Almost done with the interior of the bus. Took a look at the rear brake cans and they need to be replaced. Any advice on converting to spring brake for parking and emergency brake? I understand the concept. The guy I'm getting parts from doesn't think it can be done.
Ed
4106 may be different, but 4104 is converted by using smaller size rear cans.
Don't know how it is done because mine were installed by the PO.
I've read there is no room for regular spring brakes on a '06 and that you need to get rare and $$ Maxis which are no longer made. The '04 fits regular spring brakes. On my'04 I used the original brake can and piggy backed a spring brake on it (only because the config of the mounting is a little rare on the "04, available but less common)....Anyhoo it is still a tight fit, and i have read repeatedly that an '06 does not have room to mount regular spring brakes.
Ed,
I used to have A 4106 (PD4106566). I put spring brakes on it. Not an easy job.There is no room between the brackets and the bulkhead,you have to cut them off and relocate them so the longer springbrake cans will fit and the wrench will fit to release them if needed.You also have to replace the brake treadle valve. and the push pull release. Alot of replumbing of air lines. I bought a kit from a guy in NC can't remember his name. He has passed on and his son sold the place tha last I heard. The best part was he had a detailed instructiion booklet that was great if you could read and weld you could do it.
I sold my bus to a guy in Montanna he has those instructions, I think. I can e-mail him and see maybe he will send you a copy.
I know this post will probably open up a can of worms about screwing with the design of brake systems but it worked great got rid of that old hand brake.
I also modified my Eagle 05 and got rid of those $1000 dd3 cans.( Actually still have the DD3's promised them to a good looking busnut!!! with a MCI ;D)
Let know if you wan to try and get hold of him.
Ed
i saw on youtube someone did this conversion. search u tube.
Thanks'Chris
mci5c
Here are a few pictures on the internet I found.
I'll have to get under there (I have read all the warnings about getting under the bus) and do some measuring. Great project to take on as the weather changes. I have been looking at different cans. It looks like maybe a "3030" would be the ticket.
that can is very close to the bulkhead and when the bus is on it's weight even less room. As long as everything goes well not a problem, but very difficult to use the bolt to pull the spring in. FWIW on my'04 the capture bolt is also hard to use and if the spring is disengaged (ie air in the springbrake can) I can't get the bolt in for lack of clearance. Not really a big deal just a PITA + why would you need to cage the spring if you had air being able to disengage it.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi392.photobucket.com%2Falbums%2Fpp3%2Fzubzub_photos%2Fprevost%2520scrap%2520and%25204104%2520interior%2FIMG_1947.jpg&hash=54220508bf1c7076084078ac32b8bc17caeb81ba) this is a 30/30 on a 4104.
if the bracket needs to be relocated as in the pics of the '06, I'm not sure why they didn't get it a little closer to the axle providing there was room.
If you can find a local independent Mack truck dealer with a good parts guy he will find you the Mini/Maxie spring brakes Mack Truck used the Mini I think it was the R600 for a few years.
The Volvo owned Mack dealers are not much help.
I bought a set from a dealer in West Texas 2 years for a friend he installed those on a MCI I paid 55 bucks each
good luck
I have spring brakes on mine. To access the cage nuts, I add air to the rear bags raising the bus so the brake can clears the bottom enough to get a wrench in it. Simple and easy, just crib up the bus well enough so you don't get squished.
We run the 3030 spring system, too. We have not had any problems with the system.
As for making the rebuilt mount strong enough, a little math will tell you what the maximum load on the mount can be, then you use a safety multiplier to get all the way up to strength.
For example, if the pot is a 30", then multiply that number by the maximum pressure of your system. If you use the inversion valve, then that pressure should never be exceeded.
If your system will go to 125 pounds, then you are looking at 3750 pounds maximum force. Build in a safety factor. At 3:1, that would mean a little over 5 tons of strength. At 4:1, you are looking at a lot closer to 7 tons.
All sources of air for the brakes must come from the primary brake system, if you want it to work right.
Since a failure of the system would call into question the safety of the conversion, be very careful that the work is done correctly.
I'm not making any recommendation other than to say, be careful, whatever you do.
Good luck.
Tom Caffrey
Quote from: luvrbus on October 02, 2010, 06:17:51 AM
If you can find a local independent Mack truck dealer with a good parts guy he will find you the Mini/Maxie spring brakes Mack Truck used the Mini I think it was the R600 for a few years.
The Volvo owned Mack dealers are not much help.
I bought a set from a dealer in West Texas 2 years for a friend he installed those on a MCI I paid 55 bucks each
good luck
We have an been around for ever Mack dealer here on the shore , i know the shop foreman, and would be glad to do leg work for anyone thats needs help if they use the Mack parts
Don't shoot the messenger here. I just want to bring up legal liability and insurance here.
If anyone does do a brake conversion on their own and you do end up in an accident even if your brakes worked 100% it could cause your insurance company to be a lot less pleasant if they find out you made a major modification like this. Your insurer is not likely to have a problem with your OEM brakes (No matter how old) as long as they are maintained. If you have a professional shop do the conversion there should not be an issue.
Personally, I would still do it as your entire braking system is likely to be safer and less chance of an accident.
My friends sometimes come up with wild ideas that I point out are unsafe and would bring on a lot of liability in case of an accident.
Anything you do to a old GM park brake system is an improvement I have saw those take off rolling when the air pressure leaks off on the UCC parking brakes and the hand brake didn't hold or someone forgot to set it,spring brakes are a big improvement and a lot safer
good luck
Thank you all for the replies. This will have to be better than the tow chain with a box of rocks on the end of it I was planning to use. I just couldn't figure out how to get it to deploy properly.