What should tag bag air pressure be set to?

Scott & Heather · March 17, 2016, 08:19:40 AM

Previous owner of my 102C3 moved and set up a regulator system for the tags that is in a much easier spot to reach just inside the curbside engine door. He had the tag pressure set to 35psi. Is that right or should it be more?

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luvrbus · March 17, 2016, 08:30:29 AM

I wouldn't worry about it till you convert you bus then you will need to add more how much is going to depend on the final weight

gumpy · March 17, 2016, 01:16:42 PM

Quote from: Scott Bennett on March 17, 2016, 08:19:40 AM
Previous owner of my 102C3 moved and set up a regulator system for the tags that is in a much easier spot to reach just inside the curbside engine door. He had the tag pressure set to 35psi. Is that right or should it be more?

Off the top of my head, I believe that's what the MC9 tag pressure is set at. Check your manual. Should tell you in there. I didn't check mine, but I seem to recall that's what it is.

Scott & Heather · March 17, 2016, 04:49:48 PM

Thanks! I'll leave it at 35 psi for now then and then after weighing the coach I'll come back to the table

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luvrbus · March 17, 2016, 05:16:53 PM

Just remember the more air pressure in the tag the weight shifts to the front axle

Scott & Heather · March 17, 2016, 07:27:12 PM

Ok. I'll be weighing all my axles separately and adjust accordingly. Thanks again for pointing me in the right direction.

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Jon · March 18, 2016, 04:27:40 AM

Why isn't the coach set up as it was built?

Messing with air bag pressures transfers weight among the axles. Maybe there is a benefit to doing that but the end result is now other systems are affected such as the brake chamber size, bearings and even structure which is all designed based on the weight distribution from the original design.

Scott & Heather · March 18, 2016, 06:08:06 AM

Thankfully we aren't messing with air bag pressures, the controls were moved to an easier access location by the previous owner and once I know my converted weights, I'm going to adjust them properly according to specs I find from MCI.

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luvrbus · March 18, 2016, 06:19:16 AM

MCI has always had adjustable tags,1000's of time I wished Eagle had the adjustment the 1&7/16in wrench with a 4 ft bar and re indexing one used on a Eagle to adjust the weight on the front axle that sh!! get old in a hurry.FWIW the old dog drivers loved that feature to adjust to the driving conditions

Scott & Heather · March 18, 2016, 02:45:15 PM

Cliff, I'll actually be putting gauges in up front so when I dump tag air I'll know it's actually working. I read somewhere that dumping tag air adds +or- 7,000lbs to drive axle. That's helpful when it's slick out and you know we drive in the snow more than we care to mention.

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buswarrior · March 19, 2016, 07:56:13 AM

7k lbs may be a little high?

Go play on the scales. The MTO leave the scales turned on here in Ontario, when the coop is closed.

MCI doesn't lift like a Prevost, so the weight of the "Stuff" still rests on the ground. The Prevost is able to add the weight of the "stuff" as well, by putting it all in the air.

Best I saw on either of my MC8 was the tag carrying around 3k lbs aired up.

The switch on the side panel still leaves some air in the system (15 lbs vs 35 lbs) via a second regulator, vs the shut off valves down the back emptying them completely.

happy coaching!
buswarrior

gumpy · March 19, 2016, 08:03:21 PM

Quote from: Scott Bennett on March 18, 2016, 02:45:15 PM
Cliff, I'll actually be putting gauges in up front so when I dump tag air I'll know it's actually working. I read somewhere that dumping tag air adds +or- 7,000lbs to drive axle. That's helpful when it's slick out and you know we drive in the snow more than we care to mention.

I think it's more like 5K.

Scott & Heather · March 19, 2016, 08:20:43 PM

Ok. Nice. I wasn't sure what the weight was. 7000 sounded high to me but I'm not an expert. I don't often need to dump my tag air. But I did once when I had my drive axle suspended in a small washout from a recent hurricane downpour. Dumped tag air and dropped the drive duals on the gravel and was able to get unstuck. Definitely useful when you need it.

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mikelutestanski · March 20, 2016, 10:46:53 AM

Hello My 72 mci 7 weighs in at 6K on the axles as a conversion.
The 30 or 35 pound set point is right on. WHat you dont want is to have the reguator go to full pressure . YOu can pull the bus frame apart with full pressure. I saw one in NY where the regulator was broken and the operator just hooked up full air to one side. the framework above the bellows was crushed and the bag destroyed.
I had to turn down the welding repair because the operator was not reliable about paying his bills.. and he was a chronic complainer.
regards mike

luvrbus · March 20, 2016, 11:34:35 AM

He is dealing with a C3 aren't they different ? my D has 14,000 lbs tags the air pressure is a lot more than 35 lbs