84 replies to this topic

[theolodian]

Seems there is another option!!!

Ollie at Phoenix Motorsport has come up with a tidy little kit. After seing some of the cheap joints used on other kits on the market Ollie at Phoenix decided to design his own. It uses far more substantial joints/links, so is promised to be fit and forget.

Best bit about it ..... the price!!

£280 including a Brace Bar. He's fitting one to DrPau's car as we speak, so hopefully Paul can get some pics up asap

RESULT!!!!

Yes, please post them soon! I need to make a decision about what I am going to use in the very near future.

[Jameshs]

<!--quoteo(post=993783:date=Feb 5 2010, 15:18 :name=joe_589)--><div class='quotetop'>QUOTE (joe_589 @ Feb 5 2010, 15:18 ) <a href="index.php?act=findpost&pid=993783"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->is there any reason you cant just get a strip of metal and bolt it on the subframe therefore making your own brace bar for like.... say.... £5 <img src="http://www.vx220.org...IR#>/laugh.gif" style="vertical-align:middle" emoid="" border="0" alt="laugh.gif" />

whats stopping people from doing this?<!--QuoteEnd--></div><!--QuoteEEnd-->

I've wondered about one that is plates that bolts to the sub frame around the toe link then a bar between them more like a strut brace.

The reason to move away from a solid mount is because the arms of the subframe flex in two dimensions and as a consequence can move in the third relative to each other.
The arms can move up and down or closers etc. when they both move in the same direction then they will form a parallel shape where the 90 degree point at each end no longer match.
As Lotus found out when they used a fixed bush to locate the brace on the 111S they wear out very quickly (take a look at the US forums, some lasted one track-day!)
A bearing ended brace will restrict movement in the plane you wish to control but allows the others to move freely.
If you have a solid mount on your subframe then the joint is still under under continuos load, this in time may have either of two results either the area around the subrame where the mount is will fatigue or the brace will.
If you wanted to go that route then a custom welded bracket is probably better.
Anyway you should have some flex in the system as it was designed in as part of the structural fatigue resistance. if you remove this movement without a thorough stress anylsis you may induce stress cracks all over the place and not necessarily where you expect.

Lotus moved the 111S brace back to rod-ends, and I bet they spent more money on prior analysis before doing this that you or I are prepared to spend on beer

I would like to see your stress analysis of the OEM against your kit please

[Winstar]

The reason to move away from a solid mount is because the arms of the subframe flex in two dimensions and as a consequence can move in the third relative to each other.
The arms can move up and down or closers etc. when they both move in the same direction then they will form a parallel shape where the 90 degree point at each end no longer match.
As Lotus found out when they used a fixed bush to locate the brace on the 111S they wear out very quickly (take a look at the US forums, some lasted one track-day!)
A bearing ended brace will restrict movement in the plane you wish to control but allows the others to move freely.
If you have a solid mount on your subframe then the joint is still under under continuos load, this in time may have either of two results either the area around the subrame where the mount is will fatigue or the brace will.
If you wanted to go that route then a custom welded bracket is probably better.
Anyway you should have some flex in the system as it was designed in as part of the structural fatigue resistance. if you remove this movement without a thorough stress anylsis you may induce stress cracks all over the place and not necessarily where you expect.

Lotus moved the 111S brace back to rod-ends, and I bet they spent more money on prior analysis before doing this that you or I are prepared to spend on beer

interesting, so from a handeling point of view additional X bracing between the lower mount points and the main chassis.

I get where your coming from with the additional stiffness changing the load path through the sub frame, good job analysis costs me nothing but my free time then.

[Spitfire Engineering]

The reason to move away from a solid mount is because the arms of the subframe flex in two dimensions and as a consequence can move in the third relative to each other.
The arms can move up and down or closers etc. when they both move in the same direction then they will form a parallel shape where the 90 degree point at each end no longer match.
As Lotus found out when they used a fixed bush to locate the brace on the 111S they wear out very quickly (take a look at the US forums, some lasted one track-day!)
A bearing ended brace will restrict movement in the plane you wish to control but allows the others to move freely.
If you have a solid mount on your subframe then the joint is still under under continuos load, this in time may have either of two results either the area around the subrame where the mount is will fatigue or the brace will.
If you wanted to go that route then a custom welded bracket is probably better.
Anyway you should have some flex in the system as it was designed in as part of the structural fatigue resistance. if you remove this movement without a thorough stress anylsis you may induce stress cracks all over the place and not necessarily where you expect.

Lotus moved the 111S brace back to rod-ends, and I bet they spent more money on prior analysis before doing this that you or I are prepared to spend on beer

interesting, so from a handeling point of view additional X bracing between the lower mount points and the main chassis.

I get where your coming from with the additional stiffness changing the load path through the sub frame, good job analysis costs me nothing but my free time then.

I'm sure you appreciate that the changes in design over 30 years or so have really altered the aftermarket options, welding up a few cross braces on a Ford Mexico mild steel chassis with mild steel tub pressings etc, is one thing. Alloy structural components which are already super light and designed to operate much higher up their stress curve are of a different order. The brace design was to resist lateral forces on the sub frame longerons by transferring some of the forces over to the other side. This effectively just halves the forces causing the deformation (i.e compliance) and does not attempt to offer a rigid structural support, further the rod ends allow the vertical inputs and subsequent compliance of the subframe to go unchecked in this plane as these displacements are part of the suspension.
As an indication of the forces involved, with the Lotus Brace the strut was placed over the existing bolt which is protruding from an RSJ! so the only distortion was on about 50mm of bolt and yet that was enough to wreck the bushes set into the strut. Now compare this to the VX chassis with no rear RSJ and you can easily imagine the movement involved.

[theolodian]

Errr, OK, but the rear subframe is not alloy.

[Spitfire Engineering]

Errr, OK, but the rear subframe is not alloy.

Errr what then?

[theolodian]

Errr, OK, but the rear subframe is not alloy.

Errr what then?

Galvanized steel, throws you off until you pick it up and go "what?"

[Exmantaa]

Was reading about this on several forums. This is some US-Aus version )which seemed to hold up fine during a 12h Badhurst race..`


http://www.lotustalk...se-exige-69560/

[Spitfire Engineering]

Errr, OK, but the rear subframe is not alloy.

Errr what then?

Galvanized steel, throws you off until you pick it up and go "what?"

Ahh it's steel, but not alloy? so is this a new element?

[Spitfire Engineering]

Errr, OK, but the rear subframe is not alloy.

Errr what then?

Galvanized steel, throws you off until you pick it up and go "what?"

Ahh it's steel, but not alloy? so is this a new element?

What shall we call it?
steelinium?
steelgen?

[theolodian]

Sorry, UK/US thing I guess. Everyone says alloy wheels and alloy tub, so seemed to me to be a slang word for aluminininium (we call it aluminum). edit: In your post you distinguished between steel and alloy.

Edited by theolodian, 11 February 2010 - 08:16 PM.

[Spitfire Engineering]

Was reading about this on several forums. This is some US-Aus version )which seemed to hold up fine during a 12h Badhurst race..`


http://www.lotustalk...se-exige-69560/

Well it would hold up as it isn't doing very much.
The section of steelinium behind the brace in the picture is reminiscent of a beam holding a wall up in my house.
As this area of the subframe most certainly does not need to be reinforced, the use of a bar across the back just to double shear the toe-link is rather heavy single dimension solution.
This solution (and all the other copies of the Lotus motorsport design) miss the point of why this solution was used in the first place, clearly a bracket is a much better solution, stronger, lighter, offering 3D support instead of the one way of the support brace.

Any guesses for a free beer?

[Spitfire Engineering]

Sorry, UK/US thing I guess. Everyone says alloy wheels and alloy tub, so seemed to me to be a slang word for aluminininium (we call it aluminum).

edit: In your post you distinguished between steel and alloy.

Correct, again a loose definition, this time my fault alloy is often used to indicate a high spec steel though the actual definition is any mix of metals at the molecular level. All steels are alloys of course otherwise they would called Iron

This common language thing huh?

Gaz

[VIX]

Any guesses for a free beer?

No idea, but Okinawa number plate if that helps.

[Exmantaa]

Well, it was not about that black piece holding the number plate, but more their brace bar solution.

This is fitted onto an S2 and I see that has a different subframe with a standard lower beam between the towers.

Still not very optimal as the `double shear` forces are just split between the 2 joints, and not transferred to the subframe...

Edited by Exmantaa, 11 February 2010 - 09:45 PM.

[Spitfire Engineering]

Well, it was not about that black piece holding the number plate, but more their brace bar solution.

This is fitted onto an S2 and I see that has a different subframe with a standard lower beam between the towers.

Still not very optimal as the `double shear` forces are just split between the 2 joints, and not transferred to the subframe...

Correct, the subframe component is huge and at one point is three layers thick!
The only function of the device shown is to double shear the two toe link bolts. so as a solution is not optimal.

[theolodian]

Correct, again a loose definition, this time my fault alloy is often used to indicate a high spec steel though the actual definition is any mix of metals at the molecular level. All steels are alloys of course otherwise they would called Iron

This common language thing huh?

Gaz

Really? I haven't heard it used in reference to steel in recent memory. As you say, it is a technically accurate description.

Hey Fab, I can give you a special price on some black alloy wheels . . .

[drpau]

Seems there is another option!!!

Ollie at Phoenix Motorsport has come up with a tidy little kit. After seing some of the cheap joints used on other kits on the market Ollie at Phoenix decided to design his own. It uses far more substantial joints/links, so is promised to be fit and forget.

Best bit about it ..... the price!!

£280 including a Brace Bar. He's fitting one to DrPau's car as we speak, so hopefully Paul can get some pics up asap

RESULT!!!!

Ill get pics up when Ive had it fitted, booked in for 26th instead of next friday by accident

[siztenboots]

Well, it was not about that black piece holding the number plate, but more their brace bar solution.

This is fitted onto an S2 and I see that has a different subframe with a standard lower beam between the towers.

Still not very optimal as the `double shear` forces are just split between the 2 joints, and not transferred to the subframe...

Correct, the subframe component is huge and at one point is three layers thick!
The only function of the device shown is to double shear the two toe link bolts. so as a solution is not optimal.

why not just bolt the inboard toe link to a bracket on the rear face of the lower wishbone. I've seen this kit around as typically if you have had a kerbed wheel / accident you end up replaceing that corner anyway.

[Crabash]

[/quote]
why not just bolt the inboard toe link to a bracket on the rear face of the lower wishbone. I've seen this kit around as typically if you have had a kerbed wheel / accident you end up replaceing that corner anyway.
[/quote]

Like so...
You can just see it behind damper.