K30 / K5 Frankenstein: braking problem

[bcoke]

My braking is super touchy right now because the back drums are braking way before the front discs. Turns out I have a master cylinder, proportioning valve, and front lines for a K5, but the axles have been swapped out (owner before me) to 1 tons, which I’m guessing are from a K30.

So looks like I need to go find an MC, prop valve, and line dimensions off a K30 to match the bigger axels, right? Anyone have any advice? Or done this before and been through challenges they can share?

Any help is appreciated!

[AZBuckHunter]

You may just have a bad prop valve or air in the system. When I put tons on my K5 I didn't have to do anything but it was built into a crawler and not driven on the road much. An adjustable prop valve would probably be what I would do if I was going to be driving on the street.

[bcoke]

Yeah that’s what this one is built into (457s in the front and rear and fully rhino lined haha). Great on the trail but hell on the street, and I’ve been trying to make it more of a driver lately.

That’s a good idea, I can start there and keep doing trial and error. Any in particular that you’d recommend?

[AZBuckHunter]

I would get the best you can afford.
You got a pic of your rig on here?

[geezer#99]

You could plumb one of these into the rear line. Put it close to the master.

https://www.summitracing.com/parts/w...hoCyywQAvD_BwE

[71blksuper4x4]

Could always run hyrdroboost.

[57taskforce]

Originally Posted by 71blksuper4x4

Could always run hyrdroboost.

I agree. That and the hydraulic clutch are the two best things I’ve done to my K20. It’s really not hard to do.

[WyoRoadDog]

My guess, and only because I’ve been researching as part of a swap I did, is you have the wrong proportioning valve ( and maybe MC). Was it originally a four wheel drum vehicle? Disc drum needs a different PV from that, and MC should have a front chamber (disc) that’s larger than the rear (drum).