manual_tranny
Smyth Performance- Intern
Hi everybody! I am on a mission. I have spent so much time crawling around this and every tdi/mk4 site I can find, trying to figure out the best way to continue getting good milage AND be able to get up rough logging and climbing access trails out West. Many thanks to all of you who have done so many spectacular write-ups, especially thanks for the timing belt write-up! The Bentley manual should be ashamed of itself compared to these collection of high-res pictures and how-tos!
Anyway let me share what I am thinking already. My car is a 2002 MKIV Tdi. Last time I went down an access trail I had a full 7-day cooler and crash pad (for climbing) on roof, four climbers in the car and every inch of the car was full of gear. I am generally an excellent driver, but going up mountain logging roads with giant holes at night in my overloaded car eventually we bottomed out a few times out of necessity to get where we were going. (free camping) I figured out later I had only been banging my trailer hitch, but it really did get banged up good and it bent the underside of the car and the hitch up about one inch. The engine and rest of the car I had saved from damage, but this gets me thinking- it doesn't get much closer before I destroy my car and get stranded like this. I have to keep this amazing car, no questions about it. I also have to keep climbing and camping in far off places. I'm not going to drive a Jeep across country at 15mpg so I can use 4wd for the 15-30 miles of the trip that need it.
I've taken measurements, used calculators etc, and I believe I have come up with new parts/settings that should be ideal. I'm looking for opinions, neg and positive I won't be offended.
My plans:
-Panzer Skid Plate
-Biggest offroad/onroad tires that will work well
-DMS suspension AND/OR 3” raise (2” kit, 1” tire)
-Differential that will keep me moving when one tire leaves ground at slow speed.
-More power, especially in high altitude (already discussed)
-Better lighting! I have a roof rack and a place to mount rally lights, now just need to figure wiring
(send me links if you have had good experiences with certain rally style lights, please. I imagine bright LEDs as the most reliable way to provide huge lumens without requiring a new alternator to power them...?)
Here are my ideas spelled out:
WHEELS AND TIRES:
I currently have stock wheels and tires,
(19 lb alloy stock 15”)
(21 lb Michelin Hydroedge 195/65r15)
I think I want:
15” lightweight wheels (15.7 lbs)
http://www.nlmotoring.com/productdetails.asp?productcode=51956103&click=2
205/75R15 General Tire:
http://www.tirerack.com/tires/Spec.jsp?make=General&model=Grabber%20AT%202&partnum=075TR5GRAT2OWL&vehicleSearch=false&fromCompare1=yes
These wheels are cheap and light weight. I think they're kind of ugly too, but so cheap I could buy 5-6 and not care. I would like to keep a second set of wheels and tires so during the summer I can keep using my Michelins. I assume these wheels are not very strong, but I also assume that will be ok since I will have large diameter tires that will cushion them. Is this right?
After obsessing over tire weight and size for a LONG time, I found these 205/75R15 General Tire (exactly the size I was dreaming of) They are only 25lbs, (only 4 lbs more than my 195/65R15). With my lighter wheels, my unsprung weight should remain almost identical to my stock wheels and tires!!! With a diameter of 26.8, they are exactly 2.1 inches bigger in diameter than my “tiny” stock tires. They even have a good UTQG, which should be nice as I put on a lot of miles. This alone will help me raise the car up (theoretically) 1.05inch.
My wheel well is 28" from front to back, the tire is 26.8" diameter inflated. This leaves 0.6 inch clearance between the tire and the front and back of the wheel well. Is this going to be a problem?. Will higher speeds be a problem due to tire expansion? (80mph? 100Mph?) Will I need to modify the wheel well to use this size tire?
I will be spinning 778 revs per mile with these, while my Mich. Hydroedge spun at 842. 778 is 0.92, which should take 2500rpm engine speed down to 2300rpm, 3000prm down to 2760, 4700 down to 4324. I suspect that 1st gear will still be functional climbing steep hills, has anybody changed their final drive this much, and if so what can I expect 1st gear to feel like from a stop up a hill?
SUSPENSION:
1. http://www.dmsnorthamerica.com/cgi-bin/ec.cgi?opt=2&org=1&pid=237&a=dc
2. http://www.metalnerd.com/cat09.htm
I really need everybody's help with this, I only have rough ideas!!
What do I need to worry about when I raise the car up higher? Camber? Toe? Other geometry? Nothing? Depends on how it's done?
I am considering both or either of:
1. Rally Shocks/Springs 50mm would be going 'overboard', but if my car could reliably take big bumps and land small jumps without falling apart, and still be drivable on the interstate at 40mpg+, I would be willing to part with the $5-6K to make it happen.
2. Stock suspension + spacers: This has the benefit of being relatively cheap. Practically free compared to custom suspension. Is this hillbilly? What are your opinions? (No offense metalnerd thanks for making these parts!!) Is it possible/practical to combine 1-2” of lift with DMS suspension? I was hoping I could raise the car WAY off the ground for trails, and lower the DMS suspension with the lifts still in for driving on-road.
The further a vehicle is raised off the ground, the worse the mpg will be at high speed. This is the main reason I would like an adjustable height suspension. What is everyone's opinion for using airbags to raise/lower the suspension? I really like the instant satisfaction and convenience of height change from inside the car, but I worry about the handling characteristics of Airbag suspension. Opinions?
The General Tire 205/75R15 can hold 1609lbs each. This is a lot of weight. If I have a beefier suspension, will the car be safe loaded up with more weight than the stock limit? I once loaded my TDI up for 8 miles with about 1400lbs of bags of rocks, and I noticed that the front right and the rear left of the car (where I had put most of the weight) were lower to the ground than the front left and rear right. The car doesn't have a very stiff chassis!! Is there anything to do about this? I don't want to break my suspension with 4 bodies, 160lbs on the roof, and the back end loaded up while hitting big ruts and potholes.
DIFFERENTIAL:
Does anybody know if I would want one of these or the other? I think I like the Wavetrac better, but that might be only because it was such a neat product. Would anybody make the argument that I don't need a LSD for offroad? I get the idea having had the car stuck in frozen ice/snow crust that my current differential is no more advanced than the differentials of the 1920s or the 3-gear lego differentials of my childhood.
http://www.autotech.com/prod_drive_wavetracDiffs.htm
http://www.kermatdi.com/servlet/-strse-98/Peloquin-Limite-Slip-Differential/Detail?category=-Performance+Parts%3AFinal+Drive
TRANSMISSION:
I am also looking into the 6th gear conversion, as a final modification to deal with the off-road tire size change. Very low 1st and 2nd gears with a regular 5th and 6th overdrive. Will there be problems getting gears in non-stock sizes? Are there any manufactured gears too big or small to fit in the 6 speed transmission? (I've bought motorcycle gears before that technically fit but were too big/small and the chain would rub, I'm looking to avoid stuff like this)
STEERING/LINKAGE:
I have not yet found any information on how to strengthen steering and other components that go to wheels. Does anybody have any ideas... I don't even know where to start looking. Besides springs/shock absorbers, what are the names of the stabilizing bars/arms etc. that might be replaced with thicker, stronger pieces or adjusted to compensate for medium-duty offroad use? Is there anywhere to buy strengthened rods for MKIV offroad?
SPARE TIRE HOLDER/BRACKET:
I haven't seen any kits for mounting a wheel/tire on a car, but I've seen pictures of rally vws using them. If I put a wheel/tire on the rear door, will I be able to strengthen the shocks that keep the door up? Is there a way to mount a horizontally opening gate behind the door?
WINCH:
Laugh if you want, but by the time I have this project completed, there will still be one thing missing- a way to get unstuck. Does anybody have any ideas on where the best place to mount a winch on a MKIV is? My thoughts are that I could weld a metal bumper to the front of the car and mount the winch to that, but I am concerned that there aren't any points on the entire car that would be strong enough to use a winch without breaking off. Does anybody know where the strongest parts of the front of the frame are? Will it be necessary to weld and strengthen the frame anywhere in order to install a heavier front bumper and winch? I'm thinking using a metal bumper from an old Jeep or something at this point.
I apologize for such a outrageously long post. I haven't been able to sleep because I can't figure out whether it's worth it to dive into this project or not. Also, I apologize if any of these questions have been answered before but I haven't come across any posts that really embraced the idea of going off-road in a TDI.
I'm also trying to get an idea for how marketable all this would be. Are there many of you out there who are looking for the same thing? Let me know if you're interested in doing these modifications to your own cars, perhaps we could get a group order of steel front bumpers/spare tire brackets/winches? Maybe a group order on differentials? Lets do this!!!
Anyway let me share what I am thinking already. My car is a 2002 MKIV Tdi. Last time I went down an access trail I had a full 7-day cooler and crash pad (for climbing) on roof, four climbers in the car and every inch of the car was full of gear. I am generally an excellent driver, but going up mountain logging roads with giant holes at night in my overloaded car eventually we bottomed out a few times out of necessity to get where we were going. (free camping) I figured out later I had only been banging my trailer hitch, but it really did get banged up good and it bent the underside of the car and the hitch up about one inch. The engine and rest of the car I had saved from damage, but this gets me thinking- it doesn't get much closer before I destroy my car and get stranded like this. I have to keep this amazing car, no questions about it. I also have to keep climbing and camping in far off places. I'm not going to drive a Jeep across country at 15mpg so I can use 4wd for the 15-30 miles of the trip that need it.
I've taken measurements, used calculators etc, and I believe I have come up with new parts/settings that should be ideal. I'm looking for opinions, neg and positive I won't be offended.
My plans:
-Panzer Skid Plate
-Biggest offroad/onroad tires that will work well
-DMS suspension AND/OR 3” raise (2” kit, 1” tire)
-Differential that will keep me moving when one tire leaves ground at slow speed.
-More power, especially in high altitude (already discussed)
-Better lighting! I have a roof rack and a place to mount rally lights, now just need to figure wiring
(send me links if you have had good experiences with certain rally style lights, please. I imagine bright LEDs as the most reliable way to provide huge lumens without requiring a new alternator to power them...?)
Here are my ideas spelled out:
WHEELS AND TIRES:
I currently have stock wheels and tires,
(19 lb alloy stock 15”)
(21 lb Michelin Hydroedge 195/65r15)
I think I want:
15” lightweight wheels (15.7 lbs)
http://www.nlmotoring.com/productdetails.asp?productcode=51956103&click=2
205/75R15 General Tire:
http://www.tirerack.com/tires/Spec.jsp?make=General&model=Grabber%20AT%202&partnum=075TR5GRAT2OWL&vehicleSearch=false&fromCompare1=yes
These wheels are cheap and light weight. I think they're kind of ugly too, but so cheap I could buy 5-6 and not care. I would like to keep a second set of wheels and tires so during the summer I can keep using my Michelins. I assume these wheels are not very strong, but I also assume that will be ok since I will have large diameter tires that will cushion them. Is this right?
After obsessing over tire weight and size for a LONG time, I found these 205/75R15 General Tire (exactly the size I was dreaming of) They are only 25lbs, (only 4 lbs more than my 195/65R15). With my lighter wheels, my unsprung weight should remain almost identical to my stock wheels and tires!!! With a diameter of 26.8, they are exactly 2.1 inches bigger in diameter than my “tiny” stock tires. They even have a good UTQG, which should be nice as I put on a lot of miles. This alone will help me raise the car up (theoretically) 1.05inch.
My wheel well is 28" from front to back, the tire is 26.8" diameter inflated. This leaves 0.6 inch clearance between the tire and the front and back of the wheel well. Is this going to be a problem?. Will higher speeds be a problem due to tire expansion? (80mph? 100Mph?) Will I need to modify the wheel well to use this size tire?
I will be spinning 778 revs per mile with these, while my Mich. Hydroedge spun at 842. 778 is 0.92, which should take 2500rpm engine speed down to 2300rpm, 3000prm down to 2760, 4700 down to 4324. I suspect that 1st gear will still be functional climbing steep hills, has anybody changed their final drive this much, and if so what can I expect 1st gear to feel like from a stop up a hill?
SUSPENSION:
1. http://www.dmsnorthamerica.com/cgi-bin/ec.cgi?opt=2&org=1&pid=237&a=dc
2. http://www.metalnerd.com/cat09.htm
I really need everybody's help with this, I only have rough ideas!!
What do I need to worry about when I raise the car up higher? Camber? Toe? Other geometry? Nothing? Depends on how it's done?
I am considering both or either of:
1. Rally Shocks/Springs 50mm would be going 'overboard', but if my car could reliably take big bumps and land small jumps without falling apart, and still be drivable on the interstate at 40mpg+, I would be willing to part with the $5-6K to make it happen.
2. Stock suspension + spacers: This has the benefit of being relatively cheap. Practically free compared to custom suspension. Is this hillbilly? What are your opinions? (No offense metalnerd thanks for making these parts!!) Is it possible/practical to combine 1-2” of lift with DMS suspension? I was hoping I could raise the car WAY off the ground for trails, and lower the DMS suspension with the lifts still in for driving on-road.
The further a vehicle is raised off the ground, the worse the mpg will be at high speed. This is the main reason I would like an adjustable height suspension. What is everyone's opinion for using airbags to raise/lower the suspension? I really like the instant satisfaction and convenience of height change from inside the car, but I worry about the handling characteristics of Airbag suspension. Opinions?
The General Tire 205/75R15 can hold 1609lbs each. This is a lot of weight. If I have a beefier suspension, will the car be safe loaded up with more weight than the stock limit? I once loaded my TDI up for 8 miles with about 1400lbs of bags of rocks, and I noticed that the front right and the rear left of the car (where I had put most of the weight) were lower to the ground than the front left and rear right. The car doesn't have a very stiff chassis!! Is there anything to do about this? I don't want to break my suspension with 4 bodies, 160lbs on the roof, and the back end loaded up while hitting big ruts and potholes.
DIFFERENTIAL:
Does anybody know if I would want one of these or the other? I think I like the Wavetrac better, but that might be only because it was such a neat product. Would anybody make the argument that I don't need a LSD for offroad? I get the idea having had the car stuck in frozen ice/snow crust that my current differential is no more advanced than the differentials of the 1920s or the 3-gear lego differentials of my childhood.
http://www.autotech.com/prod_drive_wavetracDiffs.htm
http://www.kermatdi.com/servlet/-strse-98/Peloquin-Limite-Slip-Differential/Detail?category=-Performance+Parts%3AFinal+Drive
TRANSMISSION:
I am also looking into the 6th gear conversion, as a final modification to deal with the off-road tire size change. Very low 1st and 2nd gears with a regular 5th and 6th overdrive. Will there be problems getting gears in non-stock sizes? Are there any manufactured gears too big or small to fit in the 6 speed transmission? (I've bought motorcycle gears before that technically fit but were too big/small and the chain would rub, I'm looking to avoid stuff like this)
STEERING/LINKAGE:
I have not yet found any information on how to strengthen steering and other components that go to wheels. Does anybody have any ideas... I don't even know where to start looking. Besides springs/shock absorbers, what are the names of the stabilizing bars/arms etc. that might be replaced with thicker, stronger pieces or adjusted to compensate for medium-duty offroad use? Is there anywhere to buy strengthened rods for MKIV offroad?
SPARE TIRE HOLDER/BRACKET:
I haven't seen any kits for mounting a wheel/tire on a car, but I've seen pictures of rally vws using them. If I put a wheel/tire on the rear door, will I be able to strengthen the shocks that keep the door up? Is there a way to mount a horizontally opening gate behind the door?
WINCH:
Laugh if you want, but by the time I have this project completed, there will still be one thing missing- a way to get unstuck. Does anybody have any ideas on where the best place to mount a winch on a MKIV is? My thoughts are that I could weld a metal bumper to the front of the car and mount the winch to that, but I am concerned that there aren't any points on the entire car that would be strong enough to use a winch without breaking off. Does anybody know where the strongest parts of the front of the frame are? Will it be necessary to weld and strengthen the frame anywhere in order to install a heavier front bumper and winch? I'm thinking using a metal bumper from an old Jeep or something at this point.
I apologize for such a outrageously long post. I haven't been able to sleep because I can't figure out whether it's worth it to dive into this project or not. Also, I apologize if any of these questions have been answered before but I haven't come across any posts that really embraced the idea of going off-road in a TDI.
I'm also trying to get an idea for how marketable all this would be. Are there many of you out there who are looking for the same thing? Let me know if you're interested in doing these modifications to your own cars, perhaps we could get a group order of steel front bumpers/spare tire brackets/winches? Maybe a group order on differentials? Lets do this!!!
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