1982 Vanagon Westfalia AHU build

jjordan11

Veteran Member
Joined
Jan 5, 2008
Location
Lehi, UT
TDI
1988 Audi 80 quattro PD130, 1982 Westfalia TDI
Well we're at it again, this project is a colaboration between myself and my Father. I have been looking at Westys for a while with the intent of a conversion. One poped up on thesamba for sale in Albuquerque, NM so my Dad and I hoped in the truck with the car hauler for a weekend roadtrip. Two days later we arrived back with the Vanagon to start collecting parts.

Our goals are to have the mechanical portion of it completed before July 4th week as my Wife's family has a reunion planned for that week and it will be in Yellowstone. Some may be saying how did he get his wife to sign off on another conversion, but I have to say that this one was her idea. She was up with our son and I woke up with her saying we should get "that diesel camper". I didn't argue and set about getting the owner contacted and travel arrangements made.

The Westy was originally a 1.6 na diesel westy that the original owner recently converted to an A2 1.8L CIS gasser. The bell-housing, motor mounts, and input shaft are all diesel specific. I did find out that the owner took the original trans out and swapped the ABD gasser transmission into it. That is ok though because I have a DK trans in one of my other Vanagons that is now my parts van. Thanks to Andy with all the documentation of the transmissions and their codes I'm a lot more educated now. The Dk trans has the lowest (numeric) gear ratio and I just ordered new 3rd and 4th gears to gear it better.

The gear ratios are as follows:
final drive 4.57:1
1st (stock) 3.78
2nd (stock) 2.06
3rd (weddle) 1.14
4th (weddle) 0.70

I ordered the gears yesterday and will be pulling the DK transmission this weekend from my old Van. I'll be using these tools to rebuild (as of a week ago I didn't realize I had them).



With 215/75R15 tires that should put my rpms at 65mph at around 2650+-100 rpms.

The engine is going to be pretty straight forward using an AHU for the platform. Some Bosio pp520 or 502 nozzles (whichever is larger), 11mm ALH injection pump, K03/04 Hybrid turbo and a 2.5" exhaust. It'll be Mikel tuned for sure with a maf and egr delete.

We'll probably do something like rsxsr did with his with some custom motor mounts to reduce vibration. We'll have to do a custom left motormount too for turbo clearance.

The body of the westy isn't in the best condition with some rust, but we'll deal with that when it comes.

I'd like to Thank Andybees, rsxsr, pdxpaulie, and all the other threads I have gleened information and inspiration from. Should be fun. Jon
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Jon, wow!

I sure could have used those tools during my Tranny rebuild. I had the T-14 for removing the big/little nut on the main shaft. My uncle had a 'tailor' made tool to remove the adjusting rings on each of the tranny. Shifting fork positioning was by punch marks upon removal. I've done that numerous times in the past with no problems.

Keep us abreast of your progress!
 

jjordan11

Veteran Member
Joined
Jan 5, 2008
Location
Lehi, UT
TDI
1988 Audi 80 quattro PD130, 1982 Westfalia TDI
Thanks Andy, I do have another question about the rebuild. I have the VW manual for the 3 rib (002 I think) with all the measurements, I couldn't find a manual for the 091 side shift transmission. Are the measurements the same? I think I'll still mark the shift mechanisms before disassembling it then double check them.
 

tothemax

Top Post Dawg
Joined
Aug 7, 2006
Location
Northern Canada
TDI
TDIs: 2003 Jetta, 2016 Q5 3.0
Congrads jjordan11 what a great project... I have been dreaming of doing a project like this for use when I retire so I can hit the road in style...

Pls post some progress photos and share what you learn.

Good luck
 

Mike in Anchorage

Veteran Member
Joined
Jan 4, 2009
Location
Anchorage, AK
TDI
2016 Touareg Lux, 2015 Golf Sportwagen SE, new 4 Sept 2017;2009 VW Jetta TDI Sportwagen (Ruby) sold to VW on 22 SEP 2017
I've been wondering about a similar project. Great idea! Initially, 2650 RPM at 65 mpg sounds like a high rotational rate tome. Am I missing something? Agreeably, my Jetta will not need so much power or torque at 65 mph, but it's only reving about 2000 RPM. Looking forward to some pics.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
According to my GPS (speed) and ScanGuage (RPM), my stock 2000 Jetta TDI is cranking about 2350-2375 RPMs at 65 MPH.

In his conversion tranny, Jon is going with the .70 4th which will bring the RPMs down to about 2650 with the 4.57 R&P using the 205/75/15 tires. If there are issues with bogging on long and/or steep hills or EGTs tend to rise, he can go with 14 inch tires and raise the RPM about 300. So, he's right in the ball park with the tranny aspect of the project.

In my conversion tranny project (TDI in a '84 Vanagon), I went with the .77 4th gear, 4.57 R&P and the same tire size which will yeild about 2840 RPMs at 65 MPH.

The same tranny (Vanagon) stock, the RPMs would be about 3400-3500 at 65 MPH ......... big difference!
 

jjordan11

Veteran Member
Joined
Jan 5, 2008
Location
Lehi, UT
TDI
1988 Audi 80 quattro PD130, 1982 Westfalia TDI
With the gearing it's actually the lowest (numerical) ratio that I could get in it. There may be aftermarked ring and pinions that would lower the ratios lower than the 4.57, but I'd suspect they would be pretty expensive. With the engine turning a little faster it puts less strain on the engines with a load.

I should get some work done on it tomorrow, I'll take some good before photos of everything. Rsxsr, do you have any detailed pictures of your left motor mount? I can kind of see it on Andy's site and some on thesamba.

Jon
 

jjordan11

Veteran Member
Joined
Jan 5, 2008
Location
Lehi, UT
TDI
1988 Audi 80 quattro PD130, 1982 Westfalia TDI
progress

Alright so I thought I would post some pictures. It definitely isn't the most pretty body wise, but with time that will change. Right now we're going to focus on making mechanically sound. Here is a picture of it how it sits.

As you can see it's not much to look at and has some cancer. The previous owner had a bra put on the front in Florida, yet another reason I dis-like bras. The floorboards are Flintstone style in some areas, so we'll have to fix that.

One positive thing about the Van is the interior. It's in pretty good shape and has been re-upholstered for the most part. Everything works in the inside including the propane refrigerator.


I got the gas motor out and took off the oil pan, motor mounts, and bell-housing from it.

Gas motor lump:


Pulling motor:


Out:




Transmission's drain plug (Metal Mohawk Sorry for the blurry photo):


We got most of the parts ordered for it and I'll be working on it in the mornings. Our next major work day will be May 1st. Looking forward to it already.

Jon
 

jjordan11

Veteran Member
Joined
Jan 5, 2008
Location
Lehi, UT
TDI
1988 Audi 80 quattro PD130, 1982 Westfalia TDI
I received the gears from Weddle, but they sent me a .77 4th gear so I'll have to give them a call tomorrow. That's ok though, I still haven't pulled the trans from the donor van yet and in my haste to get the gears ordered I didn't order the gasket kit and seals for it. I'll update later.

Jon
 

jjordan11

Veteran Member
Joined
Jan 5, 2008
Location
Lehi, UT
TDI
1988 Audi 80 quattro PD130, 1982 Westfalia TDI
It will be quite a bit better than the wasserboxer or the original diesel. I just don't know how to keep them at stock levels. I'd be willing to bet that with larger nozzles, turbo, intercooler, and the chip it would get better mileage though and not stress the motor as much.

I spoke with Weddle today and they are going to send me the .70 4th gear. I also ordered the gaskets, seals, and o-rings for the trans rebuild. I decided to go with the oem gaskets and the like, the aftermarket stuff is probably better, but the oem was convenient and not too badly priced. The weddle gears are pretty cool, the syncro hub is detachable from the main gear, so if it gets damaged it could be replaced w/o the main gear.

I hope to pull the donor engine tomorrow, we'll see. I don't really have the time, but it needs to come out sooner than later.
 

AThreeTdi

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Joined
Oct 10, 2005
Location
NJ
TDI
06 jetta Tdi , 03 jetta Tdi
Good to see another part of my 98 jetta that was totaled will be living on as the engine wire harness will be helping bring this conversion to life!
 

914rrr

Well-known member
Joined
Aug 20, 2008
Location
St Petersburg, FL
TDI
2012 JSW w/ DSG
I've been thinking about a Vanagon TDI conversion with mods like jjordan11's. What kind of MPG's do you guys see or expect with a set up like this? Any chance it could be done with an automatic tranny?

I would agree that the performance mods would come in handy on a Vanagon, especially a Westy.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Automatic TDI in Vanagon

914rrr said:
I've been thinking about a Vanagon TDI conversion with mods like jjordan11's. What kind of MPG's do you guys see or expect with a set up like this? Any chance it could be done with an automatic tranny?

I would agree that the performance mods would come in handy on a Vanagon, especially a Westy.
Good to hear someone is thinking about a TDI bolt up to an automatic tranny in a Vanagon.

I've given it some thought as a project after I finish the one I am on now. The auto tranny has a 4:1 ring and pinion. However, the torque converter does not have he lock-up feature. I've not researched or posed the question anywhere as to the availability of upgraded torque converters or the possibility of retro-fit with the lock-up feature.

Maybe someone has already been down this road and can provide some good info!:D ......... the wifey would love it if I could do a TDI conversion with an auto tranny!
 

markward

Veteran Member
Joined
Jul 5, 2007
Location
Loxahatchee, Florida
TDI
82 Vanagon and 2011 JSW
Jon, I crunched these numbers for you. 65 mph is a comfortable cruising speed in a Vanagon. Faster than that and you are working. What makes these conversions nice is how well they do on hills. I am afraid you may be geared a little too tall with the .70. I ran the 4.57 with a stock .85 forth and with taller tires found it reasonable. If you stick with the .77 you could always upgrade to a taller tire to improve the highway rpm. Going from stock tires to 215/65/16s are good for 100 plus rpm. Just a thought.


Gearbox:- Vanagon Air Cooled Transmission 4.57 - .70 4th gear
Tyre:- 185/R14
-------------------------------------------------------------------------------------------
Top Gear gives 23.903 MPH/1000 RPM and a top speed of 95.612 MPH at 4000 RPM
Engine speeds in top gear:-
30 MPH = 1255 RPM 40 MPH = 1673 RPM 50 MPH = 2092 RPM 60 MPH = 2510 RPM
70 MPH = 2928 RPM 80 MPH = 3347 RPM 90 MPH = 3765 RPM 100 MPH = 4184 RPM
Top Speed in 1 gear = 17.706 MPH
And changes into 2 gear at 2180 RPM dropping 1820 RPM
Top Speed in 2 gear = 32.490 MPH
And changes into 3 gear at 2214 RPM dropping 1786 RPM
Top Speed in 3 gear = 58.709 MPH
And changes into 4 gear at 2456 RPM dropping 1544 RPM
Top Speed in 4 gear = 95.612 MPH
******************************************************************************************
Gearbox:- Vanagon Air Cooled Transmission 4.57 - .77 4th gear
Tyre:- 185/R14
-------------------------------------------------------------------------------------------
Top Gear gives 21.730 MPH/1000 RPM and a top speed of 86.920 MPH at 4000 RPM
Engine speeds in top gear:-
30 MPH = 1381 RPM 40 MPH = 1841 RPM 50 MPH = 2301 RPM 60 MPH = 2761 RPM
70 MPH = 3221 RPM 80 MPH = 3682 RPM 90 MPH = 4142 RPM 100 MPH = 4602 RPM
Top Speed in 1 gear = 17.706 MPH
And changes into 2 gear at 2180 RPM dropping 1820 RPM
Top Speed in 2 gear = 32.490 MPH
And changes into 3 gear at 2214 RPM dropping 1786 RPM
Top Speed in 3 gear = 58.709 MPH
And changes into 4 gear at 2702 RPM dropping 1298 RPM
Top Speed in 4 gear = 86.920 MPH
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Conversion gearing considerations

rsxsr said:
Jon, I crunched these numbers for you. 65 mph is a comfortable cruising speed in a Vanagon. Faster than that and you are working. What makes these conversions nice is how well they do on hills. I am afraid you may be geared a little too tall with the .70. I ran the 4.57 with a stock .85 forth and with taller tires found it reasonable. If you stick with the .77 you could always upgrade to a taller tire to improve the highway rpm. Going from stock tires to 215/65/16s are good for 100 plus rpm. Just a thought.


Gearbox:- Vanagon Air Cooled Transmission 4.57 - .70 4th gear
Tyre:- 185/R14
-------------------------------------------------------------------------------------------
Top Gear gives 23.903 MPH/1000 RPM and a top speed of 95.612 MPH at 4000 RPM
Engine speeds in top gear:-
30 MPH = 1255 RPM 40 MPH = 1673 RPM 50 MPH = 2092 RPM 60 MPH = 2510 RPM
70 MPH = 2928 RPM 80 MPH = 3347 RPM 90 MPH = 3765 RPM 100 MPH = 4184 RPM
Top Speed in 1 gear = 17.706 MPH
And changes into 2 gear at 2180 RPM dropping 1820 RPM
Top Speed in 2 gear = 32.490 MPH
And changes into 3 gear at 2214 RPM dropping 1786 RPM
Top Speed in 3 gear = 58.709 MPH
And changes into 4 gear at 2456 RPM dropping 1544 RPM
Top Speed in 4 gear = 95.612 MPH
******************************************************************************************
Gearbox:- Vanagon Air Cooled Transmission 4.57 - .77 4th gear
Tyre:- 185/R14
-------------------------------------------------------------------------------------------
Top Gear gives 21.730 MPH/1000 RPM and a top speed of 86.920 MPH at 4000 RPM
Engine speeds in top gear:-
30 MPH = 1381 RPM 40 MPH = 1841 RPM 50 MPH = 2301 RPM 60 MPH = 2761 RPM
70 MPH = 3221 RPM 80 MPH = 3682 RPM 90 MPH = 4142 RPM 100 MPH = 4602 RPM
Top Speed in 1 gear = 17.706 MPH
And changes into 2 gear at 2180 RPM dropping 1820 RPM
Top Speed in 2 gear = 32.490 MPH
And changes into 3 gear at 2214 RPM dropping 1786 RPM
Top Speed in 3 gear = 58.709 MPH
And changes into 4 gear at 2702 RPM dropping 1298 RPM
Top Speed in 4 gear = 86.920 MPH

Anyone doing a conversion should copy and save this info for serious review and reference!
 

PJDiesel

Member
Joined
Dec 7, 2008
Location
Blackfoot, Idaho
TDI
1998 Jetta AHU
Thanks for the input rsxsr and AndyBees. Jon and I are thinking the .70 4th gear will be a good fit for our AHU running 165 HP :eek: via a hybird turbo, PP 520 nozzles, and upgraded chips a in the processor. The RPM level in the Westy at 65 MPH will be about the same that a stock Jetta will run at 75 MPH.

As you reviewed our plans, did you take our increased horsepower into account? I have this same engine setup in my '98 Jetta TDI (rebuilt about 7,000 miles ago). We put in the highest 5th gear mod in my transmission and the engine pulls my Jetta along without breaking a sweat. At the RPM our Westy will run at 65, my Jetta would be doing about 85 MPH perhaps a similar resistance load (wind against the Jetta vs weight of the Westy).

I welcome your comments.
 

jjordan11

Veteran Member
Joined
Jan 5, 2008
Location
Lehi, UT
TDI
1988 Audi 80 quattro PD130, 1982 Westfalia TDI
rsxrs, thanks for that analysis of the gearing. It is put together very well. About the only thing that I could see as being a problem between cruising at 65 with the .70 gear and the .77 is the egt's. There will be a bit more weight and a brick moving through the air will definitely have a bit more resistance. That said, I've towed my trailer with approx. 1500 lbs but less wind resistance at 75mph, approx. 2600 rpms. I did slow down on the hills to 65, but that was to not work the turbo much.
Edit: I just had a thought, is the reasoning between wanting a little higher rpms at speed to keep the pcp's down? and keep the head gasket intact? I haven't done the math for that kind of thing, has anybody else?

When finished, I will make an honest assessment of the vehicle and report back our findings as to the gearing and rpms. I think we'll be ok, but I'll let everyone know.

Like my Dad said too, we'll be having some power enhancing modifications to the Vanagon, along with some gauges to monitor the oil & boost pressures and the egt.

I would appreciate it if others would post their modifications to their Van. Along with that the fuel economy or suspected fuel economy. Myself, I would expect anywhere between 30-35 mpg. I don't know if that is realistic, probably depends on our right foot.
 
Last edited:

markward

Veteran Member
Joined
Jul 5, 2007
Location
Loxahatchee, Florida
TDI
82 Vanagon and 2011 JSW
Other than deleting the egr, I have done no engine modifications to my ALH. The weak point on a Vanagon conversion will be the input shaft and the transmission next. I talked to someone at a VW show with a TDI Jetta. They had managed to twist the CV axles with the power upgrades. Our Vanagon is for trips only. It needs to be above all else reliable. If you can cruise at 3000 rpm, I would expect around 30 mpg. I am also running stock front brakes and NA 1.6 diesel clutch. The power increase over the stock 1.6 diesel with the stock 1.9 TDI is plenty for us. :D
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
I'm like rsxsr, reliability!

My 2000 Jetta, is totally stock with two exceptions (snow screen gone and egr mod). I very seldom drive it over 75 and 90% of the time keep between 65 and 70. Nearing 270k miles, it has served me well with a life time 50.5 mpg! It has the original clutch, two of the original GPs, and everything else works fine but the AM radio reception!:mad: I do have rotors and pads waiting to be installed!:D

So, in my Vanagon conversion project, I hope to not be twisting axles, crunching CV joints or toasting pistons. As I stated in my transplant thread, I'm attempting to put in operation as many of the systems from the TDI as possible... low fuel warning, low coolant warning, low washer fluid, fully functional cruise with the safety fearutres (clutch and brake switches), hand brake light, OBD, wiper system, etc,,,,:D

Somewhere below 3000 rpm and above 2650 rpm there will be a sweet spot for 65 mph. Road conditions, weight, etc., will be the varibles that affect the location of that sweet spot mile after mile. Hopefully, the gearing I chose and tire size will be right in the ballpark!
 

jjordan11

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Joined
Jan 5, 2008
Location
Lehi, UT
TDI
1988 Audi 80 quattro PD130, 1982 Westfalia TDI
Don't get me wrong, I'm all for the reliability. With all things, it's all in how you drive them. My '97 Jetta has about 340,000 miles on it with the original clutch, alt., 2nd set of glow plugs, and pretty much everything else is stock. It's been chipped with larger nozzles for the last 120,000 miles and gets between 45-52 mpg's, It has been dead reliable (besides a corroded charge cable) . It's all in how it's driven. The weak point with the vanagon as stated previously will be the drive train, but with the Westy, I won't be drag racing. I'm a firm believer that these little engines were not optimized from the factory. With more fueling potential and better breathing it will be able to get better economy, and more power. In regards to the drive train there are available multiple upgrade options for the 091's drivetrain thanks to the off-road community's contribution. I'll be using it in stock configuration to test them, while driving fairly conservatively I expect it to perform well and be extremely reliable. The trick will be to keep the low rpm torque limited, which will be done via programing. The 165+hp that it'll be pushing will be a little higher in the rpm range.

If in the future anything breaks due to the torque load, I'll post it here and what I did to fortify the weak spot.

I appreciate you guy's opinions and your probably right. We'll see :).

Jon
 

jjordan11

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Joined
Jan 5, 2008
Location
Lehi, UT
TDI
1988 Audi 80 quattro PD130, 1982 Westfalia TDI
I had a little extra time today and pulled the engine/trans out of Ol' Blue (my nickname for my part's van). I also acquired a 228mm flywheel and will be using a 228mm 2.0 a/c clutch disk and the pressure plate from a 1.8t transverse clutch. I suspected the shifter was different from the Westy to the donor Van, but I'll use the entire shifter assembly from the Donor.

We've received most of the parts, there are still a couple that need to be acquired though. We got the bracket machined for the 11mm ALH injection pump. Our goal was to have the engine installed this weekend as I'll have a lot of brothers here to help.

I've been thinking about the A/C system in it (or lack thereof). rsxsr did you do anything with an A/C system in your westy? If not how is it in hot Florida weather. We'd be taking it to Arizona occasionally to visit family, but in the summer that wouldn't be possible without a nice A/C system. Andy are you planning on having A/C?

Jon
 

markward

Veteran Member
Joined
Jul 5, 2007
Location
Loxahatchee, Florida
TDI
82 Vanagon and 2011 JSW
Jon, my Vanagon was originally a diesel and AC was not an option. When I fabricated my block brackets, I did not take into account adding an AC compressor, even though I had the one that came with the engine. After a summer trip in 100 plus temps, I decided AC was a must. Late last summer, I started some upgrades that included remaking the R/S block bracket and modifying the stock R/S carrier bar. My mod to the carrier bar, moved the rear attachment further out. This gave me room for the factory ac compressor. That is as far as I got. There is a company called Nostalgic Air in Tampa Florida. They have some universal combination evaporator and heater cores that are in dash. That is the direction I am leaning towards. I pack ratted a factory condensor and rad fan from a 90 Vanagon to use with their setup.

Because I need to remove the dashboard to do the next step and a trip pending, it looks like for now the AC install is on the back burner. I spent too much time upgrading to the Saab engine mounts when I should have been working on the AC. I am also thinking that if the dash air is not adequate, to do a dual ac setup and mounting the second evaporator under the back seat facing forwards. We use all of the cabinet space when we camp, and I don't like giving up any space. At some point the interior will need to come out to address any rust and body work. That might be the time to do the AC. I intend to pull all the glass when I do respray the Van, and from experience dust ends up everywhere. I believe the engine has plenty of umph to handle the load of an AC compressor. mark
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
I have an evaporator from a '76 Dasher that I believe will work in an in-dash AC system for a Vanagon. I've held on to it for that purpose. I've always thought an in-dash AC would be a nice addition. And, yes, as rsxsr said, the TDI should handle the AC very well!

I'm heading out today to Western Kentucky (Murray) to look at what appears to be a fairly nice non-Westy Vanagon. This is going to be a 10 hour round trip. Maybe I'll see something worth salavaging on the way out also!
 

emus528

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Mar 25, 2001
Location
Hollywood, FL.
TDI
See sig
I assume your, perused this forum
http://autos.groups.yahoo.com/group/TDI-conversion/messages

FWIW, I had the .77 Fourth initially; because my "rebuilder" did not upgrade the 3-4 slider to the newer, stronger-style "round cut" unit, it failed. I was unhappy with the highway RPMs and now have the .70 installed. 225/75/16 sneakers. Modifications in my signature were constant with both gearings.

Some are unhappy with the gap between 3 (1.17)-4 with my setup, but I remain happy in hilly Vermont.
 

jjordan11

Veteran Member
Joined
Jan 5, 2008
Location
Lehi, UT
TDI
1988 Audi 80 quattro PD130, 1982 Westfalia TDI
With your tune is the torque limited at lower rpms? I've been wondering if this would be a good idea to keep the gearbox together longer.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Gearing of the tranny

emus528 said:
I assume your, perused this forum
http://autos.groups.yahoo.com/group/TDI-conversion/messages

FWIW, I had the .77 Fourth initially; because my "rebuilder" did not upgrade the 3-4 slider to the newer, stronger-style "round cut" unit, it failed. I was unhappy with the highway RPMs and now have the .70 installed. 225/75/16 sneakers. Modifications in my signature were constant with both gearings.

Some are unhappy with the gap between 3 (1.17)-4 with my setup, but I remain happy in hilly Vermont.

Gees! Based on my calculations, with the .70 4th, 225/75/16 tires and a 4.57 Ring & Pinion, the RPMs would be roughly 2388 at 65 MPH ... too slow in my opinion.

Now, if you had one of the more common R&Ps, such as the 4.83 or 4.86, the RPMs at 65 MPH would be roughly 2524 (4.83 r&p) and 2540 (4.86) with the same tire/gear setup as mentioned above.

So, knowing the Ring & Pinion ratio is important with respect to the 4th gear choice and tire size. Chosing a 3rd gear involves considering those parameters and expected driving conditions become a factor too.

Based on my research, the 3rd-4th gear hub is not a weak point in the DK tranny (from the Air-cooled 80-83 models).
 
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