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Re: 1972 Travco rebuild and Cummings swap.

Unread postby ontheroad on Tue Oct 31, 2017 4:44 pm

I didn't know the ratio. I just looked it up and it's a 5.375. And I found out that they do offer a 3.90, so if I get it, I will be doing a gear swap. Yes, I plan on using the front end and all the trimmings, springs, mounts, etc. I know that my spring bushings, kingpins, tie rods, etc, are shot. Not a 100% right now, but I think I will just unbolt the spring mounts off the frame of the Isuzu and unbolt the mounts off the Travco and drill a million new holes and mount it all right back on.
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Re: 1972 Travco rebuild and Cummings swap.

Unread postby Kckalden on Thu May 17, 2018 10:19 pm

Yea I am moving slow with this project but here is an update. I spent some time a few weeks ago taking out the floor under the bunk. Good thing I did as I found a lot of rot and carpenter ants. I also picked up a newer fridge and installed it.

I was about to reinstall the cabinets when I decided to stop until I have the new running gear under it just in case the taller tires require me to modify the wheel wells. I decided on keeping the Cummins Allison set up from the donor and planned to change out the 3.73:1 gears to 3.54:1 and run 9R22.5 tires. This is the best I can do given the Dana 70 hd axle and 6 lug hubs. This combination would let me cruise at 70 mph though running higher rpms than I like. But wait one minute.

I took the rear axle out of the donor motorhome and took it apart. I had a hard time getting numbers to match that and my pinion spline count was off. Could it be? It was! The axle was not a Dana 70 hd but rather a Dana 80. This gave me more options on gearing and that afternoon after consulting with Summit racing’s tech support and Dana I ordered 3.31:1 gears. This means even lower rpms at cruising speeds. The Allison has a lot lower gears in 1,2,3rd so I should not have a problem with giddy up and go.
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Re: 1972 Travco rebuild and Cummings swap.

Unread postby Kckalden on Thu May 17, 2018 10:20 pm

Yea I am moving slow with this project but here is an update. I spent some time a few weeks ago taking out the floor under the bunk. Good thing I did as I found a lot of rot and carpenter ants. I also picked up a newer fridge and installed it.

I was about to reinstall the cabinets when I decided to stop until I have the new running gear under it just in case the taller tires require me to modify the wheel wells. I decided on keeping the Cummins Allison set up from the donor and planned to change out the 3.73:1 gears to 3.54:1 and run 9R22.5 tires. This is the best I can do given the Dana 70 hd axle and 6 lug hubs. This combination would let me cruise at 70 mph though running higher rpms than I like. But wait one minute.

I took the rear axle out of the donor motorhome and took it apart. I had a hard time getting numbers to match that and my pinion spline count was off. Could it be? It was! The axle was not a Dana 70 hd but rather a Dana 80. This gave me more options on gearing and that afternoon after consulting with Summit racing’s tech support and Dana I ordered 3.31:1 gears. This means even lower rpms at cruising speeds. The Allison has a lot lower gears in 1,2,3rd so I should not have a problem with giddy up and go.
Kckalden
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Posts: 32
Joined: Sun Apr 10, 2016 10:46 am
Location: Stephenville Texas
Travco Model: 1972 270

Re: 1972 Travco rebuild and Cummings swap.

Unread postby Kckalden on Thu May 17, 2018 10:20 pm

Yea I am moving slow with this project but here is an update. I spent some time a few weeks ago taking out the floor under the bunk. Good thing I did as I found a lot of rot and carpenter ants. I also picked up a newer fridge and installed it.

I was about to reinstall the cabinets when I decided to stop until I have the new running gear under it just in case the taller tires require me to modify the wheel wells. I decided on keeping the Cummins Allison set up from the donor and planned to change out the 3.73:1 gears to 3.54:1 and run 9R22.5 tires. This is the best I can do given the Dana 70 hd axle and 6 lug hubs. This combination would let me cruise at 70 mph though running higher rpms than I like. But wait one minute.

I took the rear axle out of the donor motorhome and took it apart. I had a hard time getting numbers to match that and my pinion spline count was off. Could it be? It was! The axle was not a Dana 70 hd but rather a Dana 80. This gave me more options on gearing and that afternoon after consulting with Summit racing’s tech support and Dana I ordered 3.31:1 gears. This means even lower rpms at cruising speeds. The Allison has a lot lower gears in 1,2,3rd so I should not have a problem with giddy up and go.
Kckalden
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Posts: 32
Joined: Sun Apr 10, 2016 10:46 am
Location: Stephenville Texas
Travco Model: 1972 270

Re: 1972 Travco rebuild and Cummings swap.

Unread postby rjsdotorg on Tue May 22, 2018 8:03 am

I'll bet a lot of people with 318s would be glad to have that 413. I had a 318 2BBL in my Chinook and it was sloooooow.
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Re: 1972 Travco rebuild and Cummings swap.

Unread postby Kckalden on Tue May 22, 2018 12:51 pm

I got one for sale
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Re: 1972 Travco rebuild and Cummings swap.

Unread postby Kckalden on Tue May 29, 2018 7:14 pm

I changed out the ring and pinion giving it a 3.31:1 ration. I took the rear out and when doing so realized there was a 3/4 lift block under the right hand spring. I assumed there was one on the other side and when I put the new axle under could only find one block. After searching the shop I came to the conclusion that only one side had a block. Compensating for the generator?

Unfortunately I did not realize the spring perches for the Dana 80 are wider and it was not until I wrestled it in place did I discovered this. Today I made the 80 mile trip to Summit Racing in Arlington figuring they would have perches, lift blocks etc. nope! It appears no one makes perches for the 4 inch tubes on the Dana 70hd and 80s. They grind them out. Also the blocks are a lot smaller with 9/16 locator pins instead of the 5/8 pin used on my Travco. I will make blocks out of some plate I have and use the old perches from the travco axle.

I would love to post pics but won’t take up time to shrike my files to meet this forums requirements.
Kckalden
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Travco Model: 1972 270

Re: 1972 Travco rebuild and Cummings swap.

Unread postby rjsdotorg on Tue May 29, 2018 8:55 pm

Kckalden wrote:I changed out the ring and pinion giving it a 3.31:1 ration. I took the rear out and when doing so realized there was a 3/4 lift block under the right hand spring. I assumed there was one on the other side and when I put the new axle under could only find one block. After searching the shop I came to the conclusion that only one side had a block. Compensating for the generator?


I did that on a Jeepster with a sag

I would love to post pics but won’t take up time to shrike my files to meet this forums requirements.


I use https://www.irfanview.com view; open a file, CNRTL-R, click 1/2, CNTRL-S
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Re: 1972 Travco rebuild and Cummings swap.

Unread postby Kckalden on Thu May 31, 2018 5:10 pm

Yesterday and today I swapped perches from the Travco axle to the donor axle. I made two 1 1/4 lift blocks and put the new rear end in. It looks good with those 9r22.5s. I will have watch the brackets behind the tires to make sure there are no clearance problems. They are at around 10:30 and 4 inches away. I also had to drill out the hanger brackets as my new u bolts are 5/8s in and the travco wre 9/16? Tomorrow I will put the front end on blocks and start scratching my head as to how I wand to tackle swapping the axle and engine and trans.
Kckalden
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Location: Stephenville Texas
Travco Model: 1972 270

Re: 1972 Travco rebuild and Cummings swap.

Unread postby ontheroad on Fri Jun 01, 2018 11:59 am

I am just finishing up my axle swap as well. When I took out the Travco rear end it had a 1" lift block(homemade) under the drivers side spring and a 3/4"(store bought) lift block under the passenger side. I was thinking it had the taller one on the drivers because of the water tank. lol. I will post some pics next week of my axle sway on the 270 in minnesota. I should be test driving it in a couple days(as soon as the driveshaft comes back from the shop).
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