What's the concensus on 11.5" lowering shocks for 1980 GS750?

[82tiburon]

Thanks.
Joe Dipietro is not only "The Man" when it comes to captaining, repairing & maintaining luxury yachts --- if he can't fix it with what's at hand, he'll fabricate it) --- but the guy came all the way over from across the county just to help a bud out.

[Steve]

Sure.
Avert your eyes from the mangled carnage,

Dang it, I mis-read that. I thought it said "FOCUS your eyes on the mangled carnage".

Yeah, it was a bit more than could be done with "average" tools, good that you had someone there that could do it.

Steve Murdoch is right, we all need a "Joe". I have access to a "Joe" here, who just happens to be named Joe. He is a welder by trade and did some work on my wifes bike a couple of years ago. He made new mounts for her 'new' saddlebags, then shortened the centerstand and side stand because of the shorter shocks we installed.

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[Chuck78]

I thought you were talking about the upper shock stud? But you mentioned lower. I was scratching my head thinking "strange, I thought all gs750 twin shock applications used a clevis lower?" You seemed to be talking a lot about the stud (upper). Very confusing because they lower clevis mount uses a bolt threaded into the shock, and if you weren't trying to save the shock, you could just cut grind the threaded sleeve on the inboard clevis???

I've taken apart many of these, many of which have been parts bikes that sat outside for decades, one even had a tree growing through it, and I've never stripped one or never had one seized. Someone could have loctited it. I've never had trouble with the bolts head stripping either. And I thought they were 14 mm, which is almost exactly 9/16"... so I don't think it got rounded off from using an English/Standard/Imperial wrench to get it out, since the 9/16 should work within a few thousands of an inch to be nearly identical. I'm going to take a wild guess here and assume that it rounded off due to using a 12-point socket or 12 point wrench (or adjustable crescent wrench), which is definitely not the preferred way. 6 point of the proper style, and not a cheapo one with a long internal taper at the beginning before the hex starts. I throw those in the scrap bin when I come across them! (Or hit them on a grinding wheel to get the hex near the end)

The biggest complaint I have is, a 3/8 inch bolt will probably be a bit sloppy on the swing arm eye mount. Did you mount an eye to eye shock on the lower clevis-accepting swingarm eye? With a thru-bolt and nut??? This will make the shocks a bit more bow-legged than is practically reasonable. This type of American Harley-Davidson engineering is not really the best thing for this bike. Hardley's barely have rear suspension! Bad example to use!

My other concern for your safety is that I hope you used a lock nut, as that type of application should ONLY be a fine thread, NEVER EVER a ever a coarse thread. Do yourself a huge favor and convert it to a fine thread and a metric fastener that fits the eye on the swing arm with the proper shoulder diameter. Unless you put some micrometer calipers on the shoulder of the proper bolt or inside of the swingarm eye, &amp; then turned down a grade 8 fastener of larger-diameter on a lathe to fit that perfectly.<br>
Grade 8 won't really matter if there is a sloppy fit, abuse is abuse, &amp; a sloppy fit on suspension will put the bolt and the eye and the rubber under a lot of abuse and stress over bumps. 1/64th of an inch will make a difference. A BIG one.


Also, I would try to preserve the ride height of the bike a good bit, and I would have cautioned you originally to not use quite as low of shocks (slightly shorter than stock = okay if you drop the front an equal amount), but rather to do what was suggested, and cost less than a rusty used Chinese pair of swap meet H.D. shocks, and that is to trim the seat foam down and also trim it more narrow, then recover the seat with a little bit of modification, all of which is basically free. Cutting the width of a pan down is a little more advanced, but that would also be very beneficial, but would require brazing torches or a MIG or TIG welder. Then a slightly shorter shock to make up the rest of the difference.


I have lowered bikes before for assistance with the rider touching the ground, and I always always try to make the seat lower but still very comfortable. That is the first goal. Then I ditch that cruiser/chopper 19 inch front wheel and lace an 18 inch rim on to the hub to improve the steering and drop the front end down (only works for spoked rims). This I realize is a bit more costly and takes a little bit more skill or ambition, but it is a nice alternative to also improve the handling while lowering the front 1/2 inch.


These bikes are really wonderful to work on and very very well engineered by some wise Japanese wizards for the most part, but the regulator rectifiers that they chose to use are definitely absolute garbage and should be upgraded. And the bikes are 35 or 40 years old, so the wiring system can use a good going through. Same with the fuel system. When gone through properly and maintained, they will beat any American bike of their time by far in terms of reliability, performance, handling, e t c. As you can tell, being a mechanic, and working on both Japanese and Harleys, I definitely don't like working on Harleys!



On the bright side, it sounds like you definitely are much better off because the spring rate was very incorrect for you to begin with. Proper spring rate even on a lesser quality shock absorber is more important than an expensive shock with too stiff of a spring.

[Chuck78]

I'm glad you got your bike headed in the right direction and are not as likely to injure yourself now!

Apologies I am a bit biased against Harley bikes after working on them a lot, and finding the Japanese bikes far superior in many many ways including wrenchability, handling, performance, weight, Etc
I don't take too well to people insulting Japanese bikes and boasting about 900 lb Harleys that are only designed to sound and perform like an antique tractor engine and haul two heavy riders at a very casual pace...

If you want to see pot metal, you should come check out my wife's 86 1337cc Harley FXR! Whopping 56hp out of a colossal 1337cc's! I think that thing is made of pig iron and pot metal!!!! 640 lbs and slow as can be, my Japanese drum brakes on my antique dirtbike stopped about 10 times better than the front disc on that thing! And that's how they were from the factory!

The only thing thought was pot metal on these bikes is the zinc aluminum alloy that the carburetors are made of, and Harleys use the same. S&S and Mikuni both use aluminum on their nicer carburetors however.

Hopefully you can take away from this my concerns and suggestions for your bike, & not try to slam superior Japanese bikes in favor of Harleys, while talking to a forum full of people that chose to go against the grain of the typical American "biker" culture ("Half the bike for twice the price" = Harley). I don't like to be referred to as a biker, instead I call myself a vintage motorcycle fanatic, a motorcycle rider, motorcycle addict, two wheeled addict in general, pedal powered, knobbies and premix, four stroke street bike, whatever!

If you need it lower than it is now, definitely look into shaving the seat. Much better option.

Best of luck, and thanks for joining the GS forum! We'll get you set straight on any mechanical issues that you have. Just be courteous come in here with a Harley-only attitude, unless you are comparing a modern Harley regulator-rectifier to the old POS GS units... I WILL NOT argue that point!!! Upgrade to a Polaris OEM # 4012941 for better reliability than most anything else - we would be glad to point you in the right direction on how to test the stator, install that, and make a few modern wiring upgrades to the bike.

[Chuck78]

Also, compared to Harley's, one of the many reasons these make a lot better horsepower up top is because they use a solid lifter type camshaft. A lot of Harleys use hydraulic lifters because they are darn near impossible to get into if one were to need to do a valve adjustment, especially some of the frames being a quarter inch above the rocker box cover. The Allen wrench needed to take the cover off is close to 2 inches tall! This is a big problem!

So just know that these will need periodic valve adjustments to keep them running like a top. I believe you have a 16 valve version, which is the easier to do valve adjustments on. No shims to swap out.

Don't let my defense of Japanese bikes and my shared experiences of poor Harley engineering dissuade you, we are generally a very helpful bunch here and I'm sure everyone will be eager to help you make this bike work well for you. If you are ever looking for something a little bit lighter weight, I would highly recommend a GS 650, as it is lower, a fair bit lighter, and makes really good power due to the advanced head and piston design despite still being a two valve per cylinder engine.

Best of luck, have fun riding, and be safe!

[82tiburon]

It’s all good. I enjoy All different kinds of motorcycles for their idiosyncrasies --- the very reason most people hate them & just cling to one brand.

BTW, Sportsters ---which are my favorite Harleys --- have solid lifters, rather than hydraulics.
Which may explain why they dominated flat-track racing from it’s very roots until the sport all but died out.
The trick to removing that last offending rocker box bolt is to simply drill a small 5/16” hole through the frame backbone directly above the bolt --- which causes no undue stress whatsoever --- and…voila!... simply unthread & pull it out with a hex key.
Easy as pie.

Some other notes:

A) I did NOT use eye to eye “chinese shocks made for a Harley”, but rather, eyelet to clevis units designed specifically for my GS.

B) At no point did I insult Japanese motorcycles or those who ride them (I came up on them myself) --- only what passed for decent metallurgy over there in the early days.

C) Neither of my Harleys is a 900 lb. rolling paperweight. They have both been extensively trimmed down with replacement aluminum parts where structurally-feasible, “speed-holed” for further weight loss & I am constantly eyeing them for any excess fat that I can trim off.
In other words, they’re fast --- not loud.

But as I said before, I’m not a hater by any stretch of the imagination, but a lover of all things on two wheels that go ZOOOOOOOM!