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Author: Subject: Chassis flex in Striker
martinnitram

posted on 29/10/17 at 03:07 PM Reply With Quote
Chassis flex in Striker

How much is normal, I know some is to be expected as its thin steel and a basic design.

Noticed some flex while working on it, jacking up etc, and also where the bonnet touches the bulkhead there are rub marks showing about 6/7mm of movement, so did an experiment today while the rear was jacked up doing the pads.

With the front wheels flat on the garage floor with dampers set full hard and the jack under the back end in the middle I grabbed the roll bar and put my weight on the rear wheel to put a twist in the chassis, it twisted enough to make the nose cone visibly wobble and flex, you can see the engine move at least 1/2" and I could see the side rails were being twisted.

Ive checked for any bad welds and cracked joints and cant see any, the movement appears to be bulkhead forward.

Its difficult to describe in words without seeing it.

Is this normal ?

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ian locostzx9rc2

posted on 29/10/17 at 03:15 PM Reply With Quote
I have had 3 strikers and I have never seen that sort of flex in the chassis !
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Shooter63

posted on 29/10/17 at 03:51 PM Reply With Quote
I must admit when I jack the stylus up ( similar design) I'm impressed by its strength, I know with ultra sticky tyres on you can get a bit of flex in the rocker arm pivot points.

Shooter

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bi22le

posted on 29/10/17 at 03:54 PM Reply With Quote
I don't think mine flexes a visible amount. If I jack up a rear corner the front of the same side will lift by about the same amount.

Have you got the bolt in stiffeners between the rear shock tops and front rocker arms?





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bi22le

posted on 29/10/17 at 03:55 PM Reply With Quote
And is this panelled up in the normal way, rivets and bonding.





Track days ARE the best thing since sliced bread, until I get a supercharger that is!

Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1

Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I

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procomp

posted on 29/10/17 at 03:57 PM Reply With Quote
Hi.

Depends on age of chassis but the older ones certainly did flex flexed a lot. Thats why the works race car had a new chassis or complete new car every season.
Some of the modern seven replicas can have 1 deg of chassis flex by hand. !

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martinnitram

posted on 29/10/17 at 05:51 PM Reply With Quote
Thanks for replies.

Seems a mixed opinion then, but to answer a few questions,

Not sure if this is an old version chassis or not its on a 2007 reg plate

It is panelled up rivetted and bonded, nice neat job as well

It doesn't have any chassis stiffeners fitted.

Had another good look round and cant see any cracks or rot at the joints, a few bits where powder coat is flaking, had my son film it with his I pad while I was swinging about on it and with the camera held against the body you can see the nose flexing.

I might get him to post it on you tube and put a link up.

Reason I started looking at this was a creaking noise from the bonnet (fastened down) when you turn the steering wheel while stationary, so I knew something was flexing, I can recreate the same noise by trying to pick up one of the front wheels by hand, so to my mind its the front that's twisting.

Proper engineering, lol !!

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martinnitram

posted on 29/10/17 at 08:46 PM Reply With Quote
quote:
Originally posted by bi22le
I don't think mine flexes a visible amount. If I jack up a rear corner the front of the same side will lift by about the same amount.

Have you got the bolt in stiffeners between the rear shock tops and front rocker arms?


Just looked on Raw's web page, they list an engine bay brace bar for 28, is this what mean, or something else.

Doesn't sound like much at that price, I give them a ring and find out what it is, got to ring them for my uprights again anyway.

Has yours got the stiffeners fitted ?

[Edited on 29/10/17 by martinnitram]

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bi22le

posted on 29/10/17 at 09:40 PM Reply With Quote
quote:
Originally posted by martinnitram
quote:
Originally posted by bi22le
I don't think mine flexes a visible amount. If I jack up a rear corner the front of the same side will lift by about the same amount.

Have you got the bolt in stiffeners between the rear shock tops and front rocker arms?


Just looked on Raw's web page, they list an engine bay brace bar for 28, is this what mean, or something else.

Doesn't sound like much at that price, I give them a ring and find out what it is, got to ring them for my uprights again anyway.

Has yours got the stiffeners fitted ?

[Edited on 29/10/17 by martinnitram]


It may well be, yes. It's a simple round bar that has some length adjustment in it. You bolt it between the rockers.

Mine has a front and rear one fitted. I have no idea if it makes a difference but I can imagine that anything tying the sides together has to help.





Track days ARE the best thing since sliced bread, until I get a supercharger that is!

Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1

Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I

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motorcycle_mayhem

posted on 30/10/17 at 10:09 AM Reply With Quote
Assuming you haven't installed a 6 litre Chevrolet diesel engine, it does sound (to me) that there is too much chassis flex.
I see JP cars as generally somewhat heavily engineered, plenty of 1" 16g square section, 'generously' MIG welded.

I'm aware that some 'race weight' chassis were produced, thinner steel box section. Perhaps you have one of these....?

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peter030371

posted on 30/10/17 at 01:43 PM Reply With Quote
Sounds odd. Both of my Strikers have not shown any signs of chassis flex like this. The first one had no engine bay brace but my current one does....

front brace
front brace


This was made from a cheap and cheerful OMP strut brace cut down and with new end fittings welded on.

I haven't got one on the back yet but will be doing that this winter and it will double as a mounting point for my extinguisher as that won't fit anywhere else!

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martinnitram

posted on 30/10/17 at 07:16 PM Reply With Quote
quote:
Originally posted by peter030371
Sounds odd. Both of my Strikers have not shown any signs of chassis flex like this. The first one had no engine bay brace but my current one does....

front brace
front brace


This was made from a cheap and cheerful OMP strut brace cut down and with new end fittings welded on.

I haven't got one on the back yet but will be doing that this winter and it will double as a mounting point for my extinguisher as that won't fit anywhere else!


Just looked at your picture and noticed part of a diagonal brace coming from the front, as well as your strut brace, where does this bar go to, do you have a full picture of the engine bay.
Mine doesn't have that bar...

Just edited, it must go to the top of the drivers foot well, on mine if you look under the dash above the pedals on the tunnel side there is nothing structural to weld a diagonal bar to, far as I can make out.

[Edited on 30/10/17 by martinnitram]

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martinnitram

posted on 30/10/17 at 07:24 PM Reply With Quote
quote:
Originally posted by motorcycle_mayhem
Assuming you haven't installed a 6 litre Chevrolet diesel engine, it does sound (to me) that there is too much chassis flex.
I see JP cars as generally somewhat heavily engineered, plenty of 1" 16g square section, 'generously' MIG welded.

I'm aware that some 'race weight' chassis were produced, thinner steel box section. Perhaps you have one of these....?


Ha ha, no nothing like that fitted, 1600 Toyota.
Its all nicely welded up, although noticed on peters car a diagonal brace mine hasn't got.
Doesn't seem to have enough triangulation either down the front sides, need to compare mine to others chassis and see whats going on.
I could soon MIG in a few bars if I can figure out where to put them.

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peter030371

posted on 31/10/17 at 08:57 AM Reply With Quote
My chassis has had some mods done to it by its previous owner. The drivers side upper brace I think was standard on many Striker including my old one. That's the one that is close to the exhaust in this picture. The lower drivers side brace is different for different engine mounting options.

Brace3
Brace3


The passenger side has been modified and the upper one added at the same time. This picture is the passenger side of the chassis, on its side and viewed from 'under' the car. You can also see where the diagonal for the engine mount has been modified to go from a Crossflow to a Duratec.

Brace2
Brace2


This is the right way up showing both upper and one lower brace, the drivers side lower brace is the same.

brace1
brace1

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JimSpencer

posted on 31/10/17 at 10:32 AM Reply With Quote
quote:

Just looked at your picture and noticed part of a diagonal brace coming from the front, as well as your strut brace, where does this bar go to, do you have a full picture of the engine bay.
Mine doesn't have that bar...

Just edited, it must go to the top of the drivers foot well, on mine if you look under the dash above the pedals on the tunnel side there is nothing structural to weld a diagonal bar to, far as I can make out.





Hi

Just to add in case it helps - I've one of the Lightweight's (i.e. a MK3) yours is too young for that, but it certainly has the diagonal brace from the top corner of the footwell to the chassis top rail and the footwell itself is a solid structure too.
Sounds like it might have been 'adjusted' a bit?

Only flex issue I've had (and it's had extensive track use) is the top wishbone mounts cracking (rattling it over kerbs!) and we cross braced the steering rack mounting as that did flex a bit - other than that not noticed anything untoward.

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martinnitram

posted on 31/10/17 at 07:38 PM Reply With Quote
Spoken to Raw today and mentioned the flex in my chassis but again its hard to describe without actually seeing it.
However, regarding the top rail to top of peddle box diagonal bar, that hasn't been fitted to any chassis for about 10 years as it isn't needed ??,

Thanks Peter for taking the time to put the pictures up, very helpful, your chassis has had a fair bit of beefing up.

Hi Jim, how do you mean your footwell is a solid structure, on mine its just plate steel bent and welded with no box section in it other than the tunnel top bar which ends at the drivers footwell, but looks like it ought to continue to the top frame rail, if this makes sense.

It doesn't look like anything has been altered, the steel still has the original coating and no lumps and bumps as if somethings been ground off, although that's not to say it hasn't.

Its a strange one, got the front end on solid axle stands now so there is no tyre deflection and the flex is still obvious when I wiggle the rear end on the jack.

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alfas

posted on 25/11/17 at 11:35 AM Reply With Quote
i owned around 5 strikers, my mates around 4 strkers...all oldschool, live axled ones from mid 90ies....ALL showed identical flex as described by you

and it never mattered if the cars where practically new (built but never used) or if they showed already lots of sings of wear (from much use)

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Christof

posted on 9/12/17 at 09:36 PM Reply With Quote
Peter
Do you have more pics/info on your strut brace, esp the fixing points?
Thanks

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martinnitram

posted on 10/12/17 at 02:06 PM Reply With Quote
Id forgot id started this thread !

I ended up making a cross brace for the front suspension top pick ups which has reduced the flex by about 50% the rest of the flex is coming from the bulkhead area / cabin.

Ive got over it now, and just assume 'they all do it', it was just a shock seeing that much movement, which you can only see when its on solid supports at the front.

id put some pictures up of my brace but my photobucket now won't allow it.

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