Ground Rear Caliper to Fit 15" Rim - Pic.

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IDAHOTEMUD

Joined
Nov 16, 2006
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I read all the threads, saw the cautions, but did it anyway. Saw some posts where folks said they knew someone who did it, but never saw a post from someone who actually did it.

My rig - '91 FJ80, not a daily driver, but occasional driver, wheeler, camping rig, Moab duty for sure. Chev. V8, 15" alloys w/ 35" MTR's.

I also have a '94 FZJ80 (was wife's daily driver) that I will be selling soon but am stealing what ever is better before I do. Took the seats, some interior pieces, and rear axle which the previous owner had a 3rd member with Toy e-locker retrofitted.

So my '91 now has the rear full floater disc brake axle w/ toy locker. And like mentioned in dozens of threads, the 15" rims will not fit over the rear calipers without grinding or spacing the wheels out.

I ground off about .25" of material from the top and outside of both calipers. I'm indeed concerned about the affects this will have on the strength of the caliper. But believe, most likely, it will be just fine. I will keep a close eye on the calipers.

Notice at the top of the caliper, the metal has gotten very thin (and even wore through) where the pin slides through. I'm no expert but don't see (or maybe understand) how this would affect strength. Anyone know otherwise??

I'm guessing if the caliper did crack at one of the now thinner spots while driving, I would immediately notice - probably similiar to one of the caliper mounting bolts coming out.

If one of grinded calipers fails, I will buy new calipers and switch to 16" wheels and tires.

Mark
Boise, ID
ToyCaliperGrind.webp
 
I know you don't want to hear this, but that's one of the most dangerous mods I've ever seen. If you've ground through the metal that holds a slider pin and into the pin itself and can't see how that's going to impact strength then I'm not sure what I can say to impart that to you.

As to how it's going to fail and if it will merely be like a loose caliper. How about the scenario where the pin breaks and the moving caliper jams against the wheel spinning tight up against the caliper. The tire locks and you flip the 80 at freeway speed. Good enough?

If that's the amount of metal that must be removed to fit a 15" wheel, then I really advise against it. I appreciate very much that you posted the photos as it has been discussed here a couple times without the pics. Thanks!

Regards,

DougM
 
IdahoDoug said:
I know you don't want to hear this, but that's one of the most dangerous mods I've ever seen. If you've ground through the metal that holds a slider pin and into the pin itself and can't see how that's going to impact strength then I'm not sure what I can say to impart that to you.

As to how it's going to fail and if it will merely be like a loose caliper. How about the scenario where the pin breaks and the moving caliper jams against the wheel spinning tight up against the caliper. The tire locks and you flip the 80 at freeway speed. Good enough?

If that's the amount of metal that must be removed to fit a 15" wheel, then I really advise against it. I appreciate very much that you posted the photos as it has been discussed here a couple times without the pics. Thanks!

Regards,

DougM
Click to expand...

Hi Doug,

Thanks for the comments. I wish I fully understood the forces being applied to the caliper during braking. The pins, which I've exposed the cavity they slide through on the outer edges of the caliper, appear to be more for alignment or guiding, rather than strength.

I would guess that if the caliper did fail it would happen while braking. If one failed while hard braking at highway speed and locked up a wheel, I think I would probably stop quicker. (I've never been able to lock up a wheel on my '91). But flip? Not sure I can see that happening.

Mark
 
I can't comment on the strength of the caliper, but as far how a vehicle would react when a rear wheel or both rear wheels lock up, this can cause the vehicle to go sideways and possibly flip.

The scenario is that you're braking, so braking forces are applied to the front tires and they want to slow down and do so by having contact with the ground.

If/when the rear tires lock up, they skid and they lose contact and braking force. With the front still braking and the rear, no longer providing any braking force, the rear wants to travel at a higher speed than the front and this is when you end up going sideways.

With the Land Cruiser's high center gravity you're at a much higher risk of flipping than a regular car.

The situation is aggravated much more by speed, road surface and weather conditions.

This is exactly why the first ABS systems on trucks and SUVs were placed on the rear wheels first, before all wheel ABS become more common.

One other nightmare scenario I might be worried about is a fire caused by metal rubbing on metal at highway speeds.

What about swapping wheels with the newer and older LC? Since you've already swapped axles, I don't think you can expect a premium price for the newer LC anyway.
 
IDAHOTEMUD said:
Hi Doug,

Thanks for the comments. I wish I fully understood the forces being applied to the caliper during braking. The pins, which I've exposed the cavity they slide through on the outer edges of the caliper, appear to be more for alignment or guiding, rather than strength.

I would guess that if the caliper did fail it would happen while braking. If one failed while hard braking at highway speed and locked up a wheel, I think I would probably stop quicker. (I've never been able to lock up a wheel on my '91). But flip? Not sure I can see that happening.

Mark
Click to expand...
:eek:

You don't understand the function of the part you just ground through?! The pins allow the caliper to "slide", so when the piston on the rear clamps, it effectively pulls the caliper to the rotor on both sides.

Those pins must stay greased and clean or else you risk stick the caliper and a) killing your gas mileage b) sticking the pads to the rotor and heating up everything c) destroying your pads, caliper (you've already done that though), and rotor, and d) possibly seizing that wheel and causing a bad accident.


What you have done is totally and completely unsafe. You need to replace that caliper and forget about the 15" rims. You are all but playing russian roulette if you decide to drive the truck like that, and it is not a matter of if but when.
 
NaterGator said:
:eek:

You don't understand the function of the part you just ground through?! The pins allow the caliper to "slide", so when the piston on the rear clamps, it effectively pulls the caliper to the rotor on both sides.

Those pins must stay greased and clean or else you risk stick the caliper and a) killing your gas mileage b) sticking the pads to the rotor and heating up everything c) destroying your pads, caliper (you've already done that though), and rotor, and d) possibly seizing that wheel and causing a bad accident.


What you have done is totally and completely unsafe. You need to replace that caliper and forget about the 15" rims. You are all but playing russian roulette if you decide to drive the truck like that, and it is not a matter of if but when.
Click to expand...

You are correct, I didn't understand the function of those pins. I was again starring at the pic. of my caliper tonight trying to figure out the 'sliding' part.

The pins are surrounded by a rubber boot which are still intact. As long as those boots aren't compromised dirt should stay out.

Trust me, I won't be loading up the family next week for a cross country drive. I will test it out and keep a close eye on the calipers.

I'd really like to hear from some folks who also did this in the past and how it turned out - or are they all dead??

Mark
 
I agree with the others in this thread. Grinding down a body panel or even suspension component might be okay, but grinding down a drive train component is not a good idea. That is especially true if you really don't "...[understand] the forces being applied to the caliper during braking".

Please don't endanger yourself or others by continuing to drive the vehicle with modified calipers. It's not safe.
 
I think what we are all getting at is this: we understand the function of this part better than you, and we are telling you what you have done is not safe.... not even borderline "you can try it" safe.

I know what you are saying "I'll drive it slow, I'll play it by ear at first" etc. What you don't realize is that it is least likely to fail when it will matter the least. When you are at a higher speed and jab the pedal a little quicker than usual and the caliper bites down hard, the forces on the structure are exponentially higher than they are at low speed and a smooth stop. As soon as something gives, in a situation like yours where tolerances are so close, I can't see anything good possibly coming of the situation.


You tried to make it work, it was worth a shot, but what you've learned is that it's just not possible. Take your lumps, be save, and call a spade a spade.
 
Agree with Nater. What I think you're hearing is several kind ways of telling you that what you did can have a dangerous outcome. People are being kind.

My thoughts on you driving it around 'carefully' and monitoring things are this. You share a road with my wife, my children, my brother in law's week old baby and the loved ones of your neighbors. You are not thinking like this, but what you're saying is that you're OK with the thought of a brake unexpectedly locking on a country road and slamming a 5500lb truck head on into someone's wife in a Honda Civic coming home from work. I don't need to elaborate further on what I think of that attitude. If you had a personal track to test it on that would be different, but for God's sake you're driving on a public roadway, man.

DougM
 
I agree with the not safe comments. Sometimes you need to follow a few cues. For example, Toyota employs a large number of very capable engineers. These engineers have to design parts that meet very strict guidlines. One of the guidelines is likely to strike the optimal balance between cost and safety. On that note, I suspect the calipers are already designed with as little metal as possible, yet still supremely safe. Another cue is that you could not find results from anyone else doing this mod. The other cues you should consider are the posts above. If I were you I would buy a new caliper and keep the old one as a trophy.

Karl
 
No way I would drive that on the road, or drive anywhere near that rig if it was on the road, if I could help it. Sorry, just not a safe mod.
 
It's the rear brakes, on the 91/92s on every single one I test drove, the rear brakes wouldn't lock up going down hill on gravels, and the rig stopped decent enough. If it breaks, and you lose one or both rear brakes, it will sucks but it's not as catastrophic as everyone is making it out to be, and I doubt it ever happens.
 
I'm surprised there has not been one dissenting opinion. I'm not going to say it's safe, because I honestly don't know if it is or not. However, there are 100s if not 1000s of people out there who have ground front calipers on GM/Ford axles over on PBB, and in 6 years on PBB have yet to hear of one failed caliper.

With all that said, I think you'd be better off replacing the calipers w/ original and finding some 15's that fit if your intent is to avoid buying new tires. Certain 15" wheels WILL fit the FZJ80 full-floater rear axle. Stock FJ60 wheels for example fit just fine.

Ary
 
alkaline747trio said:
It's the rear brakes, on the 91/92s on every single one I test drove, the rear brakes wouldn't lock up going down hill on gravels, and the rig stopped decent enough. If it breaks, and you lose one or both rear brakes, it will sucks but it's not as catastrophic as everyone is making it out to be, and I doubt it ever happens.
Click to expand...

1. It's no longer the 91/92 rear drum brakes - he swapped in a 94 full floater disk axle.

2. The issue is not loss of braking power. The issue is the potential for a catastrophic fire or lock-up of the wheel when that caliper fails and shoves bits into the rest of the assembly.

This is a bad idea. Cut your losses, fix it and move on.
 
I'm just glad he posted this info for everyone to address. All of you knowledgable people may have saved lives. I think I will be checking on mine to make sure everything looks sound. Not that I have tampered with them because I haven't. I don't want to have my fronts lock up. Scary visual!
 
Made it to work safely.....

Also, keep in mind that these are the rear calipers. Front calipers must see tremendous more force and stress - I'm sure I would not have made this mod to the front calipers.

A couple other notes for those thinking of swapping a rear full floater axle onto a '91 or '92:

Contrary to a post I read, the parking brake cables are different lengths and I DID need to swap them.

Also contrary to a post I read, the fact that the '94 has ABS made no difference with the brake lines. Both axles have a brake line 'T' on the top center of the axle - no issues reconnecting brake lines.

And finally, the master cylinder controversy....I did not swap master cylinders and I have not noticed a braking difference on either vehicle.

Mark
 
Last edited:
I'm very frightened and grateful I don't live in Idaho. Please notify the board if/when you come to Utah. I'll work from home while you're here.
 
EricG said:
1. It's no longer the 91/92 rear drum brakes - he swapped in a 94 full floater disk axle.

2. The issue is not loss of braking power. The issue is the potential for a catastrophic fire or lock-up of the wheel when that caliper fails and shoves bits into the rest of the assembly.

This is a bad idea. Cut your losses, fix it and move on.
Click to expand...

I know it's not a rear drum, but I am comparing it to the 91/92s with s***ty rear brakes.

Fire? Catastrophic failure? Worst that will happen is the caliper will split, leave gouges in stuff, and you wont have rear brakes. It's not going to explode, it's not going to fling shrapnel into your eye, and it's not gonna have sex with your wife either...
 
alkaline747trio said:
I know it's not a rear drum, but I am comparing it to the 91/92s with ****ty rear brakes.

Fire? Catastrophic failure? Worst that will happen is the caliper will split, leave gouges in stuff, and you wont have rear brakes. It's not going to explode, it's not going to fling shrapnel into your eye, and it's not gonna have sex with your wife either...
Click to expand...

Yup. Thank you.
 
Would someone please explain how a weakened caliper is likely to lockup? All forces are trying to split the caliper in half, he will lose a rear brake or both...big deal, they are designed to share 25% of the braking force...even if both rear brakes locked up he still has the control of the front end. People have been grinding calipers for years on everything, and this being on the rear? Sheesh...stop being a bunch of 80 series guys.
 
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