progressive fork springs

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two-stroke-brit
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progressive fork springs

Post by two-stroke-brit »

some time ago i got some new fork springs for my 73 buffalo .but have run into problems in instalation.
Image
i ordereed the right thing
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but a good two inches too long.
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a good 1 5/8 protruding.
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and 1/2 inch to the threads.
i am thinking maybee it has 72 lowers but it has the rotor/disc fittings so thats not it.
also the front wheel is off the ground strung up by the frame so its fully extended.
before i cut them down .
any sugestions or things to check would be helpful.
thanks mark
She will never be pretty but hoping she will be a fun ride.

1973 SUZUKI GT750K.=SOLD
yamaha speedtwinn 100 barn find =SOLD
1x 1973 kawasaki H1 (restored)
1x 1973 kawasaki H1 (basket case) =SOLD
1982 HONDA CB900F =SOLD
1982 YAMAHA RD350LC.
1985 RZ350N
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jabcb
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Re: progressive fork springs

Post by jabcb »

Have a 1975 GT750 so I'm interested in this issue & looked into it.

Found this @ HVC cycle:
http://www.hvccycle.com/suspension-progressive.html
They state that the springs must be cut for early model forks & they offer that service.

The 1972 & 1973 GT750 used the same fork spring, part # 51171-31033.
So it looks like your springs will require cutting, but perhaps someone else can provide more insight.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
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tz375
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Re: progressive fork springs

Post by tz375 »

Damper arrangement changed in 74 to a damper rod system, the springs changed too. 74 on forks are very different. If you measure teh length of your 73 springs I can compare them to a set of 74's I have here for you.
two-stroke-brit
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Re: progressive fork springs

Post by two-stroke-brit »

tz375 wrote:Damper arrangement changed in 74 to a damper rod system, the springs changed too. 74 on forks are very different. If you measure teh length of your 73 springs I can compare them to a set of 74's I have here for you.
the original springs are 17 3/4 long.
thanks tezzer
She will never be pretty but hoping she will be a fun ride.

1973 SUZUKI GT750K.=SOLD
yamaha speedtwinn 100 barn find =SOLD
1x 1973 kawasaki H1 (restored)
1x 1973 kawasaki H1 (basket case) =SOLD
1982 HONDA CB900F =SOLD
1982 YAMAHA RD350LC.
1985 RZ350N
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tz375
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Re: progressive fork springs

Post by tz375 »

Are you ready?

They are about 21 3/8" long. They came from 2 sets of forks and are all within 1/8" or so of the same length.

That's a little different to the shorties.
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Suzsmokeyallan
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Re: progressive fork springs

Post by Suzsmokeyallan »

I'd be careful about cutting those progressive springs, you could end up making the springs rate too hard if you cut the total amount off from the open wound coil side.
I'd remove the total amount shared between the two sides of the spring.
Two strokes, its just that simple.

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two-stroke-brit
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Re: progressive fork springs

Post by two-stroke-brit »

Thanks everyone i will trim to suit when i get back to work,
i was going to just cut the open end but i guess i will do what alan says and do both ends equal amounts.(thanks allan)
i just hope i dont end up like the three stogees in the "leveling out the wobbly chair" scene.
cheers mark
She will never be pretty but hoping she will be a fun ride.

1973 SUZUKI GT750K.=SOLD
yamaha speedtwinn 100 barn find =SOLD
1x 1973 kawasaki H1 (restored)
1x 1973 kawasaki H1 (basket case) =SOLD
1982 HONDA CB900F =SOLD
1982 YAMAHA RD350LC.
1985 RZ350N
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tz375
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Re: progressive fork springs

Post by tz375 »

What do the springs sit on in the sliders - is there a post that fits in there?

I'd take a look at that and see it it's not possible to modify that instead. That assumes that the bottom of the fork leg has a large enough bore to allow the springs to pass straight through.

My guess is that there is a rod in the bottom that looks like a small diameter damper rod but has no damping chores. It would be bolted in the same way a damper rod bolts in and is probably a simple steel tube with a top hat welded or brazed to the top to create a spring seat.

If that's the case, it should be easy to get them out and shorten them

Of fit a pair of 74-75 forks
two-stroke-brit
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Re: progressive fork springs

Post by two-stroke-brit »

Thanks but i think it will be easier to shorten the springs.
we have a cutoff disc grinder at work i will set a stop and top and tail them.
thanks again mark
She will never be pretty but hoping she will be a fun ride.

1973 SUZUKI GT750K.=SOLD
yamaha speedtwinn 100 barn find =SOLD
1x 1973 kawasaki H1 (restored)
1x 1973 kawasaki H1 (basket case) =SOLD
1982 HONDA CB900F =SOLD
1982 YAMAHA RD350LC.
1985 RZ350N
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tz375
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Re: progressive fork springs

Post by tz375 »

"top and tail". Haven't heard that since I left home over 3 decades ago. Your cultural heritage is showing.

Is that expression used in the US?
two-stroke-brit
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Re: progressive fork springs

Post by two-stroke-brit »

tz375 wrote:"top and tail". Haven't heard that since I left home over 3 decades ago. Your cultural heritage is showing.

Is that expression used in the US?
NO pure souwf lundun.
She will never be pretty but hoping she will be a fun ride.

1973 SUZUKI GT750K.=SOLD
yamaha speedtwinn 100 barn find =SOLD
1x 1973 kawasaki H1 (restored)
1x 1973 kawasaki H1 (basket case) =SOLD
1982 HONDA CB900F =SOLD
1982 YAMAHA RD350LC.
1985 RZ350N
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tz375
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Re: progressive fork springs

Post by tz375 »

Darn sarf?
two-stroke-brit
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Re: progressive fork springs

Post by two-stroke-brit »

tz375 wrote:Darn sarf?
my dad was a proper cockney (bow bells and all that)
when i first came to the states i played golf with an expat from the midlands,
And he was always picking me up for saying "par free" and "firty free".
i sometimes get out an old copy of "the sweeny" just to hear someone say.
"go back to his manor and spin his drum"
ahh the good old days.
cheers mark
She will never be pretty but hoping she will be a fun ride.

1973 SUZUKI GT750K.=SOLD
yamaha speedtwinn 100 barn find =SOLD
1x 1973 kawasaki H1 (restored)
1x 1973 kawasaki H1 (basket case) =SOLD
1982 HONDA CB900F =SOLD
1982 YAMAHA RD350LC.
1985 RZ350N
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