[Surly]

Hey all,

Complete mechanical noob here, so sorry if this is really obvious to you all.

Was driving the zook this morning when it began to make a horrible grinding noise. Pulled over and had a poke around. I noticed that the rear left shackle has started to rub on the fuel tank (large after-market one).
I recently changed the shackles for stock ones as it had some goofy extended ones on. When I did this, there was about a spanners width of clearance between the shackle bolt and the tank. Now there is none.
It seems to me the axle has shifted right, bringing the shackle into contact.
What causes this, and what do I do about it?

Here are some pics:

[TZAR]

Just cut the bolts down so they are the right length. they are way too long.

[Surly]

That was going to be my fall-back option TZAR. Is it normal for the axle to shift like this?
As far as I can tell, the only thing locating the rear axles is the springs, so I guess it is supposed to move a bit...

[Gwagensteve]

Surly wrote:

That doesn't look right at all. The shackle side plates are way too loose, and will be allowing the axle to swing side to side.

I'm assuming those are stock shackle pins, and you've sourced your own nuts/washers? If so, do them up until they stop. There's a shoulder on the shackle pin that prevents them from being over tightened.

I agree you may need to cut the bolts down to clear the fuel tank, but I'd get the shackles tight enough first.

It's possible that the urethane bushes are a bit undersized, and that's not helping.

Steve.

[Surly]

Hey Steve,

I bought the shackles with pins, nuts and washers in a sealed bag from suziworld. I assume they are all stock?? I have done them up pretty damn tight. I re-used the old bushes because they looked to be in good nick, but maybe I should buy some new ones?

[Gwagensteve]

I reckon I'd be looking at new bushes then. I don't think the flange on those bushes is wide enough. It should look snug against the shackle plates and spring. I bet if you had the car on chassis stands you could swing that axle left to right without too much trouble.

It's common to find this kind of thing in an older car. Since your car was manufactured urethane bushes became all the rage and there's lots of crappy ones out there that are very old and hard. I'd pick up some fresh rubber from suziworld or soft urethane from Bruce.

Have you had the other end of the spring out of its hanger? this end can wear alarmingly, especially if the sleeves around the bolts jam up. It's not uncommon to have to cut the bolts out.

Steve.

PS not sure you're aware, but you have Vitara rims on your car. These have the incorrect offset for a sierra, and will be making the track width narrower than stock. Whilst they won't damage anything in themselves, you might want to swap to some sierra rims to get the track width back to spec considering your car is quite tall and has narrow track axles. Every little bit helps.

[Surly]

Cheers Steve. I realised I had Vit rims, but mis-understood and thought they meant a wider track. Whoops. It DOES look narrow! Might have to track down some sierra stockies and shift my tyres across..
Will pull the springs off at both ends to check and replace bushes.

Thanks for your help

[Zook_Fan]

Can't see the linear alignment with your tank but can you just flip the shackle? Can you fit them so the pins face away from the tank? It looks tight but might be possible

[Gwagensteve]

My guess is they wouldn't be able to be fitted with the tank in place "back to front"

Steve.

[Surly]

Zook_Fan wrote:

Can't see the linear alignment with your tank but can you just flip the shackle? Can you fit them so the pins face away from the tank? It looks tight but might be possible

You would never be able to feed them through with the tank there.
Will buy some new bushes from suziworld on Monday, fit them up and if needed, trim the pin.

[Zook_Fan]

Okay. When you put new bushes in and tighten the bolts it looks as though the top pin will be in contact straight away. If that is loose no more than another turn of the nut and the pin will be on the tank.

[johnmath]

Surly wrote:

Now there is none.
It seems to me the axle has shifted right, bringing the shackle into contact.
What causes this, and what do I do about it?

Is there any chance the tank shifted? It appears to be off centre with the chassis rails.

BTW how many litres in the tank?

[Gwagensteve]

I'd say it's not possible the tank could shift. You can see the rear two mounting bolts in the photo. For the tank to shift to the left, the mount visible on the RHS would have to be bent. The mount on the LHS which is very close to the chassis would take a power of force to bend, and there's no obvious damage to the tank.

I guess there's a possibility the mounting holes on the tank are elongated for fitment allowing the tank to slide to the left, but this could only be a few mm and all the bolts would have to be loose for that to happen.

I'd say the tank was built "off centre" to maximise fuel capacity, whilst allowing room for the stock filler assembly on the RHS.

*Hijack*

I'm not a great fan of long range tanks in sierras, and that photo is an example of why. The exhaust placement and routing looks to have been a nightmare, there's obvious clearance issues around the shackles, and it looks to be eating heavily into ground clearance. For road/touring use it's likely fine, but for off road use, it's likely to be a bit of a pain. I guess the OP's intended use will determine how much of a hassle it is. It owuld be possibe to get the bottom of the tank changed to angle it up towards the rear. it might loos 10L of capacity or so, but it would be much better offroad.

*hijack off*

Steve.

[johnmath]

Gwagensteve wrote:

*Hijack*

I'm not a great fan of long range tanks in sierras, and that photo is an example of why.

Steve.

Cheers, Steve. On my big trek last year i took 60 lts fuel on the roof racks (plus 30 lts water) and still arranged a fuel drop on a station property near Tarcoola. That much weight up top is a bad idea and I cracked the front left gutter. I've now got three bars on the racks, but more in the tank and less up top would be nice...

*hijack off*

John

[Gwagensteve]

Which is exactly why the OP's use is important. I'd never carry that much weight on the roof of a sierra, so a long range tank is a great idea. For shorter trips into harder terrain, the loss of ground clearance a long range tank creates is a big problem.

like lots of things, it's horses for courses.

Steve.

[shep]

I can't see how the diff or bushes can all of a sudden cause issues. That top shackle mount can't move and the bush appears fine. I reckon it has to be something to do with the fuel tank moving

[Gwagensteve]

The op has just removed extended shackles and replaced them with stock shackles. I reckon that's it.

Steve.

[Surly]

The tank doesn't ATB capable of moving, but I will get under there and have a proper play tomorrow hopefully.

Johnmath, not sure how big the tank is, will measure it's external dimensions tomorrow while I am down there, but I have put over 60litres in it in one hit. Unfortunately the fuel gauge is probably from the stock tank. Gauge still reads full after 300km's... So makes things pretty tricky for range, but it was reading about 1/3 capacity before I filled it.

Shep, I did take extended shackles off, but when I replaced with stock, I was still able to get the spanner between the end of the bolt and the tank (just), so MAYBE there has been some tank shift, though the tank felt pretty damn solid and the mounts aren't bent.

As for the longrange tank being an issue offroad? It sticks out like dogs balls... I am mostly wanting a touring rig with some lighter 4WD'ing thrown in, so not an issue at this stage.

[2stroker]

You may have had clearance because of how it was jacked up to do the job. I cant see the tank or spring moving it was probably like that but you have just noticed it.

[Surly]

Hey Johnmath, the external dimensions on the fuel tank are 74cm(L)X60cm(D)X31.5cm(H)

[johnmath]

Based on those dimensions it could be 120+ litres. I thought it looked pretty big!

BTW did you work out what happened to cause the tank and suspension to shackle up together?

[KEENSY85]

That's a big tank, I was thinking about makin A larger one or fitting a vitara 1 but 120L. Wow that's Fricken huge.

[Surly]

johnmath wrote:

Based on those dimensions it could be 120+ litres. I thought it looked pretty big!

BTW did you work out what happened to cause the tank and suspension to shackle up together?

Not yet John, been a bit lazy. The sierra is not a daily driver at this stage, so not much pressure to make me get off my arse.

[got_bar_work]

120l fuel dont leave much weight for gear