"HOW TO" - Replace the Rear Sill on an FJ40 – STEP BY STEP (14 Viewers)

[DirtDauberGarage]

There are many threads about sill replacement here on MUD, but I could NOT find a comprehensive “step-by-step” guide on how to do it. Therefore, I decided to create one in hopes it might help someone in the future.

It was my first time replacing a sill, and I took my time to ensure I did the best job possible. It took me about three full days to complete the project. Someone with experience in welding and sheet metal could probably finish it over a weekend. If you're a beginner, I recommend setting aside 3 to 4 days to be safe.

A few disclaimers…

1. I am not a professional. I did this in my driveway with basic tools and a 110 welder. I am sure a professional body guy could suggest some ways to do it differently or better.
   
   
2. I am not saying this is the only way to do it. Again, this is how I did it, and it worked well. I tried to keep it simple and the least amount of work possible. I know you can jack up the tub, completely remove the quarters, or even completely remove the tube from the frame. I am sure there are many other and maybe better ways to do this. Like I said, I tried to keep it simple and easy.
   
   
3. Usually, you would need to replace the quarter panels at the same time, but @jesus888 wanted to keep as much original patina as possible, so I only replaced the rust in the lower bottoms that was attached to the sill.
   
   
4. This is a 1970 FJ40, but the process is basically the same for all years.

Here are some basic tools and materials that you will need…

• Angle Grinders – I purchase angle grinders from Harbor Freight using coupons, which allows me to pay about $10 for each one. I typically buy several grinders at a time so that I can have one equipped with a cut-off wheel, one with a flap grinder wheel, and one with a grinding stone wheel. They usually last 4 to 6 years, after which I simply dispose of them when they die and buy new ones.
  
  
• Reciprocating Saw – This tool will be useful in tighter spaces that are difficult to access with a cut-off wheel. Make sure to have a couple of sheet metal cutting blades on hand. If you have access to a small pneumatic reciprocating saw, that would be ideal, but it's not essential.
  
  
• Basic Body Working Tools – Hammer and dolly to work and shape the metal.
  
  
• Basic Hand Tools – Screwdriver, hammer, socket set, wrenches, pliers, etc.
  
  
• C-clamps - Assorted sizes and types of C-clamps. A 12 in. Deep Throat C-Clamp from Harbor Freight is $12 and is VERY helpful.
  
  
• Spray Primer, Paint, and Rust Convert or Encapsulator – To prime, paint, and seal the bare metal. (Seam sealer is recomended as well)
  
  
• Drill and Drill Bits – Assorted drill bits and a drill to drill out spot welds, etc.
  
  
• Welder - You don't need anything fancy. A 110 MIG will work fine. I would suggest setting it up with gas, especially if you are new to welding. If you don't have one, you can rent them, or maybe find a friend who will loan you his... or better yet, buy him some beer and pizza and have him come do the welding for you.
  
  
• Safety Gear - Glasses, face shield, gloves, earplugs, etc.
  
  
• New Rear Sill, Sill Cover, and Sheet Metal or Patch Panels - I ordered all these from CCOT and was pleased. There are lots of sources online, and I have even seen guys fabricate all this themselves. Like I said, I kept it simple.

For those who are interested, this FJ40 belongs to @jesus888

Follow along with his build thread if you want to see all he does to it...

Builds - Project Old Blue Eyes

Starting up a new build! I had 2 x FJ40s from Montana delivered to my sister-in-laws farm and we decided to start working on Old Blue Eyes first… She’s in much better condition than Old Yeller and I think we have a better shot at getting her back on the road this summer, and my FJ80 project is...

forum.ih8mud.com

 

[DirtDauberGarage]

**Step 1**
Begin by removing any obstacles, such as the spare tire rack, bumperettes, rear doors, emblems, etc.

• You do have to remove the spare tire rack.
  
  
• You do NOT have to remove the doors and the bumperettes, but it will make access easier, so I recommend it.
  
  
• Keep in mind that the door screws may be rusted and difficult to remove. To help with this, use penetrating oil and a good Japanese Industrial Standards (JIS) screwdriver specifically designed for Toyota screws (Thanks @cruiserpatch - see below). It has a broader tip that fits the Toyota screws perfectly.
• If the screws remain stuck, you can try using a vice grip. In some cases, my screws broke, and I had to drill them out and re-tap the holes.

You can get your JIS screwdrivers from @cruiserpatch. I recommend him highly!!

Cruiser Patch Home Page

Cruiser Patch - a small business home to Toyota Land Cruiser and Lexus LX SUV accessories, parts, and upgrades for do-it-yourself repairs and full kits of parts. We strive for quality and excellence as we serve the Land Cruiser and Toyota four-wheel-drive communities.

www.cruiserpatch.com

 

[DirtDauberGarage]

**Step 2**
Next, remove the old body mounts located under the sill and attached to the frame. There are a total of four body mounts to take out.

- Here are some pics.

- You might want to hit the bolts and nuts with some penetrating oil to help break them loose

- Use a universal joint on a socket extension to get up in the odd angles.

- It is a 14 mm

 

[DirtDauberGarage]

**Step 3**
Remove the outer sheet metal sill cover. Take your time and cut it out piece by piece if necessary.

** Be careful not to cut into the bed floor or wheel wells **

**** Especially be careful NOT to cut the bed floor under the sheet metal. You will need to attach the sill and the sheet metal cover to the bed floor under the old sheet metal cover ***

- Drill out the spot welds

- Make a small divot in the center of the spot weld with a tap, and then drill it out. They also make specific drill bits made to remove spot welds. These help make sure you don't drill into the metal underneath, but you can do it with a standard bit as well. Just be careful not to drill too far.

- Use flat-head screwdrivers, pry bars, a reciprocating saw, pliers, and other tools to carefully remove the old sheet metal.

- Some of the old spot welds will just "pop off" if they are rusty.

You may want to have a ShopVac or a broom ready because rust, dirt, and debris will come out of everywhere!

 

[DirtDauberGarage]

Here are a few more pics of the sill with the sheet metal removed and the old sheet metal in pieces...

 

[DirtDauberGarage]

IMPORTANT CHECK POINT and NOTE...

Test fit the new cover on the old sill and make sure you have at least an inch of bed floor metal beneath the NEW sheet metal cover.

You'll need to attach the new cover to the bed floor using "plug welds." The original equipment manufacturer (OEM) sill cover is only 1.5 inches wide, and most of the metal underneath it is likely rusted and deteriorated. This occurs because water gets trapped between the bed floor and the cover, creating an environment conducive to rust.

The good news is that Cool Cruisers of Texas (CCOT) offers a high-quality replacement that addresses this issue. Their new sill sheet metal cover is 3 inches wide, providing most likely plenty of room to attach to the sill cover to a deteriorated bed floor (see the attached picture of the new cover).

* Side note* My experience with CCOT is very good. The sheet metal fits well, good quality, and is nice and thick. I would recommend them highly. I've seen replacement sill covers that are only 1.5 or 2 inches, but this is usually not sufficient if you have any significant rust.
If your bed floor lacks sufficient metal or is severely rusted, you must either replace the bed floor or add metal by butt welding to its end.

Another note that @Living in the Past mentioned to me is that the orginal bed floor actually wraped around the rear sill (see pic below). Here is what he mentioned to me in a DM

"This picture is the best one I've seen that shows how Toyota assembled the rear sill. The rear floor was long enough to fold over the back of the rear sill. Besides strength it also helped keep the floor flat with a 90° bend. The vertical section was offset for the floor. Below the offset is wedge channels. Believe there was three of these with the wide part at the top. Not clear if these were suppose to be drains or something else. They match the depth of the offset on the top half. Because the floor was just stitched weld it allowed dirt and moisture to get in. To my knowledge, no one has ever built a replacement rear sill with the offset of the factory rear sill."

 

[DirtDauberGarage]

*** Step 4 ***
Detach the bed floor from the rear sill.

- The sill is "stitch welded" to the bed floor underneath the FJ40 (see pictures). It was probably spot welded or stich welded on top under the cover as well but it usualy rusts so badly under the sill cover that it is hard to tell once the cover is removed how it actually was attached.

- The easiest way to detach it is with a reciprocating saw. Take your time, go slowly, and be careful not to damage the bed floor or wheel wells.

 

[DirtDauberGarage]

*** Step 5 ***
Cut out the old sill.

- If it is as rusty as this one, it will come out easily. The recomended method is to cut it into 3 or 4 pieces.

- Cut a piece, remove it, and repeat.

- Again, be careful not to damage the bed floor, wheel wells, or the frame.

 

[DirtDauberGarage]

*** Step 6 ***
Cut into the quarter panels and remove the "sill wings".

Each person's project may vary at this point depending on how much of the quarter panels you choose to replace. You might opt to remove just the section attached to the wings (like I did), the complete lower rear third of the quarters, or the entire quarter panels.

Adjust your project accordingly.

* Side Note: I am planning to replace the quarter panels on my 1978 FJ40 "Rusty" soon. When I do, I will create a "HOW TO" thread similar to this one that covers the process of replacing quarter panels.

- A cut-off wheel is probably your best bet for this.

- Once you cut out the quarter panel sheet metal attached to the wings, the sill wings should come out eaisly. You may have to do a little persuasion to get them out.

 

[DirtDauberGarage]

Note: The wings are attached with a spot weld or two (see pic below). You may need to drill out the welds.

 

[DirtDauberGarage]

*** Step 7 ***
Clean up rust on the bed floor and the quarter panels

- Cut out rusty metal and edges.

- Use an angle grinder with a flap wheel to clean up any rust that is left.

- Try to keep as much solid metal as possible.

- You will probably need to use a hammer and dolly to straighten out any metal bent in the removal process.

* Note: This is an ideal time to use a rust converter or encapsulator to seal any rust that you cannot eliminate and to avoid removing too much metal. Keep in mind that the area under the sill cover will not be visible and is likely to develop rust again, so make sure to seal it as thoroughly as possible.

 

[DirtDauberGarage]

*** Step 8 ***
Paint and test fit the new sill by installing it with the new bolts and body mounts.

* I highly recommend getting new body mounts and bolts. They are not expensive, and you will likely break a few old ones in the process.

- Be sure to paint the new sill before installing it, as you will not have good access to it after. Use a good etching primer and then a flat or gloss black.

- Using a pry bar or a large screwdriver, you can lift and adjust the sill while inserting the new body mounts. Do not tighten them all the way down just yet, as you may need to adjust and work on the bed floor and quarter panels to achieve a good fit.

- Note that the new sill is slightly larger to accommodate potential gaps in the bed floor. There is plenty of good metal available to stitch weld the new sill to the bed floor. Thank you again CCOT!

 

[DirtDauberGarage]

More pics...

 

[DirtDauberGarage]

*** Step 9 ***
Permanently install the sill by stitch-welding the bed floor to the new sill.

- Once you have it lined up correctly and fitting well, stitch-weld the bed floor to the new sill.

- While you can completely weld it to make it watertight, this is not necessary. If you do, be careful to go slowly and take breaks to avoid warping the metal.

- You might also consider climbing underneath to add a few stitch welds, though this is not absolutely necessary.

- After stitch-welding, grind down the welds so that the sheet metal sill cover lies flat over it.

- Be sure to prime and paint any bare metal to prevent future rust.

- You may want to seal it with some seam sealer, which I would recommend.

- It's a good idea to test fit the components several times and, using a hammer and dolly, ensure that the bed floor is nice and flat.

 

[DirtDauberGarage]

*** Step 10 ***
After ensuring the sill and the cover fit perfectly, clamp it down and "plug weld" the new sheet metal sill cover to the bed floor and the sill.

- Notice that there is plenty of good metal under the cover to attach to the bed floor.

- Mark all the locations of the holes in the cover for the plug welds so you can grind off the paint and create clean welds.

- Pay careful attention to ensure the holes for the tire carrier and latches line up properly.

- Using several sizes and types of C-clamps, secure the cover tightly in place and plug weld each hole. You can move the clamps around as you go.

- After welding, grind down each plug weld so that the area appears as one solid piece firmly attached to the sill.

- You may want to run a small bead of seam sealer along the edge of the cover and the bed floor to help prevent moisture from seeping in.

 

[DirtDauberGarage]

More pics...

Again, take your time and make sure you don't get the metal too hot and cause it to warp.

Also, notice how the tire rack holes line up perfectly.

 

[DirtDauberGarage]

*** Step 11 ***
Fit new quarter panel pieces and weld in.

- I used the rear lower quarter third patch panel from CCOT, and again, it was great. Nice and thick metal that fits perfectly.

- Cut it to fit and weld it in. I added a couple of holes for "plug welds".

- You will most likely need to spend some time grinding and reinstalling the panel several times to make sure you have a good fit before you weld.

 

[DirtDauberGarage]

Driver side...

I made the patch from the leftover lower quarter third of CCOT driver side patch panel. It already had a 90-degree bend in it. I just needed to make a slight adjustment and shape it a little. Just a couple taps with the hamer and dolly gave it the right shape.

 

[DirtDauberGarage]

*** Step 12 ***
The final step would be to apply a skim coat of body filler and block sand the lower quarter panels, then paint.

- I did not complete this step because @jesus888 is having the bodywork done elsewhere, and they will match the patina.

- Additionally, I widened the rear wheel arches by five and a half inches to accommodate a rear spring flip, which will move the rear wheels back four inches for a longer wheelbase and a slightly smoother ride. I also replaced a small rust spot in each rocker panel.

Here are a few pics of the final product and a before and after of the sill...

 

[DirtDauberGarage]

Please feel free to DM me if you have any suggestions, thoughts, or comments.