| Author | Message | ||
| carl white (Carl_mci_9)
Registered Member Username: Carl_mci_9 Post Number: 3 Registered: 1-2007 Posted From: 208.108.100.1 Rating: N/A |
I have a 79 mci 9 with a 8v71 and an allison 740 transmission. How hard is it to swap and what needs to be done to switch it to a 6v92 ddec and an allison 5speed transmission that is all in one unit? I need a new transmission and I am trying to figure the best way go. Thanks Carl | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 60 Registered: 8-2006 Posted From: 207.231.81.154 Rating: N/A |
Carl, That is probably one of the easiest swaps out there. The exhaust would have to be changed, due to it now coming from the turbo on top of the engine, instead of two manifolds on the sides. I assume you are talking about a 754 trans? Putting a DDEC engine in a non-DDEC bus, with what sounds like a non-DDEC trans, complicates things considerably! I would STRONGLY consider a 6V92 MUI (the mechanically injected version). Replacing an 8V71 with a 6V92T, and a 740 with a 754 will give you LOTS better performance, less smoke, and better fuel mileage! 740 to 754 will require a shifter change also, but the change to a shorter engine and a longer trans might not be too bad? | ||
| Chris Martin (Cjmiam)
Registered Member Username: Cjmiam Post Number: 1 Registered: 1-2007 Posted From: 69.4.115.238 Rating: N/A |
Well, I've been hanging out here for quite a while, but never registered. You guys are all very informative! Carl, I did exactly what you are considering. It took two buddies (diesel mechanics) and me 2 days to do a swap. My Scout troop blew an engine 3 years ago on spring break down in Tucumcari, NM. We ended up buying a NJ Transit from ABC in MN and had a Scout dad drive it down to us. We shipped the other bus back to WI. Once back we swapped the bad 8v71 with the newer good 6v92. You'll need to remove the back bumper, disconnect a couple wire harnesses, fuel lines, exhaust, belts, drive shaft and I think 4 bolts holding the frame on the rail. Then the whole engine just slides right out. I think a couple of the sensors needed to be swapped as well. We also needed to swap the throttle cables because they were different lengths. So you may need to purchase a new one. Like George mentioned you’ll have to do a little modification to the exhaust. All we needed to do really was cut out the area around the muffler to allow for the larger size. You will need a hoist that ideally can pull out while lifting or else a way to lift and pull at once. It wasn't too bad.. Just make sure you wear something that you can throw away after you get done.  | ||
| larry currier (Larryc)
Registered Member Username: Larryc Post Number: 3 Registered: 2-2007 Posted From: 207.200.116.13 Rating: N/A |
Carl, I have the 6V92 DDEC and I can tell you that you don't want one. Mine gets 5 MPG all the time. (Eagle 20). There is an Eagle 10 @ the new Eagle Bus site with a mechanical engine (6V92TA) that is getting 10 MPG. Why don't you stay with the dry sleve 8V71TA. Its a bolt in for the most part and many times the engine. DDEC and ATEC require many new wire looms. No way. |