Whole YZF600 rear suspension swap or just wheel

SILVERGOAT · October 24, 2009, 06:08:34 PM

Hey Guys,
I just picked up a complete rear end off a YZF600. Is it worth it to swap the shock,swingarm,brakes and wheel or should I just swap in the wheel to the existing swingarm? Any advice/precautions would be greatly appreciated. Thanks, Jeff.

threejagsteve · October 24, 2009, 06:24:59 PM

Hey, Jeff,

Just out of curiosity, what are the dimensions of the swingarm compared to your FJ unit?

I'm particularly interested in the length from the pivot to the beginning of the adjustable range, the width of the pivot, and the distance between the arms at the axle.

TIA and cheers,
threejagsteve

the fan · October 24, 2009, 07:08:17 PM

I am not sure what the differences in leverage ratio is, but the YZF runs a 475-500 lb/in spring stock as opposed to the much stiffer 900lb+ spring usually desired by FJ modders. Then there is the whole mounting location issue...

SILVERGOAT · October 24, 2009, 07:20:25 PM

The YZF swing arm is approx. 1" shorter overall. As far as the spring rate, I figure the the FJ's extra tonage and carrying capacity contributes to the much higher value not including any linkage ratio values.

racerman_27410 · October 24, 2009, 11:23:37 PM

you would want to be very careful/thorough when delving into a swingarm swap and corresponding custom shock linkage zone...... i can tell you from experience that it can be tough to get a custom shock linkage properly sorted ...... Probably the main reason why more people go with a wheel swap over a swingarm swap.

Andy York successfully put a R1 swingarm on his 85 FJ11 but he took careful measurements of his stock shock linkage angles and had new pickup points welded onto the swingarm to maintain the correct linkage geometry.... even to the point of using the stock linkage.

its amazing how a small change can make such a dramatic difference on the shock action.

just one more thing for ya to think about

KOokaloo!

Frank

threejagsteve · October 25, 2009, 04:33:51 AM

Quote from: racerman_27410 on October 24, 2009, 11:23:37 PM
you would want to be very careful/thorough when delving into a swingarm swap and corresponding custom shock linkage zone...... i can tell you from experience that it can be tough to get a custom shock linkage properly sorted ...... Probably the main reason why more people go with a wheel swap over a swingarm swap.

Andy York successfully put a R1 swingarm on his 85 FJ11 but he took careful measurements of his stock shock linkage angles and had new pickup points welded onto the swingarm to maintain the correct linkage geometry.... even to the point of using the stock linkage.

its amazing how a small change can make such a dramatic difference on the shock action.

just one more thing for ya to think about

KOokaloo!

Frank

Thanks, Frank,

You seem to be reading my mind... this wouldn't by any chance be a topic you've already investigated, would it?

You said "approx. 1" shorter overall" - did you mean end-to-end?

I'm wondering...

a) Is it beefy enough to handle the weight and power of an FJ?

b) Is it a good width for mounting a 5.5x17 FZR1000 wheel, perhaps with less machining than needed to mount that rim in the FJ unit?

c) How do the mounted length and angle of the YZF shock compare with those of the FJ?

d) How do the dimensions of the pivot compare with those of the FJ?

I seem to recall someone around here saying that you can make just about anything work if you want it bad enough...

Cheers, and TIA,
threejagsteve

threejagsteve · October 25, 2009, 06:07:37 AM

Oops! I just noticed it was Jeff who said "approx. 1" shorter overall" - that's what I get for being online at 3 AM!

the fan · October 25, 2009, 08:53:28 AM

A YZF600 swing arm is boxed steel and at least as strong as a late model FJ. It measures appx 525mm from the swing arm pivot to the center of the rear axle adjustment range. The shock measures 360mm eye to clevis and is fully rebuildable.

I can't get more accurate without dis assembling my bike and the chances of that are nil.

racerman_27410 · October 25, 2009, 12:18:38 PM

Quote from: threejagsteve on October 25, 2009, 04:33:51 AM

Thanks, Frank,

You seem to be reading my mind... this wouldn't by any chance be a topic you've already investigated, would it?

I seem to recall someone around here saying that you can make just about anything work if you want it bad enough...

Cheers, and TIA,
threejagsteve

Ahhhh yes i have been through the custom shock linkage grind.... my rear shock linkage is a hodge podge of different parts... my FJ is an 86.... shock pivot arm is from a 89 FJ and the rest of the parts are hand fabricated.

in my writeup of the FZ1 swap i said the swingarm is 1" longer than stock but i neglected to add that the wheel adjustment will allow you to either keep the stock wheelbase (with wheel slid forward) or a bit longer than stock with the wheel slid back ....

yes anything can be done if one wants it badly enough but i never said it would be easy

KOokaloo!

Frank

SILVERGOAT · October 25, 2009, 05:50:28 PM

You guys are a plethora of info, thanks a bunch for your input. I have decided to swap wheels and upgrade the rear shock. This one is NOT going to be a corner carver, just a better mile muncher. I am not going for a 180 either, I just want a 160 radial.

Arnie · October 25, 2009, 08:30:18 PM

A 160/60x17 works just fine. I've used up about 5 of them since changing rear wheels. To retain ride height you'll want a shock that is longer or dog-bones that are shorter. I can't give you specific recommendations if you're changing to the YZF rear, but can if you're keeping the FJ swingarm.
You'll also want to use an 18t countershaft sprocket to retain overall gearing.

Cheers,
Arnie

Quote from: SILVERGOAT on October 25, 2009, 05:50:28 PM
You guys are a plethora of info, thanks a bunch for your input. I have decided to swap wheels and upgrade the rear shock. This one is NOT going to be a corner carver, just a better mile muncher. I am not going for a 180 either, I just want a 160 radial.

higbonzo · October 25, 2009, 09:48:35 PM

Quote from: SILVERGOAT on October 25, 2009, 05:50:28 PM
You guys are a plethora of info, thanks a bunch for your input. I have decided to swap wheels and upgrade the rear shock. This one is NOT going to be a corner carver, just a better mile muncher. I am not going for a 180 either, I just want a 160 radial.

I did the FZR1000 rim set up on my bike and it is like riding a completely different bike. It is way better handling and rides better all the way around. You will be amazed at the diffence it makes, especially if you upgrade your suspension a bit.

Later.......

threejagsteve · October 26, 2009, 12:56:56 AM

Thanks for all the info, guys,

Jeff, I apologize for (temporarily) hijacking your thread.

It seems that one would get a little quicker-turning bike with the YZF swingarm swap but since it's steel too, weight savings (if any) would be very minimal. To gain this quicker turning, you'd give up a smidgen of high-speed stability. You'd also need to respring and revalve the YZF shock and figure out how to attach it to the FJ frame, or order a custom shock.

rktmanfj · October 26, 2009, 06:42:15 AM

Quote from: Arnie on October 25, 2009, 08:30:18 PM
A 160/60x17 works just fine.

Yup, the 160 does work fine, but a 170 will fit, too. Having swapped to the 170 in the middle of the ECSR last spring, I found that I liked the 170 a lot better. I had gone slightly off the edge of the 160 a couple of times, but have yet to do it with the 170.

Randy T
Indy

SILVERGOAT · October 26, 2009, 07:28:59 AM

You guys are like mind readers. I have been wondering if I should use a 160/60r17, 160/70R17(would not need a gearing change,better ride quality,close to stock ride height)or a 170/60R17. Has anybody tried fitting the YZF rear shock in place of the FJ shock?

News:

Whole YZF600 rear suspension swap or just wheel

the fan

the fan

rktmanfj