Reference: ATC and TRX 250R shock differences

[Billy Golightly]

Well I had purchased a freshly rebuilt TRX shock with the hopes and belief I could bolt it right on minus the different bottom mounting bolt diameter but I found a bunch of other things different (that caused problems) in the process. So here, as far as I have been able to tell so far, the differences.

TRX shock slightly shorter (will lower ride height about 1/2-3/4 of an inch)

TRX shock slightly larger bottom linkage bolt. You can maybe get away with using the stock smaller ATC bolt but I would not recommend it.

ATC shock's top mount has a wider width bushing that is made into the shock and cannot be removed. The inner removable bushing will fit into the TRX shock but it is only supported by the smaller portion of the TRX shock. Your outside bushing dust covers will not fit and stay on by themselves. The TRX shock will have 3/8inch of side to side play at the top of the mount without custom made centering bushings.

TRX shock canister hose mounted to the shock body in the upper position. End of the hose and the banjo bolt head will hit on the main down tube of the frame where the airbox hooks on, and also prevent it (airbox) from going on completely. You an loosen the banjo bolt and twist the hose out of the way but you will lose most of your shock oil and probably 25-30lbs at least of nitrogen charge.

Canister hose is longer on the TRX, and mounts to the canister itself at a different angle making it very difficult (not impossible though) to mount in the stock position. Hose will rub on shock spring, and airbox externally though when mounted.



So thats what I've found...don't buy a TRX shock and expect it to be a bolt up in 30 minute job, it aint.

[torker]

I guess I'm out of luck then:cry:

Billy, is this an 1985? Is there a posibility that 86 might be diferent?:wondering
Just wondering, as I was or still am, it all depends on $$$, for an aftermarket (race) rear shock for my 86R and thought about a TRX shock as these are more plentiful (if you can call it that.)
Just a thought????:confused:

TORKER.

[deathman53]

I have an aftermarket trx250r shock on mine, the only issue I had was the top shock mount width, I put two washers on each side to make up the difference. Also 86 atc's used a bigger bottom shock bolt too, its the same thing as 86-89 trx250r bottom bolt, linkege arm, collars, seals and 86 dog bone. 87-89 trx250r used a shorter dog bone, otherwise the same its the same stuff.

[torker]

So, pretty much just need the shock. It's not imposible to make it work.
I have the complete 86 ATC system not beeing used. Cool... and
thank you both, Billy and deathman53.

Great info.
TORKER.

[Tecate250]

What about the whole rear end? Is the swinger assembly the same? Any advantages if the trx stuff will fit? I have a line on a whole parts trx frame and wondered if this would be a cheaper route for my bad axel.

[JohnR.]

It depends on the year. 1986-1987 is the same, 1988-1989 (i.e. aluminum swinger) the arm will fit but you will have to remove the rear "cradle" that bolts to the back of the engine and have a couple of brackets welded onto the frame.

John

[Tecate250]

Anyone have any info on this? I looked for a thread about it but came up with nothing. Would it be worth the mod? I have a spare 86 atc frame.

[JohnR.]

ChrisD did it to his so he could run the '89 swingarm. Its aluminum and its an inch shorter than the stock steel ones. A shorter arm will improve traction and make it turn quicker (flat track quads often have shorter than stock swingarms) but it makes the front end come up easier so its a trade off. If I were planning to re-do an R I would make a couple of 88-89 TRX style brackets and weld them onto the frame before I sent the frame out for powdercoating. That way you can easily switch to the newer style arm if you decide you want it down the road. You'll just have to make a spacer up to fill in the gap left when you remove the stock cradle.

John

[Tecate250]

Hmm. This seems to be worth looking into.