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L34/a9x Kpi

Started by _UC HATCH_ , Feb 20 2008 06:18 PM

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21 replies to this topic

#1 _UC HATCH_

Guests

Posted 20 February 2008 - 06:18 PM

Hi all,

I found the following statement

L34/A9X cars use HQ style vented brakes and 14 inch HQ GTS wheels. Holden made a special HQ style stub axle incorporating Torana KPI, and a special steering arm to compensate for the 1inch lowering.
from http://www.hoppers.c...ppin holden.htm

and was wondering if someone here that knows the L34/A9X cars can tell what the answer is about the KPI.

Are the L34/A9X stub axles KPI the same as HQ (eg 1 Tonner as have read on the forum) or are they a breed of there own being Torana KPI based on a HQ style stub axle?

Also what are the KPI figures for the HQ> and Torana and L34/A9X if different?

Thanks

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#2 _CHOPPER_

Guests

Posted 20 February 2008 - 06:59 PM

L34 and A9X stub axle is the same as a heat treated HX 1 tonner stub axle.

HQ is 7 degrees KPI
LH is 9 degrees KPI

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#3 _UC HATCH_

Guests

Posted 20 February 2008 - 07:21 PM

Hi CHOPPER

What you are saying is the L34 and A9X stub axle KPI is 7 degrees KPI same as HQ> and the statement is false.

Thanks

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#4 _CHOPPER_

Guests

Posted 20 February 2008 - 07:52 PM

Exactly, also they didn't use HQ GTS rims. They were an L34/A9X only item with a special rim outer to achieve the different offset used on those vehicles. The HQ GTS and L34/A9X rims are interchangeable. It's just that there is an offset difference of 19mm, which will alter track by 1.5".

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#5 _JBM_

Guests

Posted 21 February 2008 - 06:13 AM

The offset difference is 1/2" per side.
HQ -3/4"
L34/A9X -1/4"

They are only interchangeable in regard to similar stud pattern, the GTS wheels will narrow the track by 1".

James

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#6 _CHOPPER_

Guests

Posted 21 February 2008 - 10:52 AM

You got the HQ offset wrong. A standard 14x6 HQ rim has an offset of +13, or +1/2".

Using your figures, the HQ rims would INCREASE track by 1".

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#7 _JBM_

Guests

Posted 21 February 2008 - 11:04 AM

I was thinking that the difference (3/4") was the HQ negative offset, so Ive worked it wrong.

Sorry about confusing the issue.

James

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#8 _CHOPPER_

Guests

Posted 21 February 2008 - 11:06 AM

We all make mifftakes. As long as the correct info is eventually posted, that's the main thing.

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#9 _UC HATCH_

Guests

Posted 24 February 2008 - 05:33 PM

May be a stupid idea and even not able to be done, but if it was/is possible to re-drill the bottom arm pivot points on the cross member to shorten its length to rectify the 2deg difference, how far would 2deg be, anyone know.

Haven't looked to see if it can be done just like I said an idea I had as re-drilling seemed easier than making a longer top arm.

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#10 _CHOPPER_

Guests

Posted 24 February 2008 - 07:27 PM

You would need to do a cut and shut on the arm for that to work. Sounds really dodgy to me, even if there was enough room to do it. The spring then wouldn't seat in the bottom arm and would probably bind somewhere. That's if you could actually get the bloody thing in. This would also cause problems with the rack, unless you shortened the rack ends by the same amount and cut more thread onto it.

In short, it sounds like an idea best placed in the bin.

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#11 _CHOPPER_

Guests

Posted 24 February 2008 - 07:53 PM

I should've mentiond this in my previous post.

The KPI change is actually a good thing, as this means there are a lot less shims to use during an alignment. Anybody who has had shims fallen out of their Kingswood or Torana would know what I'm talking about. And as a bloke who probably did around 60,000 wheel alignments in my 21 years in the tyre industry, I know what I'm talking about.

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#12 _UC HATCH_

Guests

Posted 25 February 2008 - 11:19 AM

Thanks CHOPPER,

Binned!

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#13 Toranamat69

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Posted 25 February 2008 - 01:24 PM

You would have to move those holes for the lower control arm about 17 to 18mm to clear the existing holes and have enough meat between them which is tons more thn the 2 degrees difference in the stub axles.

As Chopper pointed out - it will effect several other things as well and not in a good way. i.e narrowing track and changing the rollcentre and bumpsteer.

Unless you want the front really low - you should be fine using the 7 degree KPI stubs anyway.

M@

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#14 _UC HATCH_

Guests

Posted 25 February 2008 - 08:56 PM

Hi Toranamat69,

I was thinking about it after reading your web site about you car and the power steering where you where lengthening the top arms (Nice car and are you going to update the power steering progress very interesting).

And was just wondering how far it would have to go in on the bottom if the holes were welded up or a plate welded in to get the KPI correct for the HQ type stub to get wheel alignment specs easier.

Well this is what I was thinking but with the info from chopper and yourself I have put it in the bin as chopper suggested.

Thanks
Mark

Putting thinking cap back on the shelf and plugging back in for a recharge. :ph34r:

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#15 Toranamat69

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Posted 25 February 2008 - 11:33 PM

Approximately 6mm of shims will change the camber by 2 degrees so that is also how far you would need to move the lower control arms to do the same thing.

I would be concerned with how strong the end result is with welding and redrilling the control arm mounting brackets - unless you also welded a larger washer on the outside of the brackets as well.

I am not sure if you reallise or not but the KPI is built into the stub axle itself, moving control arm mounts does not change the KPI at all. You would just be changing the static camber setting to suit the different KPI in the different stub axle so you can get it back into the normal adjustment range (if that makes sense)

Yes - aaahhmmm updating my page again - my little bro has gone home today so I can sober up again and get some work done

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#16 surfmaster

Marineboy

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Posted 25 February 2008 - 11:36 PM

There is a formula for the number of shims and where they are placed to the change in camber and castor.

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#17 _UC HATCH_

Guests

Posted 26 February 2008 - 12:58 AM

Toranamat69,

Thats good to hear you will be back to update, was a really interesting read and good pictures.

What I was thinking,(I know shouldn't do it) was that like you said the KPI is built into the stub so I thought that as the difference is 2 deg between the 2 stubs this would kick the axial part to point upwards slightly leaning the top of the wheel in and from what I have heard before is that the wheel alignment is a hassle with the HQ> stubs (this may be right or wrong I don't know myself) so by shortening the bottom (or lengthening the top) arm would bring it down to a level point to start with and make it easier to get the wheel alignment correct.

But I was wrong in my thinking :huh:

, Is a wheel alignment with the HQ type stubs a problem for getting the wheel alignment correct?

Thanks

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#18 _CHOPPER_

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Posted 26 February 2008 - 01:58 PM

Approximately 6mm of shims will change the camber by 2 degrees so that is also how far you would need to move the lower control arms to do the same thing.

Interesting you should say that. As a man with around 60,000 wheel alignments under my belt, I found that with the HQ - WB Holdens, adding (4) 1/8" shims ( 13mm) front and rear would alter camber by 2 degrees.

And UC hatch, depending on exactly where you want the alignment settings, it may or may not be a problem. Removing the spacers that the late LX and most UC's had on the bolts the shims sat on removed the problem.

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#19 ls2lxhatch

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Posted 26 February 2008 - 05:35 PM

From this thread.
http://www.gmh-toran...topic=21839&hl=

Posted Image

Edited by ls2lxhatch, 26 February 2008 - 05:39 PM.

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#20 _CHOPPER_

Guests

Posted 26 February 2008 - 08:43 PM

That chart indicates you need 8.6mm of shims to move camber by 2 degrees, which is a bit more than what matt said ( 6mm ). This indicates you only need 75% of the shims needed for a camber change on a Torana as compared to an HQ. Considering the differences in the front ends of the two vehicles, I'm not suprised there is some variation.

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#21 _UC HATCH_

Guests

Posted 26 February 2008 - 11:39 PM

Thanks to you all for the help.

That chart is a bit of hieroglyphics to me sorry to say, :huh:

.

Looks like a suck it and see when the time comes for the wheel alignment.

If they cant get the figures then try something to solve the problem.

Was just trying to think ahead.

With HQ type studs on an LX cross member and all other parts UC for a street use car would the wheel alignment figures to aim for be standard?

Would drilling the holes lower be of a benefit?

This is on a UC hatch with a Chev small block fitted (one day)

Mark

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#22 _CHOPPER_

Guests

Posted 27 February 2008 - 03:34 AM

The chart is simply a guide for alignment mechanics as to what shims to put where to correct an alignment. When you've done as many as me, you can do them in your sleep without the chart.

Drill the holes lower for sure. If you have a six, start with:

Castor: +2
Camber: -1
Toe in: 2.5mm overall

With the Chev fitted:

Castor: +0.5
Camber:-1
Toe in: 2.0mm overall

That's where I would start as a base line figure. Other people will advise on other settings.