2.87 gears installed.

[Blairg]

Stars finally aligned and got the 2.87 gears installed (Stock 1078 with Goodyears at 70psi). Since I picked up the truck last Thursday I have put around 50 miles with the new gears. Initial reaction is that it makes the truck much more usable. Combined with the soundproofing makes for a quiet ride at 65mph. Highway driving is far more relaxed and side street driving remains the same as before. Hills that I took in 6 gear has dropped down to 5th with the speed remainmg the same. Fan doesn't cycle as often either. Overall seems to be a good upgrade. Gonna add a Pyrometer and boost gauge next with the idea of bumping the truck up to 290hp.

Blair

 

[jwchameleoncorp]

Stars finally aligned and got the 2.87 gears installed (Stock 1078 with Goodyears at 70psi). Since I pickup the truck last Thursday I have put around 50 miles with the new gears. Initial reaction is that it makes the truck much more usable. Combined with the soundproofing makes for a quiet ride at 65mph. Highway driving is far more relaxed and side street driving remains the same as before. Hills that I took in 6 gear has dropped down to 5th with the speed remainmg the same. Fan doesn't cycle as often either. Overall seems to be a good upgrade. Gonna add a Pyrometer and boost gauge next with the idea of bumping the truck up to 290hp.

Blair

Great post! Thanks for sharing. What year is the truck?

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[Blairg]

Great post! Thanks for sharing. What year is the truck?

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1997

 

[fuzzytoaster]

Stars finally aligned and got the 2.87 gears installed (Stock 1078 with Goodyears at 70psi). Since I picked up the truck last Thursday I have put around 50 miles with the new gears. Initial reaction is that it makes the truck much more usable. Combined with the soundproofing makes for a quiet ride at 65mph. Highway driving is far more relaxed and side street driving remains the same as before. Hills that I took in 6 gear has dropped down to 5th with the speed remainmg the same. Fan doesn't cycle as often either. Overall seems to be a good upgrade. Gonna add a Pyrometer and boost gauge next with the idea of bumping the truck up to 290hp.

Blair

That's what I'm talking about! 2.87's are nice.

 

[jwchameleoncorp]

That's what I'm talking about! 2.87's are nice.

I'm interested in them but I have a 6x6 (M1083). I can't find the middles for 2.87s anywhere. Nobody seems to have them.

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[Blairg]

I'm interested in them but I have a 6x6 (M1083). I can't find the middles for 2.87s anywhere. Nobody seems to have them.

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I know these are the 3.07's but some might argue that they are better suited. YMMV
Blair

CA - FMTV High Speed Gears 3.07

Was saving these for a project, but have decided to go another route. These were out of low mile first gen. Mraps 3 complete axles, will only sell together. Pop the third member, or gears out and swap over into your rig. Located in the SF bay area. $6000

www.steelsoldiers.com

 

[Ohiobenz]

I'm interested in them but I have a 6x6 (M1083). I can't find the middles for 2.87s anywhere. Nobody seems to have them.

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3.07's and 14x20's
Same results

 

[jwchameleoncorp]

3.07's and 14x20's
Same results

Yeah, I was looking at that. What I wondered was are 14's hard to find and/or significantly more expensive? Trying the think about long term cost and logistics.

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[fuzzytoaster]

Yeah, I was looking at that. What I wondered was are 14's hard to find and/or significantly more expensive? Trying the think about long term cost and logistics.

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You nailed it. 14.00's aren't in demand by the military so they've dried up surplus wise. You combine that with lower top speed (56 mph), older date codes (typically), and higher demand (because all 5 tons use them too) then you end up here. Gears vs tires. One is disposable and the other not. Where do you put your money?

 

[jwchameleoncorp]

You nailed it. 14.00's aren't in demand by the military so they've dried up surplus wise. You combine that with lower top speed (56 mph), older date codes (typically), and higher demand (because all 5 tons use them too) then you end up here. Gears vs tires. One is disposable and the other not. Where do you put your money?

And there's the dilemma! I can't get the middles for 287s and 14rs over the long term aren't feasible. So practically speaking, my option is the standard 395R20 tire with 3.07 gears. Your thoughts?

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[fuzzytoaster]

I thought there was someone on the west coasts doing 2.87 gears swaps but wouldn't sell the gears unless he installed them. Going with that thinking I'd dig around a little more and try to provide your own front and rear if they'd do the middle. I wish I had more details off the top of my head.

 

[coachgeo]

14r20's as a surplus tire is drying up thus they are more spendy for a surplus tire compared to 16r20's. Not the case new though. They remain available new. here and abroad. Many Unimogs use them as well as other trucks. New 14r20 when time comes that only new is available... will save you money in long run over surplus other tires though so save up money NOW for that future event.

New have many more years and wear life in them compared to surplus tires so they last you twice as long before needed replaced. If your a parade queen weekend fun truck that may not be so true... if your an expedition truck. or commercial use truck... that is true. Then there is the higher safety margin.... then there is the ease of going back a gear ratio (go back to oem tire size) compared to regearing axles "again".

 

[jwchameleoncorp]

14r20's as a surplus tire is drying up thus they are more spendy for a surplus tire compared to 16r20's. Not the case new though. They remain available new. here and abroad. Many Unimogs use them as well as other trucks. New 14r20 when time comes that only new is available... will save you money in long run over surplus other tires though so save up money NOW for that future event.

New have many more years and wear life in them compared to surplus tires so they last you twice as long before needed replaced. If your a parade queen weekend fun truck that may not be so true... if your an expedition truck. or commercial use truck... that is true. Then there is the higher safety margin.... then there is the ease of going back a gear ratio (go back to oem tire size) compared to regearing axles "again".

Great ideas and input. Thank you, Geo!

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[Blairg]

A little more testing. Had sometime today to take the 1078 on a cruise. Around (San Luis Obispo Ca.) our test hill is known as Cuesta Grade. on
Hwy 101 . 7% grade that is a few miles to the summit. On the south side going North the truck maintained 45 miles an hour. Interesting part was that it stayed in 7th gear until midway then downshifted to 6th for the rest. I was expecting it to drop down into lower gears but was surprised. Fan came on around the same time. Driving it around town was no big deal. Transmission seems to have adapted and shifting is smooth. Only issue is that it feels like tires need to be balanced.
Blair