Bolt in disc brake and 3.73 conversion?

[SmithvilleD]

The only dual piston kit I could find was for half ton pickups, not for 3/4 ton rigs.

Don

Plus with an OEM mass produced brake setup, you have a broad selection of pad friction choices as well as most all the replacement/maintenance parts are available most anywhere. But getting all these late model parts at a reasonable cost might take finding a suitable rolling chassis donor like I found on craigslist. Otherwise separately sourcing new brake rotors, caliper holders, dust shields, unit bearing hubs, & axles would dollar up in a hurry.

This swap would add considerable unsprung weight to the front-end as these newer dual piston calipers are beefy cast-iron & the rotors are thicker/more metal mass to absorb greater braking heat loads. But the newer trucks drive quite well & the braking is dramatically better than our older trucks.

Things I'm wondering:
Is the conversion kit's modification to the '01-'07 steering knuckle is something as simple as boring different ball joint tapers into the newer steering knuckle?

Are the kit included "flat washers" some type of spacer for the ball joints? The newer truck's inner tie-rod ends are joined to the ctr link similar to the inner tie-rod setup on most rack/pinion's... so maybe the tie-rod adaptors in this kit are to mate the outer tie-rods (that fit the new strg knuckle) to our older truck's OEM ctr link?

Are the newer truck's unit bearing hubs & axles actually stouter than our older truck's? The newer HDs are rated at 9200 -vs- the older HD's 8600?

I've got the parts to figure many of these things out; but not the time/opportunity in the near future to pull my truck apart to compare the stock parts to the newer truck's parts. I'll get to it, but not for a while.

 

[SmithvilleD]

Front brakes comparison - GMT 400 K2500 HD - vs - GMT 800 K2500 HD



Here are better pics comparing the GMT 400 K2500HD front brakes - vs - GMT 800 K2500HD.

GMT 400 rotor is ~12.5" outer diameter x 1.25" thick.
GMT 800 rotor is ~12.75" outer diamter x 1.5" thick.

The brake pads the newer dual piston calipers hold are much larger. Swept diameter/depth is close to the same. The EBC Yellowstuff brake pads for the earlier truck have a rather larger chamfer on each end - which could confound interpreting the pics if not aware of it. Can't recall if the stock pads are chamfered?

Regarding the GMT 800 rear disc brakes - I believe GM went back to rear drum brakes on the newest trucks. I've read comments that they never perfected the rear disc brakes w/integral/internal drum parking brake & that there were some problems with them.

The guys I know personally w/ GMT 800 K2500HD trucks are quite happy with the braking & say the parking brake works fine. Would still like to hear from anybody knowing about problems folks have experienced w/ these OEM rear disc brakes/pkg brake?

Forgot to mention earlier - look close at the earlier pic of the entire '04 14 bolt/10.5 rear-end housing, you can barely make out that they finally put a drain plug (with magnetic insert) in the bottom of these newer castings - so the cover won't have to be pulled to change gear oil.

 

[Turbine Doc]

Now that is interesting, thing is SSBC already does a multi piston caliper kit for our trucks. IIRC Tim is running them, perhaps he'll chime in and give a cost comparison. Odds are the pricing is comparable in which case I'd rather go with the SSBC calipers.

Cheers
Nobby

My dual piston kit is for the K1500 6 lug wheel & was a simple rotor & caliper swap for front, SSBC was supposed to be coming out with a kit for 8 lug 2500 & 3500 setups I'm not sure if they ever kitted that this cost of kit linked is about $200 less than what I paid for my SSBC in 2005. But I bought their rotors, & pads & have since found equivalewnt replacement pads for less than what SSBC charges for pads. It would be interesting to know origin of kit linked as much as folks gripe about "made in China" I suspect for price listed there may be some Chinese content in that kit, I have made in China stuff on mine so this is not a shot at that as some of their stuff is good stuff, and pervasive these days & no way to escape it.

The EGR Brakes, Eldorado based front to use as a rear caliper kit has a viable parking brake feature to it, that also I don't know if EGR ever made a kit for the 8 lug trucks.

 

[Brooklyn Tow]

Would still like to hear from anybody knowing about problems folks have experienced w/ these OEM rear disc brakes/pkg brake?

4 wheel disc here on the HD and NO complaints except for the replacment pads (Uncommon Size)......Only decent replacments I can find are OEM at close to $200 a set = $400 all around.

Park brake works fine.

 

[SmithvilleD]

4 wheel disc here on the HD and NO complaints except for the replacment pads (Uncommon Size)......Only decent replacments I can find are OEM at close to $200 a set = $400 all around.

Park brake works fine.

Don't know if your 3500HD has the same rear disc's/calipers as the GMT 800 2500 HD's? If so, Summit's online catalog shows EBC offers both front & rear pads in their Yellowstuff friction that I've liked in other applications. Front or rear sets are each $143.

http://www.summitracing.com/parts/E...CHEVROLET|Model|SILVERADO+2500+HD&prefilter=1

Regarding the conversion kit brackets that allow mounting the old Eldo calipers with mechanical prking brake, guess I'd heard that setup's pkg brake was functional, but didn't inspire a great deal of confidence. Otherwise it's certainly a cost-effective setup.

My truck's original rear end gears are worn & whine under heavy load - so it would need additional work beyond the brake upgrade. Plus finding a donor rolling chassis close to home for $425 made that an attractive option. The roller also gave me a spare 9.25 front diff as well as all the front end brake & steering/steering box components.

 

[nobby]

The EGR Brakes, Eldorado based front to use as a rear caliper kit has a viable parking brake feature to it, that also I don't know if EGR ever made a kit for the 8 lug trucks.

Thanks Tim.
EGR can supply an 8 lug rear kit, thing is their hardware is actually from TSM which is where I got my rear kit from rather go to the horses mouth and I got a better feeling after talking with TSM. TSM also has the calipers they supply rebuilt/gone over in the US as they were having issues with generic rebuilt units. Of further interest TSM makes a dual caliper bracket, the reason being that the ebrake caliper has a smaller piston diameter than the non ebrake unit. Therefore for those wishing to get all the force they can one installs a non ebrake caliper for the hydraulic brakes and an ebrake caliper for the ebrakes only.

On another note GM etc going back to drum brakes on the rear as I understand it is a saving money thing.

Cheers
Nobby

 

[handcannon]

View attachment 25449View attachment 25450View attachment 25451

Here are better pics comparing the GMT 400 K2500HD front brakes - vs - GMT 800 K2500HD.

GMT 400 rotor is ~12.5" outer diameter x 1.25" thick.
GMT 800 rotor is ~12.75" outer diamter x 1.5" thick.

The brake pads the newer dual piston calipers hold are much larger. Swept diameter/depth is close to the same. The EBC Yellowstuff brake pads for the earlier truck have a rather larger chamfer on each end - which could confound interpreting the pics if not aware of it. Can't recall if the stock pads are chamfered?
.

Thanks for the pics! Besides being dual caliper, it looks like the newer brake pads contact area may be as muck as 50%, or more, larger. Now we just need to know what it would take to adapt the brake parts to our trucks, or the whole steering knuckle. I am very interested in better brakes for my truck. So far the only upgrade kits I've found are for the half ton trucks.

Don

 

[nobby]

Another thought, fitting Powerslot rotors and Hawk pads on the front makes a very noticeable difference to the front brakes. More than likely not as much as trying to fit the GMT800 units but still does not leave me wanting more on the fronts.
As already mentioned rear disc kits for the 8 lug rears can be had so for the 2500 that one is covered.

Cheers
Nobby

 

[SmithvilleD]

I'm thinking the "conversion" kit I linked to, about has to be using the newer steering knuckle. Otherwise why would it require the late model bearing hubs & axles?

The picture on that site is so small you can't really tell much.

The newer rotor/hat has more offset/depth than our GMT 400's. Need to set the older truck's steering knuckle/rotor/caliper next to the newer ones & compare.

I read one of TheFermanator's comments in another thread that mentioned the newer truck's master cyl has a larger fluid reservior. I still need to do more research to find out if the actual master cylinder is appreciably different.

I didn't see any proportioning valve in the '04 HD's chassis - just the anti-lock module mounted to the frame. The rolling chassis had no cab & the master cylinder was gone. A guy at my work drives a truck pretty much like the chassis I bought so I need to look over the complete system on his truck.

 

[nobby]

The later reservoir will no doubt have equal size large ones being disc and disc. I would not worry so much about the smaller rear drum reservoir as others have found converting to discs it works OK. The issue with the smaller reservoir will be that the smaller volume will not be enough to make up for the pads wearing so that perhaps you'll need to add fluid which of course you'll have to remove when you fit new pads. I'd be more concerned about piston diameters than the fluid capacity.

You'd think there would be a proportioning valve and like our trucks is part of the ABS module.

Cheers
Nobby

 

[handcannon]

I'm thinking the "conversion" kit I linked to, about has to be using the newer steering knuckle. Otherwise why would it require the late model bearing hubs & axles?

The picture on that site is so small you can't really tell much.

The newer rotor/hat has more offset/depth than our GMT 400's. Need to set the older truck's steering knuckle/rotor/caliper next to the newer ones & compare.

I went to that site and was disappointed in the picture of the kit. You have to put a lot of faith in the seller and his description, hoping that you are seeing and understanding everything.

I really want to see a comparison of the complete older and newer steering knuckle/brake setup.

Don

 

[SmithvilleD]

I did a little more work tearing down this '04 AAM 14 bolt/10.5 differential I'm rebuilding. It has the G80 locking diff & the internals look OK. If anybody wants to see pics of an intact/functional G80, I posted a few pics in another thread (G80 specs) here in the drivetrain section.

Regarding potentially being able to swap in the newer truck's front brakes, I have noted the modified steering knuckles being sold to convert to the newer brakes appear to have the hole/opening just below where the lower A-arm fits. Our older truck's knuckles have that opening. The newer knuckles just have a depression, but no actual hole. The newer front caliper mounting ears/bolts are much further apart that the earlier single piston calipers, which makes it seem unlikely they could easily be modified to mount the later brakes.

 

[dv8lad]

I know this is an old thread, but I have been researching this for my 2000 OBS 2500 Gmc. As is suggested on other sites, You can use the '01up (NBS) knuckles AND the lower control arms AND lower ball joint. The only thing that needs to be done is to ream out the upper ball joint seat in the steering knuckle to accomodate the OBS upper ball joint. Then you mount the NBS: hubs w/ABS sensor if equiped, rotors, pads, calpers, axles ( they are 36mm splined, OBS are 35mm). Im still not sure about the tierods, though. I know the OBS has an inner and outer attached to the center drag link and the NBS just has an outer attached directly to the center drag link, but I'm sure that can be easily adapted.

 

[SmithvilleD]

I'm just getting back to this project which got back-burnered, over a 26' GN carhauler project I bought & finished last summer. Have been sandblasting & powdercoating up the '04 brake calipers/cal brackets, knuckles, lower control arms, etc. Rebuidling the calipers, all new bearings/R&P in the newer 14 bolt, new bearings/seals in the floater hubs. New ball joints to fit the newer LCA's, old UCA's, & new steering joints arriving this week. Also have new hub/wheel bearings & new CV axles to match the GMT800 bearings.

I plan to use the '04 outer tie-rod ends which have a M14-15 female thread that will have to mate to a billet Al tie rod adjuster sleeve to fit GMT400. Going to copy M. Kasperan's lead of using a stock GMT400 outer tie rod as the starting point to make an adaptor that threads into the GMT800 female outer tie rod. Basically he cut off the GMT400 tie-rod ball joint, then turned it down the outer portion to M14 size & threaded it M14-1.5.

Also have an '04 power steering pump, lines, & hydroboost/mastercylinder, as well as the '04 K2500HD truck's Delphi steering box. Gonna put a seal kit & bushing in the pwr steering pump. Wondering if the newer truck's steering box has improvements over the older Saginaw 800 box original to my truck? The newer truck's Delphi box design certainly appears to have decended from earlier Saginaw's - & the Delphi box's "64" casting & casting # 26078664 are the same castings the aftermarket AGR steering boxes use. Wish I knew if that Delphi box is part of the reason the newer truck's steering feels better?

The newer box has a different mating stub to the steering shaft, but that stub shaft may well be swappable to the earlier design. Still researching this...found the Saginaw service/rebuild manual & will probably buy a rebuild/seal kit for the newer box (relatively cheap ~ $20) & open up the new box to see.

With all these details to sort out, & blasting/powdercoating to make it look good for long-term, it's taking a long time. But I should wind up with GMT800 quality brakes & a front end that steers at least as tight as the GMT400's did new - maybe a little better.

Will put up some pictures later.

 

[SmithvilleD]

To use the GMT800 master cylinder that matches the GMT800 front/rear disc brakes, you need a GMT800 hydro-boost that matches the master cylinder (bigger diameter bore the mc mates into on the booster). But, the GMT800 hydro-boost uses a different length pedal rod. Also, to put new input rod seals into the hydro-boost requires the pedal rod to come off. So fab'd up a quick-n-dirty pedal rod puller. This is basically an evolution of an idea another 6.5'r (Haggar) on another forum used.

This gives enough leverage to pull the staked pedal rods, & puts the force on the input rod as I believe it should to do this right.