VR6 Dropped Spindles/hub

[boost monkey 0]

you mean modify/weld the hub so that the bottom LBJ mount point is 30mm lower?

 

Nothing I guess. This is why I've been putting up screenshots of ideas as I'm sure I miss something from time to time!

[24V Renshaw 0]

I have just had an idea on how to do this, but need to check a few things out first.... Won't say any more until I have done some sanity checks, but it might be quite a neat solution.

 

If the pivot point of the LBJ remained in its existing position and the LBJ was just extended along its existing axis and the hub moved to match, could the movement of the hub carrier not be compensated for by adjustment of the two bolts between the hub carrier and the strut?

[boost monkey 0]

Sounds great Jay, look forward to seeing your ideas.

 

AFAIK The adjustment of the shock to hub bolts is purely inboard/outboard (across the vehicle) so it will affect the camber too if you were thinking of playing around there. I’m sure you know that already though.

 

That 60mm concept BJE I threw up last night has been stressed to (equivalent of) 750kg acting downwards and square to the balljoint mount face and it’s only hitting 40% of yield strength (based on a standard automotive steel with 350MPa yield strength) which gives us a factor of safety of 2.5 which is pretty good. I’ll throw up some screenshots if that would help clarify things.

[24V Renshaw 0]

The forces will be lateral on it though (think pulling on the top/bottom of the wheel) so will try and rip the post out of the top.

 

Jay

[quicky1980 0]

Thanks for clarifying, must of missed some previous posts. The only thing I would suggest is if the top part of the bje has "wings" that fold up and wrap around the hub to stop the BJE from rotating during assembly or use (admittedly the friction would be sufficient for the later).

 

I was thinking a clamped lower half like the current 16v bje, and use 16v ball joints in place of the vr6 ones. this would avoid the need to have a space in the bje for the nut and access. the upper half of the vr6 bje would compensate for the changes to the lower half.

[boost monkey 0]

The forces will be lateral on it though (think pulling on the top/bottom of the wheel) so will try and rip the post out of the top.

 

Jay

 

Good point, I'll model that and see what happens. That steel is like 3mm thick minimum on the concept so can handle some abuse

 

---------- Post added at 01:47 PM ---------- Previous post was at 01:40 PM ----------

 

Thanks for clarifying, must of missed some previous posts. The only thing I would suggest is if the top part of the bje has "wings" that fold up and wrap around the hub to stop the BJE from rotating during assembly or use (admittedly the friction would be sufficient for the later).

 

I was thinking a clamped lower half like the current 16v bje, and use 16v ball joints in place of the vr6 ones. this would avoid the need to have a space in the bje for the nut and access. the upper half of the vr6 bje would compensate for the changes to the lower half.

 

No probs. I thought it would be easier to refer back to the last few pages than try to explain it all again!

 

The wings sound interesting. I'll try to mock something up and put up some pics on here.

 

Yeah, I like your idea of a 16v lower BJE and VR upper to fit in the hub. Sounds like a great compromise really and as you say you don't need as much clearance. That would mean that a BJE for a -30mm drop would still be possible (not wishing to sound like "if I can't do it then it can't be done!" :bonk:)

 

It's good to have all these inputs, after all this is your idea! I'm just a tool (:lol:) to help you 6pot lovers along :D :salute:

 

---------- Post added at 02:10 PM ---------- Previous post was at 01:47 PM ----------

 

Just a little more info for tool clearance:

 

18mm spanner (for M12 locknut) is 40mm at widest point of open jaw. Closed end is approx 26mm. So we need to build these in if we want to be able to tighten the BJE into place :D

 

Not really sure how we're gonna sort out 6mm allen key clearance though... answers on a postcard...

[quicky1980 0]

Glad to have a tool as clever as you involved lol. thanks for putting the effort into this, I could have tried myself but I have limited ProE experience so would have took soooo much longer to get anywhere even remotely close.

 

Not really sure how we're gonna sort out 6mm allen key clearance though... answers on a postcard...

 

hence why we may need to use the 16v ball joint, other option is to have a key on the inside of the bje that rests into the tip of the bj itself (maybe a modded ball joint tip to match the key).

[boost monkey 0]

Yeah that sounds good. Did we ever discover whether the 3-bolt fixing pattern for the LBJs is the same on the wishbones?

[quicky1980 0]

i seem to remember using vr6 hubs on 16v wishbones. but would like someone to confirm.

 

I had a thought on the way home from work about shifting the bearing up, if this is a problem when the suspension droops, how do the dropped hubs off the other models work. this got me wondering if the fix is to shift the strut mount up sufficiently to clear the out cv then have the suspension take up the difference, or does this risk the suspension travel?

[24V Renshaw 0]

Has anyone got an LBJ that they can see if the ball part presses out of the plate cast part? or if its held in with a circlip or what?

 

Jay

[KipVR 1]

you mean modify/weld the hub so that the bottom LBJ mount point is 30mm lower?

 

Nothing I guess. This is why I've been putting up screenshots of ideas as I'm sure I miss something from time to time!

 

Ahh no that was me being a plonker, I couldn't see the screenshots and imagined something different, but what you've done looks like it would work well.

 

For your FEA have you taken braking and cornering forces into account? What was the max strain?

 

I think the max g you could corner a Corrado at would be about 1.1g perhaps? I have no idea on road cars really, about the same for braking. Maybe higher if it was some sort of track car with slicks....

 

Could you use a ring spanner to get to the nut on the 60mm version, or is it too tall?

 

Edit: just read Jays posts about the lateral loads...

Edited December 1, 2011 by KipVR

[boost monkey 0]

i seem to remember using vr6 hubs on 16v wishbones. but would like someone to confirm.

 

I had a thought on the way home from work about shifting the bearing up, if this is a problem when the suspension droops, how do the dropped hubs off the other models work. this got me wondering if the fix is to shift the strut mount up sufficiently to clear the out cv then have the suspension take up the difference, or does this risk the suspension travel?

 

Well the travel would be compromised yeah as you'd have to use a shorter base shock unless you wanted to run a normal length one at -40mm into bump or something.

 

---------- Post added at 09:06 AM ---------- Previous post was at 09:05 AM ----------

 

Has anyone got an LBJ that they can see if the ball part presses out of the plate cast part? or if its held in with a circlip or what?

 

Jay

 

from memory the ball goes in and then the socket is pressed inwards under high pressure to seal the ball joint in, hence why you should bin LBJs that have torn rubbers. I think a circlip would be too risky.

 

---------- Post added at 09:41 AM ---------- Previous post was at 09:06 AM ----------

 

Ahh no that was me being a plonker, I couldn't see the screenshots and imagined something different, but what you've done looks like it would work well.

 

No probs :salute: It’s literally just joining the two LBJ points in the model by building a new part inbetween. It’s still quite ugly tbh but I’m working on it.

 

For your FEA have you taken braking and cornering forces into account? What was the max strain?

 

No I hadn’t actually. I was just measuring up from 300-750kg through the top angled face (i.e. the face DIRECTLY under the LBJ mount on the hub) as the hub would be pressing down on this. Obviously the 5deg angle means the forces go off to the side slightly and leave a nice stress concentration on the first corner it finds!

 

Edit @11am: Max strain seems to be 0.4 microstrain min and 1.4 microstrain max. There seems to be one problem corner that always has stress risers on through static, cornering or braking analyses. Cornering/Lateral load of 5250N gives a stress 3x material yield strength (1005MPa stress achieved in a 350MPa material) :( I'll try to get pics up later.

 

 

I think the max g you could corner a Corrado at would be about 1.1g perhaps? I have no idea on road cars really, about the same for braking. Maybe higher if it was some sort of track car with slicks....

 

That sounds like a good starting point. But what mass value? I actually have a spreadsheet program I made for coursework at Uni somewhere that can calculate lateral loads at each corner of a vehicle (you have to put in track/wheelbase/mass etc etc etc along with corner radius in metres) and it tells you which wheels loses grip or lifts off first. Perhaps this could be adjusted to create accurate lateral loads at the front wheels for a Corrado. It would be another sub-project though.

 

Perhaps just using say 350kg (or 3500N) would be a good starting point for lateral forces. Both outwards for corner accel'n, and front/back for braking. I'll get it mocked up :salute:

 

Additionally, I’m assuming the lateral forces would be “end on” to the wishbone as it will go across the tyre contact at right angles to the wheel, regardless of steering angle? Been about 6months since I did Chassis Engineering module :lol:

 

Could you use a ring spanner to get to the nut on the 60mm version, or is it too tall?

 

Yeah an 18mm ring spanner is ~26mm diameter at its widest so I’ve allowed for that in the concept BJE. There is clearance around it for tools :D But as mentioned, there are concerns about how you’d get a 6mm allen into the top. Perhaps a much shortened allen with a 90deg bend that’s only 10mm long or something? I could mock one up in like 5 mins tops. Just a basic sweep with 6mm hex cross-section.

 

Cheers for all the input guys, keep all the thoughts coming. Internet is lame at home so I don’t check the forum that much after hours.

 

Also, my Solidworks at home has expired and it’s £80 for the basic version now I’ve graduated. Better than £2000 for the bells and whistles version I guess…!

Edited December 2, 2011 by boost monkey

[boost monkey 0]

Here are the stress plots as promised. Shows a colour scale for the stress concentrations, and yield strength of material underneath. Green arrows are fixed constraints (stop part moving) and purple arrows are location and direction of force applied. Spec as follows:

 

Static test

 

- 5000N (~500kg) applied square to upper face in the downward direction to replicate an increased load due to weight from hub and upright pressing down on BJE.

- Max Stress of 170MPa; ~50% of yield stress therefore a FOS (Factor of Safety) of 2.

 

Cornering test

 

- 5250N (~525kg; 1.5g for vehicle corner weight of 350kg) acting outwards/inwards (depending on NS/OS orientation) due to hard cornering.

- Max stress of 1010MPa. This is a catastrophic failure of the part due to Max stress ~ 3 times that of material yield stress. FOS = 0.3

 

Braking test

 

5250N (~525kg; 1.5g for vehicle corner weight of 350kg) acting forwards/backwards (depending on NS/OS orientation) due to hard acceleration/braking.

- Max stress of 115MPa; ~33% of yield stress therefore FOS of 3.

 

Pics attached.

[24V Renshaw 0]

I am afraid to say I thought it would fail. Plus this doesn't take into account fatigue, temperature, corrosion etc..

 

but this is what development is all about :)

 

Jay

 

---------- Post added at 04:16 PM ---------- Previous post was at 04:14 PM ----------

 

Actually looking at it, you have not loading the "stem" either which is where I would expect the most stresses, between the stem and the flat plate.

 

Jay

[boost monkey 0]

Yeah, this is true. tbh I can't do a fatigue study as I don't know how to set up the prerequisite motion study in SW. Temp should be fine and corrosion can always be dealt with by powdercoating etc. But development is always good!

 

Yeah I didn't load the stem. I guess it would actually be much weaker than the other parts.

 

Just some other pics from messing about with this BJE model (attached) looks like the LBJ and the BJE will have to be secured together before attaching to the hub as there's no clearance for the 6mm allen key with the BJE in place. Doubt it's a big issue for assembly/disassembly really.

 

Also as can be seen there's good clearance for a standard sized 18mm ring spanner (modelled this to answer your question Kip!) with a turning range of approx 110degrees currently (although this may decrease with strengthening webs etc). However, there are some issues with getting the spanner in and over the LBJ pin whilst in position as it may clash with some of the other parts there. Just a thought really - surprised I actually remembered to give that consideration!

 

Of course, this is all based on the fact that the LBJ and hub geometry is accurate to start with so I'm looking forward to confirming this :D

[boost monkey 0]

Jay have you gotten any further with your idea? I haven't done any more on this as my CAD package at home has expired and we don't even have broadband for me to renew it :/

[24V Renshaw 0]

Not yet, need a standard VR LBJ to see if I can dismantle it.

 

Simply, my idea is to press out the ball joint parts from the plate part and leave a hole.

Then find a suitable spherical bearing to press in, with a sleeve if required, then get a new extended stem made and a suitable rubber boot to protect it all.

 

First step is to establish the exact hole size in the OEM LBJ.

 

Jay

[Kevin Bacon 5]

Is that /\ what SCCH have already done?

[24V Renshaw 0]

Sort of. They have made custom spherical bearing holders and have a weld in drop pin.

 

I want everything to fit the OEM stuff. I think it is very very doable and just need to find/buy a LBJ to experiment with :)

 

but with getting the car useable daily, my poly engine mount Group buy and a house and family I am struggling to get round to it at the mo ;)

 

Jay

[boost monkey 0]

Same, struggling to get round to it. Not that I have a house or a Poly GB!

[quicky1980 0]

Will check my hub carriers, I think they have the bj's still fitted.

[daves16v 1]

If you can wait a few days I've got some old BJ's you can play with.

[24V Renshaw 0]

If someone can send me one that would be great.

 

Jay

[boost monkey 0]

I'd like to find out how much ally hubs would be - the reduction in unsprung mass would be huge!

[boost monkey 0]

I'm on sabbatical from this now until the new year. Will try to sort out my home copy of SW as my new job doesn't really allow me to do personal projects on the design computers :(