Suburban axle swap

[Nad_Yvalhosert]

is he maintaining rabs functionality? Or... whatever a suburban has? That could get spicy

4 wheel ABS is standard in the 95+ and it wont be a problem. There are no ABS sensors on any GMT400 rear axle. As long as the gear ratio is the same, the ABS wont know the difference. My '00 Yukon Denali is proof of that, it's got the same 3 channel ABS.
The front sensors are in the wheel bearing assy's, the rear input is taken from the VSS in the t-case.

 

[AuroraGirl]

4 wheel ABS is standard in the 95+ and it wont be a problem. There are no ABS sensors on any GMT400 rear axle. As long as the gear ratio is the same, the ABS wont know the difference. My '00 Yukon Denali is proof of that, it's got the same 3 channel ABS.
The front sensors are in the wheel bearing assy's, the rear input is taken from the VSS in the t-case.

no i mean hydraulicly, If you have enough imbalance theoretically you could lock up more than the system could compensate. But it depends on how much of a imbalance or change from form the system is doing

 

[Diptenkrom]

good question.. ;but my thought was that making everything bigger (2500HD/3500) parts, would make the balance back to intended.

Thanks for the added discussion and extra things to consider.

 

[AuroraGirl]

good question.. ;but my thought was that making everything bigger (2500HD/3500) parts, would make the balance back to intended.

Thanks for the added discussion and extra things to consider.

I mean if its all... shall we say... a set.. then most likely, but if a 1500 has 2500 brakes, would that 2500 originally had a abs that was setup the same? if so, no issue id think, but if not, there could be volume differences or something id think but the worst thing that hsould happen is it wont pump and cycle enough.. which is admittedly pretty bad scenario , but its better than locking the rear and pumping the fronts like my car does because ******* mechanic didnt replace the proportioning valves , the abs is incapable of cycling the rear more than once , but it will cycle the rear when you initially lose traction, then the proportioning keeps them from being more applied than the fronts, thus stability kept. yours is not like that but there could be weird behavior like that hidden under the surface of the actions it takes, so keep that in mind

 

[Nad_Yvalhosert]

I mean if its all... shall we say... a set.. then most likely, but if a 1500 has 2500 brakes, would that 2500 originally had a abs that was setup the same? if so, no issue id think, but if not, there could be volume differences or something id think but the worst thing that hsould happen is it wont pump and cycle enough.. which is admittedly pretty bad scenario ,

Perhaps there is a volume difference, but it's minuscule. Only an engineer would care. In practical use, the pedal height wouldn't be noticed.

but its better than locking the rear and pumping the fronts like my car does

ABS is supposed to keep that from happening. If it does, your ABS isnt working.
Do you have a '94 or older with the RWAL system?
I know we colloquially call them "cars" but to me, a car is wrong wheel drive, with a diagonal split brake system. Not a front/back split system our trucks have.

because ******* mechanic didnt replace the proportioning valves , the abs is incapable of cycling the rear more than once , but it will cycle the rear when you initially lose traction, then the proportioning keeps them from being more applied than the fronts, thus stability kept. yours is not like that but there could be weird behavior like that hidden under the surface of the actions it takes, so keep that in mind

This kinda sounds like a red herring tangent.

I thought the proportioning valve was built into the ABS module. The asterisk mechanic couldn't replace it without replacing the entire ABS assy, even if he wanted to.
Unless you're referring to an RWAL system on the older trucks. O.P. has a '97, so it's an all inclusive module...

 

[Diptenkrom]

honestly, if the thought is that it wont "ABS" properly, then i am cool with that. i would much rather have solid normal brakes than rears that lock up before the fronts, or instead of the fronts. Not ideal i know, but i have had plenty of vehicles with no, or non functional ABS, and know how to drive that accordingly.

I guess that there is nothing really more to say, since the upgrade outcome is theoretic at this point, unless someone else chimes in, i will have to do it and see. It will probably be march-april before i collect all the parts and get them all installed and working, but i will try to report back what happens at that point.

Thanks for all the help and discussion.

 

[Supercharged111]

I just want to make sure that they work well, and are balanced. I also don't want to mess with hydroboost, and extra fluid lines in the engine bay. just simple working brakes is all that i am after. Should be a benefit when towing as well, which i do little of, especially anything heavy. most of the time it is a simple utility trailer with a couple quads, a motorcycle, some furniture, or something like that, not a lot of weight. does it seem like my list is complete and compatible?

BTW these axles have started to get a little pricy from comparing older threads and price range that people mentioned 5-10 years ago.

Thanks!

In my experience, no vacuum setup in these trucks has ever been what I'd consider good. I tried everything on my 1500 before I rounded up everything to do the hydroboost swap. Absolutely worth its weight in gold.

 

[1998_K1500_Sub]

So with the 14 bolt SF 9.5" 6-lug axle swap, i should get:
(96-99?) C/K 3500 rear wheel cylinders
remaining factory (to the donor vehicle) rear drum brake hardware
front 3500 SRW calipers with brackets"
front 3500 SRW pads - (may require grinding to the outer lower pad backing to clear rotor hat)
front stock 1500 rotors
3500 SRW master cylinder
stainless lines to replace rubber ones (I assume that regular 1500 lines work, or do I need them for 2500HD/3500)

I assume you've got the 11" drums on that 9.5".

I have this set of parts (below) on my 8.5" w/ 11" drums w/ NBS MC and vacuum boost, but I like your choice of MC better.

I didn't use the larger 86mm/3.385" piston calipers that are available, I used the 80mm/3.15". My OE were 76mm/3". There's some discussion of the 86mm/3.385" piston calipers in one of the threads given below.

I haven't ever driven this combination in a situation where ABS engaged, so I have no comment on ABS. My brake combination has evolved over time and I like this combination best (so far).

I have a hydroboost valve body NIB in the basement, and the PS cooler is already on the truck, so maybe someday I'll put it all together (I still need the pedals and hoses).

Mine:

- 80mm/3.15" piston calipers ACDELCO 18R741 and ACDELCO 18FR742

- NBS MC - ACDelco 18M1159 (there seems to be a bore on this of 1.339" so it's said; I believe the 3500 vacuum MC has a 1.125" bore, hydroboost 1.25" bore, but check the specs)

- My OE 11" drums w/ 1.1875" diameter rear drum cylinders (ACDELCO 18E1362, OE for 13" DRW). My and all Suburbans are a$$-heavy, this change really helped the braking IMHO. I'm not sure I would do this on an a$$-light pickup truck.

- SS brake lines, etc., vacuum boost

ALSO...

See comments on parts here and throughout this thread: https://www.gmt400.com/threads/upgrade-front-brake-calipers.58795/post-1251999

and throughout this thread: https://www.gmt400.com/threads/jb6-to-jb7-brake-upgrade.58607/post-1248959

See comments on rotors: https://www.gmt400.com/threads/brak...e-from-different-vendors-product-tiers.58413/

 

[AuroraGirl]

Perhaps there is a volume difference, but it's minuscule. Only an engineer would care. In practical use, the pedal height wouldn't be noticed.



ABS is supposed to keep that from happening. If it does, your ABS isnt working.
Do you have a '94 or older with the RWAL system?
I know we colloquially call them "cars" but to me, a car is wrong wheel drive, with a diagonal split brake system. Not a front/back split system our trucks have.



This kinda sounds like a red herring tangent.

I thought the proportioning valve was built into the ABS module. The asterisk mechanic couldn't replace it without replacing the entire ABS assy, even if he wanted to.
Unless you're referring to an RWAL system on the older trucks. O.P. has a '97, so it's an all inclusive module...

I was referring to my car, lol, not a truck.

You must be registered for see images attach

I know its not the same setup but I was saying something that happened to my ABS system when seemingly small variables were changed, the functionality went out the window. In the case of the car, the proportioning valves are in the rear brake lines after the ABS but the shop did not replace them, which meant having to create ends with threaded connection to put them onto and then again to finish the run. So if I stand on the brake the rears will lock, the front will ABS like normal. Because its still a pretty good decent heavy car and I had **** in the rear, the lockup could be rather illfrequent , but the moment it starts, you have to let off the brakes to reapply or you will spin around , even letting off a bit. they simply cant pulse the rear after they are locked. its a pretty dumb oversight by bosch.


anyway, thats all I had to say lol

 

[Schurkey]

...the proportioning valves are in the rear brake lines after the ABS but the shop did not replace them, which meant having to create ends with threaded connection to put them onto and then again to finish the run. So if I stand on the brake the rears will lock, the front will ABS like normal. Because its still a pretty good decent heavy car and I had **** in the rear, the lockup could be rather illfrequent , but the moment it starts, you have to let off the brakes to reapply or you will spin around , even letting off a bit. they simply cant pulse the rear after they are locked. its a pretty dumb oversight by bosch.

Seems to me that you're blaming Bosch for problems created by the shop that didn't replace the proportioning valve(s) properly. But maybe there's just a failure in your ABS module.

An ABS system should have the ability to block fluid flow from the master cylinder (preventing increased pressure to the skidding wheel(s). It should also be able to relieve pressure in the hydraulic system so the skidding wheel begins to turn again. That's what the accumulator in the ABS is for. There's a blocking valve that's normally open, closes when signaled by the ABS "brain", and a relief valve that's normally closed, which opens to the accumulator when signaled by the ABS "brain". Maybe your rear relief valve is stuck shut, can't open to relieve pressure.

When the wheel turns again, the system may reapply pressure from the master cylinder. The intention is to keep that wheel's brake applied as much as possible without locking.

The old RWAL system had no separate fluid pump; as the system chattered the hydraulic system allowing fluid pressure/blocking fluid pressure/relieving fluid pressure via the accumulator/re-allowing fluid pressure, the brake pedal would sink as the accumulator filled. Newer systems run a fluid pump that keeps the brake pedal nice 'n' high while allowing/blocking/relieving/allowing fluid to the skidding brake.