63 replies to this topic

[yel327]

I will take a photo and measurements of an unmolested A9X to try to clear up the reasons why cheap ass holden did what they did to the A9X.  Yes the stubs drop it by around 20mm but it uses 14" rims vs 13" rims and that counters the 20mm back to std ride height.  Without pulling the A9X to bits I think if you measure free height to loaded height vs std torana springs you will find a bees di#k in ride height (once broken in). Its not like Toranas need ground clearance for off-roading. Ride height would be the same but of course the HD springs wouldn't compress as easy (firm ride).

 

The big limited travel blocks in the A9x are just because it was a slapped together system adapted from the HX/HZ (which has far more room under the guards). You have to remember it was all done for the race teams and bigger brakes to meet homologation requirements. Think holden mentality aka HQ bumper on LE Monaro its just throw on what they had and make it work. We are not talking Ferrari here, engineering and penny pinching in the 70's at holden was pretty crude and rude.

 

 

The A9X steering arms (P/N 92001893 and 4) where only required for bump steer correction when using the H series stub axle.  Holden didn't fit them because it had fitted the front springs (P/N 9931027) in the A9X.  Otherwise when Holden delivered every other torana with the optional P/N 9931027 springs it would have the same poor bumpsteer the A9X has if you used the standard torana steering arms.

 

I can assure you its was the H series stub axle usage that required new steering arms.

 

All of what you say makes perfect sense, except Holden slapping the HQ rear bar on the LE as being cheap. It was actually a HJ rear bar, as the LE was a HJ body. Most of the W size Holdens and Statesman kept the HQ rear styling, only sedan and wagon changed at HJ introduction. Van, ute, coupe, tonner and Statesman kept the HQ rear quarters and beaver this kept the HQ rear bar(s). Statesman did get a different bar as the tail-lights changed but the back end was still HQ. It wasn't until WB that the Statesman got a HJ sedan/wagon back end. I din't see this as cheap, it is just economics as sedan and wagon were the volume sellers and hecne it was justifiable to engineer in some stying upgrades. For the small volume of coupes (like 943 HJ plus the 580 HJ bodies made into HX's) the added cost per car would not have been acceptable. 

 

I don't see the use of HX stubs on the A9X as being cheap either, it makes sense to do it, ie use an existing part to build a homolgation special!

Edited by yel327, 17 August 2013 - 11:31 AM.

[Toranamat69]

With the top control arm in the lower position and H series stubs, depending on the brand of top balljoint used, there is not a lot of travel before the top balljoint is maxxed out in its travel.

Without  the A9X lowered bumpstop, a big hit which compressed the rubber bump stop on the lower control arm substantially could be nasty for the balljoint - some of the aftermarket ones have slightly less travel than the original holden ones.  A bit more of a saftey margin is certainly a good thing there.

[ls2lxhatch]

Interesting theory however the stock A9X position is slightly higher than the stock LX position. At the same camber setting the A9X stub axle is closer to vertical than the LX stub (due to the different included angles H-Series 7.5 vs Torana 9) so it would appear that the H series stubs on the stock bump stops would require slightly less ball joint movement than an LX stub on the bump stops.

 

 

Edited by ls2lxhatch, 17 August 2013 - 06:10 PM.

[Toranamat69]

Actually, I didn't think about that much, you are actually starting from a point with the balljoint tilted over more with the Torana stubs, not the H series stub at the same ride height.

 

I agree that Holden likely put no more thought into it than to limit the suspension travel to the same amount in bump as a standard torana whilst using the H stub axles.

 

I mentioned the ball joint thing as an aside but tend to try to keep my posts pretty breif these days so tend to oversimplify. 

 

I have some cheap balljoints here I was just using for some testing and they have about 2 or 3 degrees less movement range than the Holden ones and they actually did not  have enough travel - If I still use the standard bump stops on my setup, I will be doing an A9X type mod as it is closer than I like without them.

 

I also now have balll joints with an extra 5 degrees travel as my stubs are effectively 1" taller so mine would definately force a standard balljoint past its allowable limit.  I don't know why the original top arms were angled as they were on the balljoint plate as they are so close to the limit in 1 direction, but have a fairly comfortable amount in the other direction.

[ls2lxhatch]

Thinking about it some more I think I may have be wrong about the LX stub axle vs the H series stub axle and the upper ball joint movement.

 

If you look at the drivers side of the suspension from the front. The more shims you add to the drivers side UCA the further the ball joint swings to the left. The H series stub axle requires less shims than the standard Torana stub axle for the same camber setting due to the different stub axle included angles. Therefore the ball joint would be further to the left with the Torana stub axle than it would with the H series stub axle.

 

As the UCA swings up the ball joint will swing from the left to the right so the further it is to the left to start the more room it has to move to the right.

 

Therefore it would then appear that the Torana stub axle would have more ball joint movement available than the H series stub axle. If the ball joint was close to its maximum limit at full compression with the Torana stub axle and the UCA in the LX position then the included angle of the H series stub axle may be enough to exceed ball joint movement at full compression with the UCA mounted in the A9X position.

[76lxhatch]

Interesting, I never even considered binding of ball joints - this is on the bump stop with Torana stubs and aftermarket ball joints, maximum allowable (1/2") shims on the rear bolt for maximum caster. It definitely wasn't binding but I don't know how close as I didn't think to look at it; well and truly past normal suspension travel though, my springs would never allow this much compression

[TerrA LX]

Thinking about it some more I think I may have be wrong about the LX stub axle vs the H series stub axle and the upper ball joint movement.

 

If you look at the drivers side of the suspension from the front. The more shims you add to the drivers side UCA the further the ball joint swings to the left. The H series stub axle requires less shims than the standard Torana stub axle for the same camber setting due to the different stub axle included angles. Therefore the ball joint would be further to the left with the Torana stub axle than it would with the H series stub axle.

 

As the UCA swings up the ball joint will swing from the left to the right so the further it is to the left to start the more room it has to move to the right.

 

Therefore it would then appear that the Torana stub axle would have more ball joint movement available than the H series stub axle. If the ball joint was close to its maximum limit at full compression with the Torana stub axle and the UCA in the LX position then the included angle of the H series stub axle may be enough to exceed ball joint movement at full compression with the UCA mounted in the A9X position.

 

 

I think you are missing that both the H series and Torana stub axle place the ball joints in pretty much the same location, what you have to take into account is the top arm mounting location and the upper travel limit, ie how low the car is to start with and how much compression till the stop.

[ls2lxhatch]

The difference in the included angle between the H series stub axle and the Torana stub axle is 1.5 degrees. If you remove the LX stub axle and fit the H series stub axle then camber increases by 1.5 degrees.

 

To reduce the camber by 1.5 degrees requires 0.25" shims to be removed so the H series stub axle will have 0.25" less shims than the LX stub axle to achieve the same camber setting. If you have 0.25" less shims then UCA and therefore the top ball joint is 0.25" further to the left when looking at the drivers side from the front.

 

I believe the factory camber for the LX was -0.5 +/- 1.0 and the factory camber for the A9X was -1.0 +/- 0.5 so when aligned to factory specs LX -0.5 and A9X -1.0 the difference in terms of shim stacks would be 1 degree which is 0.17". However the maximum camber for both is -1.5 so when both are set to factory spec maximum camber we are back to 1.5 degrees difference and 0.25" of shims.

 

Shim chart posted by JBM in this thread.

Edited by ls2lxhatch, 18 August 2013 - 01:43 PM.

[ls2lxhatch]

hi my lx 77 model has the top arm bolted to the lowest part on the k thingy so we asuming it has rts .it has spaces on the bolts on the upper arm as well as the sticker on the letter box  i am just wondering what sort of springs should it have on front to match the rts 

michelle

 

The aftermarket springs available do not have a RTS and non RTS options. The position of the top arm does not affect the choice of spring.

 

Lovells list 6 cyl and 8 cyl with low, standard and raised springs.

http://www.lovellsau..._passcomm13.pdf

 

Kings list 6 cyl, 8 cyl and A9X with low and standard springs.

http://www.kingsprin...r_catalogue.pdf

Edited by ls2lxhatch, 18 August 2013 - 02:02 PM.

[ls2lxhatch]

It would appear that the service manual is wrong and that the F71 has the same working height as the standard V8 spring with just a higher spring rate. The L34 service bulletin lists the F71 working height as 9.02" which I have also seen listed for both the standard 6 cyl and V8 springs.

It makes sense that all springs for the Torana have the same working height and just different spring rates to suit different kerb weights and ride preference although sometimes there are spring options that raise the suspension.

How tall are the front and rear the bump stop extensions on the A9X?
 
If the compression travel on the front and rear suspension of the A9X has been reduced by the same amount then that would basically confirm that suspension ride height on the A9X is the same as a V8 Torana and that the A9X just has considerably less compression travel.

Edited by ls2lxhatch, 25 August 2013 - 09:49 PM.

[ls2lxhatch]

Some things are really difficult to photograph.

 

One day when you have the time these are the three measurements I would like to see.