Vehicle Info:
2000 Audi A4 1.8T Quattro
Non power, but heated seats
WHAT I NEEDED TO BUY:
Seats (complete)
Connector and wiring (for each seat) to get power to the seat motors
Hardware
My original drivers seat was busted up pretty good from the owner before me, so I found a set of S4 leathers for a fair price and jumped on them.
First things first, removing the old seats.
Both the passenger and drivers are the same. Remove this 'pin' type thing:
IMGP5313 by lorge1989, on Flickr
And then slide the seat all the way back on the track. Or to the right in this picture:
IMGP5314 by lorge1989, on Flickr
The side closest to the center console for each should pop out first then wiggle the other side out, be careful of the carpet. The seat can easily get caught up.
NOTE: I undid my battery before starting. I didn't want any funny business with the airbags or anything so I would suggest whenever either of the seats have the connectors disconnected that you also have the battery disconnected.
Here's a quick comparison, S4 seat bottom:
IMGP5319 by lorge1989, on Flickr
My A4 seats, with heat and manual adjustments:
IMGP5320 by lorge1989, on Flickr
So clearly we see how the mounting points differ. The S4 seats have two fixed points up front and then sliders in the back. Your A4 will have holes in the floor where the S4 seats go, but the will not have the threaded portion that is directly under the hold that the seat bolts into. After ripping up some carpet you can see the mounting holes:
IMGP5318 by lorge1989, on Flickr
IMGP5317 by lorge1989, on Flickr
I have solution for this that doesn't involve welding or putting a hole through the floor. We will get back to that later.
In order to wire these up all you need is a power and ground for each seat along with pins to add them to the existing connector in the car. For my car there were three connectors. Yellow, green and red. The red was the only one that changed (this is for the new to my car power seat function). On the passenger side there was no red connector to start and on the drivers I was missing two wires.
Here's what the passenger should look like when finished. (hard to see, but the top right in this pic is ground and the bottom left is power)
IMGP5328 by lorge1989, on Flickr
This is what the drivers side looks like. (note pins 1 and 2 were existing, I added 3 and 4)
IMGP5327 by lorge1989, on Flickr
Now make sure you have enough slack in the connector wiring so when you move the seat you don't rip stuff up. At least as much as shown below:
IMGP5322 by lorge1989, on Flickr
Next after you get the wiring out of the way is to start mounting up the seats.
I don't really have any efficient way of getting the nuts welded in but I think I have come up with a decent solution. On the S4s there are two allen bolts holding each seat in. I went to the store and picked up some high grade ones that look exactly the same.
Then some fender washers, regular washers and nuts. What I plan to do is cut a small slit in the floor crossmember allowing me to feed in a 13mm wrench and the associated nut onto the bolt. I believe this will give me enough strength in any type of car accident or the like.
The minimum tensile strength of Class 12.9 Metric bolts is around 1220 MPa. A good estimate of shear strength, since not tested in bolts directly is about 60% of the tensile strength.
Therefore multiplying a few things out we get a max tensile strength on a M8 bolt like this is 61300 N. The shear strength is then 36800 N. Converting that to lbs we get 8300 lb capability in shear. Considering that I have two of these per side I believe they should be okay.
For example to shear one of these bolts you would need:
F=ma
Where F = 36800 and m = 250 lb = 115 kg (a little less but you get it)
36800 N = 115 kg * a
a = 320 m/s^2
or a deceleration of 40 m/s to 0 m/s in .125 seconds.
That's a crash speed of 90 mph. And that is for one bolt. For two bolts you get double the strength so the acceleration would be double resulting in a crash speed of near 180 mph, coming to rest in .125 seconds. Also a 250 lb mass working only horizontally on the bolt is very unlikely. If I had to guess for me, weighing about 150 lbs the lateral force during a crash would be right around my body weight. This is because you have other supports for yourself and the seat other than the two bolts. (Airbag, you hands on the steering wheel, your feet on the floor, the sliders in the rear of the seat, friction everywhere etc. )
That being said I am confident the bolts will not fail. The steel you are putting the bolts through is also to be questioned. But with the amount of material present and the fact that the S4 uses nearly the same design that should be fine. The calculations for such strength is bit more than I want to do right now.
Then some fender washers, regular washers and nuts. What I plan to do is cut a small slit in the floor crossmember allowing me to feed in a 13mm wrench and the associated nut onto the bolt. I believe this will give me enough strength in any type of car accident or the like.
The minimum tensile strength of Class 12.9 Metric bolts is around 1220 MPa. A good estimate of shear strength, since not tested in bolts directly is about 60% of the tensile strength.
Therefore multiplying a few things out we get a max tensile strength on a M8 bolt like this is 61300 N. The shear strength is then 36800 N. Converting that to lbs we get 8300 lb capability in shear. Considering that I have two of these per side I believe they should be okay.
For example to shear one of these bolts you would need:
F=ma
Where F = 36800 and m = 250 lb = 115 kg (a little less but you get it)
36800 N = 115 kg * a
a = 320 m/s^2
or a deceleration of 40 m/s to 0 m/s in .125 seconds.
That's a crash speed of 90 mph. And that is for one bolt. For two bolts you get double the strength so the acceleration would be double resulting in a crash speed of near 180 mph, coming to rest in .125 seconds. Also a 250 lb mass working only horizontally on the bolt is very unlikely. If I had to guess for me, weighing about 150 lbs the lateral force during a crash would be right around my body weight. This is because you have other supports for yourself and the seat other than the two bolts. (Airbag, you hands on the steering wheel, your feet on the floor, the sliders in the rear of the seat, friction everywhere etc. )
That being said I am confident the bolts will not fail. The steel you are putting the bolts through is also to be questioned. But with the amount of material present and the fact that the S4 uses nearly the same design that should be fine. The calculations for such strength is bit more than I want to do right now.
But soon realized it was easier to cut out the part of the floor that had the hole for the S4 seats, shown above, weld a nut on the bottom, and re-install.
It was kind of a pain but IMO there is no great way of doing this. A nutsert will work IMO, and will hold up to any load it will see. Or at least you will have much larger issues before you make that fastening point fail. Most people don't realize that the force in a crash in not 100% horizontal and much of the for impacts other fastening points, AKA the rails in the back first.
Anyways....
Another thing to be done before you can mount your seats, is the front pin support (for manual seats) will need to be chopped off in order for the seats to mount in properly. This will prevent you from going back to your stock seats!
I think the switches on my seats are broken, WTF. I don't get all functions working on both seats.
Reply With Quote
Originally Posted by biketsai
- > 
Bookmarks