Early Classic Rear Drum Brake Upgrade Kit

[ShortCST]

I reached out to ECE about this rear drum upgrade kit with 2.75" drums that they sell for my '68 six lug 1/2 ton.

They're out of stock, and will be for the foreseeable future. They say that GM discontinued the backing plates.

Does anyone know how to put this kit together, part by part? I'm overdue for a rear brake job.

Thanks in advance,

John

[ShortCST]

Anyone here upgrade rear six lug drums from 2" to 2.75"? I'm doing discs at the front. Already have power assist. Looking for slightly better performance, without spending a lot more.

[68Stepbed]

In all honesty, it's really not worth the effort. 85% of the braking is done with the front brakes on trucks. The money and effort is better spent on the discs up front. If you want more "performance" out of your brakes, just step up to a more aggressive brake pad. I've been autocrossing my truck for several years with stock front disc brakes and stock drums. A couple years ago, I put some Hawk pads up front. People that rode with me couldn't believe how well it stopped with "stock" brakes.

[ShortCST]

Thanks Matt. I need new brakes at all corners. That's why I'm looking into more bite all around. I'm going discs up front (probably Wilwood D52 with 2.0" dual pistons), so I just wanted more bite with the same low maintenance as the original drums at the rear, for not too much money.

[ratty69]

I recently did this upgrade. I used backing plates, guts, and drums from an 87 Blazer. Afaik, the backing plates are all the same for the square bodies with HD brakes, JB5 on the spid iirc. If the donor truck has the 1.25" thick rotors, it should also have the bigger rear brakes with the backing plates and internal parts that you need. You can use all 2wd stuff except the drums. Order those for a Blazer.

I believe g10/20 vans through 95 also have the parts you need. The only part I'm not certain about is the backing plates. The rest of the brakes are the same as a C10 square body HD setup.

You'll also need a disk brake master cylinder, booster, and proportioning valve since you're adding disks. I used 72 C20 stuff for those.

Sorry for the long post...

[nds1968]

Pulled my setup from a military truck. You need to source the backing plates, you can buy everything else new.

[ShortCST]

Thanks guys, I really do appreciate it. So, it sounds like the HD backing plate is the key piece, and then everything else is pretty easy to find? Sorry 😐 I don't know what a spid is. Googled it and everything. Is JB5 the HD backing plate part number?

[cericd]

The SPID is the sticker on the inside of the glove box door that shows a list of the included options on these trucks. JB5 is the option number for heavy duty brakes. I think what he was saying is if you go to a parts yard and find a squarebody truck with JB5 listed on the SPID it will have the backing plates you are looking for.

[cericd]

Found this in another thread. Looks like the code for HD brakes might actually be J55. I'm not familiar with squarebodies so you might want to confirm. I was just explaining what an SPID is from the earlier post. The pic came from this thread http://67-72chevytrucks.com/vboard/s...highlight=SPID. Someone in the squarebody section of the forum would be able to let you know exactly what option # to look for.

[ShortCST]

Thanks so much Chris.🙏🏻

[cericd]

hope you find the backing plates.

[68Stepbed]

Originally Posted by ShortCST

Thanks Matt. I need new brakes at all corners. That's why I'm looking into more bite all around. I'm going discs up front (probably Wilwood D52 with 2.0" dual pistons), so I just wanted more bite with the same low maintenance as the original drums at the rear, for not too much money.

Don't underestimate the stock GM D52 calipers. They actually have quite a bit of clamping force with a 2 15/16" piston. You can also step up to a 3/4-1 ton metric caliper that has a 3 1/16" caliper and actually has more clamping force than many "performance" calipers. If you're trying to get good braking on the cheap, this is the way to go.

[ShortCST]

Thanks again Matt!🙏🏻Great info to digest. Do you know the model of the 3/4-1 ton caliper if it's not D52?

One thing that I was looking forward to was the reduction in unsprung weight at the front wheels, with the aluminum calipers. Not sure whether the original drum setup weighs more, or the disc conversion with iron vs aluminum calipers. I was considering the Wilwood 2.0" dual piston aluminum setup.

[68Stepbed]

D52 in and of itself is a code to designate the actual style of caliper. Then, there different codes to designate the size piston. Some info in this post--> http://67-72chevytrucks.com/vboard/s...73&postcount=2

As for the weight savings, in a 3800 lb truck, the 8-10lb difference would hardly be noticeable. I'm not trying to put down Wilwood products in any way, but the Wilwood D52 is actually a better upgrade for car calipers as they had smaller piston caliper on 11" rotors. The trucks calipers have 12" rotors with larger pistons that supply more pressure to help stop a truck with a heavy payload.

I learned alot of this info from a couple different people. One of those people being Rob MacGregor from NoLimit. I just don't want to see anyone spend more money than they need to.

[68Stepbed]

http://www.rockauto.com/en/catalog/c...b,caliper,1704

[jgmc]

What part number of Hawk brake pads did you use.

[68Stepbed]

Originally Posted by jgmc

What part number of Hawk brake pads did you use.

I can't find the receipt, but pretty sure it was these. https://www.summitracing.com/parts/h...del/c10-pickup

The description says low dust and noise free, but they were pretty dusty, and squealed under light pedal pressure.

[clay68c10]

Good info!! Thanks
Just when you think you know.... I had no idea about the 3/4 ton calipers. I'll be using those.