400ex suspention chassie Q's

[250rforlife]

kk im redoin my bike this winter. new topend. but im doing some gncc races this summer , but majorly just intermediate- harsh trail riding. i have a stock frame no gussets. ill have 450r shocks revalved for my weight. do i have to worry about my frame cracking? im doing no jumps over 30ft. thanks!

[slightlybent47]

I wouldn’t think so, I have been racing mx on a stock frame for going on 4 years now with no issues at all. I jump 50 footers all the time so unless you’re a big guy I think you’ll be fine.

[slightlybent47]

Ok let me add that riding conditions are not all the same so if your riding in a rocky area I think you may have more stress on the frame. Also if those 30 footers are with no landing ramp and your landing on flat ground you may have an issue. If you come up short on a jump and case it on some rocky ground that could be a problem.
I will add that I have cased it lots of times on some big jumps and it’s holding up.

[SpasticR450]

I had a lot of hard landings on my 400 chassis Because stock shocks at the time and never one crack or bend and im talking landings that when I landed all 4 tires would bounce back up off the ground.

[-TheDude-]

if your gonna be racing get your rear shock rebuilt and get a gt thunder xc link, so your rear end wont bounce all over the place. call greg at greg atv he is an awesome shock dude (740) 622-9988 tell him greg from omr told you to call he will hook you up

[CJM]

Originally posted by -TheDude-
if your gonna be racing get your rear shock rebuilt and get a gt thunder xc link, so your rear end wont bounce all over the place. call greg at greg atv he is an awesome shock dude (740) 622-9988 tell him greg from omr told you to call he will hook you up

Quick Q, could you use a XC linkage with a stock 400ex rear shock setup? GT Thunder says otherwise but I wanted real world info. Im not sure the extended travel of the linkage would work to well with my skid and GT Thunder says you should use an extended shock.

The front rides great w/450R shocks, but the rear still bounces on me to much in really rough stuff.

[slightlybent47]

I picked up a good used Elka shock and had it rebuilt and it work a bit better then the stocker. The biggest deference was in cornering; it stays much flatter and corners much better. I did not notice a big deference in the way it handles the woops and bumps though.

[CJM]

The whoops and bumps are what kills me, the rear wants to jump up in the air like crazy over very harsh terrain unless I take it easier.

[slightlybent47]

Have you tried adjusting the rebound and or the compression?

[CJM]

Originally posted by slightlybent47
Have you tried adjusting the rebound and or the compression?

Yea, I adjusted it softer than harder to see if it mattered and even lowered everything a good 1/4 inch.

Im thinking I need to give it more, right now the rear is 1.5 turns out each.

[ish416]

I have busted two 400EX frames over the years. Also cracked two stock swingarms.

Everytime the frame busted, it was at the top shock mounts. The swingarms always cracked on the right side in the middle of the swingarm.

I have only entered a few races both mx and xc.

I am what I consider to be an aggressive rider. I am bigger guy at 6'3 240lbs. So maybe that has something to do with it.

Also, the quad was jumped regularly for years over 25-60 ft doubles at my house so that may have accelerated the issue. Either way, my KFX450 has not had a single issue with the frame.

In my experience, Honda frames have had great geometry but are fairly weak. I have busted the two aforementioned 400ex frames, a 300ex frame and an 86 250R frame.

Just to be safe, I would gusset the frame and get decent front shocks. Also, check around the top shock mounts regularly as all you need is a small crack and a good ride, then it will break all the way through.

[slightlybent47]

Originally posted by CJM
Yea, I adjusted it softer than harder to see if it mattered and even lowered everything a good 1/4 inch.

Im thinking I need to give it more, right now the rear is 1.5 turns out each.


I looked at your sig and it said you have a 2000 ex, has it ever been serviced? They do wear out so maybe that’s what’s wrong with it.

[CJM]

Originally posted by slightlybent47
I looked at your sig and it said you have a 2000 ex, has it ever been serviced? They do wear out so maybe that’s what’s wrong with it.

Not since I have had it, not sure about the previous owner. I did have the shock out the other day and it felt ok, it compressed and went back out good.

It probably it needs to be serviced tho. Maybe send it out to be rebuilt by someone (where???) or totally replaced with an aftermarket. I looked at GT Thunder but was confused on what they wanted in measurements.

[slightlybent47]

I’ve been racing mine now for 2 years and it feels like it needs to be redone. Most racers service them every year. I’m sure over time a shock spring can get weak as well.
I here that the stock rear shock can be rebuilt with triple rate springs and are quite descent once rebuilt.

[CJM]

I think over the winter Im gonna contact C & D about rebuilding everything if I can get the cash.

[-TheDude-]

Originally posted by CJM
Quick Q, could you use a XC linkage with a stock 400ex rear shock setup? GT Thunder says otherwise but I wanted real world info. Im not sure the extended travel of the linkage would work to well with my skid and GT Thunder says you should use an extended shock.

The front rides great w/450R shocks, but the rear still bounces on me to much in really rough stuff.
yes they make a 400ex link. the 400 stock rear shock is a great rebuildable shock, putting a 450 rear shock does nothing but mess up the geometry of the bike

[CJM]

I dialed it in a bit better, im sure it needs a rebuild but it was working pretty good today. I added another turn in on the adjuster so its only 1 turn out.

The fronts might need some more fine tuning but they felt ok today.