[wolf_rt]

ok this one has me stumped...

got a 91 swb soft top sierra.

was just having a look underneath and the front diff seems to be 20mm forward of its correct spot?
Its all stock, but the springs are pretty flogged and the fronts sit dead flat at rest.

I was looking at doing RUF, but there is only about 8mm clearance between the tie rod and the drag link. I was surprised to hear people talking about moving the front diff forward 30-40mm without hassle?
This could be worked out in the scheme of things though, so no big deal.

Problem is, the diff appears to be so far forward that the slip joint on the front shaft has flogged out from having minimal engagement.

I could just put a spacer on the front shaft, but I would like to figure out what the hell is going on.

Everything on the front end is stock as far as I can tell...

could the front springs have been put in backwards? or are they symmetrical?
wrong front springs? the shackle angle looks ok...

the diff is centred over the 'locating bolt' in the spring pack, so the perches haven't been re drilled, unless someone has drilled a new hole right through the whole leaf pack?

any ideas?

[want33s]

A new hole through the pack is a possibility worth looking at. Not a mod I'd do.

[alien]

you hit the nail on the head at the start...

when the leaf is arched its shorter than when its flattened out, so the diff will move forward cos of the shackle being at the front.

if you're leaving flat springs in, then get a driveshaft spacer onto the front and rear shafts (the rear diff will have moved back also). The other thing to check will be the tierod and draglink fouling each other, and how much angle the shocks are on given their mounting point on the diff has moved too.

[christover1]

A 20 mm front diff move may have been done by a previous owner.

I did that to my Sierra, and I did need a tail shaft spacer.

[wolf_rt]

christover1: if someone has moved the diff, it could hove only have been by re drilling the whole leaf pack, doesn't seem like the easiest way to go about it?


alien: just seemed strange that the stock range of allowable movement would allow the front drive shaft to flog out, but then its not supposed to be like that for any length of time I suppose.

[christover1]

wolf_rt wrote:

christover1: if someone has moved the diff, it could hove only have been by re drilling the whole leaf pack, doesn't seem like the easiest way to go about it?

Not how I did it.
Redrilling the spring plates and axle plates.
2nd hole would be hard to see, without undoing.
I'll try and find a pic

[christover1]

[wolf_rt]

that looks like how I would have done it... no holes like that in mine...

the diff is good where it is, i'll just put a spacer behind the drive shaft... just seemed strange that it is so far forward without any obvious mods.

[SierraDan]

could have happened in the spring production. could have been a stuff up.

[christover1]

May have longer, or different front springs.
I forget, but there is an 80's car spring that can be a replacement, that is longer.

[TasRat]

I've been wondering if my front diff is located too far back, at rest the space from the rear most point of the front tyre to the lower corner of rear wheel arch is minimal. Only the hieght gives clearance.

Is there a measurement the diff or wheel centre should be from somewhere on the body?

The pic is on a bit of an angle but I hope you see what I mean.

[Red89]

christover1 wrote:

May have longer, or different front springs.
I forget, but there is an 80's car spring that can be a replacement, that is longer.

Carry Van I think.

[alien]

all the aftermarket manufacturers have different length leaves... i had lovells 2" springs in mine before going SPOA and while they had the reverse wrapped eye on the leaf, they still gave 2" of lift - this meant they were considerably longer than factory, and when they settled in the shackle angle was pushing it.

its just "one of those things" and depends on the brand you buy (or the brand the previous owner bought).

please please please check your steering isnt binding up before you go putting a spacer in and calling it a day.

[wolf_rt]

The leaves are DEAD flat.... there is no possible way the diff could move further forward than it is now, and I can still fit my finger between the tie rod and draglink.

I ordered a 3/4" spacer, but i will have to check that's not too much at full droop.

[alien]

sweet =) flat leaves are awesome. theres a few things i forgot, and thats your caster angle, which will have been severely altered (although most likely for the better if the leaves are flat). then theres the pinion angle - might cause the uni's to bind (doubt it, but its possible) and last of all, bump stops... you're most likely bottoming out on them over every decent bump in the road!

out of curiosity though, what tyre size are you running? must be pretty close to stock given you're not complaining about them smashing into the body?

[wolf_rt]

Yeah 1 bump stop is smashed, are the e-bay ones any good?

only had the rig for 2 weeks, and its been raining here since then... F'ing mud... cant get to the rocks.... but that's probably a good thing till i make some sliders..lol
Just fixing roadworthy items for now, as i still have to get the rego transferred. Then I'll make with the ghetto mods.

tires are 215/75/15 at the moment, but i picked up some 30/9.5/15's at the swapmeet, so they will be going on in the near future... may have to break the grinder/hammer out....

I'll have a look at the pinion angle tomorrow.(today)

Steering/handling seem fine.

Unfortunately the rear leaves are completely hammered, with a pronounced W shape... will have to make a ladder bar for the rear.

[alien]

phwoar, yeah those pics didnt load last night - 2nd one you can see its almost resting on the bump top just sitting there =) haha i bet its a rough ride! lol

i think you might need to bite the bullet and get some new springs... you'll likely want some 2" leaves to run the 30" rubber anyway.

[shep]

As long As the Pitman doesn't hit the tie rod there is no problem just check
that the tie rod and drag link aren't touching