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 Post subject: MK Indy Chassis Upgrade
PostPosted: December 31, 2013, 4:39 pm 
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Joined: December 31, 2013, 3:59 pm
Posts: 9
Hi Guys,

First post on this forum so please be gentle... I have decided I'm going to get my chassis re-powder coated since I am now adding a roll cage, so thought I would take the opportunity to make some chassis modifications whilst I am at it...

The chassis is an Original MK Indy... (not actually my chassis but similar)
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I have removed a chunk of the chassis when considering turbos obviously this will be dealt with as shown below....
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My plans are as follows, add triangulation to the front. using 25mm box section shown in purple, point A will also be triangulated to point B but couldn't show it on the diagram.
I will replace and relocate the 2 inner chassis members(blue)
Remove the existing single triangulation to the front of the car from the bulk head and replace it with 3 smaller braces, to strengthen the engine mount area(Yellow)
I will Brace the engine mount back to the bulk head (dark blue)
I will Brace the engine mount forward to the steering box, if possible but engine components may prevent this (cream)
Plate the bottom of the steering box (pink)
Finally I will brace back to the bulkhead from the upper rails, the left cannot be braced further forward due to the manifold and twin turbos.
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I will Triangulate the tunnel, ive chosen this rather than plating as it'll give me better access to the prop shaft.
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Move rear upper suspension pickup down wards and outwards, and remake wishbones 1.5" shorter to match, this should improve the camber issue that's present on the original MK Indy, and also raise the centre of roll(currently its way below ground, helping the car to corner flatter.
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I will also triangulate this area but not given it much thought yet, and don't have a decent pic to hand.

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Anyway if anyone would like to point out any flaws to my plan or other potential improvements feel free to draw on the blank above and upload, any comments or criticism welcome.


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PostPosted: December 31, 2013, 4:59 pm 
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Always Moore!
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Joined: November 9, 2007, 3:40 pm
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Location: Pittsburgh, PA
Welcome to the board.

I think your chassis modifications are on a good path (nice triangulation to the engine mounts) however I think you've placed the steering wheel on the incorrect side! :mrgreen: :cheers:

For your rear suspension, have you ran the numbers through a program? Does the stock setup not give enough camber gain?

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PostPosted: December 31, 2013, 5:08 pm 
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Joined: December 31, 2013, 3:59 pm
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a.moore wrote:
Welcome to the board.

I think your chassis modifications are on a good path (nice triangulation to the engine mounts) however I think you've placed the steering wheel on the incorrect side! :mrgreen: :cheers:

For your rear suspension, have you ran the numbers through a program? Does the stock setup not give enough camber gain?


Hi and thanks for the welcome...

It would appear the steering wheel is on the 'wrong' side but some of us would disagree :P

Forgot to mention in my post the engine will be pushing out 450BHP with lots of torque hence wanting to stiffen up the chassis to give it a fighting chance of getting some of that power onto the road.

As for the rear suspension, in its current format it actually goes into positive camber then slowly creeps back, I haven't run the numbers but I know shortening the upper wishbones and lowering their mounting points will definitely move it in the right direction, as to whether it'll be too much or not enough I don't know, but it looks about right, before welding up I will clamp in place and measure the camber gain :)


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PostPosted: January 1, 2014, 9:25 pm 
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Joined: December 31, 2013, 3:59 pm
Posts: 9
Custom rose jointed wishbones ordered along with more steel, work starts in the morning :D


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PostPosted: February 27, 2014, 8:18 am 
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Joined: December 31, 2013, 3:59 pm
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So I have done a little work on this recently....

First of all increased the size of the engine bay by eating into the passenger foot well...
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Beefed up the front end with a little extra bracing and added 'r tube'
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Decided whilst I was at it I would re-design the rear suspension geometry..... (I can never leave things alone....)

Hello angry grinder... Out with the old...
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Moved outwards and downwards...
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Decided I didn't like the contact area they had so made new...
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Change in position
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New rose jointed arms with custom shorter upper bones held roughly in place to see how it looked (thanks Danny@MK)
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thought about different bracing options...
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Cut all the bits for bracing and left it for my friend Adam to weld up for me.... clearly he got bored as I found this additional roll protection welded to my car
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Welded up
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Mounts for cage welded in
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Engine in siute, yes the manifold does fit.... just, as does the dry sump pump
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Removed my external wastegate on my tubular manifold so I could fit in a Y brace, will have to reposition the wastegate when I get some stainless tube.
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Anyway that's it for now, the setup should hopefully strengthen things up nicely and with the rear suspension modifications the car should roll less due to the centre of roll being raised nearer the centre of gravity and the negative camber in roll significantly improved due to the shorter wishbones and repositioned upper mounts.

Any other suggestions welcome.


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PostPosted: March 12, 2014, 11:47 am 
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Joined: August 3, 2013, 1:20 am
Posts: 33
Location: Tracy, CA
What bellhousing and transmission are you using to mate the Saab engine to a rear wheel drive transmission?


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PostPosted: March 13, 2014, 11:10 am 
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Joined: December 31, 2013, 3:59 pm
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Gearbox is a Borg Warner T5 (taken from a TVR as it has good ratios (same as Sierra Cosworth) but with beefed up internals)

The Bell housing is a custom GM(Vauxhall) to Ford T5 item available from RWD Motorsport.

I am using a custom spec clutch pressure plate and AP Paddle.


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PostPosted: March 18, 2014, 3:14 pm 
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Location: Park Hills, KY
Its a shame that bell house is so expensive to have shipped to the states... I considered doing the Saab motor for a while, but almost $500 was too much to spend on the single part for me. Its a fantastic motor, though! Great power cheap!


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PostPosted: March 18, 2014, 6:28 pm 
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Joined: December 31, 2013, 3:59 pm
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With a little patience you can take the standard saab bell housing cut off the flange which bolts to the engine, then remove the flange that bolts the T5 box from your chosen donor bell housing and tig them together, obviously this will not be 'easy' and alignment will be a task in itself, if you can't tig you can tack in place with a mig and have someone weld it up for you, I took the easy route as financially it made more sense to save my time and pay for the bell housing, but its certainly not impossible to do something yourself.

Agreed it is a great little motor, i'm looking forward to playing with sequential charging


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PostPosted: March 29, 2014, 2:07 pm 
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Joined: October 3, 2009, 1:33 pm
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Location: FL
Another way to change the rear suspension would be to use the shock mount for your UCA pivot and relocate the shock mount. This would provide a change in UCA length as well as increase the static angle of the UCA. It should also reduce the loads fed into the chassis mounts by about 10% by increasing the leverarm length between the hub LCA pivot and the UCA pivot. G;-)

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PostPosted: March 30, 2014, 9:13 am 
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Joined: December 31, 2013, 3:59 pm
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glenbinegar wrote:
Another way to change the rear suspension would be to use the shock mount for your UCA pivot and relocate the shock mount. This would provide a change in UCA length as well as increase the static angle of the UCA. It should also reduce the loads fed into the chassis mounts by about 10% by increasing the leverarm length between the hub LCA pivot and the UCA pivot. G;-)

I have seen that done before, I will see how I do with this setup I can always modify it later :)


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PostPosted: May 16, 2014, 9:55 am 
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Build is looking great :D


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PostPosted: May 20, 2014, 5:43 pm 
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Joined: December 31, 2013, 3:59 pm
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Thanks there have been a fair few updates since this post, will try and update the thread at the weekend :-)


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