2nd Gen Non-Engine/Transmission Question on 2001 brake components

[SMorneau]

wow it's been forever since I have posted here. Here goes. .



I have obtained a hydraboost from a 2001 4x4, complete with lines to the combination valve, power steering lines, and the old Master cylinder. I am going to put these into my 1996 CTD.



I have new hoses and now I am looking at master cylinders. It seems there was some kind of split in 2001 and I have the earlier small reservoir 1. 25" bore master for disk drum applications. Here is the rub, I would like to use a slightly larger bore like the 1. 312" bore. Two are listed for with a larger bore including the one I ordered from Rockauto, the Raybestos MC 390732 that is used in the 2001 4x2 hoping that would fit but the shoulder diameter is too large for the adaptor plate and the hole in the piston where the rod from the hydraboost fits it too shallow.



I noticed there is also a Raybestos MC390782 that has a 1. 312 bore and is listed for the 2002 4x4.



The same hydraboost was apparently used in 2000, 2001, and 2002 so I figure I should be able to build and adaptor and to make one of the MC mentioned above work but I would rather just find one. Also how do you remove the rod from boost unit (the one between the booster and MC) in case I go that route and have to shorten the rod.



Anybody been here before?



BTW, I am interested in a larger bore to use some of the increased brake line pressure to supply a slightly larger slug of fluid to the wimpy calipers used on the 96 4x4s which eat up pedal travel due to flexing. This is the reason for the infamous falling brake pedal which so many have noticed and tried in vane to fix. I believe this to be true after measuring the calipers with a large micrometer and running thru the calculations. Well also I checked about 6 different vacuum boosted trucks and they all did the same falling pedal crap (even though the owners did not ever notice it). My truck is actually stopping fairly well with the vacuum booster but I am looking for more.

 

[DFerverda]

Quote" Also how do you remove the rod from boost unit (the one between the booster and MC) in case I go that route and have to shorten the rod.

Anybody been here before?

There is a set of recessed nuts,beside where the mc bolts up. Take off the adaptor and you will get the rod and spring.
I just replaced my boost a few months ago. The new one showed up With the rod, It was weird the peddle traveled pretty far before the brakes started to work. I finally pulled stuff apart to see what was goin on... . The rod installed in my new boost was short, but fit the gap. I had the old rod from my old mc and it measured 5 inches the one installed was 4. 5 inches.
Just for S&G i put the 5 inch in, and brakes were back to normal, the mc must have needed the extra travel.
Be careful pulling the rod out, it has a plastic insert on the end that looks about the size of a nickel, to keep the rod centered, you don't want to break it.
Dirk

 

[SSolderitch]

I just got the hydro/mc used & installed only the MC (used) but all were from a early disc/drum. I would stick with the correct year/model parts.

 

[SMorneau]

I will take a look at removing the adaptor and rod.



Not sure what is meant by sticking with the correct/model parts. I guess you mean match the 01 boost to the same size/type of MC as it was delivered by Chrysler?



Actually, that is what I am going to do. First I will try a new stock MC and if necessary I will worry about a larger bore MC later. I may not have the best brakes around but I sure know one hell of a lot more about brakes than I did before I bought this truck in 96.



Thanks for the feedback.