First issue real issue with the 55 and some ?'s

[DaveInDenver]

In SA mini's there's some combo of stock calipers and rotors that gets you vented rotors. It could be that if it has SA Mini parts on it.

I thought all solid axle minis had non-vented rotors, the upgrade is to use Cruiser rotors and IFS calipers, right?

 

[ntsqd]

Yes, but there is more than one combo possible. I don't recall all the details. The most common is LC (60? 80?) rotors & IFS calipers, but there is another combo out there that results in a different track width (more scrub radius). AIR Mike Carter did this latter swap on his SA 'rnnr.

This vented rotor conversion looks to me like the more common version.

 

[DaveInDenver]

Yes, but there is more than one combo possible. I don't recall all the details. The most common is LC (60? 80?) rotors & IFS calipers, but there is another combo out there that results in a different track width (more scrub radius). AIR Mike Carter did this latter swap on his SA 'rnnr.

This vented rotor conversion looks to me like the more common version.

Oh, you might be talking about the complete IFS hub conversion? There's a way to run complete IFS hubs by mounting the caliper on the outside of the knuckle rather than on the inside like stock. I think this is an unsafe ghetto fab.

 

[AndrewP]

I really think the illustrated one is the unvented rotor. That's the most common swap, where any 79-85 mini truck (knuckle, spindle, disc, caliper birfield, hub and lock out) can be used.

The vented rotor swap is best done using FJ60 parts, since everything is basically the same except the rotor (which is thicker and vented) and the caliper which is slightly wider.


To this FJ60 type conversion, you can add IFS 4Runner (and possible mini) up to 95 or so. This gets you a caliper with slightly larger pistons and thus slightly more braking power. I can't see using that booty fab caliper on the wrong side thing. That's asking for trouble.

I would not use 76-78 FJ40 (or 55) parts to do this swap. The knuckle uses a smaller stud pattern, the studs are smaller and weaker, the birfield is an orphan non-standard size, and you can only run Warn or other aftermarket lockouts on it.

There are tons of FJ60 parts around, this makes a great swap, it works 100% of the time, and gets you all of the best parts. I even did the swap on my 76 FJ40, just to standardize all of my parts. That truck is now history, but the brakes live on in my 71!

 

[DaveInDenver]

I can't see using that booty fab caliper on the wrong side thing. That's asking for trouble.

We've actually diverged here. That caliper flip thing is to gain track width when you do a solid axle swap on an IFS mini truck, since the IFS rear axles are 3" wider than the solid was. So guys typically use spacers to match the front axle width to their existing rear. But someone figured out that using the whole IFS hub you would push the wheels out and match the track width without using wheel spacers. I don't see any reason to do it on a Cruiser unless you really want a sketchy way of increasing track width.

 

[ntsqd]

I really think the illustrated one is the unvented rotor.

This looks vented to me. What illustration are you referring to?

I don't like the "wide track" conversion for a variety of reasons, but I don't see anything that causes me safety concerns.

 

[DaveInDenver]

I don't like the "wide track" conversion for a variety of reasons, but I don't see anything that causes me safety concerns.

My thought was running the calipers this way is mounting them such that the unfinished sides of the caliper and knuckle castings are contacting rather than the machined sides. Obviously the bolts aren't the concern, but I don't like that the mating surfaces are not finished. You're the ME here, doesn't the connection rely upon the trueness and surface finish of the two faces to have a particular friction? Just thought by doing it this way you'd be relying on the bolts in shear more than the right way.

 

[ntsqd]

For the record my degree isn't pure ME. It's Prototype Engineering, a combo of ME & Mfg Engineering. I missed out (not really) on the heavy Thermo & heavy Dynamics, but among other things I got to hang out with the marketing folks for a semester. The rare gal in Engineering is not one you usually want to date. Marketing girls on the other hand.......

Anyway, You have a good point about the contact area vs. bolt shear but the forces involved are surprisingly low. The closer the bolts are to the pad centroid the less loading (torque) they'll see b/c of the shorter lever length.The part with the final say in how high the brake loads are is the tire. Once it slips on the ground the max loading has been hit. Early in my design time at wilwood I worked out the loads would be in a caliper bracket and was surprised to find that everything out there should've broken. Bill Wood pointed out the tire part. On pavement the best mu you can hope for is about 0.5 Now all those parts work just fine.

I'd be more concerned about uneven wear. Those unmachined surfaces may have draft in them or not be square to the rotor, which would cause the caliper to mount at an angle.

 

[cruiser guy]

I would not use 76-78 FJ40 (or 55) parts to do this swap. The knuckle uses a smaller stud pattern, the studs are smaller and weaker, the birfield is an orphan non-standard size, and you can only run Warn or other aftermarket lockouts on it.

Not entirely true! I have a '76 FJ55 with Aisin hubs which are slightly different in length than a regular Aisin hub. The birfeild joint is the same, just the stub axle is slightly longer.

I can't speak to the knuckle studs pattern or size as I've never looked closely.

 

[ChuckB]

Whoa! What happened to my thread ?? J/k good info!!!

Just got home with the parts and It appears to me anyway that these things were installed wrong. I just broke the other one... It seems that these clips have been riding on the disc and it eventually wore through them. Luckily, I picked up two from the dealer. Does anyone have a picture of these properly installed?

 

[AndrewP]

Not entirely true! I have a '76 FJ55 with Aisin hubs which are slightly different in length than a regular Aisin hub. The birfeild joint is the same, just the stub axle is slightly longer.

I can't speak to the knuckle studs pattern or size as I've never looked closely.

I know. We've talked about this on Mud before. There are some exceedingly rare, deep bodied Aisin hubs that came only on 76-78 FJ55s. I had a set once, plus an extra body. One of the local guys heard about the fact that I had these and scooped them up. The fact remains that 76-78 are not good to use for the reasons listed. Much weaker steering, and the non-standard birfield. You can run a later birf in that knuckle, but you can't run the outer retaining clip. Instead you need to run a fender washer and a bolt. It works, but it's a booty fab special.

 

[ChuckB]

Update Bigger Problem!!!

I have been in the garage for the last 30 minutes or so trying to put everything back together and I ran into a bigger problem than the rattle clips.

The bolt that I was missing turns out to be the upper #10 in the below picture. I didn't realize it last night, but this is one of the bolts attaching the caliper to the rest of the vehicle. I picked up a new one today from the dealer. But for whatever reason it appears that the threads in the hole are stripped and I cannot get it to tighten properly. Am I looking at a bigger tear down? What are my options here? TIA.

 

[cpg]

I have been in the garage for the last 30 minutes or so trying to put everything back together and I ran into a bigger problem than the rattle clips.

The bolt that I was missing turns out to be the upper #10 in the below picture. I didn't realize it last night, but this is one of the bolts attaching the caliper to the rest of the vehicle. I picked up a new one today from the dealer. But for whatever reason it appears that the threads in the hole are stripped and I cannot get it to tighten properly. Am I looking at a bigger tear down? What are my options here? TIA.

If it is stripped you will have to insert new threads (heli coil or something similar) or replace the stripped part.

 

[AndrewP]

I had one like that, and you could try a helicoil. I drilled it out, the ear of the caliper out, and tapped it for a fine thread 1/2 inch grade 8 bolt. Works perfect. You need to use exactly the right drill bit that's speced for the tap(on the tap package), then tap is using lots of cutting fluid. Mine came out very clean and literally as good as new. In the end I got another knuckle because I did not want 2 different size caliper bolts. Up to you though.

The only other option is to source another knuckle.

 

[ChuckB]

In the end I got another knuckle because I did not want 2 different size caliper bolts. Up to you though.

The only other option is to source another knuckle.

Well, I haven't ever drilled and tapped anything in my life up to this point. In fact I'm already getting in over my head. Sad but true. I think I may go the new knuckle route, because I'm sure I would probably mess up the original one anyway while trying to drill it.
Since, I don't need to get this up and running soon. I would like to do the work myself. I need to think about this some more and see what the cost is going to be like. Would this be a good time to do a knuckle/birfield repack?