Minitruck FDB questions

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dgangle

dgangle

total rice
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I'm doing a minitruck FDB conversion and ran into a question.

The bolts that attach the rotors on my donor 79 minitruck hubs are 8mm while the 81 FJ40 rotors have 12mm holes. This allows for a real sloppy fit. I put flat washers under the lockwashers but when I tighten the bolts it pulls the washer into the larger 12mm holes. Probably OK buy hey, it's only the brakes.

What have others done or did I possibly get the wrong rotors?

Dave
 
dgangle said:
I'm doing a minitruck FDB conversion and ran into a question.

The bolts that attach the rotors on my donor 79 minitruck hubs are 8mm while the 81 FJ40 rotors have 12mm holes. This allows for a real sloppy fit. I put flat washers under the lockwashers but when I tighten the bolts it pulls the washer into the larger 12mm holes. Probably OK buy hey, it's only the brakes.

What have others done or did I possibly get the wrong rotors?

Dave
Click to expand...

It shouldn't be a problem after the wheel studs are pulled through. Those two little bolts are not really holding anything on.

P.S. I don't run them. Instead of bolting on my spindle I use four studs per side (plus four stock bolts). Makes install easier. You can get them from AllPro. I used half a kit on the 4Runner, and half a kit on another truck (i.e., instead of replacing all eight I used four per side). Those studs hit the bolt heads you are having a problem with. Split a kit with a buddy. http://allprooffroad.com.ipflow.net/index.php?option=content&task=view&id=72&Itemid=112
 
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Instead of bolting on my spindle I use four studs per side (plus four stock bolts).

From the link, looks like you use the same studs you would use for the steering arm?

Great idea. Getting the spindle/seal/backing plate/gaskets in place can be clumsy. Studs (even just 2 of them) solve that mess.
 
dgangle said:
The bolts that attach the rotors on my donor 79 minitruck hubs are 8mm while the 81 FJ40 rotors have 12mm holes.

What have others done or did I possibly get the wrong rotors?

Dave
Click to expand...

Dave, get 76-80 FJ40 rotors and they should bolt right up.

Dave
 
Pappy& Mr Toad,
You apparently don't understand what I am talking about. I am talking about the (6) 8mm bolts that attach the rotor to the hub, not the (8) bolts that attach the backing plates & spindles to the knuckles. These 8mm bolts are being pulled into the 12mm holes in the +'81 rotors when tightened. The Allpro studs are a great idea but not what I'm working on here.

beanz2,
You sound like you're on the money. Do you know if the 76-80 & +81 rotors have the same physical dimensions (diameter, offset and thickness)? Anyone?

dave
 
I used the vented cruiser rotors with my conversion, but you will need the later model truck calipers.

I don't remember the exact years of the parts. I will have to look again.


Brad


I looked and I used the '90 truck calipers and '78 LC rotors.
 
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yeah, sounds like you got very early minitruck brakes if the lug studs dont press through the rotors. 76-78 L.C rotors are identical to later ones, except they are designed to use the 6 bolts to attach the rotors to the hubs.
 
I did not read closely enough last time.

My '78 rotors have the 12mm holes so you press in the wheel studs to mount the rotor.


Sorry if I added in additional confusion.
 
dgangle said:
beanz2,
You sound like you're on the money. Do you know if the 76-80 & +81 rotors have the same physical dimensions (diameter, offset and thickness)? Anyone?

dave
Click to expand...

Yes, same dimensions but the mounting is the same as the 79-80 minitruck hub.

Dave
 
dgangle said:
Pappy& Mr Toad,
You apparently don't understand what I am talking about. I am talking about the (6) 8mm bolts that attach the rotor to the hub, not the (8) bolts that attach the backing plates & spindles to the knuckles. These 8mm bolts are being pulled into the 12mm holes in the +'81 rotors when tightened. The Allpro studs are a great idea but not what I'm working on here.

beanz2,
You sound like you're on the money. Do you know if the 76-80 & +81 rotors have the same physical dimensions (diameter, offset and thickness)? Anyone?

dave
Click to expand...

I know exactly what you are talking about. I don't use the two little bolts that bolt from the rotor into the back of the hub. They hit my spindle studs. They also don't do anything structural.
 
pappy said:
I know exactly what you are talking about. I don't use the two little bolts that bolt from the rotor into the back of the hub. They hit my spindle studs. They also don't do anything structural.
Click to expand...

No you don't. I think we're working on two different designs here. I don't have the two bolts that attach the rotor to the hub. I have 6 and they are the only thing that holds the two together. My lug studs do not go through both, only press into the hub. The two bolts you speak of are to insure the rotor is aligned with the hub so you don't get runout on the rotor from not having the two intimately pressed together. I appreciate your help.
 
pappy said:
I know exactly what you are talking about. I don't use the two little bolts that bolt from the rotor into the back of the hub. They hit my spindle studs. They also don't do anything structural.
Click to expand...

No you dont understand. there are two different styles of rotor attachment depending on vintage. early FJ40(76-78) and early mini-truck(79-80) use a style different than late FJ40s and all FJ60's, as well as post 80 minitruck.

early style is 6 10mm bolts attaching the rotor to the hub... Lug studs go through hub only, and do not need to be removed for rotor replacement.

later style is 2 10mm bolts and 6 lug studs attaching rotor to hub. Lug studs are pressed through rotor and must be pressed out to swap rotor.

The vented rotors of the different vintage have the same offset, diameter etc, and differ only in pattern drilled for mounting rotor.
 
cruiserbrett,
Thanks for clearing this up. You definitely know your s***.

....................................................................................

EDIT: 2/17/05 correct rotor info

If I can add further clarification for vented rotor upgrade to minitruck to FJ40 front disc brake conversion:

If you have a 79-80 minitruck hubs use 76-80 FJ40 rotors #43512-6001. Both 79-80 mini & 76-80 FJ40 use same hubs.

If you have 81-85 minitruck hubs use 81-83 FJ40 rotors #43512-6010.

Advance auto calls for same rotor (Bendix 141510) for all years FJ40 which is wrong! This is the 81-83 style with (6) larger 15.1mm holes

http://tinyurl.com/4pj58
 
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