| Author | Message | ||
| Tom Dessert (Mci5er)
Registered Member Username: Mci5er Post Number: 105 Registered: 12-2005 Posted From: 96.39.162.176 Rating: N/A |
I'll probably use incorrect terminology on this post so please bear with me. On all of the MCI buses I've seen so far the belt tension for the gearbox driven cooling fans are set by a pneumatic ram. The ram lifts the front of the gearbox mounting plate as air pressure builds. So, is the rear of the gearbox mounting plate hinged like a clam shell? The reason for asking .... the gearbox on my 5A is bolted to a stationary plate and the front of the gearbox uses rubber shims to set tension. Which by the way is a real pain to keep tight after a new belt is installed. I resently saw an installation were the air ram had been removed and large bolts from under the front of the mounting plate pushed up to lift the plate increasing belt tension. Is that a kit or home made approach. Sure seems easier to do than what I have going. Any input appreciated.... Tom | ||
| ED Hackenbruch (Shadowman)
Registered Member Username: Shadowman Post Number: 195 Registered: 11-2003 Posted From: 75.211.189.60 Rating: N/A |
Tom, i think that is what i have on my 5, along with the pulley that changes its width as the rpms increase, which tensions the belt. Will look at it closer in the morning. | ||
| Paul Karasz (Neverlearn)
Registered Member Username: Neverlearn Post Number: 9 Registered: 11-2009 Posted From: 74.4.253.24  Rating: N/A |
Hi Tom, I have the type with the pneumatic rams - however the air lines were capped off thereby disabling the automatic adjustment. I don't know what, if anything was done to set the adjustment after they were disconnected. I'm not able to check on mine until repairs are complete and I get the bus back home - but I am interested in hearing about the different adjustment methods. Under the assumption that the rams were disconnected for leaking, I planned on rebuilding them so they could be functional again. If the automatic adjustment is not worth the effort and a fixed manual adjustment works just fine then I may go that route. | ||
| Rob Norgren (Robsedona)
Registered Member Username: Robsedona Post Number: 179 Registered: 11-2007 Posted From: 70.212.190.27  Rating: N/A |
I have a Manuel Adjustment on my 66 5a 2 bolts screw up pushing the pulley up with a lock nut on each side. Once I used a good belt from a truck source and stretched bad 5 years ago I got one from MCI (Its a special belt Manufacturer will not say what its made out of) tightened and still going strong the 2 blots are the only adjustment! (Message edited by Robsedona on December 02, 2009) | ||
| Rob Norgren (Robsedona)
Registered Member Username: Robsedona Post Number: 183 Registered: 11-2007 Posted From: 75.208.221.197 Rating: N/A |
Here you can see the Bolts and nuts for adjustment  Here you can see the welded nuts that the adjustment blots go through  | ||
| ED Hackenbruch (Shadowman)
Registered Member Username: Shadowman Post Number: 196 Registered: 11-2003 Posted From: 75.210.84.231 Rating: N/A |
Yup, i have the same setup as Rob plus i have the self adjusting pulley. Have been told these are hard to find and when they go bad are usually replaced with a solid pulley. Part # is 6C-6-79 if anybody wants to check on them and see if you can still get them. Also be advised that there are 2 different sizes of belts. One is 111" for use with the standard axle ratio and the other is 110" for the optional 3.7 axle ratio. Parts # are 8B-27-2 for the first and 8C-27-5 for the latter. | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 701 Registered: 3-2007 Posted From: 71.53.153.91  Rating: N/A |
You can get adjustable pulleys at MacMasters or Miller bearings. Gomer | ||
| Rob Norgren (Robsedona)
Registered Member Username: Robsedona Post Number: 184 Registered: 11-2007 Posted From: 75.209.132.131 Rating: N/A |
Can you post a Pic of the adjustable Pulley? | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 704 Registered: 3-2007 Posted From: 71.53.153.91 Rating: N/A |
Rob; I can't get a photo of the pulley however you can go on-line and see it. It has a stationary piece that is secured to the shaft and the other piece screws on to make the distance you need and then locks in also with allen screws. The larger on the fan end will decrease the speed and samaller will increase. When you screw it in or out.. Gomer | ||
| ED Hackenbruch (Shadowman)
Registered Member Username: Shadowman Post Number: 198 Registered: 11-2003 Posted From: 75.208.220.74 Rating: N/A |
Here is a couple of pics of my pulley. As you can see there is a spring that is part of it. As i understand it, as the rpms increase, the spring pushes the halves of the pulley together, which changes the diameter and tensions the belt.   | ||
| Tom Dessert (Mci5er)
Registered Member Username: Mci5er Post Number: 106 Registered: 12-2005 Posted From: 96.39.162.176 Rating: N/A |
Rob, can you measure the general length and size of the bolts that are used in your adjuster. They appear to be the center bolt from a steering wheel puller w/the puller end caps. Anyone got any idea where I can find them? Ed, is that belt length standard for 8v71 and 6v92 in our application. Since my adjuster uses the shims, the last time I had the belt changed the guy didn't remove the shims he just put on a longer belt which vibrates. So my plan is to change over to this manual adjustment with a new MCI belt and get an adjustable pulley if I can find one. I'll keep you posted... Thanks Tom | ||
| ED Hackenbruch (Shadowman)
Registered Member Username: Shadowman Post Number: 199 Registered: 11-2003 Posted From: 75.210.24.82 Rating: N/A |
Tom, don't know about the 6V92 but those part #s are what is listed in my book for my 68 5A 8V71. Luke could probably tell you more if needed. And if you happen to find more than one self adjusting pulley i would probably be interested in getting it. :>) | ||
| Tom Dessert (Mci5er)
Registered Member Username: Mci5er Post Number: 107 Registered: 12-2005 Posted From: 96.39.162.176 Rating: N/A |
Ed, never noticed it in my box but it actually shows the adjustable pulley. Also looked at some pictures of the blower gearbox mounting located in the Cooling section of my manual. The picture (Plate 6-25) has a caption saying effective prior to coach unit 5578. Mine's 5545. The picture appears to be what I have a bunch of rubber shims that raise the drive front and rear for adjustment. The coach units after 5578 got the adjustable blower puller and what appears to be your configuration with the big manual screws. After 6883 everybody got the air cylinder setup. I bet I'll never find the orignal parts even in a junk yard. I don't have enough detail to see if I can get one made. Well, I'm call MCI tomorrow to see what they say. Maybe call Luke too. Thanks Tom | ||
| Rob Norgren (Robsedona)
Registered Member Username: Robsedona Post Number: 191 Registered: 11-2007 Posted From: 75.208.200.87 Rating: N/A |
Ok I'll measure the general length and size of the bolts that are used in my adjuster today Befor it starts to rain again LOL | ||
| Rob Norgren (Robsedona)
Registered Member Username: Robsedona Post Number: 193 Registered: 11-2007 Posted From: 75.211.65.97 Rating: N/A |
Bolts are 5in and yes I guess could be the center bolt from a wheel puller with the puller end caps nuts are 1 1/16 | ||
| Rob Norgren (Robsedona)
Registered Member Username: Robsedona Post Number: 194 Registered: 11-2007 Posted From: 75.211.65.97 Rating: N/A |
ok my book does not have plate 6-25 for the self adjusting pulley assembly in 1987 MCI wanted 473.04 for the whole unit so the PO but on a reg. pully. Call Universal Coach Parts Inc. Parts 800-323-1238 or Teck Support 800-241-2947 and they can tell you the other numbers for parts if they do not supply anymore at least I have gotten them for bearings that they can not get anymore makes it easer to get from Napa or a truck supply! The # in the book are OEM #s | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 374 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
If all else fails, install an adjustable idler pully. That is what has been done on my MC1. Relativly simple and yet effective. Joe. |