We are now involved in changing out my Spicer for an Allison. The question has come up about where to mount the transmission cooler. This is an MC5a, by the way. One option is to use two of them, one in front of each radiator since the shutters do not work anyway. We have also talked about putting it on the roof in some inconspicuous way. I wanted to know where other nuts have mounted theirs. I realize that we could use a double oil cooler or one that uses the engine coolant but was concerned about putting more load on the standard cooling system. Thanks all.
Lin, another way to achieve cooling is mount 2 filters 1 for supply and 1 for return where the air supply can reach both.
That setup seems to work as good as a cooler without a fan.
good luck
Lin, 68 5A, two coolers, mounted about 5-6 inches in front of each radiator, no shutters, no problems. :)
Lin -
Another thought: A oil > air radiator/cooler mounted on the transmission access door curbside with a thermostatically controlled cooling fan (off any front-wheel drive car's cooling system). You've already got the louvers OEM from the factory, so no sheetmetal cutting is necessary. Or mount two, the other on the street side access door.
FWIW & HTH. . .
;)
Lin , what engine in your 5A , My dad had a 5A with an 8v71 was told only one allision would fit due to length.
ED
Ed,
It has been repeated many times that a 740 will not fit, and one must go to a 644. I happen to have a 740, but Don has confirmed that it will not fit. However, when trying to arrange a swap with a transmission rebuilder, he told me that he can modify my 740 to save 6 inches and make it fit. We are currently waiting for his figures. The 644 is rated to 300 hp and 780 ft/pds of torque. This is probably okay since the bus is probably around 250-270hp. But if the 740 could work, it would certainly provide a significant safety factor.
We cut an opening in the passenger side engine compartment door and installed this cooler and fan. Jack
Here is an outside view. Jack
Jack, does your fan pull or push? Is there a vacuum at that door while moving?
I did virtually the same install as jack except on the opposite side. I decided to run it with out a fan to see if I actually needed one. At 85 ambient pulling some decent hills in Utah after running for 200 miles from Colorado I measured 150 on the hot side. That seems to be plenty of room to reject heat. I may need a thermostat if I run it in cooler temps. You can always add a fan later YMMV.
Lin, supposedly my 8V71 has been bumped up to 318hp, (aren't they all? ;D ) Even though the 644 is only rated at 300hp i think they may have lowballed the figure a little just because they knew people would push the limits. I think i heard somewhere that the 644 could handle 350 hp but i am not sure on that. Anybody else know anything about it?
Quote from: bottomacher on July 30, 2009, 05:32:44 PM
Jack, does your fan pull or push? Is there a vacuum at that door while moving?
Iniatially, I had the fan pulling in outside (cooler) air, but it was fighting the normal air flow from the blowers above the engine compartment. I reversed the fan direction. In actual use, I have never needed the fan. I have a switch on the dash to control the 3000 CFM fan, but have only turned it on a few times when climbing hills. As soon as I installed it (I still have OEM trans fluiod to water cooler in series with new cooler), I noticed a 5-10 dregge drop in all temps (transmission, oil, and water). Jack
Jack, the doors on a 5 swing up instead of to the side like yours. The nice thing about the way the PO put in the coolers on my 5 is that they are out of the way and don't need any fans added. Simple setup and i will never bang my head on them when accessing the engine from the sides. :)
Ed,
How big are the coolers you are using? I see some Haydens' that are 12x15x1.5. Are your two bigger than that?
Clifford,
The dual filter idea is very interesting. I will talk to Don about that.
Lin, was out of town for a couple of days and just got back. :) Coolers are 20 inches tall by 9 1/2 inches wide by 1 1/2 inches thick and are mounted 5 inches in front of the radiators and not centered but slightly more towards the back of the bus.
In commercial service, a 644 would have been eaten up and spit out.
However, in busnut service where the duty cycle is light, as is the coach, I don't know how you would destroy a good example of a 644....
IMO, as long as you cool it properly, you won't have a problem related to under spec'ing.
happy coaching!
buswarrior
BW,
Yes, that seems to be the info I have gotten. A couple of transmission places have told me that the 644 is overrated; that if they install them for various commercial uses, they will last about two years. It is really just a 640 with the torque converter from a 740. Nothing internally has been upgraded. Our service is much lighter though, the MC5's are relatively light, and the bus is owner operated so they can last fine. That might be the way we end up going, but as I said earlier, I have a 740 and was looking to trade it for a 644. One shop says he can shorten it to fit. Someone told me that the 746 was shorter than the 740, so that it is possible to to do. We are waiting to see what price he comes up with to do the job though. If it is reasonable, we'll do it. If not will trade for the 644.
Ed,
Are your two coolers plumbed inline or separately?
Lin, the 746 is shorter but is a electronic transmission never saw one installed a mechanical engine good luck
Clifford,
I did not mean to say that a 746 was an option, just that a 740 series transmission could be possibly reconfigured to shorten it as this rebuilder claims.
Lin, I had a MCI 5 with a 8v71T and a 644 with a Stone /Bennett never had any problems for the time I owned the bus for 5 years.
The guy I sold it too just changed the engine and
transmission a few years ago so I would not worry about a 644 behind a 8v71.
I am going to call Don and see how the guy is going to shorted the 740 it will have to be done from the front of the transmission I would think.
good luck
Lin, they are inline. From tranny to first cooler, to second cooler, to filter, and back to tranny.
Just make sure that whatever tranny cooling setup you use has enough gpm capacity to not restrict the oil flow. That could defeat your purpose. Somebody needs to refresh my limited memory of the rated flow that the Allison's require. I'm thinking it was 30 gpm but don't quote me on that. Later