• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

GMT 800 Brake Conversion > Silverado HD 2500

Big T

Well-Known Member
Messages
4,559
Reaction score
3,837
Location
Fullerton, CA
I pulled these yesterday. The definitive answer is that there is no difference in the spindles for a GMT-800 2500 whether 2wd or 4wd. The difference is in the bearing hubs with the 4wd having the splined donut hole to accept the CV axle. Bearings are held on by 4 bolts.

The GMT-800 1500 trucks have bearings held on by 3 bolts, so their spindles and bearings are different. Their brake calipers and brackets are also smaller.

Would be intersting to know if the GMT-800 3500 DRW had even larger Pistons in their calipers.

I also noted that the attachment bolt and bracket for the brake line is different than the GMT-400. I'll probably have to buy new braided stainless lines with fittings to make these work.
 
Last edited:

tanman_2006

Just a farm kid...
Messages
5,694
Reaction score
906
Location
Seiling, Oklahoma
My 1500 HD and 2500HD both had the same knuckles. I know srw 3500's had the same calipers as a 2500HD and front 1500HD's. DRW looked to be the same up front as far as I could tell, rears might be different for the spacing but I bet they are the same.
 

Big T

Well-Known Member
Messages
4,559
Reaction score
3,837
Location
Fullerton, CA
My 1500 HD and 2500HD both had the same knuckles. I know srw 3500's had the same calipers as a 2500HD and front 1500HD's. DRW looked to be the same up front as far as I could tell, rears might be different for the spacing but I bet they are the same.
So he 1500 HD got the jumbo brakes and 4 bolt bearings. Good to know, as it expands the potential donor population.
 

tanman_2006

Just a farm kid...
Messages
5,694
Reaction score
906
Location
Seiling, Oklahoma
Yes sir, the fronts were identical to a 2500HD. I used my spare parts stock piled for my K2500hd to rebuild it. I was thankful for that break, if there was a difference I didn't find it.
 

Big T

Well-Known Member
Messages
4,559
Reaction score
3,837
Location
Fullerton, CA
Yes sir, the fronts were identical to a 2500HD. I used my spare parts stock piled for my K2500hd to rebuild it. I was thankful for that break, if there was a difference I didn't find it.
Will I have to change the brake hose due to the different fitting than the GMT-400?
 

tanman_2006

Just a farm kid...
Messages
5,694
Reaction score
906
Location
Seiling, Oklahoma
Picked up an 05 Dodge dually rear axle last week, now to just decide if I want ifs with gmt 800 parts or sas with brake upgrades
 

THEFERMANATOR

FRANKENBURBAN
Staff member
Lead Moderator
Messages
10,057
Reaction score
4,317
Location
ZEPHYRHILLS FL
Be careful though as there are 2 different GMT-800 knuckles used for 8 lug trucks. There is the 99-00 style, the nthere is the 01+ style. The 99-00 used different tie rod ends, and ball joints I believe than the 01-07 did. So they may fit easier, or they may not fit at all. And from what i have found, all 8 lug trucks in the gmt-800 body style got the same calipers.
 

Big T

Well-Known Member
Messages
4,559
Reaction score
3,837
Location
Fullerton, CA
Be careful though as there are 2 different GMT-800 knuckles used for 8 lug trucks. There is the 99-00 style, the nthere is the 01+ style. The 99-00 used different tie rod ends, and ball joints I believe than the 01-07 did. So they may fit easier, or they may not fit at all. And from what i have found, all 8 lug trucks in the gmt-800 body style got the same calipers.
The knuckles I pulled on Friday came off a 2003 Silverado 2500 HD 2wd.

That truck arrived in the yard 1/12/16 and they had already stripped the complete drive line and the entire front body was gone. There are always tons of GMT-400 trucks and Suburbans in the bone yards, but rare to see GMT-800s. The salvages must be paying more than the pick yourself yards.
 

THEFERMANATOR

FRANKENBURBAN
Staff member
Lead Moderator
Messages
10,057
Reaction score
4,317
Location
ZEPHYRHILLS FL
Found a 2001 Suburban 2500 at a pick and pull yard in Wilmington, California (about 30 miles from us):

http://www.lkqpickyourpart.com/locations/LKQ_Pick_Your_Part_-_Help_Yourself-262/recents/

Would the spindles from this work for the GMT-800 brake conversion?
Should. 8 lug trucks from 01-07 classic are all supposed to be the same. From what ican find, it looks like if you found a knuckle off of a 99-00 2500, the tie rod ends from the GMT-400 would work as they list teh same taper and stud for the 99-00 2500 as the GMT-400 trucks. The ball joint connections are the same as the 01-10 though.

Also, from what i can find, it looks like the 07-10 new body style also uses all the same knuckles, ball joints, tie rod ends, brakes as the earlier 01-07 trucks.
 
Last edited:

handcannon

Well-Known Member
Messages
1,751
Reaction score
112
Location
Albany, OR
The question I have is, does the disc brake rotor attach on the inside of the hub the same as the earlier-98 GMT-400 body style. Or, does the disc attach on the outside of the hub as the 01 and later GMT-800 body style. The later hub configuration with the disc on the outside is so much easier to replace the rotor.

Don
 

Big T

Well-Known Member
Messages
4,559
Reaction score
3,837
Location
Fullerton, CA
The question I have is, does the disc brake rotor attach on the inside of the hub the same as the earlier-98 GMT-400 body style. Or, does the disc attach on the outside of the hub as the 01 and later GMT-800 body style. The later hub configuration with the disc on the outside is so much easier to replace the rotor.

Don
Appears that GMT-800 trucks have a rotor over hub design and yes it's much simpler. Aside from the obvious difference in size of the brake calipers and pads, the rotor over hub design is the other great benefit of this conversion. The 4 bolts that hold the bearing to the spindle/knuckle are not recessed, so they are much easier to remove. I had to grind out the bolt head and sacrifice a knuckle on my '99 because it came with nature's weld from Illinois.
 

Big T

Well-Known Member
Messages
4,559
Reaction score
3,837
Location
Fullerton, CA
I got a set of OEM bearings for a 2wd in good shape. Just pay shipping. Otherwise, I'm throwing them out.
 

Big T

Well-Known Member
Messages
4,559
Reaction score
3,837
Location
Fullerton, CA
After a summer of projects where I needed the truck, I finally got around to reaming the Spindles (aka Knuckles) for this conversion. I've got a couple questions.

First, following instructions, I harvested knuckles from 2001 and later 3/4 ton trucks. One was a 3500 Sprinter van, the other was a 2500 HD Truck. The harvest was done at separate yards with both knuckles off the van and the knuckles for the 2500 HD came from separate trucks at separate yards. As I went to ream the knuckles from the van, it was apparent they are taller than those from the HD Trucks. I took measurements from top to bottom and the van knuckles are 14 1/4", while the HD Truck knuckles are 13". I measured the knuckles on my '99 Suburban K2500 and they're 13 1/4" with a bend in the tape to get around the CV joint of the axle. So they match the 2500 HD truck knuckles for total height. See attached pics.
 

Attachments

Top