Rear shock mounting problems

[Guest]

GS1000G, 1980. The rear shock upper mounts are studs with double diameter, a 10mm plain section (on which the steel sleeve of the shock bush fits) and an 8mm threaded section.

I have several problems.

First, the 10mm OD plain section protrudes a good 4 or 5mm from the shock eyes, meaning I need 10mm ID washers or a spacers to take up that distance.

Next, the 8mm threaded section is MUCH longer than the depth of thread on the stock domed nut and one washer. There's enough for at least 4 plain washers in there, if not 5.

Next, the threads on both studs look on their last legs - a previous owner has messed around here by fitting a Givi carrier, which I guess was allowed to vibrate on the threads, enough to wear them. The nuts do still grip but I don't like the look of the threads and I wouldn't want to tighten them as much as I normally would.

So, I have a set of questions I very much hope somebody might be able to help me with.

Main question is, are these studs welded to the frame? Looks like it to me but there's plastic mudguard stuff in the way of a proper view.

If they are part of the frame, I'm hoping I might be able to run a 5/16" UNF die along them and cut a better thread for that size. 5/16" is 7.8mm, so I might get away with that as a repair? Or is this a problem others have successfully tackled some other way?

The other big question is, in what order are washers / spacers etc meant to go? Are there meant to be washers or a spacer on the inside of the shock, so that on the outside, none of the 10mm plain section of stud is showing? That would look right to me, but I can't see anything helpful in the parts book (and I can't see why anyone would have changed it from stock, unless it was to make the Givi carrier fit?).

I am guessing that in order to remove the shocks, you have to remove the silencers? Or is there just enough clearance to get the lower eyes off with the silencers in place? I'd prefer not to disturb the exhaust if at all possible at this stage, as it has no leaks and sits just right.

I'd be really very grateful for any advice on all or any of the above questions, thanks, Jon.

[hampshirehog]

The parts diagram shows 3 washers either side of the eye on the shock (or 2 plus lift handle on the LH side). The nut doesn't have to be super tight, it's only there to stop the shock falling off sideways and all the pressure is on the 'up and down'. If the threads are good enough for that I would leave them alone but if they're really fooked then your idea of using the UNC die might do the trick.

There are other ways to sort the mounts out and there are several threads on here on how to do it. There's one by Chris (Tatu on here) that I liked and might mimic next time I need to sort out a mount.

Here's how he did it:

http://www.thegsresources.com/_forum/showthread.php?232668-Stripped-Shock-Mount-Repair&highlight=Shock+mount

[Steve]

Personally, I would NOT re-thread the shock studs.

The thread pitch will be different, so you will be cutting across existing threads (not virgin steel) to form your new threads. That will weaken everything considerably.

Yes, the studs are welded in place. Some have reported success by cutting/grinding the stud off flush with the frame, drilling a 10mm hole where the stud used to be, sliding a shoulder bolt through the hole, then welding it in place.

.

[Crankthat]

Cannot answer all of your questions Jon.
Possibly not even this one as our bikes and shocks are a bit different.

I am guessing that in order to remove the shocks, you have to remove the silencers? Or is there just enough clearance to get the lower eyes off with the silencers in place? I'd prefer not to disturb the exhaust if at all possible at this stage, as it has no leaks and sits just right.

On my 750 I can take off the silencer bolts that are under the shocks (1 on either side of the bike) and gently pry outwards and have just enough room to remove the bottom bolt for my shocks.
I have clevises on the bottom of mine where if I am not mistaken you have another eye as you have on the top.
Not sure which setup this would be easier on.
The bike will need to be supported well as removing the shocks will compress the space between your swingarm and seat/fender.
It works well to remove the bolts with the rear tire just starting to lift.

Make sure you are being careful while jacking the bike up.
And the weight will shift from the rear to the front when the shocks are removed, so expect it.
If this is your first time jacking the bike up a strong helper would be advised to help balance the bike and as a extra set of hands if your jacking technique is unstable.
If you have strong rafters above your workplace tying the bike off will help also. (STRONG RAFTERS)

[bwringer]

Measure again...

Unless something has already been badly Mickey-Moused somehow, the stud diameter in the smooth portion is 12mm, not 10mm, and the threaded portion is 10mm diameter X 1.25mm pitch, not 8mm or 5/16".


Yes, you do need one to three washers, but remember the shock still needs to be able to move a little.

I've repaired these with a metric shoulder bolt. Cut off the remnants of the stud flat, then drill a slightly undersized hole (29/64", IIRC). Remove the inner fender and clean up the old weld goobers on the inside as needed, then tap a shoulder bolt through from the inside. Some also add a few welds, but that's not necessary as long as it's a tight fit. The head only sticks out a bit, so there's no need to grind it off or anything.

12mm shoulder bolts are only available with a courser thread, M10X1.5, so you'll also need a new acorn nut.

I don't recall the needed length dimension to go through the frame and give enough length to mount the shock, so measure and ponder the diagram at McMaster-Carr carefully.

http://www.mcmaster.com/

Search for "shoulder bolt" and choose 12mm for the shoulder diameter.


Assuming stock exhaust and bike on centerstand, to remove the shocks just remove the upper nuts, pull the shocks outwards and off the studs and then angle the shocks backwards. Raise the swingarm (a board or lever under the rear tire helps) and remove the lower nuts. Loosen the lower nuts first and it's a bit easier.

You do NOT need to remove the exhaust to remove the rear shocks. To remove the rear wheel, you do much the same -- take the shocks loose at the top and lower the swingarm so the axle clears the muffler, or raise the swingarm so the axle clears the muffler.

[Jon]

Thanks for the replies, all of them are helpful. To be honest I was guessing at the stud diameters and probably got them worng: 12 7 10 is probably what they are, I'll measure tomorrow (not used to thinking in metric).

So, it's possible to pull the tops of the shocks off without simultaneously doing likewise with the bottom halves? If so, that's very good news, if a little surprising.

One thing I'm still unsure about is whether there are meant to be washers inboard of the upper shock eyes or not. Or do all the washers go to the outside? And - just out of curiosity - why did Suzuki make them that way - I mean, if they wanted to thoughtfully provide enough spare stud for fitting a carrier, why didn't they just make the dome nuts deep enough, without the clumsy and very out of character approach of using loads of washers?

[hampshirehog]

There are meant to be 3 washers on each side of the eyes. No idea why Zook made them like that - maybe they over- ordered on washers.....

[Crankthat]

Would imagine the need of washers comes in as Suzuki left extra room for various aftermarket sissy bars and luggage racks.

[Jon]

OK, just been cleaning & measuring etc, and the left hand thread is fine. The righ side thread is dodgy but I think I can get away with it. The last couple of turns before the thread runs into the plain section are qutie good but before that they are quite worn. The nut still turns OK on them even so, and on the last two it should grip tight enough (assuming not very tight is tight enough on these, especially with a dab of Loctite?)

You were of course spot-on, Bwringer, the diameters are indeed 12 & 10. Interesting that there are meant to be 3 washers each side. I think there's one washer on the right inside and none on the left inside, so I'll correct this. I am supposing that, with 3 washers on the insides, none of the 12mm shoulder shows on the outside, and 10mm washers are all that should go there?

Changing the subject (I'll start another thread for this), I can see that the air intake rubbers are not sealing perfectly where they enter the airbox (well, I can see that on the left hand one anyway), so that's yet another task....

[tatu]

OK, just been cleaning & measuring etc, and the left hand thread is fine. The righ side thread is dodgy but I think I can get away with it. The last couple of turns before the thread runs into the plain section are qutie good but before that they are quite worn. The nut still turns OK on them even so, and on the last two it should grip tight enough (assuming not very tight is tight enough on these, especially with a dab of Loctite?)

You were of course spot-on, Bwringer, the diameters are indeed 12 & 10. Interesting that there are meant to be 3 washers each side. I think there's one washer on the right inside and none on the left inside, so I'll correct this. I am supposing that, with 3 washers on the insides, none of the 12mm shoulder shows on the outside, and 10mm washers are all that should go there?

Changing the subject (I'll start another thread for this), I can see that the air intake rubbers are not sealing perfectly where they enter the airbox (well, I can see that on the left hand one anyway), so that's yet another task....

The rear shock mounts are very important High stress areas of the structure and therefore fundamental to the safety of the machine's function, do you really want to hang all that on a couple of threads?

[bwringer]

The rear shock mounts are very important High stress areas of the structure and therefore fundamental to the safety of the machine's function, do you really want to hang all that on a couple of threads?

Without seeing the OP's shock stud threads in person, I can't comment on whether they'd be safe.

But you have to remember, there's really no force pushing the shock sideways off its stud. It doesn't take much to retain them. As long as the nut stays in place, it'll be fine. Personally, I'd clean the threads up with an M10X1.25 die or a 1.25mm thread file and then decide whether they seem sufficient.


As far as the washer questions, eyeball the bike from behind and make sure the shock is aligned straight up and down. Also note that the eyes are off-center on some shocks, so make sure the alignment of everything makes sense. You may need to shuffle washers to get this right.

[bwringer]

So, it's possible to pull the tops of the shocks off without simultaneously doing likewise with the bottom halves? If so, that's very good news, if a little surprising.

Yep, there's enough give in the rubber bushings to make this possible.

[Brendan W]

As others have said, clean the threads and re-assess. There isn't much side load so a bit of thread lock might be the answer.

[tatu]

Without seeing the OP's shock stud threads in person, I can't comment on whether they'd be safe.

But you have to remember, there's really no force pushing the shock sideways off its stud. It doesn't take much to retain them. As long as the nut stays in place, it'll be fine. Personally, I'd clean the threads up with an M10X1.25 die or a 1.25mm thread file and then decide whether they seem sufficient.


As far as the washer questions, eyeball the bike from behind and make sure the shock is aligned straight up and down. Also note that the eyes are off-center on some shocks, so make sure the alignment of everything makes sense. You may need to shuffle washers to get this right.

I agree, clean it up and see what you have got, but for my way of thinking being at flat chat, layed over and hitting a sunken drain cover is a h3!! of a time to find out if the shock is staying put when at a time like that your hands'd already be full.

[Jon]

You were quite right, Bwringer - the shocks came off their upper mounts just as you said (and I even remembered to only do one at a time!). I bought a selection of 12mm ID stainless washers plus a set of 4 polished stainless dome nuts & washers for the clocks 'chrome' trim piece, plus a few other washers, from my local marine stainless fasteners supplier. Total was £2. Wish I'd thought of that before having bought 6 genuine Suzuki washers (the 10mm ID ones only) from Robinsons at £1.40 + VAT each! And they're not even stainless!

I cleaned the dodgy right-hand thread as best I could using a wire brush and a scriber to pick around between each thread. I put some Loctite 470 on the threads and tightened the nut as much as I dared - which was more than I'd expected, and it was quite tight as I left it. But that was the last time I disturb that shock without fixing the thread properly. I'm toying with the idea of reducing the diameter of the existing stud from 10 to 8 and threading that, and Helicoiling a standard dome not to fit. I can;t see why 8mm shouldn't be plenty strong enough in this application.