Funny all these years reading stuff on this forum and I still come across things I've not read before. I didn't know putting van master cylinders on was a thing.
CK5
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'84 K5 Build (Midlife Crisis)
- Thread starter Fastereddie
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- four link magnum tire carrier
It's a box van like a FedEx type truck with bigger brakes. The one I used was for a 1983 chevy P30 with 4 wheel disc brakes, diesel engine and hydro boost. Bolts right on but has a bigger piston.
Yeah the application I looked up said 1994 p30 with rear disc. Had a v6 lol. Also says c3500hd is the same application
Not many realize but the P30 really is just a modified C30 with straight frame rails. The front suspension is interchangeable. But because the P30 was used for higher GVW applications like step vans and RV it usually had bigger brakes.
It's something to watch out for because when they bumped the GVW up in the early nineties it exceeded the weight rating of the park pawl in the 4L80e trans. So those will typically have a overly complex auto apply park brake system that had a big drum on the output of the trans. The early ones used power steering fluid pressure to *release* the brake since is was spring loaded to apply. Those transmissions have no park pawl so keep that in mind if you come across a cheap 4L80e that came from an rv.
That’s interesting
Workhorse continued the P30 on pretty much unchanged in the frame/suspension for the step vans. The P30 rv chassis got the "widetrack" front end in '99 or '00 which really was adding 6" box channel to the side of the frame to push all the suspension mount points further out to widen the track. Control arms were the same. They were able to bump the GVW up to 18k from 16k at the same time too with heavier air bags in the front coils and beefier rear springs.
Hard to believe a chassis design that developed in the late 60's and put into service in '73 lasted all the way up to 2005 before Workhorse replaced it with the w16 chassis for commercial and rv.
Would it bolt up to my vintage 1984 hydroboost that was in my old CUCV K5 and got transplanted to the crew cab?
Actually the crew cab had hydroboost and I just swapped the hydroboost unit since it was rebuilt and high-flow modified. So the master cylinder is a 1989 vintage.
I don’t know if the hydro boost has the same size pilot as vacuum boost or not. I’ve never had it
I specifically did a P30 with diesel engine and hydroboost the same year as my blazer and it bolted up just fine to my hydroboost.
I used a mc from an 04 hydroboost on my truck for conversion. I had to update to an 81+ vacuum booster as the 80 and down had a smaller hole.
Just sitting here wanting to drive...I got the e-brake just about working right. Got the brakes bled. Topped off the diff. Going to pull the links for paint tomorrow and work on making gussets
So I took an easy drive around the neighborhood to get a feel and check for leaks etc... Brakes are definitely better even without the new pads and rotors bedded in yet. It feels different but the same too. The sway bar definitely works because it feels like it still has leafs on the rear as far as stability.
I have two issues I need to address. The parking brake needs some love and the exhaust has to change. Somehow I need to get the exhaust routed out from under the truck. I have an idea but have to see if it will work.
I have two issues I need to address. The parking brake needs some love and the exhaust has to change. Somehow I need to get the exhaust routed out from under the truck. I have an idea but have to see if it will work.
FYI but be careful with panic stops until you know if you need to add an adjustable prop valve to the rear circuit. Mine would spin in circles on snow and ice due to the rear locking up first. You won't probably notice it til you have to panic stop somewhere.
10-4, once I get them broken in, I’ll try some slides on the dirt. Cause I‘ain’t got no ice or snow haha.
Wet roads with a panic stop are fun too! Even dry slick city roads. I've done 180s on both with other trucks. Lol.
Got a couple gussets tacked in after work. This 4pm dark shit blows...
