auto trans rebuild
_________________
Don't harsh my mellow...
1985 Hightower Vanagon 1.8T- Gone
1972 Panel Bus- Gone
1967 Bug- Gone
1964 Euro Sunroof Bug- Gone
1969/72/63 Sunroof Bug- Gone
1975 Brazilian Bug in the Philippines 🇵🇭- New to me |
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?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
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| Posted: Mon Oct 20, 2014 3:48 pm Post subject: |
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| I just thought I'd add in ACTUAL datapoint here based on experience (not some theory based on mathematics). The 3.73 R+P with 27" diameter tires will result in 4,000 rpms @ 70 MPH on flat ground. Hit a hill and the RPMs will go UP for a given speed. My understanding is that at that rpm, stall speed will basically be irrelevant. The 1.8T will also be well within its powerband. |
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madspaniard
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Joined: August 18, 2008
Posts: 3795
Location: Alameda, CA
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| Posted: Mon Oct 20, 2014 3:49 pm Post subject: |
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I think Jon hit the nail in the head here. I didn't pay attention to your tire size. I run Nokian WR C Van 205/70R15 which are about 3.1% taller than stock diameter. I have a 3.73:1 R&P in a box ready for engine conversion. This combination of tire and R&P would give me about 12% taller than stock gearing, combined with a chipped 1.8T engine it should be perfect.
Althought the combined taller gear might have a signifficant role here, I still think that in ThankYouJerry's case there seems to be something else missing creating this problem. Somebody mentioned weight and that is another clear factor, it is not the same testing with a light weight Vanagon than it is with a fully loaded Westy of Weekender ready for several days of camping, family inside, and maybe the AC on.
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1991 Westy auto w/ Peloquin TBD
"The only difference between me and a madman is that I'm not mad” - Salvador Dali
Last edited by madspaniard on Mon Oct 20, 2014 3:55 pm; edited 1 time in total |
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?Waldo?
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Joined: February 22, 2006
Posts: 9752
Location: Where?
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| Posted: Mon Oct 20, 2014 3:55 pm Post subject: |
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| Jon_slider wrote: |
| A 3.73 Ring and pinion with 26.5" diameter tires would go 70mph@ 3544rpm (5% tall) |
| madspaniard wrote: |
| I think Jon hit the nail in the head here. |
From experience I have to say that I don't think Jon hit the nail on the head. I think he's off by about 600 rpms on flat ground and more on hills. |
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madspaniard
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Joined: August 18, 2008
Posts: 3795
Location: Alameda, CA
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| Posted: Mon Oct 20, 2014 4:13 pm Post subject: |
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for reference, this is also actual data posted for the even taller 3.27 R&P
source: http://www.thesamba.com/vw/forum/viewtopic.php?t=4...;start=100
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1991 Westy auto w/ Peloquin TBD
"The only difference between me and a madman is that I'm not mad” - Salvador Dali |
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?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
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| Posted: Mon Oct 20, 2014 5:04 pm Post subject: |
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| That chart disturbs me a little. I have a receipt for the 3.73 R+P in my trans and yet my rpms with 27" tires are remarkably close to what is posted for the 4.09. That makes me want to pull it and count the teeth. |
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Jon_slider
Samba Member
Joined: April 11, 2007
Posts: 5091
Location: Santa Cruz, Crowdifornia
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| Posted: Mon Oct 20, 2014 7:30 pm Post subject: |
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| Andrew A. Libby wrote: |
| I just thought I'd add in ACTUAL datapoint here based on experience (not some theory based on mathematics). The 3.73 R+P with 27" diameter tires will result in 4,000 rpms @ 70 MPH on flat ground. Hit a hill and the RPMs will go UP for a given speed. My understanding is that at that rpm, stall speed will basically be irrelevant. The 1.8T will also be well within its powerband. |
I encourage you not to shoot the messenger. Mathematics is not a theory. 2+2=4.
I would look for a math error, if I made one, tell me where.
I would also want to verify your data
1. is your speed GPS based
2. is your tachometer calibrated to Vag-Com
3. What exact make, model, and size tire are you using, so I can verify your belief that it is 27" diameter.
4. IS your Ring and Pinion really a 3.73?
This discussion should not become an argument about whose opinion is right. I would prefer to discuss facts, and evidence. Im not attached to being right or wrong. I AM attached to being ACCURATE!
So I invite you to post FACTS, that are VERIFIED, not approximations or estimates.
> The 3.73 R+P with 27" diameter tires will result in 4,000 rpms @ 70 MPH on flat ground.
that statement seems to contradict the reference I gave from GoWesty, but I dont have data on what tire size they used, so unable to verify.
Anyway, regarding ThankYouJerry's poor fuel mileage and lack of power, 2 facts stand out
1. he has a ring and pinion that is 9% taller than stock (FACT, not theory)
2. his 26.5" tire is 4.7% taller than a 25.3" tire (again FACT, not theory)
It is certainly possible that the tire ThankYouJerry has is not 26.5", I have not verified that claim.
However, TequilaSunSet believes he has the SAME 26.5" diameter tire, but he has a Stock 4.09 Ring and Pinion, and has NONE of the issues ThankYouJerry is having.
So IF ThankYouJerry and TequilaSunSet's tire diameters are ACCURATE, it is FACT, that the difference between ThankYouJerry and TequilaSunSet's gearing is the 3.73 Ring and Pinion.
I also agree that as Madspaniard points out, it is possible that there is a weight difference between ThankYouJerry's Van and TequilaSunSet's van.
afaict so far, Neither ThankYouJerry, nor TequilaSunSet, have chipped their 1.8ts. Please correct me if any FACTS are not accurate.
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madspaniard
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Joined: August 18, 2008
Posts: 3795
Location: Alameda, CA
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| Posted: Mon Oct 20, 2014 7:37 pm Post subject: |
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There are many many posts on The Samba from different people stating that with stock R&P and tire diameter you get about 4,000 rpm at 70 mpg, not just GoWesty. That is why I'm a bit surprised about Andrew's numbers.
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1991 Westy auto w/ Peloquin TBD
"The only difference between me and a madman is that I'm not mad” - Salvador Dali |
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?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
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| Posted: Mon Oct 20, 2014 8:22 pm Post subject: |
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| Jon_slider wrote: |
I would also want to verify your data
1. is your speed GPS based
2. is your tachometer calibrated to Vag-Com
3. What exact make, model, and size tire are you using, so I can verify your belief that it is 27" diameter.
4. IS your Ring and Pinion really a 3.73? |
1. Yes, it is GPS verified.
2. No my tachometer is not Vag-Com verified. It is an mTDI so there is no way to hook up Vag-com. The tachometer accuracy is verified, though, with a diesel pulse adapter and rpm equipped timing light.
3. BFG 27x8.5x14
4. That's my big question at the moment. I have a receipt saying it is, but I have not pulled it apart to count teeth. |
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ThankYouJerry
Samba Member
Joined: September 01, 2012
Posts: 2271
Location: Shakedown Street
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| Posted: Mon Oct 20, 2014 9:33 pm Post subject: |
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| Jon_slider wrote: |
In my opinion, youre having to use 2nd gear too much because your gearing is 14% taller than stock, AND your 1.8t is not chipped.
I would not have recommended a 3.73 ring and pinion.
I think a stock ring and pinion with your 5% oversized tires would be a better match.
fwiw, Stephans gearing is 10% taller than stock IF he still runs 215x75x15, which are 27.8" diameter
Most people I know with 10% tall gearing with a 1.8T are ecstatic! Their gearing change is from the tires only, no ring and pinion change. They do run a stage 1 chip tune, recommended.
your gearing is just 4% taller than those people. So there may be other factors at play.
your low gas mileage seems to be a mountain based measurement. I suggest you find some reasonably level highway to develop some MPG data.
iirc Stephan was getting 17.5Mpg, and I know someone who gets 20mpg with the same motor and tires, and a stage 1 chip. Stephan is chipped to stage 3 I believe. (needs confirmation)
So, to be comparable to other 1.8Ts besides your ring and pinion disadvantage, your lack of a chip tune may be relevant.
| ThankYouJerry wrote: |
| Nokian WRG2 215/65/15… Nokian specs show them at 26.5" |
where do you find that info, can I have a link? I dont know where Nokian specifically lists their tires diameter.
Analysis
a 3.73 is 9% taller than a stock Auto R&P of 4.09
a 26.5" tire is 5% taller than a stock 25.3" diameter tire
add those together and you've got 14% taller than stock gearing.. Not something I would recommend. (I avoid double digit % tall gearing)
Assume a stock auto tranny with stock 25.3" diameter tires goes 70mph@4100rpm
A 3.73 Ring and pinion with stock 25.3" diameter tires would go 70mph@ 3731rpm (9% tall)
A 3.73 Ring and pinion with 26.5" diameter tires would go 70mph@ 3544rpm (5% tall)
references:
http://www.gowesty.com/library_article.php?id=116
At 75 mph, for example, the 4-speed Vanagon will have an engine speed of about 4000 RPM, whereas a AT Vanagon will be closer to 4400 RPM.
http://www.gowesty.com/ec_view_details.php?id=3862&category_id=&category_parent_id=
We are now offering you the option to lower your RPMs across the board by 9%. This is achieved by installing a TALLER RATIO European-only ring & pinion set with a 3.73:1 ratio (instead of the standard 4.09:1 R&P ratio all USA-delivery vehicles got). For example: If you are used to doing 70 mph at 4000 rpm, your new cruising RPM at the same speed (70 mph) would be 9% lower at 3640 rpm
| TequilaSunSet wrote: |
| My tire set up is slightly taller than stock, at 65mph (GPS) my speedo reads 62mph... not sure how to quantify that difference into RPM etc. |
If you tell me the specs for the diameter of your tires, I can tell you how tall your gearing is over stock (not a tape measure of your wheel, I need manufacturer spec for your make model and size).
Since you have not changed your ring and pinion that wont be a factor. Do you have a chipped 1.8t or stock?
Your speedometer error is not relevant. You would need an accurate tachometer, and GPS speed, to calculate how tall your gearing is. But if you just give your tire diameter spec, I can calculate it, even if you have no tachometer.
sample calculations:
26.5" tire, divided by 25.3" stock diameter, -1 = 5%
27.8" tire (215x75x15 BFG AT KO), divided by 25.3" stock diameter, -1 = 10% taller than stock gearing |
1. IIRC, I'm at about 3700 RPM at 70 MPH... according to the ScanGaugeII.
2. Can't find the specs for the WRG2 tires now as they have been discontinued  . I dug up the measurement from another thread on the same sized WRG2s.
3. My MPG was roughly the same (13-14mpg) traveling up the I-5 (flat highway)... according to the ScanGaugeII. Granted I was doing 75mph.
If you were me... At this point would you:
A. Chip it and leave the 3.73 R&P in place... (my newly rebuilt GTA auto trans also has: all the bronze Audi/Porsche internals, 4 gear planetary; larger direct reverse drum; extra clutch in forward clutch and an RV stall converter).
B. Don't chip it and remove the 3.73 R&P.
C. Some other choice???
As an aside... Stephan also suspects that the stall converter is part of the problem of why cruise control doesn't work effectively with my van (in addition to "the ratio"). He is looking into the cause and a fix.
Thanks for the advice.
_________________
1990 Multivan - "Ohana"
1.8T, Auto w/3.27 R&P + Peloquin TBD |
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madspaniard
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Joined: August 18, 2008
Posts: 3795
Location: Alameda, CA
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| Posted: Mon Oct 20, 2014 9:43 pm Post subject: |
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I would go from cheap to expensive. What is more expensive, change tires to a 15" lower diameter option or chipping the engine? Maybe try one first and then the other. I would change the R&P last due to the higher cost.
The other thing here is that this is all a compromise, the 3.73 R&P is a great compromise to lower your rpms when a good percentage of your driving is on flat terrain, how often do you drive over passes? Maybe chipping the engine is all you need and you still retain lower rpms in flat road driving.
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1991 Westy auto w/ Peloquin TBD
"The only difference between me and a madman is that I'm not mad” - Salvador Dali |
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ThankYouJerry
Samba Member
Joined: September 01, 2012
Posts: 2271
Location: Shakedown Street
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| Posted: Mon Oct 20, 2014 9:52 pm Post subject: |
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Note: I have pinged Peter at VC to see if I can get an accurate measurement of the Nokian WRG2 215/65/15s that I have. The tire specs are no longer listed on Nokian's website since the tires have been discontinued.
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1990 Multivan - "Ohana"
1.8T, Auto w/3.27 R&P + Peloquin TBD |
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ThankYouJerry
Samba Member
Joined: September 01, 2012
Posts: 2271
Location: Shakedown Street
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| Posted: Mon Oct 20, 2014 9:56 pm Post subject: |
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| madspaniard wrote: |
I would go from cheap to expensive. What is more expensive, change tires to a 15" lower diameter option or chipping the engine? Maybe try one first and then the other. I would change the R&P last due to the higher cost.
The other thing here is that this is all a compromise, the 3.73 R&P is a great compromise to lower your rpms when a good percentage of your driving is on flat terrain, how often do you drive over passes? Maybe chipping the engine is all you need and you still retain lower rpms in flat road driving. |
1. Actually, my driving is mostly in mountainous terrain.
2. Chipping will be cheaper than a set of new tires. My current tires have about 1500 miles on them.
3. Do I worry that my auto trans cannot handle the extra power from chipping? Stephan has his concerns about it.
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1990 Multivan - "Ohana"
1.8T, Auto w/3.27 R&P + Peloquin TBD |
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TequilaSunSet
Samba Member
Joined: May 30, 2012
Posts: 2109
Location: Philippines
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| Posted: Mon Oct 20, 2014 9:58 pm Post subject: |
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I mentioned it before, your tires are 26"
_________________
Don't harsh my mellow...
1985 Hightower Vanagon 1.8T- Gone
1972 Panel Bus- Gone
1967 Bug- Gone
1964 Euro Sunroof Bug- Gone
1969/72/63 Sunroof Bug- Gone
1975 Brazilian Bug in the Philippines 🇵🇭- New to me |
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ThankYouJerry
Samba Member
Joined: September 01, 2012
Posts: 2271
Location: Shakedown Street
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| Posted: Mon Oct 20, 2014 10:03 pm Post subject: |
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| TequilaSunSet wrote: |
| I mentioned it before, your tires are 26" |
I believe you but... link please? I can't find the specs anywhere.
_________________
1990 Multivan - "Ohana"
1.8T, Auto w/3.27 R&P + Peloquin TBD |
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madspaniard
Samba Member
Joined: August 18, 2008
Posts: 3795
Location: Alameda, CA
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| Posted: Mon Oct 20, 2014 10:10 pm Post subject: |
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I'm no expert but this is my opinion. Like mine, your tranny has the internals of an Audi 5000 turbo, I'm not sure what kind of power that Audi makes compared to a chipped 1.8T but maybe a light foot and some careful mountain driving with reasonable rpms is all is needed. If you are concerned about it then maybe going back to the 4.09 R&P is the way to go for some piece of mind.
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1991 Westy auto w/ Peloquin TBD
"The only difference between me and a madman is that I'm not mad” - Salvador Dali |
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ThankYouJerry
Samba Member
Joined: September 01, 2012
Posts: 2271
Location: Shakedown Street
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| Posted: Mon Oct 20, 2014 10:28 pm Post subject: |
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The Audi 5000 Turbo made about 160 HP. The stock 1.8T is rated at 180 HP + 30 HP for the chip + 20 HP with the SS exhaust. BTW... GTA only warrantees their "auto turbo trans" with "stock engines".
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1990 Multivan - "Ohana"
1.8T, Auto w/3.27 R&P + Peloquin TBD |
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TequilaSunSet
Samba Member
Joined: May 30, 2012
Posts: 2109
Location: Philippines
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| Posted: Mon Oct 20, 2014 10:35 pm Post subject: |
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| ThankYouJerry wrote: |
| The Audi 5000 Turbo made about 160 HP. The stock 1.8T is rated at 180 HP + 30 HP for the chip + 20 HP with the SS exhaust. BTW... GTA only warrantees their "auto turbo trans" with "stock engines". |
You have the SS exhaust so I wouldn't chip it too... these auto trans don't grow on trees.
Tire size
http://www.jekylhyderacing.com/HeightofTires.htm
This list all tire sizes (posted on page one)
_________________
Don't harsh my mellow...
1985 Hightower Vanagon 1.8T- Gone
1972 Panel Bus- Gone
1967 Bug- Gone
1964 Euro Sunroof Bug- Gone
1969/72/63 Sunroof Bug- Gone
1975 Brazilian Bug in the Philippines 🇵🇭- New to me |
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