Foreman 400 and 450 Bottom end differences?

[AKATV 785]

Was going to piece together a good Foreman 400 engine and thought both 450 and 400 bottoms were the same except for mainshaft length, had a few questions for anyone who has done same

Had two bad Foreman 400 lowers, both cranks shot, one case had a stripped oil drain and the other looked like the cam chain rode without a tensioner till it broke, man it wore thru the plastic chain guide down through the metal guide nub above the fuel pump and you could also see where it was slapping the top of the case for a long time...both oil screens were clogged and sucked up sideways....

Had a good 450ES bottom with good crank but bad 3rd gear (how does that happen....?) only 3rd, dogs were half gone and heat discolored, but only 3rd gear?

So....after gutiing all 3 apart and the parts all spread all over out in the driveway on 4x8 sheets of plywood, I started putting one good one back together

Anyways, I tried to put an 03 400 trans gear pack into a 450 case and it would bind when fitting cases, so ended up using the 400 case with the worn guide area ( I was able to repair it by building up the guide pin metal and putting new plastic guide on) that went together fine and then I put the crank from the 450 into the 400 case and buttoned all back up

Anyways here are my questions...

-Can you swap the 450 engine into a foreman 400 and vice-versa, if you just swap out the main output shaft? (the 400 is shorter than the 450) are they plug and play that way?

-Should the transmission pack have been swappable from 450 to 400? I know the first gear on the 450 was solid and the 400 had "spokes" but side by side they looked the same

-What things generally make a particular gear/dog go bad inthe transmission pack? -I did notice a bent shift fork on this pack that had the bad third gear, but its an ES so no one was stomping on the gearshift lever...

 

Plus,  now I just now saw an 03 450ES in good shape on craigslist with a cracked engine case (looks like timing chain maybe let go and bound up..?)

so now I have a good use for the ES cases laying outside...it never ends........

Heres a pic of that -what do you think happened...?

 

 

Edited April 21, 2020 by AKATV

[shadetree 5,791]

pic is way too small to see it ^^^ ?. i dont go swapping motor parts, so i can't answer you if a 450 and 400 will swap out ?, perhaps check the case part numbers, see if they match ?, if they do ?, then its just a matter of getting the right tranny in one of them. personally, i would not touch a es, but this is me...lol. if i was gonna build one of them ?, i would go with the trx450, and convert it to a manual shift.

[jeepwm69 7,413]

Pull this up, and if you click on the individual part numbers, they'll show interchange at the bottom right of the page "related fitment"

 

https://www.partzilla.com/catalog/honda/atv/2002/trx450fe-a-fourtrax-foreman-es/transmission-trx450fe

 

I haven't been into a 450, but I've always been under the impression that they were the same other than the output/final shaft.

[shadetree 5,791]

1 minute ago, jeepwm69 said:

Pull this up, and if you click on the individual part numbers, they'll show interchange at the bottom right of the page "related fitment"

 

https://www.partzilla.com/catalog/honda/atv/2002/trx450fe-a-fourtrax-foreman-es/transmission-trx450fe

 

I haven't been into a 450, but I've always been under the impression that they were the same other than the output/final shaft.

if the output/final shaft is different, then how will the gears all line up if you swap in the shafts from a 400 ?.

[jeepwm69 7,413]

Sooooo, while you're in there, do you have extra gears laying around?  I'm trying to work on something and need a 20 tooth gear from a 400/450 transmission.  #19 here

 

https://www.partzilla.com/catalog/honda/atv/1998/trx400fw-a-fourtrax-forman/transmission

 

 

[jeepwm69 7,413]

Just now, shadetree said:

if the output/final shaft is different, then how will the gears all line up if you swap in the shafts from a 400 ?.

If I recall correctly, the 400 is a smaller diameter.  A local guy tried to do the 02-04 front diff swap in to a 400 and said the 450 front driveshaft coupler swallowed the 400 output shaft.

[AKATV 785]

Fixed pic-

I usually dont swap/mix and match ,but had these laying around and generally through the years had heard they were the same, except for the mainshaft lengths, so thought i would try at least. I know that the crankshaft is the same by part number, so essentially thats all I swapped into a 400 engine

I work on a lot of the ES machines, they arent as bad as everyone says-I have not had one I could not figure out---yet lol, mostly angle sensors and gummed up grease( 25 below temps doesn't help)

There is a lot of them around up here and a lot of veterans / disabled ride them too (no foot, leg, paralyzed) or ride the automatics, so its good to keep them going

 

[AKATV 785]

18 minutes ago, jeepwm69 said:

Sooooo, while you're in there, do you have extra gears laying around?  I'm trying to work on something and need a 20 tooth gear from a 400/450 transmission.  #19 here

 

https://www.partzilla.com/catalog/honda/atv/1998/trx400fw-a-fourtrax-forman/transmission

 

 

I do have what you need, I can take a picture for you, its in nice shape

 

Edited April 21, 2020 by AKATV

[jeepwm69 7,413]

I sent you a PM!

[AKATV 785]

6 hours ago, shadetree said:

if the output/final shaft is different, then how will the gears all line up if you swap in the shafts from a 400 ?.

The final shaft is about 1/4 longer on 450 for rear output, front output shaft length is like an inch or so shorter on the 400 and longer on 450, so if you just put engine in withput swapping the shaft out you will either be to short to reach front prop shaft or too long and wont fit into prop shaft

Dont know if you can just swap propshafts etc... as I had to tear engines down to clean them out and rebuild anyways, splines are the same on both

Here is a picture of the 2 shafts side by side, the shorter one is the 400, longer one 450

Edited April 22, 2020 by AKATV

[AKATV 785]

Well place your bets- what do you think broke?- and how fast can I pull the engine out?

Picked up a 03 Foreman 450ES with cracked case, going to pull engine today and open it up

What do YOU think went bad inside?

 

On a side note-what do you think the fastest an engine can be pulled from a complete all together Foreman 450ES?

Just for a hoot this time, I  am going to have my son hand me tools while I try to break the world record, and not bolts- haha

Not sure but think I can do it in under an hour if all goes smoothly

Only prep is laying out the common tools and pb blaster on exhaust bolts-and coffee.....

Ready set go!

Will update

Edited April 24, 2020 by AKATV

[jeepwm69 7,413]

No impact, or is that cheating?

[AKATV 785]

I got the old man wrist, as well as the back......., going to be using impact  and air ratchtet- lol

[shadetree 5,791]

55 minutes ago, AKATV said:

Well place your bets- what do you think broke?- and how fast can I pull the engine out?

Picked up a 03 Foreman 450ES with cracked case, going to pull engine today and open it up

What do YOU think went bad inside?

 

On a side note-what do you think the fastest an engine can be pulled from a complete all together Foreman 450ES?

Just for a hoot this time, I  am going to have my son hand me tools while I try to break the world record, and not bolts- haha

Not sure but think I can do it in under an hour if all goes smoothly

Only prep is laying out the common tools and pb blaster on exhaust bolts-and coffee.....

Ready set go!

Will update

thats on the final shaft side, deff something went wrong on the tranny gears ?, or final shaft ?. with an impact, i've removed a trx500fm from start to finish all the way out in under an hour, not hard, assuming all bolts dont give ya trouble ?..lol.

[AKATV 785]

thats where my money is too

Owner said he was accelerating on gravel/dirt (spinning tires) and hit pavement and "pop"

I bet its on of those transmission gears that have the cutouts or "spokes" in it that fractured

should have pics up here soon

Good news is I have the cases from the 450ES I just pulled the crankshaft from for the 400, same year even-

Finishing coffee and heading out...........

Edited April 24, 2020 by AKATV

[shadetree 5,791]

2 minutes ago, AKATV said:

thats where my money is

Owner said he was accelerating on gravel/dirt (spinning tires) and hit pavement and "pop"

I bet its on of those transmission gears that have the cutouts or "spokes" in it that fractured

should have pics up here soon

Finishing coffee and heading out...........

and what do we win for being right ?..dont say a cookie !..rofl.

[AKATV 785]

Well........no cookie shade... not one for me either.....there was not a single broken gear inside, everything looked good

will post pics tomorrow HUGE crack in bottom of case- maybe it took a hit on the bottom from a rock

I have no idea how it happened, but the crack shown in the picture was the end of it coming up from down below

When I split the cases a piece of case actually fell out of the bottom

On one side- glad to not have this grenaded on the inside, but on another it bugs me trying to puzzle out what happened

I will post pics and we can speculate ......

PS  I did not break world record getting this out of the frame took me about  2 hours- no helper and

spent a least 20 minutes fiddling with front prop shaft-couldnt get it to clear the output splines and when it did it was like.5mm clearrance

should not have unbolted motor mounts first.....lesson learned

teardown went well, piston was scuffed from oil dumping out bottom crack, crankshaft was in great shape-got lucky

cam chain tensioner had 1/4 inch left so it wasnt on its last leg

have to get center case gasket and piston, chain, and few odds ends and will button in back up in the new(used) case

more to follow