2nd Gen Non-Engine/Transmission Mstr cylndr + hydra assist

[Bseg]

Anyone replaced a master cylinder and the hydra assist assembly on a 97?



Pretty sure that mine is sticky and not allowing the brakes to release. They eventually release fully but tend to hold on enough to cause a drag when you start out from a stop.



Is there any special technique to bleeding, and do you have to bleed the hydra assist system too?

 

[Dave M]

Anyone replaced a master cylinder and the hydra assist assembly on a 97?



Pretty sure that mine is sticky and not allowing the brakes to release. They eventually release fully but tend to hold on enough to cause a drag when you start out from a stop.



Is there any special technique to bleeding, and do you have to bleed the hydra assist system too?

I haven't replaced the master cylinder but have replaced the Hydroboost on my 97. I got a new (not rebulit) hydroboost unit from www.hydroboost.com for about $275. They sell retrofit racing units so their pricing on the site is for that application. You need to email or call for OEM pricing. Paul is great to work with and full of knowledge and very helpfull.



I have heard some have trouble with rebuilt units and some don't. I wanted a new unit and not worry about trouble with rebuilts. The hydratech unit cost about $275 plus shipping and new from dodge was about $525. The downside is you have to send your unit in so they can remove the pushrod and firewall bracket and install on the new. Truck was down about 2 weeks waiting for parts but they turned it around in 1 day for me. Very satisfied with the Hyratech booster and customer response.



I had to bleed the power steering by jacking up front end and pouring p. s. fluid in resouvoir and turning steering wheel lock to lock while randomly applying brakes. When air is gone you won't see bubbles in resouvoir. The booster is basically self purging. I had no problem. But I didn't draining the fluid from the lines or pump. I don't know what would happen if they were empty to begin with.



I changed the fliud to synthetic so I pulled the return line at the power steering pump and plugged the end of the line. Then put another hose on return pump fitting and let fluid drain into container while I added new fluid while turning wheel and hitting brakes. I kept reconnecting the return line and repeating wheel turing many times so fluid would be cycled thru system as I transferred fluid. Did that about a dozen times till most of the fluid was transferred.



Why don't you try either the boost unit or the master cylinder one at a time. The hydroboost unit was not that bad of a job. I left master cylinder hanging with line connected and worked around it. I never needed to bleeed the brakes. There is no direct fluid connection between the boost and the master cylinder. When you push on the brake pedal the motion is tranferred thru the booster and a short rod comes out the other end of booster and pushes on a cupped metal thing in the master cylinder. You'll see this if you disconeect the booster mechanically from the master cylinder. Your problem could be either part.



Hope that helps some. I haven't needed to bleed my brakes yet, so can't help you there.



Dave

 

[Bseg]

Thanks for the info. I'm not sure yet if the hydraboost unit or the master cylinder could be the problem. I replaced both front calipers for the second time in the last year and noticed that afterwards the pads drag a little and then eventually release. This has happened in the past when I put new pads on so it might be due to the new pads having a lot of material and need to get seated in.



If you are wondering why I replaced calipers for a second time in a year, what happened was a week after I replaced the pads the caliper on the pass side broke where the pad clips onto it. Not sure why but it sheared off there and I replaced that caliper and then the truck started pulling to that side during braking, so I replaced the other side and now it brakes in a straight line. Just seems like the brakes aren't releasing after I come to a stop.



I'm also going to try some other type of high temp grease on the slider bolts and the mating surfaces, maybe what I used can't take the temp.