Disc Brake swap for a 3/4 and 1 ton

[dwcsr]

I started posting this in another thread and realized I was hijacking the thread so I'm starting this one. The intent is to add disc brakes with off the shelf parts and stock spindles 47-52 or 53-59.

The hope here is that we can do a swap with either spindle , early or late and just add a spacer to the early inner bearing and use an off the shelf outer and inner bearing.

47-52 spindles are 1.406 +/- on the inner journal and 0.84 on the outer
53-59 spindles are 1.496 inner and 0.87 outer
You will need to take into consideration the wear from the bearing spin.



We are using the 47-52 spindle and making a bearing spacer for a 3387 bearing cone. This is a normal taper bearing with no seal land like the stock roller ball bearing so the spacer needs to have this machine into it. Some have used the stock ball bearing on there disc swap so keep that in mind.

Below is the test spacer without the seal land.
The length of the spacer will be 1.45 from the spindle face to the edge of the cone. ID is 1.404, OD is 1.495. It makes for a slight press fit

I'll rough machine a seal land and weld it to the spacer then re machine to true it all up.

[dwcsr]

This is a mock up of the spacer, the tube is Stainless and the seal land is aluminum because they are easier to cut than the 4130 I'm going to use. The chamfer inside allows the seal land to sit up against the knuckle. it may take additional machining to allow the oil slinger to fit in there as well. The land width is still unknown, once I have the truck back from sand blasting I can measure the original parts. The purpose of this mock up was to see if it was doable and it looks like it is. I think it will be a one piece spacer just like the one for the 1/2 ton.

[dwcsr]

I did a little more on the spindle spacer. Its made from 4130 Steel 2.25 diameter round bar.
The spacer dimensions are as follows

Seal journal diameter 2.110", The seal National 40973S ID is 2.093" OD 3.150" x .250" thick and leaves us with a .017 interference fit or seal lip stretch
Seal surface width 0.845" , this may be trimmed later
Spacer ID is 1.406" use 1.404 if you want a very snug fit, Measure your spindles first
Spacer bearing seat is 1.495" OD and 1.100" long
OAL 1.950 This may change.

[dwcsr]

We are back on the disc brake swap and have the bracket template made. I just need to get it into a cad file for the water jet people. We still need to figure out the shims and spacers but is very close as is.
It going to be 3/8 CRS, we clocked it at 10 instead of 2 for clearance.

The disc and caliper are 2005 Chevy Express 2500 8600 GVW LBS truck.
Disc PRT5261 Bendix
Caliper CRB134348 Wagner
Pads RD784 Bendix

We have to make sure the disc sits flat on the hub and make some stud spacers. The stud holes are bigger that the studs. It may require longer studs and if that's the case I'll just go with bigger ones to eliminate the spacers.

[dwcsr]

One little addition, I wanted to see if the original backing plates could still be used and they fit surprisingly well after a little trim. We have the cad file now for the caliper brackets so its off to the water jet guy in the morning. I'll post a picture when we get it back.

[dwcsr]

We have the brackets back from the water jet guys. 3/8 thick 4140 steel, we made some spacers to get the disc in the correct place, Used a 1' wheel adapter/spacer. The original wheel fits with good clearance. haven't done anything with the bearings yet.

[Purcell69]

Very nice! I purchased a similar kit almost 20 years ago for the 3100 front axle. With the bracket and spacer, I was able to run F-body and G-body rotors and calipers as straight bolt ons, with the passenger car wheel bearings. It worked well.

It's good to see support for the 3/4 ton and 1 ton guys is coming along.

-Joe

[dwcsr]

Originally Posted by Purcell69

Very nice! I purchased a similar kit almost 20 years ago for the 3100 front axle. With the bracket and spacer, I was able to run F-body and G-body rotors and calipers as straight bolt ons, with the passenger car wheel bearings. It worked well.

It's good to see support for the 3/4 ton and 1 ton guys is coming along.

-Joe

3100 kits are all over the place and fairly cheap it would have been nice to get a set and be done with it but our problem was the calipers were to small for a 8800 GVW truck so we couldn't use F body or even C10 or C20 calipers we needed the late model 2500 and up dual piston calipers which are a lot bigger and rated at 8600 GVW. With this bracket its going to be a bolt on kit it just needs some refining in order for it to be a kit that's not to costly.

[Purcell69]

Originally Posted by dwcsr

3100 kits are all over the place and fairly cheap it would have been nice to get a set and be done with it but our problem was the calipers were to small for a 8800 GVW truck so we couldn't use F body or even C10 or C20 calipers we needed the late model 2500 and up dual piston calipers which are a lot bigger and rated at 8600 GVW. With this bracket its going to be a bolt on kit it just needs some refining in order for it to be a kit that's not to costly.

Absolutely! when moving substantial weight like that, good brakes are key. Thanks for stepping up to the plate and designing something for the big truck guys.

-Joe

[Hogger54]

Will the width be the same as stock, or will these widen it a little?

[dwcsr]

Originally Posted by Hogger54

Will the width be the same as stock, or will these widen it a little?

1" wider on each side. We needed a wheel adapter 8 lug to 8 lug with a 14mm studs to solve two issues. One was the hub fitting into the disc and the second was the getting longer wheel studs to pass through the rotor. The 1" wheel adapter solved both issues. The adapter has 14 mm studs that better fit the rotor bolt holes and we could turn the wheel adapter down a few thousands to fin in the rotor.

[dwcsr]

We are adding power assist to this truck, using the original steering box and pitman arm. The unit is from a 68 C10 which is the same as corvette up to 82. We had to drill out he ball studs on the steering arm and pitman then make some taper bushing to accept the new taper rod ends. We also had to make a sleeve to go into the control valve and accept the tie rod end. One end is an external 1-1/16-18 thread that screws into the control and the other 11/16-18 internal that takes the rod end.The assist cylinder will bolt to one side of the axle at the spring and the other end at the tie rod.

Making the drag link is the problem and unfortunately there is no 1-1/16-18 die so doing this as a DIY project may not work unless you have a lathe and can cut threads. You can get a 11/16 tap anywhere. The tie rod end is a 80-94 Jeep Cherokee rod end.

We didn't use a Toyota box because is not rated anywhere near a one ton vehicle.

[b.sharp]

Are you going to sell these adapters? I just bought a 1950 3800 factory dually and would really like to put disk brakes on it. I want to use this truck as a good hauler vehicle. This is great work and thank you for doing the hard part. I would be interested in purchasing a whole kit if you have all the available parts and instructions on the assembly.
Bryan

[dwcsr]

I have a couple of updated pictures. We have the 14 bolt in it. Its a bit wide at 67" but we are sending the wheels to Stockton Wheel to have the original centers put into new tubeless rims and we'll have then do the offset to make them clear the fenders. The frame is painted along with almost all the body parts, power assist is nailed down and just need to make some brackets to keep the hoses out of harms way. Its near the end of this build hopefully by mid august it will be driving. We did upgrade the tie-rod to 1.25" and 7/8" rod ends so we don't have any flex with the ram assist

[dwcsr]

Originally Posted by b.sharp

Are you going to sell these adapters? I just bought a 1950 3800 factory dually and would really like to put disk brakes on it. I want to use this truck as a good hauler vehicle. This is great work and thank you for doing the hard part. I would be interested in purchasing a whole kit if you have all the available parts and instructions on the assembly.
Bryan

I don't have it in kit form yet. It still needs some R&D and cost reduction but I will offer it in some form.

[dwcsr]

Here is the final assembly on the disc brake swap
All the parts are from a 2003 2500 HD other than the custom made brackets and spacers and
Wheel spacers which are 1" aluminum.

We did the kingpins first so all it nice and tight. The backing plate was trimmed to fit with the caliper The old brakes has two studs on the bottom that has a stud sticking out. These bolts need to be replaced with grade 8 same size but 1/2 longer.
Next shows the spacers that match the caliper bracket we use 3 per side the fourth being the bracket.

[dwcsr]

Next is the bracket bolt up. For the bottom bolts you put them in with the head at the steering arm side and the nut toward the wheel. We need to do this for clearance because we moved the arms inboard by 3/8 inch. You may have to trim or smooth the axle and or arm at the point of full turn. We did but it was a very small amount.
Next is the caliper mounting bracket with a spacer in place
Next pads are in and look properly set
Put on the caliper.

[dwcsr]

We have the hose mounted and no kinks when turned lock to lock
We do have to remove on bracket from the hose
We also made the stock box a short shaft box with a sealed bearing in the top housing so we can put a set of u joints in for safety.
And its done.

[dwcsr]

I just wanted to update this thread to the final result. We ended up not changing wheel bearings because there is no direct conversion and I found others have had issues with outer taper bearings burning up after the conversion so we left it alone. The rotors are 2003 HD along with the calipers. At this link is a complete list of whats needed to do this conversion along with part numbers. http://www.thehollisterroadcompany.c...converion.html

For the booster we used a 7" dual with a bracket that allowed us to keep the stock pedals. Master was a 1.125" corvette type and a remote reservoir kit so the fill is on the firewall. This truck stops with very little pedal effort and may give you the impression of a low pedal when you set this up prior to driving it but it reaches 1200 PSI line pressure using the stock foot pedal which is enough to do the job. here is a picture of what it looks like wheels on. It can use 16' wheels but these are stock 17" converted to tubeless.

[Sven010]

Hello,

I know it was long time ago... but does someone downloaded the list at:

http://www.thehollisterroadcompany.c...converion.html ??

or downloaded the youtube video from Thread:

"Upgrading brakes on 1950 1 ton 3800. "



Thank you for sharing some informations about this truck!