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HX stubs or not?


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#1 _XY driver_

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Posted 05 November 2016 - 11:43 AM

G'day blokes,

 

I've been charged with a complete front end overhaul for old mate Ben and his ludicrous LX sedan. You could say he's serious about skids... an aftermarket 400 Chev, a blower, EFI and alcohol head the list of madness... but at the bottom there is also standard Torana front brakes. O.o

 

I've got a complete UC front end that needs the Opel mounts cut off it. (I'm assuming they weren't any different from a 6 cyl otherwise) It'll probably get some tow hooks added to make it easier to winch onto the trailer and possibly some protection for the front two primary pipes of the exhaust, they go under the crossmember. Maybe I could make some room for them to go above...?

 

We have a chassis connector kit from CRS so that should finally get a gig. Some welding to do around the crossmember mounts under the floor. There will be some other work to do I'm sure before she goes to Summernats.

 

What I'd like to do is make the damned thing steer. Thankfully Ben agrees with me that front runners look more dangerous than cool... 245/50 15" on Convo Pros are the wheel of choice. Perhaps it's a bit much but way better than razor blades.

 

Ben doesn't want power steer, but does want a strong tendency to self center, so a lot of caster is in order. Tyre life doesn't matter really, the rears always do a lot more kays than the fronts anyway.

 

I've lurked all over the current threads about front end work and I'd like to clarify if we went to HX spindles & UC (or preferably Harrop) arms then do we also pick up 50mm of track width? I'm aware of the 20mm lower and increase in negative camber but extra width might be a killer with the wheels I have to retain.

 

Secondly, I know it's common practice to lower the top UCA mount, but has anyone canted this mounting to retain caster under brakes? There was some mumbling about "anti dive" tendency but I've not got a good answer yet.

 

I'll post this now, more to come

 

Cheers



#2 yel327

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Posted 05 November 2016 - 12:39 PM

If you plan to lower the UCA months, just use a late LX (non A9X) 6cyl or V8 crossmember and use the UC UCAs and steering rack. Will save you having to cut off Opel mounts (if it is a UC with Starfire they are the same mounts). The rest is essentially the same. If you really want to you can weld some shock absorber metal cups to the crossmember (copy off UC). I don't know if there is 25mm each side difference between HQ-WB rotor and stubs versus Torana/Sunbird stub and rotors. I might be wrong but i'd have thought it closer to only a small gain.

 

I'd not hesitate to use the HQ-WB stubs and rotors, with any luck you'll get some PBR calipers with the UC and with the right pad carriers it is a straight bolt up. Just use at least UC steering arms as already said.


Edited by yel327, 05 November 2016 - 12:40 PM.


#3 _LS1 Taxi_

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Posted 05 November 2016 - 12:45 PM

What ^^^byron said.

By any chance did you used to write hot car magazine articles back in the 80s and 90s?

#4 _XY driver_

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Posted 05 November 2016 - 02:09 PM

No I don't write for anything more than a hobby like this, or trolling science deniers on social media occasionally :P

 

The Opel mounts are a bit of a pisser, but I don't have any other crossmemembers at hand until I get the one out of the car. It's had a hard life, so I thought starting with a 4 cyl one that might've suffered less trauma was a good point.

 

Brakes will probably be a 290mm upgrade from Ultimate(?) eBay whatever his name is... I contacted him some time ago and he's offered that we can have Torana stud pattern on a HX stub kit. At least that way they'll be bigger than the Ford vented discs on the 9 inch ;)

 

Cheers



#5 orangeLJ

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Posted 06 November 2016 - 07:17 AM

Have a read of the UPC brake thread here on the forums.

Bit hit and miss from memory

#6 _XY driver_

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Posted 06 November 2016 - 08:46 AM

http://www.ls2lxhatc.../suspension.htm



#7 ls2lxhatch

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Posted 06 November 2016 - 01:01 PM

Power steering is worth considering as it will reduce the number of turns from lock to lock.

 

 

HQ stub axles do not make a significant difference to track. The track alters as the lower control arm (LCA) moves up and down. When the LCA is horizontal track is at its maximum. Track reduces as the arm moves away from horizontal. There will be a small difference in track between HQ and LX stub axles with the body at the same ride height due to the different angles of the LCA. This could be a small increase or small reduction depending on ride height.

 

 

HQ discs on LX stub axles or HQ stub axles do not do not make a significant difference track.

 

 

The Hopper Stoppers 290 mm kit for Torana stub axles used to be available in two versions. The standard offset version did not alter track and the Commodore offset version increased track by 16 mm (8 mm either side). I am not sure if the standard version is still available as it required a different hub to the majority of the Holden brake kits.

 

 

The Hopper Stoppers 300 mm kit for HQ stub axles is only available with the 16 mm increase in track. The increase is required so the brake caliper will clear the taller caliper mount on the HQ stub axle.

 

 



#8 _XY driver_

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Posted 11 November 2016 - 11:27 AM

So I've been doing some examination not the car is on the hoist... it's had a hard time.

 

I think solid crossmember mounts are in order as the existing rubbers... don't actually exist anymore, and the chassis rail has suffered a bit too. With some luck it'll get some reinforcement and a tie up with the bolt on chassis kit.

 

Just for interest, I've done some rough measurements with the loosely assembled front end, lowering the top arm does indeed improve camber gain. Canting the mounting causes issues with the arm fouling on the crossmember, if it's taken to the extreme. Might lower the back of the arm as much as possible & then the front a little as the space allows.

 

Decisions have to be made though. I don't really need the lower ride height of a HX Stub, however I'd like the extra camber gain and I think the extra negative camber would be handy. So I wonder if getting longer top ball joints out of the US is an option for increasing camber gain while retaining the Torana stub.

 

Other ideas include making a captive nut assembly to retain the top arm, with bolts through from the wheel side instead of studs welded in place. Laborious perhaps, but easier to use washers when aligning, because there's no room in the engine bay anyway.

 

Has anyone reinforced the crosmember to prevent it "closing up" and leaving us with no adjustment?

 

 

 

Cheers



#9 axistr

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Posted 12 November 2016 - 07:24 PM

Even with UC upper control arms and a good straight k-frame, 1 1/2 - 2 degrees positive caster is about it with out destroying the camber. Negative camber reading below 3/4 degrees static isn't much good unless you intend on doing fast track work. You would be better off making the lower inner control arm mounts adjustable. With caster reading above 4 1/2 degrees would give you much more cornering camber gain then repositioning the top arms, much quicker return to centre, more steering feed back and should give the steering a better toe out on turns. Don't forget K.P.I also makes the steering return to centre.

 

The only down side is you may need a gym membership to improve the arm muscles if you intend on using the manual rack, and a bit of guard trimming in front of the front wheels may be needed/ 



#10 Lazarus

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Posted 14 November 2016 - 11:01 AM

The extra track comes when you fit HQ offset wheels. If you use the same wheels you have now the change should be minimal.



#11 _XY driver_

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Posted 15 November 2016 - 06:38 PM

So this is what I'm up against... The crossmember mounts are shagged and there's going to be some steel required to get things back into shape. I'll end up with some solid mounts and then some extra material to pick up the chassis strengthening kit further back down the chassis rail. Noise? Vibration? Harshness? Yep we've got heaps! Experiments in geometry are getting interesting. With an engineer to chat to and borrow the super accurate digital level from, I'm making progress. I still haven't got any H series stubs to experiment with but 5 different data sets to graph already. So far it seems canting the top arms is a goer, adding about .350“ to the top ball joint has been effective too. Some parts have rocked up but it seems I'm the proud owner of the last pair of whiteline offset LCA bushes in captivity... pity is I'd like another pair. Superpro have offered they can make some, but I still need to clarify if they're the same style or just a fixed offset? Oh and Hoppers says that Convo Pros are impossible to fit decent brakes into... can anyone add to that?

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#12 76lxhatch

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Posted 16 November 2016 - 06:02 AM

If you're talking about offset bushings for the lower control arm, I modified some Superpro ones to fit an old pair of (modified) Commodore IRS offset crush tubes:
http://www.gmh-toran...e-8#entry849759

I didn't bother with the anti-dive in favour of maximum camber gain, since its very limited without more significant modifications. Managed to achieve around 6.5 degrees of static caster anyway.

I believe there is a thread around here somewhere regarding brake clearance issues with Convos. Problem is you can't get decent tyres for smaller wheel sizes either, kind of need at least 17s to get a good enough tyre to take advantage of the suspension improvements :-(

#13 _XY driver_

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Posted 21 November 2016 - 06:41 PM

76lxhatch I like your style and moreover substance of your work... that's a great project you have bolted together there. It's not often you see the nouse applied in such a thorough and exacting way. I commend your ability to fabricate and make good without resorting to style, or budget over substance.

 

I've been talking to more people, Dick at Savy motorsport seems to be a damned useful bloke who not only races a lot of historics but also stocks extended ball joints and makes up adjustable tie rod ends. I might even make another post because he's looking at making a set up for a Torana and would be interested to know if there's going to be a demand. He seems to think the new management at Harrop aren't interested in supporting the slow moving stuff so repro A9X arms may not be available... I've not actually asked.

 

Dick said he's had a lot of success with "anti dive" settings by using spherical bearings in lower control arms. Comaro compatible parts are what he supplies. He's also used longer lower ball joints to increase camber gain.

 

So I haven't been idle these last few days, I've been learning how to make data into pretty pictures. I think the raw figures are reasonably good, they seem to be repeatable, just have to check that the plus and minus numbers are correct on my "standard UC" setup.

 

The rig uses an arbitrary zero/ride height that has the LCA slightly down at the outer end, the lower ball joint is about 55mm below the bottom of the crossmember, we are trying to maintain ride height like a rally car I guess. From there there is 40mm of droop and 80mm of compression in the suspension... 7 stations to measure 20mm apart. I have no shims in the top arm and the steering rack is centered. Each measurement starts at ride height with the digital level zeroed, so I'm comparing change in angles not gross numbers.

 

I've mapped the standart UC set up and the lowered UCA position you normally see. I've also played with canting the top arm to increase caster gain, an extended top ball joint and an offset LCA bush in the rear just for interests sake. Old mate with his improved production car has both bushes offset and has got a reasonable amount of negative camber and 6 degrees of caster so far.

 

I think I've got something useful, there's more experiments to be done, but I'd like your feedback blokes... bearing in mind I've been talking about track day terrors with tyre life and steering effort at the bottom of the priorities... what would you aim for?

 

I'll see if I can attach graphs here...

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#14 _XY driver_

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Posted 21 November 2016 - 07:38 PM

And I should edit the 19mm canted image before posting it...

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#15 Toranamat69

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Posted 21 November 2016 - 08:29 PM

Very interesting stuff.  I haven't tried all those combos and I have tried a few different ones using the A9X stubs and steering arms but your results look very similar if not identical to my measurements.

 

I have built a bit of a cant into the top control arm also - I went for 3 degrees but I can't remember how much lower that made the mounting hole, but I don't think it was 19mm, maybe half that, Id have to check to be sure.  I was looking for close to constant castor through the range whilst using 6 degrees static castor.



#16 _XY driver_

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Posted 21 November 2016 - 10:33 PM

Next trick is to grab a HX stub axle and try a few combos with that. Possibly the next option is to set up some shims/washers for a more accurate idea of what can be achieved, or not, with a wheel alignment.

 

Does anyone know how wide the gap between the towers is meant to be, before the crossmember gets bent out of shape with age and punishment? 

 

The 19mm cant was as much as I could get with the froward bolt in the factory UC position. The limit was the rear/inside of the top arm hitting the crossmember.

 

If we have bump steer, I guess toe in would be preferable under compression...



#17 76lxhatch

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Posted 22 November 2016 - 05:32 AM

Unfortunately bump steer figures are a bit useless unless you have it close to final static alignment settings, it just makes too much difference (as does the steering arm used). Absolute figures would also be nice to see where the caster and camber zero points are in relation to each other.

There are as many supporters of toe out bump steer as toe in. Some of the Locost and similar forum posts make interesting reading.

Some crossmember measurements here:
http://www.gmh-toran...member-rebuild/

#18 _XY driver_

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Posted 22 November 2016 - 11:59 PM

So tonight she got divorced... the Torana from the dirty rotten Chev that is. Drained fluids, removed bolts, vandalised the exhaust a bit and extracted the steering column too, so in the end it was pretty easy to lift the car off the entire front end with the whole engine/trans/pipes intact. We could be onto something here, as a service method, I'm thinking it's easier to drop the whole front for a lot of reasons, provided we get a few bits sorted, like easily detached trans cooler lines. I need to ask the gurus again though, the rear crossmember mounts look to have been victimised..? The bolts are a bit bent, the reinforcing washer that's welded to the inside of the chassis rail looks to my mind to be pretty skew whiff... I've tried to capture it with some pictures. Tomorrow we'll offer up the chassis connector kit and see how it fits, but I'm not 100% sure what to do with this thing. It's tempting to cut out the big droopy knob of MIG weld and do some straightening before welding something back that at least looks someone cares about it.

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#19 N/A-PWR

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Posted 23 November 2016 - 12:11 AM

Seen in a 2006 thread,

 

 a guy say that HX stubs has better steering geometry.

 

 

I don;t know.



#20 axistr

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Posted 23 November 2016 - 06:07 PM

I would be sticking close to the UC setup due to the relatively low camber, caster and toe movement from neutral. The more change you get in any direction from ride height will give the vehicle a tendency to wallow around high speed cornering. If its track work only your after then stiff suspension and anti roll bars are properly what your after and you may not get that huge camber change your after with longer ball joints ect. in the right direction. I  know we are still all playing around with old design front ends so its hard to compare with vehicles like M3 & C63AMGs but if you look at these cars they rely on big camber changes through high caster settings. The tighter the corner the higher the camber gain you get, its nice and progressive.

 

If you add lots of caster using the A9X arms would be the go to try and compensate for the roll upward of the steering arms. I did some graphs some time ago, A9X arms and UC stub axle and still retained good numbers between 5 & 6 degrees positive caster using the lower control arm mounts to change caster/camber. More positive caster can help reduce the amount of negative camber you need and you will get better front end braking due to the better tyre foot print on the track surface. Most of the hard braking is done before hard turn in.

 

Its important to remember a bump steer curve is not just about toe change, any change in alignment angles due to suspension travel can give the vehicle a tendency to go in an unwanted direction.

 

HX stub axles also have  different K.P.I The higher the K.P.I the more self centring effect you will get. An interesting fact, I supplied a power steering rack to a customer a few years ago for track racing and Targa. They reported saying on tight closed circuits the car was 2.5 seconds quicker per lap with power steering many due to be able to down shift and short shift during hard cornering which they previously couldn't due as they needed both hand on the wheel to pull it through corners.               



#21 _XY driver_

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Posted 26 November 2016 - 11:18 AM

More progress, of sorts.

 

Upon closer examination it looks like the original crossmember is cracked, at least the rear arms are trying to part company. I'm sure there's going to be some welding and reinforcement involved with the new one, going on how this is panning out.

 

We need a front mount anti roll bar, because at the very least, the mechanic doesn't like having to remove it to get at the oil filter.

 

How much power can a T350 handle? Well I think the trans in the car has been tricked up with full manual, reverse pattern & no engine braking. Seems none of that matters much when there's a massive crack down the back of the bellhousing & into the fluid line area. The mechanic is mumbling something about a powerglide now.

 

I'll pick up some HQ stubs tomorrow, do some more front end measurements, then it's out with the bushes and off to the sandblaster.

 

Is there anything tricky to know about the steering rack or getting it apart?

 

More importantly, does anyone know if you can machine the outside diameter of an SFI spec "ProRace" neutral harmonic balancer?

 

I'd like to make it into a multi rib belt pulley because there isn't much room to fit a decent alternator and the current setup is complete rubbish. The voltage regulator has been fried by the exhaust because it's basically rubbing on the primary pipe and the belt alignment is also crap.



#22 axistr

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Posted 26 November 2016 - 03:12 PM

Chev with serpentine belts.

 

 

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#23 _XY driver_

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Posted 29 November 2016 - 09:18 AM

Really nice looking belt setup!

 

Sadly all the room I have is taken up with a blower belt... but I've talked to the bloke who designs and machines ProRace balancers and there is plenty of material to play with... something like 25mm of wall thickness so a 4mm deep grove isn't going to bother it much.

 

Incidentally the bloke, Peter Hunter, is bloody fascinating to talk to, generous with his advice and appears to make a world beating product. Going on his say so, I am surprised anyone uses an ATI damper when a ProRace is so much tougher. All Ford racing crate engines use them apparently...



#24 _XY driver_

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Posted 29 November 2016 - 09:29 AM

Once we had large diameter custom machined mountings... Now there are stacks of washers and nuts for spacers and the belt alignment is crap. Bloody mechanics :P This view shows why I'm looking to reverse mount the alternator. Just need to source a fan for correct rotation now.

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#25 _XY driver_

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Posted 03 December 2016 - 01:11 AM

The new parts arrived today and they're expensive... but there's .900" extra length in the top ball joints which will make more room for brake calipers.

 

I've fitted the extended top ball joints and done some more experiments, along with some HQ spindles.

 

If I get really keen tomorrow I might even set up some shims and try an alignment of sorts, at the moment all the figures are relative to zero at ride height, so they're indicating change not actual figures.

 

See what you think;)

 

 

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