DIY Disc Brake Conversion

[mechanixman]

Hey guys
I understand this thread was made for 8 lug trucks. Which tend to have the same steering setup as well. So I was hoping I could get some help in that respect as well.
If anyone would be so kind, I need to know the distance from center to center of the ball joints the drag link attaches to.

Basically the distance between the green lines but in the stock position.

[dwcsr]

12" , Why so far ahead of where it was?

[mechanixman]

Thanks Dave!
I have it that far forward because I can't fit anything on the frame next to the motor. The picture is of when I first had the motor in the frame, and I realized how little room I had.

It's funny though. Where it is at now, it needs to be shortened about 3/4".
I have one more question.
The angle of the pitman arm seems kinda steep for going straight.
Do you think I should have the pitman going more vertical?

[dwcsr]

The more level the drag link the less chances for bump steer. What will happen is the axle goes up or down and it moves the steering arm forward or backward just slightly but enough to make a change in direction. That's how you get bump steer on a straight axle. Jack up the front axle and have all the weight on it and see where it ends up. The Pittman arm should be in the middle of lock to lock and straight down when centered. This way you don't pull the drag link to a steep angle when you turn.

[mechanixman]

Alright thanks again.
Yeah I knew they had to be level, and they are within 1/2", I figured I was pretty spot on. yeah, right now that drag link goes just about points straight forward when I turn it to left lock.

[55dude]

toyota 4x4 box pre 1986 will sit on top of frame and clear V8!

[47AD]

55dude,

On that pre 1986 Toyota 4 x 4 steering box, is that the non-power steering box or power steering box that fits with a V8? My 47 AD will have a 265 V8 with the log style headers. I have seen a couple of pictures of these steering boxes before but couldn't tell if it actually allowed more room next to the header. If the power steering box mounts in the same spot as the stock box and would clear the header that would be an excellent problem solver. I think I had looked at Golden State Pickup Parts online some time ago and saw that they sell a kit (very expensive) for this upgrade.

Dan

[mechanixman]

55dude,
it may fit otherwise, but I have my motor mounted awfully low. I need to trim the frame just a little bit so I can bolt on my exhaust. it's so close.

Dan I believe they're the power steering units. (i forgot why but) I believe the reason I didn't use that box is because I want manual steering.

[Nate_]

Hey Mike,
Did you have a chance to see if those brackets fit? I am waiting to see your results before I purchase mine.

Been reading around the site for a while and finally decided to join.

Nate

[Nate_]

Nick,
My brakes were almost in the same condition as yours when you started. I am stuck at the backing plate. How do these last two bottom bolts come out? They seem to go through to the other side and attach the steering linkage. I have tried everything and I am at the point where I will torch them off. Sorry, I had to take the picture upside down... Any help would be great.
Thanks,
Nate

[mechanixman]

You're right.
They do go through. It should be a stud with two nuts on either end. One for the steering linkage and one for the backing plate.
I'll see if I can take a picture of mine next time I come home from school.
If it's spinning while you're cranking on it, there is a section of the bolt behind the steering arm that you can put a wrench on.
I hope that helps. If it doesn't. let me know, I'll find a way to show it.
Thanks for the interest,

[mikec4193]

Originally Posted by Nate_

Hey Mike,
Did you have a chance to see if those brackets fit? I am waiting to see your results before I purchase mine.

Been reading around the site for a while and finally decided to join.

Nate

Sorry my truck is still sitting...I gotta bunch of Willys parts and I trying to get something built on that end..not sure when I will start on it actually. parts are sitting under the bench in the garage. As soon as I can get the Willys rolling I am thinking about pushing it into the garage...

MikeC

[Nate_]

Originally Posted by mechanixman

You're right.
They do go through. It should be a stud with two nuts on either end. One for the steering linkage and one for the backing plate.
I'll see if I can take a picture of mine next time I come home from school.
If it's spinning while you're cranking on it, there is a section of the bolt behind the steering arm that you can put a wrench on.
I hope that helps. If it doesn't. let me know, I'll find a way to show it.
Thanks for the interest,

Nick,
I was able, with the help of a large hammer, got the bolts out. I guess 60 years of rust was holding them in. Now onto the rebuild. Also, do you know if the king pin is the same on a 3/4 vs 1/2ton? I think I may need to replace one and the 1/2 tons are a lot easier to find.
Nate

[yossarian19]

Originally Posted by Nate_

Nick,
do you know if the king pin is the same on a 3/4 vs 1/2ton?
Nate

They aren't. 3/4 and 1 ton are .921". I don't recall what that comes to in fractions. Anyway, try rockauto.com - it's a clunky website but has darned near anything you'd ever need.

[dwcsr]

Originally Posted by yossarian19

They aren't. 3/4 and 1 ton are .921". I don't recall what that comes to in fractions. Anyway, try rockauto.com - it's a clunky website but has darned near anything you'd ever need.

yes 3/4 and 1 ton .921 std. and .931 over size. I got mine at rockauto.com

[Nate_]

Originally Posted by whitedog76

I've actually bought a set of those bearings. They are Japanese made by a company called MBS. They are quality pieces too! The OEM felt seal won't work though. Try Timken 40973s. It's a little tight around the middle, but any seal thicker than .25 won't work.

http://s1074.photobucket.com/user/wh...ml?sort=6&o=32

Hey whitedog,
You have some part #'s for the tapered bearings. Chevys of the 40s are out of business. Not sure where to get them now...
Thanks,
Nate

[yossarian19]

I might be barking up the wrong tree but I noticed Speedway's 1/2 ton hub kit (billet hubs) used easily found 3500 lb trailer axle bearings.
I wonder if a trailer bearing & race set could be found that would either tap into place or wouldn't take too much machine work on the heavier hubs? Depending on local labor costs, might be cheaper / easier than tracking down a custom bearing.

[Nate_]

Well I found the actual site for chevsofthe40s.com. They do have the roller bearings in stock but they are about 220.00/side. Not what I want to pay but I want to make sure that I have everything and that its safe.

[tmoble]

that's ridiculous. buy one side and get the numbers off the bearings.

[SCHRUMGMC]

Can the original rims fit on these updates?

[OrrieG]

Usually not, the inner part of the wheel has to have a different profile to clear the calipers, I found that out on mine, 59 wheels would not work with 74 front hubs and calipers.

[Nate_]

Does anyone have any updates for the disc brakes? I'm thinking about getting the brackets that Mike got from ebay. I need to get moving on my truck in order to meet my May goal of being on the road.

Also, has anyone found the kingpins with the needle bearings for the 3/4 ton truck? I have found them for the 1/2 ton but not the 3/4.

Anyone else find the tapered roller bearings for the wheels for a "reasonable" price?
Nate

[dwcsr]

Originally Posted by Nate_

Does anyone have any updates for the disc brakes? I'm thinking about getting the brackets that Mike got from ebay. I need to get moving on my truck in order to meet my May goal of being on the road.

Also, has anyone found the kingpins with the needle bearings for the 3/4 ton truck? I have found them for the 1/2 ton but not the 3/4.

Anyone else find the tapered roller bearings for the wheels for a "reasonable" price?
Nate

What needle bearings are you looking for. King pins are bushings and the pivot bearing is a ball bearing.

You don't have to convert to taper wheel bearings. The ball bearing is rated correctly for your truck and the disc addition doesn't change that. As long as they are in good shape leave them.

We have been selling 3/4 and one tom kits for a while now.

[Nate_]

I have seen kits with the needle bearings in place of the copper sleeves that go into the axle. At least that's how it am interpreting it. I have read that the ball bearings are not good or will not work with the disc brakes and are the ball bearings ok for "today's" highway speeds?

[dwcsr]

Originally Posted by Nate_

I have seen kits with the needle bearings in place of the copper sleeves that go into the axle. At least that's how it am interpreting it. I have read that the ball bearings are not good or will not work with the disc brakes and are the ball bearings ok for "today's" highway speeds?

They work with disc brakes fine. I've never read anything from a bearing maker or a car maker that states otherwise. I have seen as much negative internet lore against swapping ball to roller as I have about using ball on disc. I haven't read yet that anyone says yes that happened to me first hand, its always I heard it can or some one wrote there cousins first wife's nephew ............ As long as your using good bearings and they are clean and properly greased and adjusted there should be no issue. Ball bearings are use in a multitude of high speed high temp applications. Is taper better,,, Yes,, but there is no direct swap from ball to taper its a make fit swap.

The real issue is making sure the bearing is adjusted properly on a disc, its much more critical that on a drum brake. Angular contact bearing, which are the ball type on the spindle now, are characterized as capable of much higher RPM. Taper roller ( modern spindle) have more thrust radial load capacity, (not radial tire load), and are stiffer that angular contact. that means they can use a smaller bearing and get the same load capacity.

With that said he angular contact ball is capable of 100% load in radial or thrust postilions or a combination of 100%

Would a angular ball bear be good for road race where there is a lot of thrust load, no. Taper would be better.