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Discussion Starter #1
My brother has a 1995 Foreman 400 that he acquired. I'm pretty sure the front differential is on its way out. Was practically caked with mud inside, and bearings feel loose and lots of shavings in oil.

I can find lots of good used front differentials for 02-03 Foreman 400's, but nothing for the 95-01's. Looking at the parts diagrams it's obvious they used differ guts, but does anyone know what it would take to use an 02-03 front diff in a 95?

Or anyone have a front diff from a 95-01 for sale?
 

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Discussion Starter #2
I did refine my search and found some used differentials for the 95-01's. Price is definitely higher on those though.
 

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unless the gears and pinion gear are bad ?, just rebuild it.
 

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Discussion Starter #4
unless the gears and pinion gear are bad ?, just rebuild it.
If it were mine, it would have already been rebuilt. And if I had the dexterity, I'd rebuild it for him. Dropping in a replacement diff falls into something he'd let me coach him in doing. Rebuilding one....well, maybe.
 

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unless the gears and pinion gear are bad ?, just rebuild it.
If it were mine, it would have already been rebuilt. And if I had the dexterity, I'd rebuild it for him. Dropping in a replacement diff falls into something he'd let me coach him in doing. Rebuilding one....well, maybe.
compare the price difference between rebuilding the diff to replacing with a used one :). my money says ( unless the used one is dirt cheap ? ), it's cheaper to rebuild the old one.
 

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Discussion Starter #7
Might look at putting in a selectable 450 Foreman front diff. Would require a little work, but if you're replacing it anyway.....

Front Diff swap???? - Honda Foreman Forums : Rubicon, Rincon, Rancher and Recon Forum

Do a little interweb search. The late 450's had selectable 4wd, and 450 and 400's used the same front diff.
Thanks Jeep, that's what I was wondering. The part numbers don't directly cross-reference but I figured someone would know what it would take. So no issues with putting an 02-03 Foreman 400 diff in a 95?

And I like the selectable idea as long as the electronics doesn't get too complicated. Would even a 400AT front diff go in? Honda Rancher 400 AT 4x4 04-07 Front Differential 5627 Looks fairly similar and seem to be a lot available for a good price. Probably from all the 400AT's that have been parted out due to dead hondamatics.
 

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I'm not sure on that. I've got a couple of 400AT diffs in the shop. They will go into a 350 Rancher but not sure about a 400/450, and I don't have a 400/450 to use for reference.

From the post I linked, the 400 and non selectable 450 front diffs are interchangeable, and since one can put a 450 selectable in an older 450 it only makes sense that one could do the same in a 400.

As far as electronics, you wouldn't have the protection that a stock machine has in that the stock selectable machines have a computer that won't allow the actuator to be energized if the front and rear wheels aren't at the same speed.

You just run 12V to the switch, and then to the actuator, and remember that when you flip the switch, it's going to be in 4wd even if your front wheels are sitting still and the rear wheels are spinning at 40mph.

In other words, make sure you're stopped on rolling on firm ground with front and rear wheels moving at the same speed before you flip that switch.
 

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Discussion Starter #9
I'm not sure on that. I've got a couple of 400AT diffs in the shop. They will go into a 350 Rancher but not sure about a 400/450, and I don't have a 400/450 to use for reference.
Since I do own a 400AT, might just have to make a winter project out of taking parts out of it and seeing if they swap right into the Foreman. If they do, then just buy parts to put back into the 400AT
 

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my bud has a front differential for a trx450 I believe he said ?, it has the selectable drive, not sure what he wants for it ?, but as jeep said ^^, the electronics from a 400 to a 450 gets complicated !..lol. one good flip of the switch when going fast, and boom !..lol.
 

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gonna call him, and ask him what that differential came from ?, pretty sure he said a 450 , just don't remember the year ?, will let ya know.
 

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just got off the phone, he has the whole front end, trx450 front differential, still don't know the year yet ?, but he wants 450 for all of it.
 

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Discussion Starter #14
just got off the phone, he has the whole front end, trx450 front differential, still don't know the year yet ?, but he wants 450 for all of it.
Ok, sounds good, thanks for checking. Currently looking into a couple local leads that are under $125/$200 for the front diff off a 1st gen Rubicon. And powersports nation still has them for $140. Based on the metal pieces we found in the oil, I think it's beyond just a take apart and replace the bearings kind of rebuild. Probably needs bearings and gears. A good used diff seems to be the best bet still. For who will be using, also probably going to go with one that came off a full time 4wd machine and avoid the whole electronics deal. If it were mine, I'd do the upgrade.
 

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I forgot to post back to you , I looked for you on Power Sport the other day and all I found was rear diffs for the 400 @$140 , never did find a front -------the part break down between the 1st gen and 2nd gen front diff is totally different internally

Shade you mentioned " one flip of the switch and boom " , you are scaring me , I have the 2002 450 and shift on the fly all the time , have never heard any noises , but now I am going to the operators manual and see if any recommendations are given on engaging the front diff while moving
 

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I read the 2002 trx450FM owners manual last night about the 4wd selector , paraphrasing all it says is " move the 4x4 selector to 4wd when desired " , not a mention of being stopped or going slow ----- all the time I hit the ruts in 2wd and if it feels like I need it I will stick it into 4wd without letting off the throttle -----only once did I have a scare when the 4wd wouldn't engage , turned out I blew a fuse , replaced and the fuse and it has been months and never did blow it again ------
 

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Discussion Starter #17
I forgot to post back to you , I looked for you on Power Sport the other day and all I found was rear diffs for the 400 @$140 , never did find a front -------the part break down between the 1st gen and 2nd gen front diff is totally different internally
Exactly. Except I did find one or two at PSN available. Decided that going with a 2nd gen 400FW front diff would be smartest, as price seem to be a bit better, and rebuild kits are also more available when compared to the 1st gen. But best thing with the 2nd gen is that it is identical assembly number to the front diff used in the 1st gen Rubicon (500FA). And tons of those bikes get parted out after the tranny grenades. So there are 2 of those available at different places locally. Plus what PSN has available. Just waiting for my bro to decide what he wants to do here. If it were mine, it would've been replaced long ago. And that's what he's deciding, whether he wants to own this thing, or just sell it to me for what he now has into the whole rebuild.
 

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Fish the factory equipped selectables won't actuate the front diff until the front and rear speed sensors are synced up. So if you're spinning rear wheels with the front wheels stationary, the 4wd light will blink, and it won't go into 4wd until your rear wheels are moving the same speed as the front.

If you retrofit the front diff to an older bike, you aren't activating the 4wd through the computer, so you don't have the protection afforded by the computer on the factory equipped bikes.

Make sense?

Front speed sensor is on the front of the diff. Rear is on the clutch pack on the back of the front diff, so on, for example, a 400AT front diff (which I'm going to put in a 350 Rancher) there are three plugs on the front diff; front speed sensor, rear speed sensor, and the actual switch, which is the only plug I'll use, and will wire it to 12V via a switch.

It will work fine, just have to think before you hit the 4wd switch.
 

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Discussion Starter #19
@fishfiles bro just ordered a 2nd gen (2002-2003) front diff from PSN. going with a traxlok diff was tempting but he wanted a more simple drop-in. i noticed in all this that the CV axle part numbers are different from 1st gen to 2nd gen, but you and others have repeatedly said all the foreman diffs are interchangeable, so I'm not expecting any issues with the axles. the inner CV joint is the same part number though so no reason they shouldn't pop right in.

one funny thing is this all started with what we thought was a bad axle. after replacing those it became very clear the diff was the problem though. had already installed the new aftermarket CV axles though. so we have a good set of old Foreman 400 CV axles now. assuming they are OEM but we don't know the full history of this machine.
 

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Fish the factory equipped selectables won't actuate the front diff until the front and rear speed sensors are synced up. So if you're spinning rear wheels with the front wheels stationary, the 4wd light will blink, and it won't go into 4wd until your rear wheels are moving the same speed as the front.

If you retrofit the front diff to an older bike, you aren't activating the 4wd through the computer, so you don't have the protection afforded by the computer on the factory equipped bikes.

Make sense?

Front speed sensor is on the front of the diff. Rear is on the clutch pack on the back of the front diff, so on, for example, a 400AT front diff (which I'm going to put in a 350 Rancher) there are three plugs on the front diff; front speed sensor, rear speed sensor, and the actual switch, which is the only plug I'll use, and will wire it to 12V via a switch.

It will work fine, just have to think before you hit the 4wd switch.
That is a very good explanation , makes a lot of sense that it is set up that way to protect from slamming into drive ------------- makes me still wonder about mine , my front wheels will engage the second I hit the switch even if the rear wheels are spinning under power and the front only turning from moving forward , which would be different speeds right ------ now the neutral is by-passed , because I was told it has to be with the reduction . ??? so the neutral light stays on all the time and it will start in gear = it is a 2002 450FM
 
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