| Author |
Message |
Tim (Timkar)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 25, 2005 - 1:03 am: | |
My stripped out 87 MCI 102A2 with a 6V92T and Allison has a GVWR of 36800Lbs with a max front weight of 14400LBS and rear max of 22400.
I have read somewhere (though I can't remember where, hence the reason for this post) that it is not recommended to use the A2 for towing. Has anyone else read this before? I am trying to determine if it is the manufacturers recommendation or a personal opinion I may have read somewhere.
I want to ensure that I can tow a car trailer with this unit, before I start the conversion process. |
Sojourner (Jjimage)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 25, 2005 - 9:08 am: | |
Here in Florida, DOT have spot check routinely at some city to weigh each truck & trailer axle.
If you are not over the legal limit per axle with or without loaded trailer, then you’re safe.
FWIW
Sojourn for Christ, Jerry |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 25, 2005 - 7:14 pm: | |
Tim, first of all, do a search on this board and you will find a ton of posts.
Next, we need to know more about what you are towing.
The big issue is the structure of the bus. Any trailer hitch design will attach to the engine cradle system on most busses. The cradle was not designed for some of the large loads that trailers can impose on them. This can be made worse by corrosion and fatigue which can reduce the ability to handle large loads.
There are two kinds of load: horizontal (straight pull as in a tow bar and toad). The second is vertical load. In my opinion, most engine cradles that have not been compromised by corrosion will handle reasonable horizontal loads/pulls (i.e. most any size toad). It is the vertical loads that are a concern. Any trailer should have at least 10% of its weight imposed on the trailer hitch. Thus a 5,000 pound trailer will impose at least 500 pounds on the hitch minimum. That is a lot of load on the engine cradle structure.
Some folks use equalizer hitches to take some of the load off the trailer hitch. That works to some degree, but puts some different loads into the system that can cause problems if the hitch is not properly designed.
Lots of folks tow large trailers and have had no problem. Having said that, there are also folks who have reported frame problems. In my opinion, you are really pushing the limit, if you have a trailer that weighs more than 5,000 pounds.
Larger trailers can be used with auxiliary trailer tongue dollies or specially designed trailers. As a part of gathering information for an article I am writing, I have described some of those systems on my web site:
http://www.rvsafetysystems.com/Trailer%20Towing.htm
You mention GVWR. That is for the bus only and the trailer would not normally count against that rating. The rating that includes trailers is GVCWR where the “C” is combined which includes the bus and trailer. Since buses were not designed to pull trailers, they do not have a GVCWR. The main issue with the weight rating is to make sure that no axle is overloaded (each axle will have a rating) and the trailer impact on the brakes. If no auxiliary brake are used, you should not exceed the GVWR which is a real challenge with some conversions.
There are some other issues that might come into the pictures. Overall length can be a concern in some states on some highways. Having enough power and gearing can also be a concern.
Sorry for the long post. Probably more than you wanted to know.
Let us know what you want to pull (if I did not cover it here) and we will give you some more input.
Jim Shepherd
Evergreen, CO
’85 Eagle 10
Bus Project details: http://www.rvsafetysystems.com/busproject.htm (updated 2/17/05) |
Tim (Timkar)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 25, 2005 - 8:14 pm: | |
Thanks Jerry and Jim for your reponses. I have read a lot of the previous posts, but my concern was pulling a trailer with an A2. Most of the posts I have read are from guys with tag axles, but I haven't seen too much from the guys with the single axle ie: GMs, etc.My intent was to pull a car trailer and car with an approx weight of 4500#. I can remember reading somewhere (after I purchased the A2)that when MCI designed these A2s that they were not to be used for towing. If I can't find the site again, I'll have to try calling MCI to see if they can shed some light. Once again thanks for your valued input. |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 25, 2005 - 10:16 pm: | |
Tim, to give you a feeling, your trailer should put about 500 pounds vertical load on the hitch to handle correctly. <<<the rest of this message contained a stupid calculation error on my part. See next message>>>
Jim |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 25, 2005 - 10:26 pm: | |
Oops! Wow, when I mess up, I really mess up! Lets try this again. If you had a 25 foot wheelbase and 10 foot overhang in the rear, the 500 pound load would put 700 pounds extra on the rear end and take about 200 pound off the front axle.
That is the static loading. Of course, the dynamic loads can become quite a bit higher as you go over rough road, dips, etc.
If you have a good hitch designed and mounted, you could use an equalizer hitch which could reduce the rear axle load quite a bit, while distributing some of the load to the trailer axles and front axle.
Jim |
RJ Long (Rjlong)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 26, 2005 - 1:44 am: | |
Tim -
Can you pull the car four-down, rather than on a trailer??? That would eliminate the vertical-loading problems with the hitch.
If not, highly suggest you look into the "Tuff-Tow" unit for the trailer, again, to minimize the vertical loading challenges. www.tufftow.com
Whatever you do, in order to spread the towing loads better, be sure to tie the hitch into the rear axle's radius rods as well as the engine cradle.
HTH,
RJ
PD4106-2784
Fresno CA |
Geoff (Geoff)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 26, 2005 - 7:48 am: | |
The only difference I see between a 3 axle and a two axle bus for towing is the greater weight capacity of the 3 axle. As long as Tim isn't overloaded in the rear he should have no problem towing a trailer as long as he has a good hitch. I tow a 20' race car trailer (7,000lbs) with my two axle RTS and handling is not a problem.
--Geoff
'82 RTS CA |
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