98 K2500 Hydroboost to NBS/GMT800 Hydroboost

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CTX-SLPR

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The hydroboost is leaking on my 98 K2500 Suburban, it's wet back where the cast iron front and rear halfs meet up. I've done some searching but most of what I see is for 1500 Vac to hydroboost. I would love to make my brakes work a bit better on my Suburban with the GMT800 Master as well which I believe requires the GMT800 hydroboost. It seems easy enough to go hydroboost to hydroboost other than swapping the mounting plate from the GMT400 hydroboost over.

Big question I didn't see an answer to was the pedal pushrod? I have pulled a pushrod out of a hydroboost before so I could do that but it does leave the crimped socket a bit mangled. Seeing as the core value is pretty minimal on the GMT400 unit can I cut and splice them like was done to extend the GMT800 in this thread (https://www.gmt400.com/threads/gmt400-vac-to-gmt800-suburban-hydroboost-conversion-detailed-write-up.27168/) ?

Thanks
 
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rojas84

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I have one ready to go into my c2500 that I swapped the pushrod and the mounting plate I removed from an 04 yukon XL haven't got around to installing yet but will get it done as soon as the snow melts .. I did put a tac weld on the 800 hb when I put the 400 pushrod in

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yevgenievich

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Interested in the same swap. Will try to see if gmt800 with hydroboost comes by the local yard.
 

CTX-SLPR

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Well I've been limping along with this for months now and it needs to be fixed soon. The price difference between the GMT800 and GMT400 boosters has narrowed so it's not as much a cost question as a benefit question at this point. Going to the GMT800 booster really only makes sense if I was doing the matching master cylinder. Is that worth it?
 

CTX-SLPR

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and matching wheel cylinders/calipers..... at least in how big the pistons are...
Please do say more. While conceptually I get the idea of matching all of the system specs over to the GMT800 system, I've not read others going through that to get the improved brake feel that's generally the desire to achieve with the swap. Maybe being a 2500 vs. a 1500 it's less discussed.

Thanks
 

thegawd

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You could be right with 2500 vs 1500. all 2500s should have really good brakes and they could all be the same. or maybe it depends on how heavy Duty the axle is... I'm not sure....

the size of the piston in the MC matches the size of the piston in the brake cylinders and calipers.

theres a bunch of different brake rpo codes and they all have different specs. this is why sometimes when people swap in a gmt800 MC and report having good brakes and others report a severe down grade. it's just simply mismatched parts.

theres a thread on here with all the different brake rpo codes and what those codes came with.
 
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thegawd

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here it is.....

 
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