[ozzycouch]

Hi guys, am in need of a bit of information for a 91 vitara, SWB, Manual
My rear drive shaft has been vibrating when road and engine speed are equal (no load but in gear) ever since doing a small lift (45mm). Killing unis in the process…
While doing the lift, I found the shocks wouldn’t fit. Clearance to the diff was nill. So I changed the top mounting point on the diff 180 degrees forcing the front of the diff towards the ground, giving enough clearance for the shocks to fit in the back. But, also pulling the drive shaft further out of the gear box. Both unis were replaced about a week before the lift.
Not too sure what’s standard on these cars, so...

Questions.

Which way should the top bracket on the diff be facing?

How much driveshaft should be hanging out of the gear box?

Am I in need of a drive shaft spacer?

Pics attached

Any other suggestions for a fix.... Cheers

Chris

[christover1]

Yes you need a tailshaft spacer.
Tail shaft could be loose on the splines that far out.
That could cause vibrations.

The angle of diff and output at transfer case need to be the same,
or vibrations can occur.

A spacer at the top joint can help with handling,
not sure if that would help the vibrations.

Front diff drop brackets could be wise, helps protect cv's

[Scrawny]

As Christover says, spacer could be the go

[ozzycouch]

Thanks for the ideas,

Yokes are on the same way they as they came off... which could be wrong, as the cars a bitza...

Can anyone confirm the location of the top mount? Or should it be how I found it, spun 180 degrees to where it is in the photo.
Would like to sort it before making additional spaces up.

Thanks for you help.

[christover1]

Looks like yours is right way now.
Heres mine, its functioning great.

[christover1]

These can allow fitting of Fatter shockers,
and also help with lost travel with some lifts. )IE coil spacers.

[christover1]

My build thread may help.
Also check out the other builds in Rigs of AZ

http://auszookers.com/forum/viewtopic.php?f=4&t=9990

[ChrisRinai]

i cant help much except to say you can't just change the angle of the driveshaft/tailshaft and expect everything to be hunky dory! driveline angles are very important and if you dont fix it you'll keep crapping uni's or worse, the tailshaft will remove itself from your car which could be very dangerous

[Gwagensteve]

christover1 wrote:

A spacer at the top joint can help with handling,

Sorry for the hijack, but this is interesting. Can you explain why this is the case?

My take on vitara handling is that in stock form they are dangerous, and mostly due to the large mismatch in roll centre front to rear. I would have thought raising the rear roll centre even more at the rear would degrade handling.

Vitaras handling generally improves when the front is lifted because the front roll centre rises with lift, and the rear doesn't. This more closely aligns front and rear roll centre and levels out the cars roll axis. Raising the rear roll centre along with lift would only, IMHO, amplify the vitaras handling problems.

Steve.

[christover1]

Gwagensteve wrote:

christover1 wrote:

A spacer at the top joint can help with handling,

Sorry for the hijack, but this is interesting. Can you explain why this is the case?
Steve.

I don't know enough big engineering words to explain it.
But I can feel the difference,
especially when suspension is doing its stuff.

My theory is Suzuki know more than I do about suspension geometry,
so if I change anything,
I try to match those changes in rest of the suspension.

IE it is close to its original travel,
only starting further 50mm down.

[Gwagensteve]

Sorry for harping on this, but you are right - suzuki do know more than you (us) about suspension geometry, so why did you raise your rear roll centre when you lifted the car? How does it handle better? What's better about it?

I'm not trying to sound aggressive, but I have some specific issues with vitara suspension design and I can't see how raising the rear roll centre helps in any way. I'm generally interested in why/how you think it is better. Exactly what feels better about the car?

I'll add that in crawling, a very high roll centre might be useful, but that's not the case in a road driven car.

The best handling vitara I have driven had a calmini kit in it. The calmini kit raises the front roll centre heaps but the rear very little. Whilst tall and soft, it feels very intuitive - like a normal car. Vitara's generally feel terrible so it was a revelation to me.

Steve.

[atari4x4]

Gwagensteve wrote:

The best handling vitara I have driven had a calmini kit in it. The calmini kit raises the front roll centre heaps but the rear very little. Whilst tall and soft, it feels very intuitive - like a normal car. Vitara's generally feel terrible so it was a revelation to me.

Steve.

I'm jumping on board this HiJack train....

Would running a rear sway bar be beneficial in balancing out the F/R roll centres on my calmini equipped Vitara? As you said I find it quite balanced even with no front swaybar, but I always feel the rear being looser due to the 3 link A frame design.

Gus

[Gwagensteve]

No. Roll stiffness and roll centre are different things. Adding roll stiffness with a sway bar would increase oversteer, and vitaras need more oversteer like a hole in the head.

Steve.

[royce]

Gwagensteve wrote:

No. Roll stiffness and roll centre are different things. Adding roll stiffness with a sway bar would increase oversteer, and vitaras need more oversteer like a hole in the head.

Steve.

x700, push into a corner that is a lot tighter than you thought and get ready for the giggles, at least they will slide pretty tamely once they let go

[christover1]

royce wrote:

Gwagensteve wrote:

No. Roll stiffness and roll centre are different things. Adding roll stiffness with a sway bar would increase oversteer, and vitaras need more oversteer like a hole in the head.

Steve.

x700, push into a corner that is a lot tighter than you thought and get ready for the giggles, at least they will slide pretty tamely once they let go

Mine under steers, possibly a function of lockers and LWB ?

[want33s]

Gwagensteve wrote:

No. Roll stiffness and roll centre are different things. Adding roll stiffness with a sway bar would increase oversteer, and vitaras need more oversteer like a hole in the head.

Steve.

How does this work Steve?
I only ask because in my experience with sway bars I have found that fitting* one to the front increases oversteer and fitting* one to the rear increases understeer.



*Fitting one where one never existed or upgrading existing.

[ozzycouch]

Thanks christover1,
That's exactly the picture I was after.
Might look into the shock brackets and put some spring spaces in while I'm under there...

Thanks.

Now back to roll centers and sway bars...
Love the passion on this site.

[Gwagensteve]

christover1 wrote:

x700, push into a corner that is a lot tighter than you thought and get ready for the giggles, at least they will slide pretty tamely once they let go

Mine under steers, possibly a function of lockers and LWB ?[/quote]

Chris, you've done a critical thing to change the handling balance - you've lifted the front. This raises the front roll centre and makes the car handle in a more neutral way.

All cars are set up to understeer from the factory. If a car inherently oversteers its dangerous and likely to have been modified by someone clueless. It's what happens if you do something silly like load the car up at close to the limit of its grip and then snap the throttle shut that's the key to a cars inherent behaviour. Vitaras do understeer, but in stock, SWB form, when they loose grip it tends to be the rear first and the car rotates spectacularly. My ex GF had a hardtop SWB and it scared the bejeesus out of me - they spin quite quickly and unexpectedly. I think they are dangerous and I'm surprised there hasn't been a consumer reports type witch hunt about them. I think they are that bad.

want33s wrote:

How does this work Steve?
I only ask because in my experience with sway bars I have found that fitting* one to the front increases oversteer and fitting* one to the rear increases understeer.

*Fitting one where one never existed or upgrading existing.

This is contrary to both suspension theory and normal experience, and without knowing what car you were experiencing this with, I can only assume it was due to an inherently mismatched or poorly setup car from scratch.

It's possible that adding a front sway bar might increase steering "bite" and therefore the speed of turn in, and therefore increase the speed the car transitions to oversteer, but I'm guessing that that's in a car that already has quite stiff rear suspension/high rear roll stiffness and was already prone to oversteer.

It's also possible that fitting a rear sway bar might reduce body roll to an extent that the car sat flat enough to keep its front tyres loaded better than therefore understeer was reduced.

However, as I've said, this must have been a strangely set up car to start with, but I'll also add it's important to separate "turn in" from the activity of the car through the corner.

I'll use the example of Piggles. With high rear roll stiffness, (radius arm rear) and relatively low front roll stiffness ( OME front leaf) my car would turn in very quickly ( understeer reduced, I guess) but would then transition to oversteer very quickly as the outside rear tyre was overloaded and the inside rear tyre would go light.

Doing nothing other than removing a radius arm bolt - so NO parameters have changed except roll stiffness, the car would turn in slower but once into the turn it was almost impossible to oversteer - the car would lift an inside front wheel and the resulting overload of the outside front would push the car into understeer. It's actually nicer to drive like this, but not as much fun.

Now coiled front and 3-link rear it's still prone to understeer which is exactly what the theory says it should do.

I've had the same experience with my Gwagen - removing the front sway bar massively improved turn in and reduced understeer.

Steve.

[want33s]

Gwagensteve wrote:

want33s wrote:

How does this work Steve?
I only ask because in my experience with sway bars I have found that fitting* one to the front increases oversteer and fitting* one to the rear increases understeer.

*Fitting one where one never existed or upgrading existing.

This is contrary to both suspension theory and normal experience, and without knowing what car you were experiencing this with, I can only assume it was due to an inherently mismatched or poorly setup car from scratch.

It's possible that adding a front sway bar might increase steering "bite" and therefore the speed of turn in, and therefore increase the speed the car transitions to oversteer, but I'm guessing that that's in a car that already has quite stiff rear suspension/high rear roll stiffness and was already prone to oversteer.

It's also possible that fitting a rear sway bar might reduce body roll to an extent that the car sat flat enough to keep its front tyres loaded better than therefore understeer was reduced.

However, as I've said, this must have been a strangely set up car to start with, but I'll also add it's important to separate "turn in" from the activity of the car through the corner.

I'll use the example of Piggles. With high rear roll stiffness, (radius arm rear) and relatively low front roll stiffness ( OME front leaf) my car would turn in very quickly ( understeer reduced, I guess) but would then transition to oversteer very quickly as the outside rear tyre was overloaded and the inside rear tyre would go light.

Doing nothing other than removing a radius arm bolt - so NO parameters have changed except roll stiffness, the car would turn in slower but once into the turn it was almost impossible to oversteer - the car would lift an inside front wheel and the resulting overload of the outside front would push the car into understeer. It's actually nicer to drive like this, but not as much fun.

Now coiled front and 3-link rear it's still prone to understeer which is exactly what the theory says it should do.

I've had the same experience with my Gwagen - removing the front sway bar massively improved turn in and reduced understeer.

Steve.

The cars in question were mostly stock standard XY-XF Falcons and HR-WB Holdens.
Falcons tend to lean towards oversteer standard whereas Holdens all understeer, especially HQ on.
I found that fitting a rear bar to a Falcon made it want to push through corners(understeer).

[banga]

Gwagensteve wrote:

The best handling vitara I have driven had a calmini kit in it. The calmini kit raises the front roll centre heaps but the rear very little. Whilst tall and soft, it feels very intuitive - like a normal car. Vitara's generally feel terrible so it was a revelation to me.

Steve.

never thought i would here the day that steve would say something nice about a calmini kit. i do agree that the handling is alot better after i installed mine and when running right offset rims. just need to get rid of steering play.