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Stiffening chassis?
sebastiaan - 15/1/11 at 07:16 PM

Hi guys,

I've taken the engine (pinto) out of my MK this afternoon in anticipation of the winter upgrades. Now that the engine is out, I'd like to take the opportunity to increase the chassis stiffness a bit. The Indy chassis doesn't have the "R" tubes at the top of the engine bay nor the alternative "Y-braces" and this of course does not do the torsional stiffness any favours. Due to the design of my inlet & exhaust manifolds, those braces would also not fit my car. Has anyone done something to increase the chassis stiffness of the Indy? I know the "aussie mods" and have also seen Cymtrik's work on this but maybe there are other ideas out there...

Sebastiaan


interestedparty - 15/1/11 at 07:51 PM

I suggest you put up a photo of the car without the engine in it, it would make it easier for people to make suggestions as to where stiffening could be added.


jacko - 15/1/11 at 09:54 PM

What makes you think it needs stiffening ? MK have sold lot's of indy's and i cant think of any i have seen with the R tube or Y bars Track or Road
Jacko


sebastiaan - 16/1/11 at 10:38 AM

quote:
Originally posted by jacko
What makes you think it needs stiffening ? MK have sold lot's of indy's and i cant think of any i have seen with the R tube or Y bars Track or Road
Jacko


That's exactly the point. The R-braces add a lot of stiffness to the chassis and have been omitted from the MK chassis in order to be able to fit a lot if different engines easily. if you look at the top rails making up the engine bay, the whole thing is in essence not triangulated at all...

I'll see if I can dig up a picture.

*Edit* found something in the photo archive.


Early days
Early days


[Edited on 16/1/11 by sebastiaan]


sebastiaan - 16/1/11 at 11:29 AM

This'd be the simplest way of adding the R-tube, but my exhaust interferec with it as it drops slightly below the level of the top chassis rail between the engine and the side rail (Pinto with MK manifold)

Simple R-race added
Simple R-race added



Doubling up on the R-braces gives this, which also does not work at the inlet side because of the inlet manifold....
2x R-brace added
2x R-brace added



And this is me going wild...
Descriptiolots of bracing
Descriptiolots of bracing


jacko - 17/1/11 at 06:29 PM

Back to my first post
what makes you think you need them ? if no other Indy's have them
Have you read /seen any indys that have fallen apart etc ?
Maybe because the indy has steel bulk heads that add's strength ?

Ps i don't have anything to do with MK
Jacko

[Edited on 17/1/11 by jacko]


indykid - 17/1/11 at 07:05 PM

quote:
Originally posted by jacko
Back to my first post
what makes you think you need them ? if no other Indy's have them
Have you read /seen any indys that have fallen apart etc ?
Maybe because the indy has steel bulk heads that add's strength ?

Ps i don't have anything to do with MK
Jacko


i find i get significant scuttle shake from the front end over rough surfaces as the completely undamped spring of the front end wobbles about.

torsional stiffness isn't essential (and there have been many cars with floppy bodies produced over the years), but it certainly helps the suspension do its job. adding the engine braces and probably a tube across the top of the footwells would add a lot of stiffness.

MKs aren't built as a serious racer and they suit their purpose for the majority. that doesn't mean it's wrong to want to improve them though, nor that they can't be improved because they don't fall apart


jacko - 17/1/11 at 07:42 PM

quote:
Originally posted by indykid
quote:
Originally posted by jacko
Back to my first post
what makes you think you need them ? if no other Indy's have them
Have you read /seen any indys that have fallen apart etc ?
Maybe because the indy has steel bulk heads that add's strength ?

Ps i don't have anything to do with MK
Jacko


i find i get significant scuttle shake from the front end over rough surfaces as the completely undamped spring of the front end wobbles about.

torsional stiffness isn't essential (and there have been many cars with floppy bodies produced over the years), but it certainly helps the suspension do its job. adding the engine braces and probably a tube across the top of the footwells would add a lot of stiffness.

MKs aren't built as a serious racer and they suit their purpose for the majority. that doesn't mean it's wrong to want to improve them though, nor that they can't be improved because they don't fall apart

Fair point
i will get my coat
Graham


RichardK - 17/1/11 at 08:11 PM

I stuck an extra one in that doubles as a front engine mount too.



Although my scuttle doesn't tend to shake, just the rest of the car!

Cheers

Rich


Hellfire - 17/1/11 at 08:19 PM

Fit a bike engine as part of your upgrade and you get the additional bracing to aid installation.........

Phil


jacko - 17/1/11 at 08:45 PM

Yes but a bike engine doesn't have the TORQUE of a proper engine


sebastiaan - 17/1/11 at 09:50 PM

quote:
Originally posted by Hellfire
Fit a bike engine as part of your upgrade and you get the additional bracing to aid installation.........

Phil




Well, I almost asked for that one, didn't I?


Hellfire - 17/1/11 at 09:53 PM

quote:
Originally posted by jacko
Yes but a bike engine doesn't have the TORQUE of a proper engine


What you fail to remember, is that bike engines have a torque multiplier in the form of a primary reduction gear

Phil


Hellfire - 17/1/11 at 09:56 PM

quote:
Originally posted by sebastiaan
quote:
Originally posted by Hellfire
Fit a bike engine as part of your upgrade and you get the additional bracing to aid installation.........

Phil




Well, I almost asked for that one, didn't I?


LOL


mcerd1 - 17/1/11 at 10:11 PM

quote:
Originally posted by sebastiaan
And this is me going wild...
Descriptiolots of bracing
Descriptiolots of bracing



if you were going to do something like that (which is probably way ott) then what about something more like this on the sides:
Description
Description


that way you save those two vertical bits you had comeing up from the engine mounts, but keep the extra stiffening at the mounts

(I'm no chassis design expert, but its what I'd do on any of the lattice structures I design at work)


if you want to see a chassis with lots of bracing have a look at a dax:




[Edited on 17/1/2011 by mcerd1]


James - 28/3/11 at 10:47 PM

Sebastiaan,

Missed this post before.

If you're still looking for a solution, have a look at the 'spiderweb brace' that Liam put over the top of his Honda engined 4x4 Locost. Very neat solution.

Cheers,
James


bob - 28/3/11 at 11:01 PM

Are the latest MK's the same as the chassis picture posted, just a thought as i know the pictured chassis was made in 2001.


mad4x4 - 29/3/11 at 01:36 AM

If we were to brace a chassis like that - small question ? Where do you fit the engine? there making it strong and inflexible but we also need to leave space for engines of differing sizes, the braces between the tunnel and the nose would foul my exhaust and my in lets on the zetec.....


snoopy - 29/3/11 at 07:30 AM

quote:
Originally posted by bob
Are the latest MK's the same as the chassis picture posted, just a thought as i know the pictured chassis was made in 2001.


latest mk chassis


chassis1
chassis1


bob - 31/3/11 at 08:14 PM

Snoopy, Yes exactly my point although that isnt an Indy its the newer version. Not sure if they are making the Indy chassis the same as mine as 10 years ago.

[Edited on 31/3/11 by bob]


Mr Whippy - 31/3/11 at 08:42 PM

bare in mind though if you make the front super strong it might not collapse in a crash and instead make you passenger compartment into the crumple zone...


Steve Hignett - 31/3/11 at 08:59 PM

There are some pics of a triangulated chassis in the following thread:

http://locostbuilders.co.uk/viewthread.php?tid=132958

Although it's not complete at the time of the last photo...


snoopy - 31/3/11 at 11:12 PM

well this is a westfield chassis which i would assume most of us would say was suitably built



sebastiaan - 1/4/11 at 06:27 AM

I appreciate that the Westy chassis looka s lot like the MK (bar the short engine bay stiffeners and the rail across the scuttle area), but I'm simply after ways to stiffen the whole thing up a bit to further improve things.

And, as a sidenote: my MK is perfectly adequate for the odd sunday drive I use it for. It even self-centres (a bit.... ;-))


HowardB - 1/4/11 at 06:37 AM

quote:
Originally posted by Hellfire
Fit a bike engine as part of your upgrade and you get the additional bracing to aid installation.........

Phil






that is one stunning engine bay!

[Edited on 1/4/11 by HowardB]


sebastiaan - 17/1/12 at 06:29 PM

Just to follow-up on this; I've since stripped the car back a bit, ordered some additional steel tubing and plan om doing this:



It's designed to tie the two bulkheads together and use the additional strenght and stiffness to channel some of the loads into the transmission tunnel (which I might end up triangulating as well). The "double R braces actually go down to the rear pick up points of the top wishbones as that way they clear the alternator & manifolds and that is of course also where the loads are introduced into the chassis. Together with triangulating the front suspension box these mods should provide a decent increase in torsional stiffness. If I wil actually notice this on the road I do not know, but I will report back once the car is back on the road.

At the rear, there is some additional bracing going in to stiffen up the rear suspension box (where the diff sits) as this is just a square box with no appreciable triangulation (and a couple of pre-failed tubes, LOL) as standard.

And let me stress AGAIN that the car is perfectly suited to the odd blat out on the open road, I just want to see if I can improve things a bit. Here's hoping I don't mess it up


sebastiaan - 14/5/12 at 07:09 PM

Right, it's been a few months....

I just took the Indy out for a first drive after the winter mods. I ended up adding just one R-brace to the passenger's side and making the top panel for the footwell on that side structural (bonded and riveted on). Effectively, this mimicks the BEC setup for the old MK Indy chassis.

In addition, I triangulated the "suspension box" on both sides, adding diagonals from the rear mounting point of the top wishbones to the opposite corner in the very front lower corners of the chassis. Also added a V-brace behind the rad.

And, does it drive any better?

It seems it actually does, although this is of course very subjective. It's also been quite some time since I last drove the car. But to me, it seems like the car actually self-centres a bit better and that it is more stable over bumpy surfaces. It also seems that some of the rattles and squeeks are gone.

In all, I'm quite happy I did these mods. To further improve the self centering, I might fit some haynes roadster top wishbones as these should fit and increase caster by some 2 degrees.

Hope this helps for some of you....