98 K1500 brake issues.

[pursuit2450]

I have read and read all I can about the apparent crap brakes my truck has. I am not here for assistance on bleed issues or the sorts, not yet at least.

Back story. Bought a 98 Silverado Z71 from a buddy of mine. I decided to do all the usual maintenance, oils, filters, plugs, BRAKES, etc.

I bought front rotors, pads and calipers and complete rear drum kit. Also replaced front and rear hoses. Obviously still have a soft pedal. So my next step is the MC.

Here's my delema. The glove box shows JD7. JD7 BRAKE HYD POWER, DISC/DRUM, 8,400 LBS. But I have vacuum not HYD. So now I cant go by the RPO in the glove box because it seems it's not original to that truck. So I guess that when I go shopping for the MC I need to buy the JB5/6/7 RPO code MC, which is BRAKE POWER, DISC/DRUM, 8,400 LBS?

I will also confirm something else when I get home. My MC is aluminum, I believe. Now looking at AutoZone MCs, the aluminum MC is for JD7 and cast iron for JB5/6/7. I don't know if the same is true for OEM MCs.

 

[pursuit2450]

Ok, so I confirmed 2 things. The RPO sticker isn't for my truck, it has a different vin on it. Also, my MC is aluminum. I guess I have to buy the JB5/6/7 MC with the 1.5 bore.

 

[kylenautique]

Ok, so I confirmed 2 things. The RPO sticker isn't for my truck, it has a different vin on it. Also, my MC is aluminum. I guess I have to buy the JB5/6/7 MC with the 1.5 bore.

There JB5 vs JB6 is pretty easy to tell. If you have a 14bolt rear end, its JB6. 10bolt, JB5. If you want that truck to stop great, get your self a hydroboot from a 2500/3500 and some new 1 ton calipers. You will also need a brake pedal or modify yours for the throw change. Its a night and day difference.

 

[pursuit2450]

There JB5 vs JB6 is pretty easy to tell. If you have a 14bolt rear end, its JB6. 10bolt, JB5. If you want that truck to stop great, get your self a hydroboot from a 2500/3500 and some new 1 ton calipers. You will also need a brake pedal or modify yours for the throw change. Its a night and day difference.

I did the next best thing after some reading here on the forum. I got the 2500calipers and the MC. Regardless, I am pretty sure my ABS unit is short and probably air bound. That will be the next thing I tackle. Either delete it or see about a used unit.

 

[Schurkey]

Bought a 98 Silverado Z71

All "Z71"s are 1500s...right?

JB5 and JB6 use the same (step-bore, 3-chamber, Quick Take-Up) master cylinder. Note rear of casting larger than the front, huge piston at rear.

You must be registered for see images attach

JB7 takes a different, 2-chamber, Non-QTU master. All of these are aluminum with a plastic reservoir.

Obviously still have a soft pedal. So my next step is the MC.

I'd have said your next step is to properly bleed the ABS.

I guess that when I go shopping for the MC I need to buy the JB5/6/7 RPO code MC, which is BRAKE POWER, DISC/DRUM, 8,400 LBS?

As said--5 and 6 are the same master cylinder, 7 is different.

I will also confirm something else when I get home. My MC is aluminum, I believe. Now looking at AutoZone MCs, the aluminum MC is for JD7 and cast iron for JB5/6/7. I don't know if the same is true for OEM MCs.

5, 6, and 7 would all be aluminum master cylinders. 8 is aluminum, I'm pretty sure. JF9 might be iron--probably not. JF9 is really rare. I've never seen a JF9 truck.

I got the 2500calipers and the MC.

WHICH "2500 calipers and MC"? JB7?

Regardless, I am pretty sure my ABS unit is short and probably air bound. That will be the next thing I tackle. Either delete it or see about a used unit.

START by connecting a scan tool and PROPERLY bleeding it. Do you have a "BRAKE" or "ABS" light lit-up on the instrument cluster?

Download the service manual set for your vehicle from the links in the Sticky thread section of the Engine forum.

 

[pursuit2450]

All "Z71"s are 1500s...right?

JB5 and JB6 use the same (step-bore, 3-chamber, Quick Take-Up) master cylinder. Note rear of casting larger than the front, huge piston at rear.

You must be registered for see images attach

JB7 takes a different, 2-chamber, Non-QTU master. All of these are aluminum with a plastic reservoir.


I'd have said your next step is to properly bleed the ABS.


As said--5 and 6 are the same master cylinder, 7 is different.


5, 6, and 7 would all be aluminum master cylinders. 8 is aluminum, I'm pretty sure. JF9 might be iron--probably not. JF9 is really rare. I've never seen a JF9 truck.


WHICH "2500 calipers and MC"? JB7?


START by connecting a scan tool and PROPERLY bleeding it. Do you have a "BRAKE" or "ABS" light lit-up on the instrument cluster?

Download the service manual set for your vehicle from the links in the Sticky thread section of the Engine forum.

Yes, JB7 caliper and MC. Already checked ABS with scanner. ABS is shot. I want to keep it simple and just delete it and add a proportioning valve. I have seen were some people have used the late 70's Camaro valve but make no mention of all the lines will screw right in or if you need adapters. Still searching.