Gen2 Sequoia Subframe Rust and Replacement (1 Viewer)

[feza]

I bought this 2010 limited with 150k early in the pandemic before the used car market went too crazy. This is my third Toyota SUV and have way too much rust experience and I wanted a southern truck with less rust than my 80 and 100. This guy came up locally for a good price. The main frame rails and brake lines all looked 8/10 for a maryland car and the price was decent so I went with it. A few days latter I dropped the spare tire and my jaw dropped when I saw the rear subframe. Hidden behind that spare was the worst rust of any vehicle I have ever owned. Instant regret, kicked my self for not flying to the southwest and picking something up. So I cleaned it up and fluid filmed it and drove it with a mental note about the crappy subframe.

Fast forward 2 years (last month) and 15k miles and it is time for new tires. The old tires didnt wear great and the alignment shop informed me that the rear toe was out all the rear camber bolts were seized. I have dealt with this before so I prepared to go at it cutting them out if need be. I also noted that the driver side toe in cam tab on the spring perch control arm was bent over which was probably the cause of the alignment issue. I had used the center of subframe as jacking point and I noticed that it has crunched a little. The entire bottom of the subframe was filled with rust flake sludge. After pressure washing I was left with a large pile of rust on the ground. It rusted from the inside and is worse then it looks, all the metal in the bottom 2" is paper thin. Photo shows the status after poking at it with a screw driver when I made the call to replace the whole thing. Off to car-part.com to find a replacement.

 

[feza]

A few weeks later I have a southern junkyard subframe and was able get a decent package deal on the control arms (and all the $$$ cam bolts). New parts will be getting a wash and fresh paint before starting the project. The main issue that I am hitting now is the lack of info on the rear subframe in the Haynes manual and the only FSM I have is for a tundra. There are a few threads on the internet of people talking about these subframes rusting out but no documented threads with instructions. So I will most likely I will be buying a 2 day TIS subscription and posting info in this thread.

 

[1911garand]

The rust belt sucks. In MN here and I have similar issues with vehicles. Good luck and keep us posted with good pics on how the parts replacement goes.

 

[feza]

Wow this job sucks. As a bad omen all except one of the 10/12 mm bolts holding the ABS and brake lines snapped off with very little torque. Then I did not realize that every bolt holding on the control arms would be "sleeved and seized" just like the cam bolts normaly do. So every bolt was it's own fun little project. My friend loaned me a fancy inductive bolt heater however It doesn't do anything for bolts rusted into sleeves. After a few hours i just cut my losses focusing on the bolts into the actual frame then just cut the control arms off with a grinder since I have extras. So far the star of the show has been a grinder, air hammer and my new invention, "Palm hammer". It is a $20 HF palm nailer and a cut off 3/8 3" bolt. It was very useful for saving the upper control arm bolts without cutting. Another thing I didn't realize was the gas tank needs to be dropped to remove the driver side upper control arm, so that is going to be fun. Tools that I had to run out and buy so far was a 6 point 24mm shallow socket and an equivalent 15/16 box end wrench and a 14mm hex bit for the differential bolts. I also gave a touch up paint job to the new subframe. This thing is going to get so much fluid film... I might even spring for the new fancy b'laster surface shield which I have read has better staying power than fluid film or wool wax.


Another note, south western cars are amazing. My new control arms are from a 2010 with 150k miles. When I lubed up the junk yard lower camber bolts on the knuckle I was able to break free the bolt the first try using an 8" box end wrench and a little wack with my palm. Then I was able to turn the cam with a 6" adjustable wrench with zero resistance. These things freeze up in a week up north. Amazing weather down there.

 

[feza]

The rust belt sucks. In MN here and I have similar issues with vehicles. Good luck and keep us posted with good pics on how the parts replacement goes.

I forgot to buy one of the nice spring compressors before this project and I saw your post on using the rental spring compressor from autozone. After a accident using a floor jack as a compressor on my first car as a teenager am terrified of springs. I was able to get one side off using the autozone compressor and the other side just fell off when i cut off the shock because it was broken just like yours. My long term plan is to put dobinson 2.5 springs in the back so I invested in one of the heavy duty side mount compressors that should be here for reassembly next weekend.

 

[feza]

First thing yesterday I set out to remove the diff and it came out without any fuss. I dont have a tranny jack so I made a custom one! The diff was missing one of the front 4 mounting bolts which has me a little concerned that someone has been in here before. I just happen to have an extra locking rear diff from an 1994 80 and a ford 8.8 axle in my driveway to compare against. Hard to tell from the pictures but it dwarfs the 80 series diff and is noticeably bigger than a ford 8.8. The sequoia diff will get new CV seals, breather, and a paint job before getting reinstalled.

 

[feza]

The 4 bolts holding on the subframe... WOW. It is almost as if toyota did not design this to be taken off with the body still on the frame. On the drivers side you have very little clearance and the nut flanked by the fuel filler neck and vent. Same deal on the pass side except there is an exhaust and the rear AC lines. You also have to remove the fuel pump controller ECU and the EVAP system valve thing and charcoal canister. All the bots looked nice and rusty so I have been spraying these daily with PB Blaster for 2 weeks. The first nut started rounding off with a 12 point box end on top and a m18 high torque impact on the bottom. Switched to a 6 point socket and spent 20 min trying to find a combination of extensions and wrenches that would fit between the fuel lines. Ended up using a short 1/2" to 3/8 adapter in a flexhead 3/8 socket. A 12" 3/8 breaker bar would have been nice here but apparently I do not have one. The nut would not turn at all and I was ready to just cut the whole subframe off. But then I remembered about the $$$ Mini-Ductor Venom HP and this is it's big redemption. 2" from a gas line i was able to hit a bolt for 3x 20 second bursts and the line didnt even get warm. I hit it while hot with PB Blaster and it came right off like butter! Easily saved me 2-3 hours of cutting.

 

[feza]

Success was short lived however. There is a difference between the junkyard subframe and my rusty one. Mine has 4 16mm bolts holding it on and the junkyard one had 4 18mm bolts holding it on. The mounting holes in the subframes are also 16mm and 18mm respectively., Apparently toyota rev'ed this at somepoint but I do not see a part number change. Both cars are 2010 and are only a month apart according to toyota's VIN lookup. 512960C011 is what i see online for everything 2008-2022 but mine are definitely different. Luckily the holes on the frame side all closer to 20mm and the subframe appears to use locating pins for alignment. My issue is that every bolt/nut combo is $32 list price and I do not have a complete undamaged set of either kinds. This is going to be a fun question at the parts counter.

 

[feza]

Mystery solved, there was a revision to the subframe bolts. Went over all the parts and only needed to get a few things. Local dealer was friendly and should have the parts I need this week.

I have not broken open the brake system yet and I was on the fence about doing the hard lines. I decided that everything is so open right now it would be stupid not to replace everything in the back. The hardlines going from the wheels to the junction under the pass side B pillar were only around $100. Also picked up centric rubber lines from rockauto. The actual disc and drum hardware was all replaced by me when the car was purchased so it will all be reused.

 

[1911garand]

This is a great write up - keep it coming.

When I replaced the rear springs in my 2012 sequoia, I sure wished it was a solid axle. This rear suspension and subframe is complex and lots of nooks and crannys for rust to work it magic.

 

[feza]

This is a great write up - keep it coming.

When I replaced the rear springs in my 2012 sequoia, I sure wished it was a solid axle. This rear suspension and subframe is complex and lots of nooks and crannys for rust to work it magic.

"Gen2 Sequoia Solid Axle Swap" was the first search I did when starting this project . And after this project I dont think I will ever willingly own another IRS AWD.

With the subframe removed there is a ton of space under there to fit a tundra axle. I think the issue is going to be that the frame is the wrong shape to mount leaf springs without a lot of fabrication. There is a significant height difference between the middle and rear frame rails. It would need a lot of custom fabrication that is beyond my abilities without buying a kit with directions. However the 2023 tundra and sequoia are about the same width and come with a trailing arm coil spring suspension that looks just like a LC. I would think it wouldnt be that bad to clone that geometry.

 

[feza]

Subscribed to TIS last night. Nothing in the FSM about the torque for the "rear suspension member" as they call it. The older bolts are 18mm with two notches which decodes to m18 class 5t and the new bolts have one notch which are m20 class 6t. Max design torque for these should be around 500ft-lbs and most of the other bolts on the car are torqued to about 50% of the max so i was going to go aboutt 250ft lbs and some blue loctite just to be safe. Fudging the numbers for such an important fastener was going stress me out though. This morning I was going over all the other sections and I found T-SB-0144-10 which covers the bolt change over I mentioned above. 51296-0C010 (18mm) switched over to 51296-0C011 (20mm) due to rust causing vibration issues and this conversion happened about 200 cars after my VIN. The real important part here is that the torque for attaching the "rear suspension member" (512700C010 or 512700C012) to the frame is listed as "Torque: 324 N*m(239 ft*lbf)".

 

[1911garand]

Good progress if you are torquen'. This is amazing.

 

[feza]

While everything was off I decided to replace the brake lines with OEM for around $100. All the clips along with frame rail were brittle and I snapped a few of them before I resorted to just cutting the old line and sliding it out. Routing the driver side line to the junction under the pass side B piller sucked because it was already bent a little from shipping and you have to bend it a little to fit it around the bends. In hindsight I probably could have just spliced nicopp line in for the last 3" before the rubber lines. If I ever do this again I will be doing full nicopp.

 

[feza]

Spending so much time under the car I realized that the boxed frame had a lot of junk for it. Saturday was all ready a damp day so I decided to try washing it out. WOW, I am no longer a toyota box frame elitist. I dont have any pictures from my first pass but I got about 2 quarts of rocks and spent an hour washing out mud that washed away, then I washed all the rocks away into the yard without getting a picture. Second pass I had better technique and got another 2 quarts of rocks and even more mud. Pictures are of the collected second pass rince. Frame is now clean inside based on the view from my $20 amazon endoscope.

 

[feza]

Pressure washed the rear diff, then went over it with some amazon knock off rotoloc sanding discs. Then painted it with the finest rust primer and semi gloss spray paint walmart has to offer. I installed new seals and new breather. I was able to use my custom 3d printed seal press that I am very proud of. The rear seals are the same as the front seals on the 100 series which I already had a spare set of.

Parameterized Seal Press by nightilizer

This lets you generate custom sized oil seal presses. For me this replaces trying to find the perfect sized socket or soup can every time I need to replace a seal.

www.thingiverse.com

 

[feza]

Installing the subframe went great using my custom wooden transmission jack. The 4 nuts on top did not want to spin when torquing from the bolt heads on the bottom so that made things a lot easier. 239ft lbs is quite a bit and I could not get my trusty CDI wrench to click. For fathers day with the 20% coupon I picked up the Harbor Freight Icon 56683 digital torque wrench so I decided to use that for the first time. This is the most amazing torque wrench that I have ever used. While pulling on it there are little stoplight colored LED status indicators of how close you are to the set torque value.

Then when installing the diff, on the last freaking bolt, disaster struck. I hand tightened a few turns then switched over to a m12 3/8 ratchet. It made it 5ish more turns then stopped. After pulling it out i see that there was a bent over thread midway up the bolt which had chewed up the first 1/2" of the threads in the soft cast diff. I measured the bolt as m16-1.5mm which I do not have a tap and die for. Luckily I found the top knuckle bolt on one of my extra knuckles was the right size. I was able make a thread chaser with a file and a rotary tool and it worked great. I was able to clean up the diff bolt with a file then chased it with the knuckle nut. Assembled it like it was made of glass and it was able to hold the 148ftlbs of torque. The front diff bolts are 89ft lbs.

After this I reattached the charcoal canister and fuel pump ECU and then was promptly rained out the rest of the day. Probably have 4-6 hours left in this project and I hope to nock it out one night this week.

 

[feza]

I was looking over the old subframe and found some more weak spots. Drivers side lower control arm mount was barely holding on. I am very happy that I made the call to do this project.

 

[feza]

Weather didnt look great the rest of the week so I took off last Tuesday and kocked out most of the rest of the work. The control arms came fully assembled from the junk yard and I really didnt fell like messing with taking it all apart. I took the upper arms off both sides and mounted that first. Then with help from my father I was able to position the lower 3 bolts and CVs in place while he slid the bolts in. I struggled for an hour trying to do it myself but it only took 10 min to do both sides with the extra hands.

Based on the lift threads I was expecting a fight with the springs. However with all the bushings freed up and the bushing bolts loose and the top knuckle bolt out there was plenty of space to slide the spring in without using a compressor. There were not any bad angles and it was not sketchy at all to compress the spring using a floor jack. After doing this part of the job I fell like any one that lifts should be loosening all the rear bushing mounts to reclock them.

 

[feza]

Most of the rear brakes went great... I picked out the 2 best rotors out of the 4 I have, cleaned them up and checked the runout. Funny little tidbit, in maryland when a rotor rusts to the hub it is usually a really horrible job that destroys the rotor. One of the junk yard rotors fell right off and the other one took a few seconds with the threaded holes to press off. I have never actually had success with those holes on any other seized rotor. Normally I have to resort to silly removal methods (see pic of an 80 axle). Replaced the parking brake hardware and adjusted. Then on the absolute last bolt of the job, the 4th slider pin, the threads came right out while torque to the FSM specified 65ft/lbs. I am not dealing with a helicoil on a caliper and did not have time to wait for rock auto so I picked up a replacement set from napa the next day for twice the rock auto price. Then again on the 4th slider bolt stripped out even easier than the first one. My digital torque wrench didnt even register so it was under 12.5ft/lbs. Napa took it back and replaced it the next day and the replacement took the proper torque. I assume the rebuilders don't check the threads which sucks. So I ended up spending 4 days waiting on brakes which is funny considering the scope of what I am doing here. This was a very very frustrating part of the job.