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richinny · 05-26-2009, 10:30 PM

Quote:

Originally Posted by bkahler

since this is a 310 its likely going to have two rubber hoses for the rear brakes, one for each rear caliper. While its possible I would be surprised if they both failed at the same time.

how does the line run to the rear axle? does it go from a single line along the frame to a rubber line on the axle and then split to two steel lines to the calipers?

check for a squashed steel line too.

dljosephson · 05-27-2009, 12:20 AM

To Mike Leary: The Mico Levr-Lock is a manually controllable check valve that allows you to step on the brakes, shift a lever, and hold the brake pressure just as if you were still stepping on the brakes. This 310 had no parking brake (maybe it had a drive line brake before the Gear Vendors was added, but there isn't one now). I first used them in fire trucks that had Allison automatic transmissions (which have no Park).

I see that the Mico instructions say not to use these things for more than an hour. Maybe that's the problem, I used it at least overnight, maybe these hoses don't like to have pressure for that long. I think I have enough info to chase this all down now... arrgh.

To rchinny and overlander63, thanks for the troubleshooting points. Aside from this problem, the brakes work fine -- they are certainly more powerful than the Isuzu or 11,000 pounds empty going downhill. There is one steel line to the back, a cube-shaped tee and steel lines to the calipers, with short rubber sections. The mechanic who came out to look also mentioned this possibility that the rubber lines had deteriorated to the point where they would act like checkvalves ... we'll see.

Now I wonder why Bendix/GM disk brake calipers have metric bleeder screws !?

Mike Leary · 05-27-2009, 07:59 AM

Wow, I wonder how many 310s that had Gear Vendors installed have the Lever-Lock?
I have a U.S. Gear od with the drum brake on the stern.

dljosephson · 05-28-2009, 05:10 PM

Quote:

Originally Posted by Mike Leary

Wow, I wonder how many 310s that had Gear Vendors installed have the Lever-Lock?
I have a U.S. Gear od with the drum brake on the stern.

I don't know. Lever-Locks are popular on fire trucks, delivery vans, tow trucks, etc. The "mobile mechanic" who responded when we were locked up on the road was of the opinion that Lever-Locks were illegal in California. Looking this up a bit more, it seems to be not quite the case -- they are OK but we do need a parking brake that is entirely separate (except for drums, rotors, shoes, etc.) from the service brake system. So I guess we will be looking for a drive line brake system anyway.

Mike Leary · 05-28-2009, 08:29 PM

Better check first to see if the stock parking brake fits the rear of the Gear Vendor,
then the fun of getting the driveline shortened to fit starts.

pwhittle · 06-18-2009, 07:43 PM

Quote:

Originally Posted by pwhittle

I just replaced my master cylinder to address a leak, and I was hoping my brake pedal would have improved. However, it remains the same. We flushed the fluid out when we replaced teh MC.

My pedal travels a long way before the brakes start to apply, then it still seems soft.

I will flush out the power steering fluid and check the pedal to hydroboost linkage to see if that helps.

What do your brake pedals feel like? Mine are not very confidence inspiring, but I want to make sure my expectations are set correctly.

What are the symptoms of a failing HydroBoost?

Paul

Last weekend I flushed out the power steering as best I could and the brake pedal became much better. I am happy now.

Could not find any instructions on flushing the fluid, but I undid the hoses into the steering box and let it all run out, then refilled with new fluid, ran it for a bit, and repeated a second time.

Paul

MaryContrary · 10-29-2009, 08:53 PM

wow found this thread just in the nick of time...
we are on the road now and found a leak in the MC so we replaced, bled the lines and the breaks are firm when the engine is off.(we have bled thru 3 large containers of dot 3 untill it ran clear and clean)
However, as soon as the engine is on, breaks go squishy and almost to the floor and i'm not very confident in even driving 5 miles to a service station

tomorrow morning we will bleed the power steering just as stated above

i pray this is not a hydroboost problem....but i'm kinda guessing it is.

MaryContrary · 10-30-2009, 07:09 PM

arrr! bad MC from napa!
2 days of bleeding breaks and finally we now see brake fluid gushing from between the reservoir and cylinder.

...and a petal that wont return from the down position.
i'm walking in youz guys footsteps, your information is invaluable.

bkahler · 10-30-2009, 07:45 PM

Quote:

Originally Posted by MaryContrary

arrr! bad MC from napa!
2 days of bleeding breaks and finally we now see brake fluid gushing from between the reservoir and cylinder.

...and a petal that wont return from the down position.
i'm walking in youz guys footsteps, your information is invaluable.

Mary, I feel your pain

. We went through something similar when we had our brake m/c and booster replaced. Took the shop a month to figure out they had the wrong parts/bad parts/miss matched parts. I posted a long thread on it a couple of years ago.

One thing to keep in mind, the shop doing our work couldn't get the brakes bleed until they bought a power bleeder. They still went through 3 or 4 gallons of fluid before they got it right. However a shop that had worked on our brakes previously (and did a great job) told me that the key to bleeding the brakes was slow steady down pressure on the pedal while the bleeder was open. He said fast pedal pushing during the bleeding cycle didn't help things, actually made it worse.

Good luck and let us know how it works out.

Brad

klattu · 10-30-2009, 09:09 PM

When they let us rebuild the MC with a kit, we never had this problem.
Had the Lever-Lock on a VW dune buggy, same results...locked up the brakes even though the knob popped up as if it had released.
If you can use the vacuum method, it is a one man job.
Just be sure to draw fluid from low to high.

MaryContrary · 11-03-2009, 10:51 PM

2nd MC installed...just about 4 or 5 gallons of break fluid later....and 4 qts of power steering fluid....and countless hours slowly bleeding the breaks
but now i have solid breaks

but guess what...now the power steering is acting up and making a grinding noise when i make right hand turns
...how 'bout a new belt and pump and possibly replace those lines too

GlenCoombe · 11-04-2009, 05:45 AM

Mary, seems to me I recall that air in the power steering system can cause the noise. If I'm not loosing my mind...(unlikely) you will get the best results by lifting the front end off the ground and cycling the steering from lock to lock a number of times to bleed the air out.

Without going into search mode, due to limited available time, I'm doing this from faulty memory.

Perhaps others will chime in on this subject too.

bkahler · 11-04-2009, 07:35 AM

Glen,

From what I remember I think you're right on the money about getting the front wheels off the ground and turning the steering wheel lock to lock to bleed the air from the system.

I would think if the power steering was working ok before the brake work then it should be ok after the brake work.

Just my $0.02

Brad

Mike Leary · 11-04-2009, 08:20 AM

Check the power steering hoses while the coach is off the ground; they do wear out and leak, causing way more fun.!

MaryContrary · 11-07-2009, 07:57 PM

wow thank you guys sooo much
once again these threads saved us while on the road
everything is working tip top now.

Brad i am so glad you documented all your brake nightmare, i am following in your footsteps
and Mr Mike Leary, i think we just passed you in Flagstaff...!@#!
We are in Albuquerque, and headed north to Santa Fe
...time to look up all the threads about winterizing..lol
i'd love to meet up...where are you headed?
4000 mile trip and the only major repair was the MC and power steering issue..but i can blame that on Big Sur, Ca.

PLDodd · 11-07-2009, 08:31 PM

when the brakes lock up, loosen the master cylinder mounting bolts instead of releasing the fluid at the caliper. If this releases the brakes, adjust the brake booster pushrod. On gm p30 chassis there are about 10 different master cylinders that look almost the same and will bolt up so it could easliy be the wrong one.

Mike Leary · 11-08-2009, 06:58 AM

Quote:

Originally Posted by MaryContrary

Mr Mike Leary, i think we just passed you in Flagstaff...!@#!

That indeed was us, sorry to miss you! Were you on 66? We're headed south, but hanging north until the weather cools; northern thick blood, you know. Send us a pm if you're in the area.

Myrtle lynn · 03-19-2011, 05:25 PM

Ok. Have my 87 345 in shop for 2 months with hydro boost problems. Has there been an update for this thread since 2009? I am going to relate the post from this thread to them on Monday. I was just checking if there was an update. Thanks for any help.
Dan

dljosephson · 03-19-2011, 11:34 PM

For the full report on my brake problem see
http://www.airforums.com/forums/f159...-td-70005.html

It has stayed fixed :-)

I learned more about this brake system than I ever wanted to know. Alignment between the hydroboost and the brake cylinder is critical. Does your 345 have a Mico Lock or any other difference from the stock system? What problems are you having?

jjhypnotist · 03-20-2011, 02:36 PM

These repair shops want to argue all day long however If the hydroboost has been replaced then it is not the issue...
I went through hell with mine too The master cylinder must be shimmed out to the right distance or it will slowly but surely activate the brakes..
Once I had mine fixed I never had another issue with it.....

The lock up issue did cause parts in the transmission to wear out prematurely though.
Justin