| [GMCnet] Gmc brake problems [message #270736] |
Thu, 29 January 2015 12:08  |
Advanced Concept Ener
Messages: 112
Registered: December 2014
Karma: 0
|
Senior Member |
|
|
Thanks for all the replies to my problem. Most of the things I have already tried. New shoes, turned down drums, purged master cylinder before and after installing etc. The matching of curve on shoe to drum makes a lot of sense. Burts explanation makes it easy to understand. Thanks for such a clear explanation. So now where do I find the radius of the shoes other than by trying to measure and calculate it's? Any clever ideas on how to do this without first having to rip them all apart again? Once I determine that this is the problem than I can decide on a remedy. My existing drums are no where near the limit as I checked on this after they were turned down. New drums are a $1000 delivered and I am told they are of questionable quality. Anybody have any comments on hydro boost kit? But that would still require better shoe contact. Then there's the conversion to disks . Just put new emergency brake cables and pulleys so there is more dead money. This money pit gets deeper every
day. $35k in to it and have not had one day camping.
Ken just called and said he tired of working on it. He confident it will stop now after replacing sensitized booster for second time but pedal is still a bit low. Coach is a stretch and they welded at least 1000# of steel up by the radiator to compensate. Now it requires even better brakes.
Sorry for ranting! Need more advice on shoe curvature if someone has it.
Jon J Darcy
646-464-3123
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
|
|
| Re: [GMCnet] Gmc brake problems [message #270750 is a reply to message #270749] |
Thu, 29 January 2015 14:07  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
Number one reason for spongy or soft feeling brake pedal is AIR IN THE
SYSTEM. Reasons for low pedal can be several, but, high on the list is poor
adjustment on the drum brakes. One of the best ways to do this is to
tighten the star wheel adjusters until thew cannot be turned further. Then,
back off 5 clicks, and try to turn the drum. If you cannot, back off 5 more
clicks. Repeat until you can turn the drum and only a slight drag is felt
and heard. REMEMBER, DRUMS EXPAND AWAY FROM THE SHOES WHEN AT OPERATING
TEMPERATURE. If you still have a low pedal, check pushrod length or correct
master cylinder for your application. Last on the list would be
distribution valve in my opinion.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Jan 29, 2015 11:55 AM, "Larry" wrote:
> Advanced Concept Ener wrote on Thu, 29 January 2015 12:08
>> Thanks for all the replies to my problem. Most of the things I have
> already tried. New shoes, turned down drums, purged master cylinder before
> and
>> after installing etc. The matching of curve on shoe to drum makes a lot
> of sense. Burts explanation makes it easy to understand. Thanks for such a
>> clear explanation. So now where do I find the radius of the shoes other
> than by trying to measure and calculate it's? Any clever ideas on how to do
>> this without first having to rip them all apart again? Once I determine
> that this is the problem than I can decide on a remedy. My existing drums
>> are no where near the limit as I checked on this after they were turned
> down. New drums are a $1000 delivered and I am told they are of questionable
>> quality. Anybody have any comments on hydro boost kit? But that would
> still require better shoe contact. Then there's the conversion to disks .
> Just
>> put new emergency brake cables and pulleys so there is more dead money.
> This money pit gets deeper every
>> day. $35k in to it and have not had one day camping.
>> Ken just called and said he tired of working on it. He confident it will
> stop now after replacing sensitized booster for second time but pedal is
>> still a bit low. Coach is a stretch and they welded at least 1000# of
> steel up by the radiator to compensate. Now it requires even better brakes.
>> Sorry for ranting! Need more advice on shoe curvature if someone has it.
>>
>>
>> Jon J Darcy
>> 646-464-3123
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> Where did you get your sensitized booster?
> --
> Larry
> 78 Royale w/500 Caddy
> Menomonie, WI.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] Gmc brake problems [message #270753 is a reply to message #270736] |
Thu, 29 January 2015 14:18 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
|
Senior Member |
|
|
Advanced Concept Ener wrote on Thu, 29 January 2015 12:08...Coach is a stretch and they welded at least 1000# of steel up by the radiator to compensate. Now it requires even better brakes.
...
Really? I don't own a stretch and don't have any close friends that do either but I've never HEARD or READ of this being done or required. That only means that it is news to me. It might very well be common practice but it's news to me if so.
I can see where it might increase front end traction a bit on steep hills/driveways but I think I'd rather try and re-balance the load by moving things up front than by just adding ballast.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
|
|
|
|
|
|
| Re: [GMCnet] Gmc brake problems [message #270757 is a reply to message #270736] |
Thu, 29 January 2015 14:36 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
|
Senior Member |
|
|
I do not have personal experience with hydroboost brakes in a GMC motorhome. However I have seen and experienced quite a few of hydroboost upgrades in other vehicles. Very common in off roading, and Jeep Grand Wagoneers most claim it is their best upgrade.
every hyrdoboost upgrade I have seen is like putting your brakes on steroids. very little brake pressure needed to get action to stop. I have heard the same comments made on the forum by people who have done hyrdoboost upgrades.
Now I am not telling you to do a hyrdoboost to fix this problem, because I think stock brakes can stop just fine. I would think there is some other issue that is being missed, but I am no expert. But if your stopping is an issue because of extra weight of strech, and whatever they did to add weight to the front, then maybe hydroboost setup would make ownership/drivability much better for you. I know on a jeep grand wagoneer, when you go with bigger 33-44" tires, the brakes are not very confident, but you put a hyrdroboost master cylinder in there, you will kiss the windshield if you press on the brake pedal too quick.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
|
|
|
|
| Re: [GMCnet] Gmc brake problems [message #270763 is a reply to message #270736] |
Thu, 29 January 2015 17:10 |
GMC.LES
Messages: 505
Registered: April 2014
Karma: -2
|
Senior Member |
|
|
To verify if the brake shoe curve matches the drum diameter, you need to have both the drum and the shoes off the vehicle. It is as simple as holding the brake shoe in the drum and eyeballing the friction surfaces to see if they match. If the shoe fits with no rocking from end to end of the shoe, the fit is good, if the shoe only touchdown at the middle, and rocks easily end to end, then the shoe could benefit from some re-contouring on a special machine.
To understand what you are looking for, simply draw a circle, then draw a smaller circle inside of the first one with it offset enough that the two touch on one side. The smaller circle represents the shoe, the larger represents the drum. Re-contouring the shoe requires removal of lining material and increasing the shoe's effective diameter until it's "circle" matches that of the drum.
Ask if ken Frey had the drums off while working on your coach. If he did, then I would expect he looked at this. If he didn't, then It could still a possible source of your problems.
Here is some related reading that might help you understand a little better.
http://model-a-wis.com/brakearc.pdf
I'll see if I can find a photo that shows what you need to check. If I do, I'll post it later.
Les Burt
> On Jan 29, 2015, at 1:08 PM, Aces4nrg wrote:
>
> Thanks for all the replies to my problem. Most of the things I have already tried. New shoes, turned down drums, purged master cylinder before and after installing etc. The matching of curve on shoe to drum makes a lot of sense. Burts explanation makes it easy to understand. Thanks for such a clear explanation. So now where do I find the radius of the shoes other than by trying to measure and calculate it's? Any clever ideas on how to do this without first having to rip them all apart again? Once I determine that this is the problem than I can decide on a remedy. My existing drums are no where near the limit as I checked on this after they were turned down. New drums are a $1000 delivered and I am told they are of questionable quality. Anybody have any comments on hydro boost kit? But that would still require better shoe contact. Then there's the conversion to disks . Just put new emergency brake cables and pulleys so there is more dead money. This money pit gets deeper eve
ry
> day. $35k in to it and have not had one day camping.
> Ken just called and said he tired of working on it. He confident it will stop now after replacing sensitized booster for second time but pedal is still a bit low. Coach is a stretch and they welded at least 1000# of steel up by the radiator to compensate. Now it requires even better brakes.
> Sorry for ranting! Need more advice on shoe curvature if someone has it.
>
>
> Jon J Darcy
> 646-464-3123
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] Gmc brake problems [message #270768 is a reply to message #270763] |
Thu, 29 January 2015 17:40 |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
|
Senior Member |
|
|
When I did the Manny Reaction arm/disc brakes I had a similar problem. I'd added the Jim B booster and a 34mm master and the pedal was just too low for my liking. I installed a 2 lb residual pressure valve in the rear brake line at the master and presto, good pedal. I also had an issue with the vacuumn pump running when I hit the brakes so added a rubber seal between the master and booster which fixed the problem.
Here's the valve;
http://www.summitracing.com/search/part-type/residual-pressure-valves?sortby=Default&sortorder=Ascending&keyword=Residual%20Pressure%20Valves& amp; amp;kr=Residual%20Pressure%20Valves
Worked for me, Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
[Updated on: Thu, 29 January 2015 17:40] Report message to a moderator |
|
|
|
GMCforum
Search
Help
Register
Login
Home
