Solid Axle Swap BS Thread

Gotcha...Hope you find the cause soon man

 

Thanks bud it's pretty frustrating. Hopefully I can get the tires swapped for some round ones. Seems like a flat spot since it kinda suddenly dips down.

 

Get some round tires and that will all go away. My old tires did the same thing, one day they were fine up to 60, other days they were shaking at 20mph.

 

Keep in mind though, tire imbalance could be an issue, and possibly setting up the death wobble but it's not the root cause. You can have a tire out of balance bad and not cause one to death wobble if it's 'right'.
Make sense? Same as one saying a steering stabilizer 'stopped' death wobble, it's masking an underlying issue not correcting it. Yours does seem a bit odd though, being you've seemingly addressed the typical causes, like caster angle, toe-in, loose bolts etc... Have you taken a close look at the panhard bar and it's mounts? Is it heim on both ends, if so is there a chance there is some deflection in one of the joints? Death wobble almost always occurs due to the axle moving back and forth in a lateral direction. With the truck parked and off have someone rock the steering wheel back and forth with you under it, look for any lateral movement, especially around the ends of the panhard bar. You'll also want to look at the frame itself where the panhard bar mount is welded, look for deflection.

 

The panhard is on heims, and everything is brand new. I'll take a closer look tho. And I agree, I have HA ready to go in, but I want to fix the DW before installing it.

 

Are you asking for the actual measurement of the spots where the brackets are physically welded on the frame? Trying to cheat on your link geometry?

My lowers ended up being 38" from center bolt to center bolt I think. Initially they were going to be a few inches longer.

Can't remember the length of the upper, it's a bit shorter than the lowers.

Panhard bracket sits outside the frame on the frame side - which is typical because you want it as long as possible, but I have seen some guys that place it right under the frame

I'll see if I can take a pic of where the brackets are and take some measurements to give you an idea.

That tire shakes like crazy!

Another random thought...Have you ensured that your lower links are the same length?

Talk to @Ritchie. He had similar issues to yours after he did his SAS. If I remember correctly, he ended realizing that one of his lower links (can't remember which one) was a bit shorter than the other one. All he had to do was adjust one of the heims. After doing that everything got resolved for him.

Not sure if this is the same situation but it wouldn't hurt to check it out.

 

Wow, that video looks bad.
I did not have the wobble rather my DS wheel was literally hopping.
In the end, my wheelbase was not the same for both sides. The PS was 3/8" more forward. Since the 4 wheel alignment, DS measures 106" and PS is 106.1". Over all, my wheelbase grew 3.3", from an OEM length of 102.7.
It's a regular cab SB if that helps.

Good luck.

 

Okay, seems like it the was steering box adjustment screw. I drove the adjustment screw down just until it became snug, then backed off a super small amount and retightened the lock nut. Drove to town on the freeway. Gone. Got it to around 55-60 mph.
I can feel it still trying to shimmy, and I think that's just because of tires being out of balance, especially around the bends. As the tires start syncing up with each other, can feel it and get worse, then gets better. Will try and see if 4wp or Maui off road will balance them properly.

Thanks for the help guys. I had a feeling it was the box since all the heims are brand new, and I checked the torque on the links and steering a few times. Gonna read up on how to rebuild and properly adjust the IFS box.

 

Reminds me of my last jeep lol

 

I don't want to burst your bubble... it's not the box. I too went through many months of adjustments in very small increments. The steering was sloppy and the truck wandered badly.
My wheel hopping only occurred after I hit a bump in the road but went away after slowing a bit.

To adjust the box, there are procedures in setting it up properly. I'll have to locate the link for you.
Good luck.

 

The box has to be adjusted when on center by the way.

 

I don't know what else it could be? Before I adjusted it, I could grab the tire at 3 and 9 o'clock position and shake the tire. Now it's more solid and I can drive on the freeway without wobble.
Tires are still out of round and unbalanced too.

Yeah, it was centered and axle on jackstands when I adjusted it. I checked it for binding while adjusting it.

 

Here. I'm not sure how much runout is acceptable on these larger tires, but even the guys at goodyear didn't want to balance them because they are out of round. I made a video using a dial indicator to measure runout. Most of the tires I get around 0.080" TIR.
https://youtu.be/Tf7z0rxFGns
You can see some are pretty stable until it hits a high spot and low spot. One tires has two low spots. I have also unmounted the tires and checked the wheel runout and they are true.
When mounting the tires, I very slowly and evenly draw the two halves together to keep them straight, and used RuGlyde lube to seat them.

 

Your tires are round enough that it's not them. Most tires will have a small flat spot from where they were sitting with the truck's weight. You've got something else going on. @slander had TSL's that were egg shaped and no DW as a result.

 

Death wobble has been gone since I tightened the steering box. Just drove it on the freeway again today and picked up my daughter from school. Just some vibes from the tires.

Also one of the tires has a bit of lateral runout, and is egg shaped.

 

Those tires were perfectly round and currently for sale for a damn good price in the tire and wheel market place.

 

T100 MC/booster upgrade.

Today I decided to install a dual-diaphragm booster and master cylinder from a T100. Found a couple of surprises.

First...As it turned out, my 1999 tacoma came with a dual diaphragm booster already. I had no idea. I had assumed I had a single diaphragm in mine. Now I know what they look like Oh well...

Then I Had to think hard about the T100 MC. Put mine next to the T100 for a side to side comparison and they looked identical in size. [sorry, no pics]

Looked up the part numbers to confirm. The T100 has a 1.063 bore. This is their "1 ton" version.

Also learned that some Tacomas came with 13/16 bore MC, while others had 1" bore. Does that sound right? I thought the T100 MC would be much bigger.

So I went ahead and replaced the MC, hoping that the bigger 1.063 bore of the T100 MC would make at least a bit of a difference in pushing more fluid to my 1 ton calipers.

I can tell there is a slight braking performance improvement. The pedal is not as soft as with my old tacoma 1" MC but it is not hard either. [And yea...the brakes are properly bled and the MC bench bled!]

Those of you running the T100 with 1 ton brakes....did you notice a huge difference? Trying to gauge things from my experience.

Anyway, still need to install a manual proportioning valve because I removed the factory LSPV crap and am running a single brake line from the MC to the rear brakes. Want to reduce the amount of pressure to the rear tires.

 

@1999RegCab I didn't notice a whole lot of difference when I went to the t100 setup being as I'm still running stock drums in the back, but then again I did it in anticipation of the fj80 axles going in. I'm running a single line to the rear brakes as well. When I get around to it I need to lengthen the push rod in the booster. My pedal has a little more take-up than it should. I bought my booster used too so I don't know if that's a factor as well. It passed the test of turning the key to ACC and pushing the pedal and it getting progressively firmer. In my opinion the manual prop valve made the most difference. The factory one is suspect at best. Even the tricks of raising the mount on the axle or pulling the arm up and fixing it there to "trick" the valve into thinking there's a heavy load in the bed are overly complicated solutions to an extemely simple problem = Man. prop valve. I think the 1 ton T100 MC+booster is still the best setup that toyota has to offer our platform. I think you will like the manual prop valve. A couple panic stops on a quiet street/road to get it dialed in so the back doesn't want to come around and its good to go.

 

FWIW my stock mc and booster worked great for my 80 rear discs and I am also using the lspv. With 1tons you will most likely need a real 1ton mc, I think the t100 mc is just Toyota message board lore. I looked into them and it had damn near the same specs as the stock one on my .02.

 

That's interesting. Thanks for the reply and info. It helps me have a point of reference to compare it with. So I guess I was expecting a more dramatic difference

Where did you place your proportioning valve?

I actually tried to install one when I swapped the T100 MC. But I could not get it to fit anywhere around the MC with the stock rear brake line. After the SAS my charcoal canister got pushed next to the MC in order to make room for the shock hoop. There is absolutely no room whatsoever to put anything between the rear brake line and the MC.

Instead, I ended up installing it under the truck. It was an "ok" solution but I ended up not liking the location at all. I ended up removing it because I really want to have it inside the engine bay for ease of access and to protect it better.

My next project is to build two custom brake lines that will allow me to place the manual proportioning at a remote location in the engine bay away from the master cylinder.

I think people with the smaller 13/16" MCs and single diaphragm boosters probably experience a really significant improvement; hence the reason why the T100 parts are so popular on toyota forums when people talk about brake upgrades.

But for those with dual-diaphragm boosters and 1" MCs already I do not think the improvement is that dramatic. I just didn't know what I had I got the T100 parts used, so it is not a big deal other than the time spent swapping the parts.

As you said, I would need to do a real 1ton MC swap in the future if I want the pedal to feel very firm like stock again. The calipers on my d60/14bolt are really big compared to any toyota calipers. I am ok with the way the brakes are now; just missed the factory "feel".