Installing S4 seats into A4

[nizmosx]

Hey guys, as the title says, i will be installing a pair of heated and electric s4 seats into my 2000 audi a4 avant with non power and non heated seats. I'm not worried about getting the heaters to work as i know its not as simple as it sounds.

I hear from some people that since i have a 2000 a4 my harnesses are already wired for power even though i have non power seats. i also hear from others that this is not true... can anyone who has done this verify. People are telling me to simply plug in my s4 seats and they will work.


Here is what i plan to do.


1. Remove old a4 seats.
2. Cut off original A4 three point mount.
3. Install nutserts Using my threaded insert gun (purchased from harbor frieght tools), i will then have these nutserts welded for extra peace of mind
4. Wire seats for power
5. enjoy


Before i tackle this job, i want to know if my seats should be plug and play or if i really do have to wire them up with a power and ground.

Does anyone have any pictures of how these seats are wired in, and or a how to. every diy i have seen goes into detail on how to bolt these seats up, but none really specify how to wire and or run the cables and how they connect to the harness under the seat.



Also, i read everyone saying to USE level 8 dgrade hardware... what does this mean, where can i find it, and does the nutsert that i bought with my gun meet this requirement? will the oem bolts i was planning on buying not work?

Any help would be appreciated!

[lorge1989]

Grade 8 is just a measure of the strength of the fastener. Should be able to find them at most hardware stores. OEM bolts should be fine. Many will say that the nutsert option is not a good idea because lack of strength and possible failure in an accident situation. They will most likely be fine IMO.

Wiring them up should be rather easy. But I have never touched the heaters because mine came wired from the factory. FWIW my heaters do not work in my S4s right now, but I believe that's because the seats themselves are messed up, and not because of the wiring that was unchanged.

[biketsai]

Your car should be plug and play. When in doubt, cross reference your connectors.

[nizmosx]

thanks guys. I was thinking that with the nutserts installed and tack welded they should be fine theoretically. The only other thing i have seen someone do is actually drilling a hole in the surrounding metal and welding a nut to the back side.

[revolution337]

thanks guys. I was thinking that with the nutserts installed and tack welded they should be fine theoretically. The only other thing i have seen someone do is actually drilling a hole in the surrounding metal and welding a nut to the back side.

Another option is to drill straight through the existing holes in the floorboard, the whole way through the floorpan to the underside of the vehicle. Then secure the seats with large bolts and nuts.

[nizmosx]

Yea i just dont see that as an option for me. Really dont want to go that far. thanks for all the pointers.

[nynoah]

I am putting S4 seats into my 2001 A4. I personally would never trust Nutserts. Yeah they will get the job done, but would I trust my life on them.... HELL NO!!!!

The metal that is under the A4 area where the bolts go is NOT reinforced like the S4. Its just a REALLY bad idea in my opinion to put a nutsert into that thin metal plate. What should be done is have that area reinforced. I will post pictures of what I plan on doing later. I will do my best to explain though in words what my plan is.

1 cut up a piece of 1/4 in thick metal about 3 to 4 inches long and about 1 to 1/2 inch wide. Drill a hole in that for the seats. Weld a nut on the back of that. Then cut a 3 sided hole around where the hole is for the seats (I wish Audi had just reinforced this to begin with ... arg). That hole will be about 1.5 inches wide. On either side I will drill 2 pin holes about 1/4 in (so 4 hose total) Peel that 3 sided cut hole back. Insert a bolt into the metal plate into the nut on the back use the bolt to manipulate the plate into position. Tack weld all 4 of the 1/4 holes. Weld the inside seem of the 3 sided trap door cut. Bend the metal back and then weld that back in place. Do that for all 4 holes. Then you are DONE, now that mounting point has a massive plate to distribute weight and torque force. With it done like that you will be at or above stock reinforcement level.

All those measurement numbers are rough. I will have to measure and change a little once I get into it.

Don't do nutserts... I can tell you from first hand experience when I seat breaks off the rails it F'ing HURTS. I am lucky I am still alive after that happened to me in Germany in some German mini crap car. My head nearly went through the windshield. The seat belt saved me from that, but that did limited good when the seat broke off the rail causing my body to twist out of the seat belt.

[danphines]

Another option is to drill straight through the existing holes in the floorboard, the whole way through the floorpan to the underside of the vehicle. Then secure the seats with large bolts and nuts.

This is what I did, much easier.

[nynoah]

When you drill through the body that way, you still have only a thin piece of metal holding the seat in. No reinforcement like stock.

[JumboBlack1.8]

I am putting S4 seats into my 2001 A4. I personally would never trust Nutserts. Yeah they will get the job done, but would I trust my life on them.... HELL NO!!!!

The metal that is under the A4 area where the bolts go is NOT reinforced like the S4. Its just a REALLY bad idea in my opinion to put a nutsert into that thin metal plate. What should be done is have that area reinforced. I will post pictures of what I plan on doing later. I will do my best to explain though in words what my plan is.

1 cut up a piece of 1/4 in thick metal about 3 to 4 inches long and about 1 to 1/2 inch wide. Drill a hole in that for the seats. Weld a nut on the back of that. Then cut a 3 sided hole around where the hole is for the seats (I wish Audi had just reinforced this to begin with ... arg). That hole will be about 1.5 inches wide. On either side I will drill 2 pin holes about 1/4 in (so 4 hose total) Peel that 3 sided cut hole back. Insert a bolt into the metal plate into the nut on the back use the bolt to manipulate the plate into position. Tack weld all 4 of the 1/4 holes. Weld the inside seem of the 3 sided trap door cut. Bend the metal back and then weld that back in place. Do that for all 4 holes. Then you are DONE, now that mounting point has a massive plate to distribute weight and torque force. With it done like that you will be at or above stock reinforcement level.

All those measurement numbers are rough. I will have to measure and change a little once I get into it.

Don't do nutserts... I can tell you from first hand experience when I seat breaks off the rails it F'ing HURTS. I am lucky I am still alive after that happened to me in Germany in some German mini crap car. My head nearly went through the windshield. The seat belt saved me from that, but that did limited good when the seat broke off the rail causing my body to twist out of the seat belt.

Very interested to see this. Please post pics.

My seats are mounted VERY unsafely, to be honest.....

[nynoah]

No problem will do. I am amassing parts right now. Currently my car is in pieces in my driveway. I don't plan to do the seats till I get it up and running. Mainly because I want to drive to a friends house who can TIG weld it for cheap. I am sure I could get away with MIG. But since I know a guy with a complete home professional TIG setup.... well do it right the first time.

[SIMPLXA4]

I have done this I put S4 seats in my 97 A4. What I ended up doing was cutting around the 10mm hole that is already under the carpet welding a nut to the back of that metal and welding the "flap" back down to the car. I had all this done by a local profesional shop, so I trust the welding is top notch. Shop also cut the front mounting bracket, have only had this set up for about 3 weeks so far so good. I did have to get the connectors and a bit of wire from a donor car are wire up power for the seats since neither driver or passenger were power. The easiest way I found for the ground was grounding directly off one of the bolts that hold the seat down to the car that way you dont have another wire to worry about. I havent hooked up heater yet or looked much into eventually I will get around to it.

[Urtorsen]

I've done it too, made up four stainless steel plates around 2"x2"x 3/8 with 8mm threaded hole and a grade 8 nut welded to the back of it to match the threaded hole,so about 1/2 inch of threads. Then I bored out the pre punched holes in the floor just big enough for the nut to fit into. Then seam welded the plates on each edge , nut side down, onto the floor ,welded by a custom hot rod builder that does his own frames and cars from the ground up for peace of mind.

[Urtorsen]

I had to pull the carpet out though, I was doing a grey to black int. swap so had to be done. Also the wiring looms had to be made from the seats to switches to fuses all I had was the pig tails but well worth it.
These things were way more of a bitch than the provisions for the seat rails. Why couldn't Audi or the chassis builders just have put the nut in place.

[Urtorsen]

Mine is the early 99 so you won't have as much hassle.the heat wiring is straight forward enough. There's a couple cables for the RTD(or whatever the heat probe is called?) and a couple for the heat elements all wired back to the switches

[un1ko]

Subscribed - I just bought S4 seats and I was wondering how easy or hard it is to do the swap. Good info

[nizmosx]

you guys should post pics.

what i was planning on originally doing before learning about the nutsert idea was to.

1. Cut a piece of steel metal plate about 1x2 inches with a hole in the center.
2. weld a nut on the back side of said plate.
3. Enlarge the hole opening on the chassis of the car so that the new welded nut will fit through it.
4. weld the 1x2 inch steel plate onto the car.


i did want to try to do all this myself but the welding might be a great idea.

i might choose to do this since the shop that performed this install is local to me.

http://www.audizine.com/forum/showth...light=s4+seats

[nizmosx]

I've done it too, made up four stainless steel plates around 2"x2"x 3/8 with 8mm threaded hole and a grade 8 nut welded to the back of it to match the threaded hole,so about 1/2 inch of threads. Then I bored out the pre punched holes in the floor just big enough for the nut to fit into. Then seam welded the plates on each edge , nut side down, onto the floor ,welded by a custom hot rod builder that does his own frames and cars from the ground up for peace of mind.

LOOKS like you already did what i was thinking. haha

Here is what the factory s4 mounting points look like from the donor car i got my seats from.

notice the dimples

[nynoah]

Interesting, I did not realize that the factory had bumped up that portion of the metal a little higher. Only reason I was not wanting to weld a plate on the outside was the height change. I might do what Utorsen did and weld a plate on the outside. I still might do the 4 hole pin weld points in addition to the full ring weld of that plate for extra measure though.

[Urtorsen]

You will be sitting a little higher in the s4 seats anyway,but this is more so the rear/ass of the seat I feel like they are a around an inch or so higher than the original manual seats. It's really nice to have all the adjustability with the s4 seats though. Test your motors before you install. I had 2 of them seized when I tested them. Just split them open, clean the corrosion, contact cleaner and white grease, good as new. Getting the nerve to cut out the old centre mounts is the only part of it I didn't like, no turning back to old seats after that.

[nynoah]

Odd question here, But how flat do the seats fold? When I take long trips, I tend to just roll the seat back and sleep in the car. I can make it coast to coast in 3 days that way. Not to mention save a lot of money. I was hoping the power S4 seats would fold flatter than my old A4 ones. The seats in my Mazda Millenia folded flat as a bed.

[Urtorsen]

Your a4 already has raised sections on this cross member anyway.the s4 just has a threaded plate spot welded into it. It's only raised about 1/8" (to accept the plate.anyway you can lower the front of the seat under the thigh seperate to the ass of the seat which is adjustable. As long as you penetrate with the welds you'll be fine, if I were to do it again I would prolly use an extension nut or 2 nuts welded to the back of a thinner plate.

[nizmosx]

So i believe im going to steen chassis in long beach ca tomorrow to have my s4 seat brackets welded in and the a4 mount cut off.

Before my appointment i want to run all the wiring that is needed to get power to these seats. I know my car WILL NOT be already powered like others have stated. does anyone have any picurtes of what was needed to wire the POWER and GROUND?

Please help. i dont want any surprises tomorrow and want to make sure i run everything.

Does anyone know if i need to go back to the donor car and cut off any harnesses or anything like that or do i simply just add a power and ground to the existing harness. If so what parts are needed and any diagrams as to where to tap power. i believe these seats need to be full power even when the car is off.

Im assuming i have to tap into the 30 amp power under the driver side kick panel. any pictures would be of great help.


as a reminder my car never came with power or heated seats on both driver and passenger. NOT even the lumber was powered because i didnt have that option. its hard to believe audi would waste money wiring this seat for power if it had none of those features.

[nynoah]

what year is yours? Because if it is an 01.5 like in your signature, it might be there. As to getting the donor cars harness; I would. But only after I checked to make sure the wires did not exist in there already.

[nizmosx]

My car is actually a 2000 audi a4 1.8t qms... My sig or whatever is outdated.

After doing research it seems like my driver side will be powered and the passenger side NON powered. Im going to plug in my s4 seat after work to see if its plug n play on the driver side. if it is that's all im worried about working for the time being so i can drive the car home after the modification to the frame of the car. After that's done, i can take my time to wire the passenger side once i get the harnesses from the donor car.

i will keep you posted with my progress.

Here are pics of my driver side harnesses vs my passenger harnesses for reference purposes.

Driver side harness


Passenger side harness

[nynoah]

Well you could always get the guy to weld the mounts and NOT cut the center bracket and reinstal your old seats. You can cut the bracket yourself later when you are all ready to go. It might be a little more personal work. But it might save you some headache and let you take your time. When you rush, you mess up. Be careful to not blow your airbags. Stuff like that can happen if you are in a rush.

[nizmosx]

definitely... i do plan to disconnect the battery while i take care of all this stuff. My current car has airbags in the seat so i am positive those are just plug and play. i should hve no issues there as long as i respect the system and remove the negative terminal from the battery.

[nizmosx]

Update:

I just removed my stock seat and tried to plug in the new s4 seat to check for power and I got nothing. I am now certain that 2000 a4 models with non power lumbar seats won't have the proper power and ground wire. A good way to tell is if your red connector has 2 or 4 leads/pins in it. For instance if you look at the images above that I posted, I have 2 leads going into and the s4 seat has 4.

I'm hoping the chassis shop calls me to do the welding job today. I'll keep you posted and try to take photos of the process

[nynoah]

Make sure you go get that harness. It is always preferable to have to correct plugs.

[Urtorsen]

What he said!!! Grab the pigtails as far down as possible from an S4 including the heater part, airbags and power. If you get the wiring schematic for the seats it will give you all the info you need including the heat circuits and wire gauge and even tells what color the wires are. If you cant find them pm me and I'll send you the file.I didn't know but the S4 came with a heated steering wheel untill I saw those diagrams!!

[nizmosx]

.::UPDATE::. The car is now 100 percent OEM plumbed for power seat wiring. I didnt get a chance to drive over to the chassis shop to have the a4 seat bracket cut off and nuts welded in.

Im trying to decide on hardware. I'm not sure of it but im almost positive the OEM seat bolts from an s4 are 1/4" but the chassis shop is telling me that is too small of a bolt and too small of a nut to be welded. He is recommending i go with 3/8" aircraft quality bolts (he has these in stock and says they are much stronger than grade 8 hardware) he said he has seen the snapping pressure of a 1/4" bolt and he wouldnt feel safe welding those to my car.

can anyone verify the actual size of the stock s4 seat hardware. Pictures would be nice as well. Simple google searches didnt pan out.

Ill post a picture of the factory a4 seat mounts for people to reference compared to the s4 setup as well as my wiring if people care to see.

[nizmosx]

What he said!!! Grab the pigtails as far down as possible from an S4 including the heater part, airbags and power. If you get the wiring schematic for the seats it will give you all the info you need including the heat circuits and wire gauge and even tells what color the wires are. If you cant find them pm me and I'll send you the file.I didn't know but the S4 came with a heated steering wheel untill I saw those diagrams!!

please pm me those diagrams. i have all the OEM wiring and harnesses needed for the heated seats but it seems to be a daunting task. i may need all the help i can get. i am by NO means any sort of electrical guru but i must admit the OEM wiring for powered seats was pretty cake short of removing half your interior to install it.

[Roach-the-Great]

Im trying to decide on hardware. I'm not sure of it but im almost positive the OEM seat bolts from an s4 are 1/4" but the chassis shop is telling me that is too small of a bolt and too small of a nut to be welded. He is recommending i go with 3/8" aircraft quality bolts (he has these in stock and says they are much stronger than grade 8 hardware) he said he has seen the snapping pressure of a 1/4" bolt and he wouldnt feel safe welding those to my car.

This is one of those times to go over boared. Take the guys advice that dose this for a living. And if it was me I wouldn't go with anything under 1/2" but I really really like to be able to use all my appendages

[revolution337]

I sorta skimmed over the rest of this thread so this offer may not be of any use to you now, but I have the OEM S4 seat pigtail connectors when I got my seats if you still need them.

edit: ETKA lists the S4 seat mounting bolts as an M8x30 allen head bolt.

[nizmosx]

Thanks for your offer revolution337, however i have already sourced all OEM wiring and pigtails needed from a donor car and have since installed them.

I had a few pictures i wanted to share while most of my interior is still out just for the sake of documenting everything in one thread. i will perhaps create a solid write-up afterwords if there is enough interest.




^^^ This picture shows the OEM powered seat wiring. This portion of the picture shows the ground/ power and the thermal fuse harness.




^^^ This picture shows a close up of one of the thermal fuse harness.




^^^ This picture shows a close up of one of the thermal fuses that gets plugged into the harnesses shown above. These are not standard fuses, they have the capabilities of blowing when over powered OR over heated. (this is according to Audi) i am not sure what would happen if you just stuck a 30amp fuse in here instead of the OEM thermal fuse... i wouldn't recommend it though.




^^^ This picture shows a close up of my wired up seat harness. This is the driver side harness which includes 1 power (red wire with blue) and 1 ground wire (big brown wire) for powered seats. The other 2 smaller wires in the picture are for the seat belt chime when the car is on and the seat belts are NOT plugged in. The passenger side DOES NOT HAVE the 2 smaller wires. The harness looks the same on the passenger side sans the seat belt wiring.




^^^ This picture shows the passenger side mounting points for the OEM seat. This picture also shows the powered seat wiring already in place and routed underneath the carpet all in OEM locations. I have not yet decided to take on the task of the heated seat option but i will probably make a write up for that down the line when i choose to install it. Notice the passenger side seat power harness only has the 2 wires (power and ground) as i mentioned above.




^^^ This picture shows a close up of where i cut off the OEM carpet to expose the factory mounting points of where the Audi s4 seats will now bolt onto. The carpet was perforated so it made removal very CLEAN and easy. There is no way to mess up this step really. You can see there are NO threads here. My plan is to drill out that OEM hole larger that you see in the picture. I will then get a 3/8" plate (1.5" x 1.5"), drill a hole in that 3/8" plate, weld a nut to the back of it and then slip it over the OEM opening on the car and then weld it onto the chassis.





^^^ This picture shows the eyelid of the factory OEM Audi S4 seats. The factory S4 seat hardware is a M8x30 Allen head bolt. However i have chosen to take the chassis builder recommendations and go with a aircraft quality 3/8" bolt. In the above images you can see that the 3/8" bolt fits into the OEM S4 seat eyelid.


I have an appointment on sunday morning to get the welding done so i will bring my camera and take photos of the process as well so that we can get all the questions answered in this thread.

I hope this helps some people visualize how involved this swap is.

[nynoah]

The worry I have here is does the bolt fit on top when the seat is fully back. We know the stock one will. But is the head on the non allen bolt going to fit the small dimensions.

Something to consider.

[nizmosx]

^^^ the bolt head seems to fit with absolutely no problems. On sunday when the seats get installed i will take a photo of how much it clears. The bolt head doesnt even surpass the tallest part of the factory seat bracket. i do however want to make sure i have enough room to get a socket in there to tighten the seats down and that the factory plastic slip cover will still work. I wanted to mention that when wankel did this found here. you can see he used 3/8" as well but he never put on the factory slip cover.

Here are pics from his thread.

[Urtorsen]

I remember having to use a socket head Allen bolt cause a hex head wouldn't take a socket. Socket head Allen's are better anyway in a place like that IMO

[Urtorsen]

Slip covers are all missing on mine, believe me you wouldn't miss them.

[Urtorsen]

Any why is it the drivers leather goes all glossy looking instead of they way the passenger seats look, it bugs the crap out of me. I'm looking for a drivers seat to take the heater element and leather off of.