61 replies to this topic

[Tony H]

Am interested in one of these. Will they only fit with your toe links?

[Spitfire Engineering]

Am interested in one of these. Will they only fit with your toe links?

 

not necessarily but we will need to know what you have. They cannot fit with the OE setup obviously.

 

[Spitfire Engineering]

Hi Gaz

 

I would like to be on the list for Plan A please

 

Copied, I will U2U you soon.

[WazzaVX220]

I'll be needing one of these......

 

Yes.

[Spitfire Engineering]

 

Hi Gaz

 

I would like to be on the list for Plan A please

 

Copied, I will U2U you soon.

 

 

message sent  

[The Batman]

i got a subframe with a crack in it you can have if you want to do some testing on it

[sford]

I think I need one of your kits plus the brace bar. I use standard toe links and just replace them regularly (every two years) but want something better. Plus the addition of the brace bar is welcome. Can you PM me the cost of the full kit? Mines an early NA with the smaller bolts in the uprights, standard exhaust.

[FLD]

Gaz,
Just mulling this one over.....
I remember the reasoning for the rose joints on the brace bar but given the Elise one has a solid bar welded in does it need the freedom of movement? I'm guessing lotus spotted a potential flaw snd that was their fix. I would assume they did all the required load modelling etc to either rule out the requirement for rose joints or spec material with enough flex to take it whilst also supporting the frame.

Just thoughts going through my head. I'd be interested in your thoughts about the Elise frame.

[Spitfire Engineering]

Hi

Not sure what you mean by the Lotus Elise one??

I have never seen a welded one on an Elise.

 

[FLD]

The stock Elise frame has a box section between the two tower parts. It's spot welded in at fabrication. I'll try and find a pic.

[siztenboots]

TRACK USE CHASSIS BRACE KIT

(Toyota Powertrain) Fits: Elise & Exige Part No: LOTAC05377

[Spitfire Engineering]

Ahh OK, you mean the later Toyo subframe, this is something else altogether, It's not a tacked on section, the rest of the subframe is built around it and the section is made from several layers of panel which are shared with adjacent sections. it's an entirely new construction and has been modelled, analysed and tested as such. This bears no resemblance to a tacked on section to a pre-existing subframe as you will change the basis of all of the modelling and analysis.

 

If you send me your normal email address Ill send you some toyo subframe images and the brace data sheet.

 

Gaz

[FLD]

Does the latest lotus subframe not have a bar welded in along the bottom of the two tower parts?  Kind of like a welded in brace bar (hope that makes sense).  The one I saw was part of the subframe and was about 2" wide by 1" high and made up of a folded sheet spot welded in.
Summat like this:

 
I'm not trying to rubbish the top work by spitfire (and it is top work!!) I'm trying to assess the need for the movement in some directions

 
 
It's good to question!
 
Briefly, 
Two points, firstly when comparing brace possibilities you cannot compare the Toyo subframe above with the VX subframe, as you mentioned this is fabricated with an RSJ running along the back.
Secondly but more importantly, this subframe still flexes. 
As with all complex structures it was designed to flex and it has to do to avoid stress fractures or premature overloading of fasteners due to raised peak loads. A good way to look at structures is to imagine they are made of rubber, this will help you to visualise what will move if pushed or pulled at a certain point. Which bits are stretched, compressed twisted, etc.
All the forces are taken up by the entire structure.
 
Designing in the flexibility required to ensure several million stress cycles is a complex calculation taking in a very large number of factors, material, structure form, loading pints, support points, just to start with.
 
Adding bits to a pre fabricated design is also complex if done correctly, I cannot imagine anyone on this forum has either the time or resources to do a recalculation on this subframe so you have to be as sensible as you can and for our thinking at Spitfire this means to sort what needs sorting and leave the rest alone especially is this includes introducing lever moments, shear moments and torque moments onto a non rotating fixing.
 
The only known BIG issue with the VX subframe is the compression of the rear section, this can be sorted with a brace.
Our philosophy is not to chance stress fractures occurring elsewhere or to (ever) have a rotating section under the head of the major fastener.
The second point will cause an issue sooner or later as the loaded components must wear on each other and in doing so the torque of the fastener will be reduced. Lotus used a bush on the Toyo subframe by the way.
 
We designed the VX brace over 10 years ago and have over 150 in service.
Never seen or heard of any primary or secondary damage caused to the subframe nor any handling issues.
The feedback on the brace on track has only been positive.
 
Hope this helps

Gaz

Already discussed Clearly my memory isn't what it once was.
Be nice if the frames were interchangeable and you could just sort a rear engine mount
.

[siztenboots]

I think these are the early spitfire toe-links and brace bar with the box section between the subframe towers ?

 

[Spitfire Engineering]

TRACK USE CHASSIS BRACE KIT

(Toyota Powertrain) Fits: Elise & Exige Part No: LOTAC05377

 

 

This is for the Toyota subframe.

It can work because the two sides are already connected with a very large and rigid section so the above kit just supports the back toe link bolts by putting them into double shear. it does not in any way support the subframe.

 

The construction of the Toyota subframe bears no resemblance to the VX/Europa subframe in this section. F

[Spitfire Engineering]

I think these are the early spitfire toe-links and brace bar with the box section between the subframe towers ?

 

 

Correct, it is an alternative fit for those who do not wish to drill the subframe for brackets for warranty reasons, or they just wanted a simple bolt on solution. But again this is not a subframe brace, it is not adding to the strength of the subframe as it is bolted onto a to length of RSJ!

[siztenboots]

 

TRACK USE CHASSIS BRACE KIT

(Toyota Powertrain) Fits: Elise & Exige Part No: LOTAC05377

 

 

This is for the Toyota subframe.

It can work because the two sides are already connected with a very large and rigid section so the above kit just supports the back toe link bolts by putting them into double shear. it does not in any way support the subframe.

 

The construction of the Toyota subframe bears no resemblance to the VX/Europa subframe in this section. F

 

 

I mentioned it only as I recall the exige s2 having this as the factory / motorsport dept official fix

 

Nothing like it was available for the VXR which would also have gone through the same motorsport workshop

[Spitfire Engineering]

 

 

TRACK USE CHASSIS BRACE KIT

(Toyota Powertrain) Fits: Elise & Exige Part No: LOTAC05377

 

 

This is for the Toyota subframe.

It can work because the two sides are already connected with a very large and rigid section so the above kit just supports the back toe link bolts by putting them into double shear. it does not in any way support the subframe.

 

The construction of the Toyota subframe bears no resemblance to the VX/Europa subframe in this section. F

 

 

I mentioned it only as I recall the exige s2 having this as the factory / motorsport dept official fix

 

Nothing like it was available for the VXR which would also have gone through the same motorsport workshop

 

 

Yes it was the official fix but not the one Lotus Motorsport initially wanted.

The first plan was a bracket as per all the other models but this was an issue because it was considered too risky for the new market in the US and the litigation hungry population, for in the event that any rust at all appeared on the subframe they would probably demand a new subframe.

As the subframe had been in production for some time in the Euro markets it was too late to add blind fasteners and otherwise the volume behind the panel where the subframe bracket would have mounted is not accessible.

 

This meant the only sensible solution left was a brace to double shear the toe link bolts and to lock it onto the subframe for good measure.

This last action was none to brilliant as the original toe link brace fitted via tubes with a bush and the system kept eating bushes and in the US I believe this cost quite some funds in free parts and fitting. Neither of the later brace options had this fit.

 

But all of this is academic in the VX scenario as the VX subframe is not even close in design and the whole purpose of adding a brace is as a subframe brace not a toe link brace, the toe links are already/will be supported with double shear brackets for this purpose.

 

[CHILL Gone DUTCH]

Found a cracked subframe on mine
Pretty serious track car
R888R tires 255 rears

It's a sc car

[The Batman]

chill can you take your toe link bracket off to see if the crack originated from the bolt hole