54 replies to this topic

[yel327]

Thanks for that.
Just one question though. Are you sure the A9X/L34 arms are different for any reason other than to get more clearance under the caliper since the big HQ caliper and even bigger HZ Girlock are normally rear mounted away from the steering arms? HK-WB and LH-UC stubs aren't all that different. The H series example simply has the axle (and hence caliper mount) situated slightly higher on the knuckle, plus a bit more inclination.

And also, I think the L34 part numbers for stubs are as you say HX 1-tonner with cast iron calipers, but from memory I think the part numbers for HK-WB stubs chopped and changed a little. From memory in early HQ the tonner was the same p/n as the rest. I know there was confusion in GMH spare parts at one stage when HK numbers superceded to HQ numbers, meaning the HK stubs then had arse about part numbers with odd numbers being RH and even numbers LH which broke with convention. One of my HK parts catalogues has pen marked up part numbers with big ? marks and other text. I think this confusion also happened when the L34 parts list was typed, as it is obviously wrong in group 6.020 otherwise the L34 would have rear mounted calipers.

Anyway, all good stuff. Looks like I have L34 calipers and steering arms on a normal LH crossmember. Probably has HQ stubs as well. Not sure about the upper control arms though.

Edited by yel327, 11 February 2008 - 04:03 PM.

[REDA9X]

I think I answered the question about the upper control arms having different part numbers, it's due to different bushes to a standard SLR upper arm. The upper arms came as an ASSY. I'm not sure what the difference between an A9X and L34 stering arm is, but I know they are not the same as I remember speaking to one of our members who had an L34 and A9X and he mentioned they were different and showed me 2 new ones he had on the shelf.

[REDA9X]

I'll see if Greg still has them when I get home

[yel327]

Thanks for the steering arm pictures - that is exactly what I was after.

Just checked the part numbers for the stubs. Interesting that in HT the disc brake stub part number changed from HT, but the drum stayed the same. The numbers stayed (but swapped sides) right through to HX for disc and HJ for drum, except during HQ the tonner ones changed but not right from the start. For some reason from HX to WB the part number changed for the cast/alloy calipers - does A9X also change from L34 then due to the cliper change?

[Toranamat69]

Talk the Welby...He posted in one of my front stub threads a pic of his...still in the grease proof GMH wrapping..the 2 correct parts numbers of A9X front stub axles with the heat proofing lines on them

I still have those pics Welby posted and I have looked at them heaps and compared with several other HX and HZ stubs I have and I can't see any difference in the amount of 'meat around the top balljoint'.

I reckon that is another old wives tale until someone can physically show me the difference.

I am very keen to see some L34 steering arms if someone has some pics.


M@

[MRLXSS]

Great pic! I also am interested in this topic. And that pic shows exactly what i am after! Anyone got some UC Steering arms or A9X ones lying around they want to give me? My HZ Caliper rests on the tie rod end...

[Dangerous]

Ouch! My brain hurts!

To the best of my knowledge/recollection -

L34s had front mounted HQ style cast iron calipers

L34s and A9Xs used the same steering arms, which dropped down further at the front to correct the steering rack geometry (ie make it sit horizontally at rest, with the combination of LH/LX steering rack, HQ style stub axles and different steering arms). They do have different part numbers though, which I suspect may be for different shaped 'ears' for limitinig the steering to stop the (different) calipers from hitting the upper wishbones.

A9Xs use the later cast alloy HZ style caliper, with different brake line and bleeder points, and the cast caliper bracket was scalloped to provide clearance for the tie rod end.

I don't think that A9X and HX commercial stub axles (which share the same part number) are physically any different to the HQ stub axle - ie no extra 'meat'. I believe they are heat treated only, to provide more strength. I do know however that the A9X and HX onwards one tonner stub axles have subtle differences. Given that the HQ stub axle is so beefy though, I don't see how you could bend or break one anyway, without bending or breaking substantial parts of the car itself.

L34s did not have offset upper wishbones, as the A9X and UC did. They did however have metal removed from them to provide more steering clearance, which would account for a difference in left and right parts (and part numbers), when compared to standard LHs and LXs.

I still don't reckon there was any difference in the position of the mounting holes for the upper wishbone between LH and any LX (except for the A9X and L34 versions).

I can't see any reason for the L34 and A9X front crossmembers to be any different, unless the L34s didn't have the steering coupling shroud mounts?? Both had two sets of upper arm mounting holes.

Datto, A9Xs did have UC geometry top arms, ie offset upper ball joints (except a few), but if the part numbers were different (and from memory they aren't), it probably would have been due to different compound bushes being fitted.

Quoting REDA9X, "L34 steering arms are similar to HJ one tonner", Red, I'm pretty sure you meant stub axles, not steering arms.

Quoting Yel327, "From memory in early HQ the tonner was the same p/n as the rest." - Yes, I agree. Heavy duty stub axles weren't in the oringal HQ lineup.

Quoting Rory - "Not true Chop...I have proved that they are heat treated.One on the right is stock HX...left is heat treated A9X or one Tonner.
R" Yes, I agree. I think you'll find that the sets you have will have the part number cast in them too, signifying different parts, even though they look nearly identical.

Chop, you said "I still state that the only real difference is the extra metal around the top ball joint. IF all L34 and A9X stub axles are heat treated, a non heat treated stub axle can easily become a heat treated one.

Question:

Do we all agree that it would be impossible to tell the difference between heat treated and non heat treated stub axles on a street driven vehicle by taking it for a drive?"

I disagree on the first bit (ie no extra metal - this is the case between LX and HQ stub axles, not A9X and HQ), but I certainly agree on the second bit.

[yel327]

Ouch! My brain hurts!

To the best of my knowledge/recollection -

L34s had front mounted HQ style cast iron calipers

L34s and A9Xs used the same steering arms, which dropped down further at the front to correct the steering rack geometry (ie make it sit horizontally at rest, with the combination of LH/LX steering rack, HQ style stub axles and different steering arms). They do have different part numbers though, which I suspect may be for different shaped 'ears' for limitinig the steering to stop the (different) calipers from hitting the upper wishbones.

A9Xs use the later cast alloy HZ style caliper, with different brake line and bleeder points, and the cast caliper bracket was scalloped to provide clearance for the tie rod end.

I don't think that A9X and HX commercial stub axles (which share the same part number) are physically any different to the HQ stub axle - ie no extra 'meat'. I believe they are heat treated only, to provide more strength. I do know however that the A9X and HX onwards one tonner stub axles have subtle differences. Given that the HQ stub axle is so beefy though, I don't see how you could bend or break one anyway, without bending or breaking substantial parts of the car itself.

L34s did not have offset upper wishbones, as the A9X and UC did. They did however have metal removed from them to provide more steering clearance, which would account for a difference in left and right parts (and part numbers), when compared to standard LHs and LXs.

I still don't reckon there was any difference in the position of the mounting holes for the upper wishbone between LH and any LX (except for the A9X and L34 versions).

I can't see any reason for the L34 and A9X front crossmembers to be any different, unless the L34s didn't have the steering coupling shroud mounts?? Both had two sets of upper arm mounting holes.

Datto, A9Xs did have UC geometry top arms, ie offset upper ball joints (except a few), but if the part numbers were different (and from memory they aren't), it probably would have been due to different compound bushes being fitted.

Quoting REDA9X, "L34 steering arms are similar to HJ one tonner", Red, I'm pretty sure you meant stub axles, not steering arms.

Quoting Yel327, "From memory in early HQ the tonner was the same p/n as the rest." - Yes, I agree. Heavy duty stub axles weren't in the oringal HQ lineup.

Quoting Rory - "Not true Chop...I have proved that they are heat treated.One on the right is stock HX...left is heat treated A9X or one Tonner.
R" Yes, I agree. I think you'll find that the sets you have will have the part number cast in them too, signifying different parts, even though they look nearly identical.

Chop, you said "I still state that the only real difference is the extra metal around the top ball joint. IF all L34 and A9X stub axles are heat treated, a non heat treated stub axle can easily become a heat treated one.

Question:

Do we all agree that it would be impossible to tell the difference between heat treated and non heat treated stub axles on a street driven vehicle by taking it for a drive?"

I disagree on the first bit (ie no extra metal - this is the case between LX and HQ stub axles, not A9X and HQ), but I certainly agree on the second bit.

Excellent summary.

Couple of points - There are 2 different part numbers for HX stubs - one to use cast iron calipers (HQ-HJ), and one to use alloy (HZ-WB). Does the A9X use the early or late part number?

RTS LX definitely has it's upper control arm mounting holes lower than pre RTS. Much lower - up to an inch.

[yel327]

Missed one point. Did L34 have holes in the rear crossmember arms for sway bar mounts? A9X should have I think. That would explain one difference.

Years ago I set up an LX hatch with A9X style brakes and suspension. I used a UC crossmember, UC control arms, UC rack, Torana steering arms, HQ stubs/discs and UC PBR alloy calipers with WB pad carrier. It was almost perfect geometry, with a maximum of -0.5deg camber. In which direction does the KPI vary using HQ stubs over Torana? If using the Torana stubs increases the camber (ie makes it more positive) then it makes sense that the A9X would use lower upper control arm mounting holes than UC to lower the camber (make it more negative). I think this is how Holden achieved more -ve camber in phase 1 RTS ie by lowering the upper control arm mounting point.

[Toranavista]

RTS LX definitely has it's upper control arm mounting holes lower than pre RTS. Much lower - up to an inch.

Just to clarify. I think up to an inch lower than UC not (LH & Pre RTS LX).

[Dangerous]

Couple of points - There are 2 different part numbers for HX stubs - one to use cast iron calipers (HQ-HJ), and one to use alloy (HZ-WB). Does the A9X use the early or late part number?

RTS LX definitely has it's upper control arm mounting holes lower than pre RTS. Much lower - up to an inch.

A9X stub axle part numbers are 9943695 (left) and 9943696 (right).

Re the RTS LX control arm mounting holes - got any pics? This was also a topic in this thread Difference between LX RTS & UC RTS ??? , which has quite a few pics, and a method for measuring and comparing mounting hole heights.

[Dangerous]

Dangerous..

I did look at HQ and HX/A9x side by side and the later ones are about 6mm thicker in the casting...you can see them physically as well..especially at the bend for the top balljoint...I will try to get 2 together...other than that...spoton!
R

Interesting, Rory - I wasn't aware that early HQ stub axles were much smaller than later ones. The description sounds just like an LX vs HJ series stub axle.