Quick question - linkage 'dogbones'

[idl1975]

Just a quick question - I have used the search function and not found anything precisely on point:

I recall having heard or read somewhere many years ago about using YZF 750 'dogbones' to increase ride height at the back. Can anyone fill me in as to whether this is do-able, whether any YZF-750 year will do, and whether any other mods to the linkage or rear suspension are needed?

If not, are there any companies doing different length dogbones commercially, or any other way to solve the ground clearance/slow steering issues without buying a ride-height adjustable shock? I saw the thread with the way-cool adjustable dogbones, but making those would be outside of my mechanical abilities.

Thanks to anyone who can assist!

[phuk72]

Any year YZF 750 dog bones raise the rear by about 20mm or so

Straight swap for TRX items (about £8 from Yamaha)

The alternative is to raise the forks through the yokes but this can cause ground clearance issues

[trixynut]

As I understand it, YZF dogbones are shorter so make the rear higher, so will quicken up the stearing a bit.

Best place to get them would be new from your Yam dealer: £10?

Otherwise, leave the rear alone, and raise the forks through the yokes to get the same effect. Standard is about 8mm showing above the yoke, so drop them to 10 or 12 mm will sharpen things up. If you've got a bellypan fitted, there may be a grounding issue if you're a 'knee-down' sort of guy!

Dave.

[phuk72]

Too slow

[Kirk]

I've actually got the yzf dogbones on the back, the forks should have 19.5mm showing from the top of the clipon to the base of the fork cap, I dropped mine down so there was 25mm showwing, and then I dropped the clipons under the top yoke!!
Much, much better, but a bit hard on the back/ wrists.
But certainly do the dogbones, makes the whole bike feel lots better.

[idl1975]

Thanks everyone!

The forks are already dropped 10mm through the yokes, and yes, the (non-recessed) bellypan allen bolts touch down first, which makes it hard to get the bellypan off the bike.

Last time I rode this bike on the track was Cadwell about 8 years ago (it has been in long-term storage until a few months ago), but I recall that getting into some of the quicker corners was 'interesting'. I.e. a wrestling match.

So I was hoping to raise the back end for both ground clearance and handling reasons. I shall trot off to the local dealership and pick up a set!

As I understand it, YZF dogbones are shorter so make the rear higher, so will quicken up the stearing a bit.

Best place to get them would be new from your Yam dealer: £10?

Otherwise, leave the rear alone, and raise the forks through the yokes to get the same effect. Standard is about 8mm showing above the yoke, so drop them to 10 or 12 mm will sharpen things up. If you've got a bellypan fitted, there may be a grounding issue if you're a 'knee-down' sort of guy!

Dave.

[dfh]

Just a quick question - I have used the search function and not found anything precisely on point:

I recall having heard or read somewhere many years ago about using YZF 750 'dogbones' to increase ride height at the back. Can anyone fill me in as to whether this is do-able, whether any YZF-750 year will do, and whether any other mods to the linkage or rear suspension are needed?

If not, are there any companies doing different length dogbones commercially, or any other way to solve the ground clearance/slow steering issues without buying a ride-height adjustable shock? I saw the thread with the way-cool adjustable dogbones, but making those would be outside of my mechanical abilities.

Thanks to anyone who can assist!

I have a set of the YZF750 dogbones coded 4BH that are 172mm centre to centre. ( standard TRX coded 4FM-10, 182mm centre to centre) Took them off as they added way too much rear ride height.. from memory 35plus mm. I have now fitted the Metisse dogbones part # 110035 that are I think about 176mm C to C. Tail rise now about 25mm.

My bike has a 120/70 rather than the stock 120/60 and with the forks at their standard pull through in the clamps, 18.5mm from top of the clip on mount to top of the fork tube excluding fork cap. This means that the tyre gives a ride height gain at the front of approx 10mm, combined with the 25mm in the rear gives an overall attitude change of plus 15mm at the rear. The steering feels pretty sharp with this setup, just feeling a touch unstable at really high speeds and ground clearance is not a problem.

The downside is by raising the ride height at both ends I have raised the C of G and the bike pitches and dives a fair bit more. Next on the agenda is a set of dogbones 178mm C to C to give me 15mm rear rise, then I can slip the forks up in the clamps by 10mm, keep the quicker steering geometry but lower the ride height 10mm overall and regain some stability.

Two things to be aware of. Changing the dogbones changes the swingarm angle. The owners manual recommends setting the chain slack @ 20-30mm with the bike held upright . If you do this with the YZF dogbones then the chain have no slack at all when the suspension compresses under load causing serious grief to the chain and countershaft bearings..... Get round this when you have the suspension bolts out changing the dogbones by jacking the rear wheel up so the countershaft , swingarm axle and rear axle are in line. This is the point of maximum chain extension, set the chain slack for 5mm, and when you put in the suspension bolts in and let it rest on the wheels, measure the slack like in the manual and it will read something like 45mm. Mark your measure point and slack reading on the swingarm for easy adjustments in the future ( after the beer has dulled your memory)

Secondly changing the ride height to fix ground clearance issues with the stock suspension is a waste of time. If you weigh like a standard issue westener then the spring rates ( especially the front) are too soft and will blow through the travel under load - que scraping at the apex- and squat under power on the way out, the most common reason for folks wanting more rear ride hight. Get get correctly specced springs front and rear and your shock rebuilt first or you will be chasing shadows.

Cheers DFH

[Triton]

Not discounting your dogbone measurements dfh, they're spot on, just the ride height gains. I have tried 173 c to c, 175, 177 and currently 178 (2003 ZX6-RR alloy and still fitted) which give an average 7mm increase at the rear on the blue bike above. With a front drop of 5mm this gives a very slight increase in overall ride height with a decrease of about 1/5 of a degree in rake, measured by an old fart with a laser pointer strapped to the fork legs. The science of suspension geometry is actually simple - until you tilt the bike over and add gravitational effects. Then I'm lost - I rely on lap times and 'feel'.
My advice is to take it one step at a time and make accurate notes whenever you modify anything. My garage wall is covered in TRX suspension 'notes', everything from static sag figures to spring rates tried, valving and tyre pressures/rear shock adjustments etc. Trouble is, once I get the perfect (for me) set-up, I'll buy those flatslides, add an extra 5 hp and totally fuk up the settings!

[dfh]

Not discounting your dogbone measurements dfh, they're spot on, just the ride height gains. I have tried 173 c to c, 175, 177 and currently 178 (2003 ZX6-RR alloy and still fitted) which give an average 7mm increase at the rear on the blue bike above. With a front drop of 5mm this gives a very slight increase in overall ride height with a decrease of about 1/5 of a degree in rake, measured by an old fart with a laser pointer strapped to the fork legs. The science of suspension geometry is actually simple - until you tilt the bike over and add gravitational effects. Then I'm lost - I rely on lap times and 'feel'.
My advice is to take it one step at a time and make accurate notes whenever you modify anything. My garage wall is covered in TRX suspension 'notes', everything from static sag figures to spring rates tried, valving and tyre pressures/rear shock adjustments etc. Trouble is, once I get the perfect (for me) set-up, I'll buy those flatslides, add an extra 5 hp and totally fuk up the settings!

2003 zx6rr eh? .. thanks for the heads up. Off to the wreckers soon or maybe I can buy your 177mm DB's

I suspect we may differ in measuring methods. I measure rear ride height when changing dogbones from rear axle to a point marked on the rear subframe with the wheel off the ground. I do this as the rising rate curve is also affected by the dogbone change and the change in static sag change will be a combination of the two. Thats just the way I do it but it doesn't matter which system we use.

We seem to be at the same point.. 1. that the YZF dogbones give too much rise. 2 That an overall rear rise between 10-15mm is optimum. 3. That part of the fun in TRX ownership IS the collection of notes, the 4 sets of fork springs, the 3 shock springs, 2 shock shim stacks and a partridge in a pear tree....

Spend 20 grand on a R1 and replica helmet to satisfy your inner Valentino Rossi

Spend <9 grand on a TRX, suspension bits, pipes, jetkits and tools to satisfy your inner Geremy Burgess......

Long live the TRX

DFH

[Triton]

PM me your address and I'll send the 177s...

[idl1975]

Thanks guys!

Think I may go for longer than YZF ones. The forks and shocks were revalved for track use, but the springs are stock and I was told at the time that the spring rates were OK for my weight. I haven't had this bike on the road in years, as it's been in storage, but I don't recall having a fork travel issue, i.e. no bouncing off the bump stops. My big problem was the awful fork damping - wallowing and weaving in fast corners on two clicks or locking up over bumps on 3. I'm sure this sounds familiar to many!

So while I will review and fit heavier constant-rate springs as necessary when I get around to fork servicing, I still think a touch more rear ride height would help. Especially as it is 10mm through the yokes at the front already...

On another note, does anyone know of a fork brace for the TRX (or YZF 600R) forks? I recall having the bike shuddering under heavy braking at Oulton Park and suspected at the time was the fork tubes twisting/flexing enough to cause stiction.

Cheers!

Not discounting your dogbone measurements dfh, they're spot on, just the ride height gains. I have tried 173 c to c, 175, 177 and currently 178 (2003 ZX6-RR alloy and still fitted) which give an average 7mm increase at the rear on the blue bike above. With a front drop of 5mm this gives a very slight increase in overall ride height with a decrease of about 1/5 of a degree in rake, measured by an old fart with a laser pointer strapped to the fork legs. The science of suspension geometry is actually simple - until you tilt the bike over and add gravitational effects. Then I'm lost - I rely on lap times and 'feel'.
My advice is to take it one step at a time and make accurate notes whenever you modify anything. My garage wall is covered in TRX suspension 'notes', everything from static sag figures to spring rates tried, valving and tyre pressures/rear shock adjustments etc. Trouble is, once I get the perfect (for me) set-up, I'll buy those flatslides, add an extra 5 hp and totally fuk up the settings!

2003 zx6rr eh? .. thanks for the heads up. Off to the wreckers soon or maybe I can buy your 177mm DB's

I suspect we may differ in measuring methods. I measure rear ride height when changing dogbones from rear axle to a point marked on the rear subframe with the wheel off the ground. I do this as the rising rate curve is also affected by the dogbone change and the change in static sag change will be a combination of the two. Thats just the way I do it but it doesn't matter which system we use.

We seem to be at the same point.. 1. that the YZF dogbones give too much rise. 2 That an overall rear rise between 10-15mm is optimum. 3. That part of the fun in TRX ownership IS the collection of notes, the 4 sets of fork springs, the 3 shock springs, 2 shock shim stacks and a partridge in a pear tree....

Spend 20 grand on a R1 and replica helmet to satisfy your inner Valentino Rossi

Spend <9 grand on a TRX, suspension bits, pipes, jetkits and tools to satisfy your inner Geremy Burgess......

Long live the TRX

DFH

[phuk72]

On another note, does anyone know of a fork brace for the TRX (or YZF 600R) forks? I recall having the bike shuddering under heavy braking at Oulton Park and suspected at the time was the fork tubes twisting/flexing enough to cause stiction.

Much more likley to have been due to wheel / head bearings or discs than the fork tubes flexing.

[Max]

Mine did that, till I swapped out springs and played with the oil level. It was actually kinda funny feeling, like abs or something.

It was bottoming out and the shudder was the tire becoming the last link in suspension...

[idl1975]

Mine did that, till I swapped out springs and played with the oil level. It was actually kinda funny feeling, like abs or something.

It was bottoming out and the shudder was the tire becoming the last link in suspension...

Ah, ok, that will have been it then!

[cheesie]

anyone know the part number for the zx6r tail risers