Swapping 13"x2.5" to 13"x3.5" drum brakes

[xXxPARAGONxXx]

I apologize if this has (and it probably has) been asked before. I did some searching but nothing jumped out at me.

Assuming my K2500 has 13"x2.5" drum brakes, and I am almost certain it does (5.7L, 8600 GVWR, JB7 code), would it be possible for replace the 2.5" components with 3.5" components (e.g., drums, wheel cylinders, hardware, etc.)? (Sorry, just have not had time to take a peek at the rear brake component yet.)

I plan on installing the hydroboost brake booster, so I'd like to do swap the rear brakes out, too, if possible. I am not interested in doing a rear brake disc conversion.

 

[1998_K1500_Sub]

JB7 is 13.00 x 2.5 in rear, as you mention.

3.5" is for the DRW setup IIRC. DRW uses deep drums... the hub is a long way from the backing plate.

Is your rear full- or semi-float?

I'm interested in to read what the knowledgeable people have to say about this.

 

[xXxPARAGONxXx]

Is your rear full- or semi-float?

I'm interested in to read what the knowledgeable people have to say about this.

Semi-float. I think all 2500s with the 5.7L have a semi-float rear axle.

I thought some of the SRW GMT400s could come with 3.5" wide drums, but if that's not the case, that makes it a lot easier for me (to stick with the 2.5" wide drums).

 

[stutaeng]

Could it be the SRW trucks? I think my K3500 srw has JB...8?

I can check when I get home.

@Schurkey is going to be the one that probably knows.

 

[Dropped88]

My 99 c3500 SRW has the 3.5 drums so it was a option.

Also they where slip on drums vs the dually which has studs through back

 

[HotrodZ06]

There was a 13x3.5 single wheel option in a 1 ton (JB8) looks like it may be possible to swap. Would need backing plates as well as hardware, shoes, and drums for sure, only way to know for sure is to try it. I'll keep researching I'm pretty interested if its possible.

 

[xXxPARAGONxXx]

My 99 c3500 SRW has the 3.5 drums so it was a option.

Also they where slip on drums vs the dually which has studs through back

Could you let me know your RPO code when you have time?

 

[HotrodZ06]

As far as i can tell using a GM Parts Catalog and Rockauto's catalog, would need backing plates, shoes, and drums for JB8 single wheel, provided you didn't have any other worn parts and would only work on a 10.50 ring gear axle.

 

[xXxPARAGONxXx]

As far as i can tell using a GM Parts Catalog and Rockauto's catalog, would need backing plates, shoes, and drums for JB8 single wheel, provided you didn't have any other worn parts and would only work on a 10.50 ring gear axle.

Sounds right. Different axles (9.5" SF versus 10.5" FF) then different inner diameter of the axle shaft hole in the backing plate. Maybe even difference in bolt spacing for the four backing plate bolts (not certain).

I will stick with the 2.5" wide drums and maybe just upgrade the wheel cylinders.

 

[stutaeng]

Could it be the SRW trucks? I think my K3500 srw has JB...8?

I can check when I get home.

@Schurkey is going to be the one that probably knows.

Confirmed: JB8
I thought it was standard on C/K3500 srw, at least the 97-00?