34 replies to this topic

[Toranamat69]

Does anyone know the KPI of both the Torana and the HQ stub axles?

I seem to recall the HQ has 2 degrees more but can't remember figures.

M@

[dattoman]

7 and 9 degrees

Torana is 7

HQ is 9

From my memory
Its definatly 7 and 9 but I might have them the wrong way round. Can't find my CRS catalogue

[355LX]

I'm pretty sure it's 9 degrees for Torana, and 7 degrees for kingswood. How's the suspension mod's coming along Matt?


Dave

[makka]

kpi is King Pin Inclination (sp?)
are drum brake torana any different? I have got a pair lying round somewhere

[dattoman]

yup
sure does
Matt will explain it all I'm sure

[Toranamat69]

I'll post some pics of my progress on the front end this weekend hopefully. Still in the early stages, planning, checking (and learning) but I think I have it all planned out. But these things always develop as I learn more. I would love to get my hands on some suspension modelling software but everyone wants $$$ for that.
I at least now know enough how to draw it on autocad and calculate the different characteristics etc now, so I can manually do most of the things I want to check.

Starting to get some good bits together though. I got a nice UC sunbird front end from Torana05 last weekend so that should get things moving having the starting piece to work on.

The King pin inclination effects a few things - the main 2 being:

1. The 2 degree difference from the Torana to the HQ stub will have a small change in the scrub radius of the front wheels which will make the steering 'feel' slightly different. this also depends what wheel offset you run though.
Ideally, you should have no scrub radius as it makes the steering heavier and will cause harsh feedback through the steering wheel when you hit a bump.
The 2 degree difference is not huge but significant.

2. The second thing is when you turn into a corner, the outside wheel on the turn will progressively lose negative camber as you turn the wheel. This is only fairly small (1 degree of camber by the time the wheel is turned at 45 degrees) but given the option, you would choose the stub with the lower KPI.

The other difference is with the Torana upper control arms, it is pretty easy to run out of adjusting shim room in the upper control arm if you use the HQ stubs and want to run lots of Camber and Castor - the torana stubs will allow more adjustment.

M@

[Litre8]

But as Brock and others showed you can still make them handle and negotiate corners pretty well with the HQ heritage stub assembly.

[Toranamat69]

As far as I know all HQ,J,X,Z stubs are the same KPI and all the Torana ones are the Same from LC to UC, Drum and Disc versions.

I just wanted to be sure which was 7 degrees and which was 9 degrees before I went and bought the CRS 2" dropped ones. Hence the reason for my original query.

My comments above assume the Torana ones to be 7 degrees and the HQ's to be the 9 degrees which I think is the case.

I have to measure my camber curve on the HQ stubs I am currently using to comment exactly what the camber does through out the range of suspension in degrees but mine certainly seems to actually lose negative camber as the wheels go up through their suspension travel. The Torana and HQ stubs will give you the same actual camber curve through the full range of bump and extension of your suspension (this is determined by the height of the stub axle between upper and lower balljoints) but the car will sit 1" higher in the curve with the HQ stub axles assuming the same ride height or alternatively the car will be 1" lower and operate at the exact same height suspension wise. I would really have to measure them to say which is the better or worse part of the curve to operate in.

The CRS 2" drop will again give the exact same camber curve as the HQ and Torana stub but will let the car sit 2" lower.

As I mentioned above, you will lose an additional 1 degree of negative camber when the wheels are turned 45 degrees with the 9 degees KPI and that is about where full lock would be so for a normal type high speed corner, you are more likely to be turning about 12to 15 degrees so you would only lose 1/4 degree negative camber on that corner.... for a race car, you could compensate this by running an additonal 1/4 degree static negative camber and probably not notice it a lot but for road cars where tons of negative camber kills front tires, this is nice to reduce the amount of camber gained in a corner. The less static camber you run, the better the straight line braking. I hope this setup I am planning will run around about 0.5 to 0.75 degree static negative camber.

I plan to run the 7 degree CRS 2" drop stubs as my setup at this stage unless my measuring etc shows up something unexpected.

The bad effects of the short length of the stub axles is far worse on these cars than the 2 degrees difference in KPI but I am out to capture all the nice options in this front end rebuild.
I am sick of the shit you hear from the Suspension shop 'Experts' who want to sell you the off the shelf item they have in their store hence why I am undertaking this task.

SLR6000, I'd also be looking at that rear end if you are planning some drifting.
Do you have any current plans for the rear?

[Toranamat69]

SLR6000, The only things better on a UC front compared to an LX are:

1. The Steering rack

2. The upper control arms

3. The steering arms.

If you can find those and put them on your LX, there is no need to change to the UC front.

Depends what you want to achieve at the end and what you actually have on yours now and how much you can get a UC front end for.

I won't be using any of those above even on my UC front end when I am finished.

M@

[Toranamat69]

Okay,

I rang CRS today to get the run down on their stubs.

They reckon the Toranas has 9 degrees KPI and the HQ 7 degrees <_<

Does anyone have anything from GMH to verify what either the Torana or HQ KPI is? as I though they were the other way round for some reason.

The other thing I discovered is the 2" drop HQ stub they do is still 1" lower than their 2" drop torana stub for those wanting the lowest they can possibly go.

Unfortunately, I wanted a stub with 7 dgrees KPI and 2" drop from the Torana height but it appears they do not do one. Aaaahh more investigation needed before I even purchase my stub axles.

M@

Edited by Toranamat69, 20 December 2005 - 06:39 PM.

[Toranamat69]

After checking a bit more I recon the CRS 2" drop HR stub to suit commodore brakes should do me nicely - I need to get someone there at CRS who actually knows what they are talking about.

I did a bit of reading today and it seems pretty unanimous that the HQ-HZ has the 7 degree KPI and the torana 9.

Interrestingly the main concern seemed to be that people couldn't remove sufficient shims to get back to a decent camber for the street as you run out of shims to remove with the HQ stubs on torana front ends.

Has anyone else had this drama?

I am currently running this system and have no dramas with that at all. Is this perhaps a case of the old sagging LX crossmembers being responsible not the stub axle?


M@

[dattoman]

Sag could be an issue
I recall..... in my distant memories that if you remove all the shims your still left with 1 deg neg. Since you probably run alot more than this you never noticed the lack of adjustment

CRS spindles in commy pattern is ideal. As commy brakes bolt straight up
Be careful though with caliper choice. Dave has Brembos on his..... fit fine. Phils trying to put AP's (CP5200) on his and the caliper fouls the tierod end. So new brackets will need to be fabricated to suit
This is on a 330mm commodore disc.

Minor problem...... but still a headache