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Mega Chassis Strengthening and Tweaking Advice


Dan Ingram

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Dan Ingram
20 hours ago, Terry Everall - WSCC Competition Secretary said:

In my experience you need triangulation next to the bottom diff mounting lugs as that is where most failures seem to occur 

 

That's where mine had cracked. 

Inked20210107_172853838_iOS.jpg.4fb1add47a4d23c449ea4c617b2c69a4_LI.jpg

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Thanks for the pictures @Andy (Sycho) . I've seen someone elses Mega S2000 chassis on here that gave me the idea about strengthening mine. I'll be adding some triangulation to the diff cage.  

Had a couple of hours off from Dad school today so did some weight removal.   Chopped most of the lump off with a cutting disc as shown in @Glen_I picture.   Ground it down with a

The circled bits in the upper photo are the various mounts for inertia reel seat belts. The red circled towers have been removed by some, but from memory, I don’t think it was easy. I’ve a feeling the

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Terry Everall - WSCC Competition Secretary

I mean just behind the DIFF mountings towards the rear of the car not the wishbone mountings you have shown

 

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  • 1 month later...
Dan Ingram

Managed to get a bit done this week while it's half term. Finished a load of bits of welding I'd missed and replaced two of the lower arm mounts. The bolt holes had ovaled, probably due to everything being out of line.

 

Now everything is straight again I've made a start on adding the extra bits. Fitted the diff to see what space I had. I've added some extra tubes around the diff mounts. The upper ones go up to where a couple of other tubes meet so there should be plenty of strength there. Don't be too harsh on my welding. It's not the prettiest but it does the job.

 

As for bolting the diff in I'm sure I've seen somewhere that you can helicoil the casing and use bolts instead of the threaded rods which are a pain. Has anyone done it and what size helicoil did you use?

 

 

20210220_155759470_iOS 1.jpg

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Dave Eastwood (Gadgetman) - Club Secretary

M12 helicoils ring a bell, yes I've done it for those reasons, the studs are a PITA, also a popular mod with sprinters and racers.

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Glen_I

I done the same regarding the diff as you quite rightly say, those studs are a pain in the wotsits.

 

And yes they are M121043387743_20201026_155325(1).thumb.jpg.c21e3da6014ff88fa8bf17449380405f.jpg670574600_20201026_155355(1).thumb.jpg.b5765d0f7e44d482e7de687a51783746.jpg1515920853_20201026_155503(1).thumb.jpg.e610749708545d56e4832b88b5a87e6f.jpg

 

I done it before sending diff off for rebuild in case it went pear shaped afterwards.

 

I am kicking myself for not strengthening the diff area up before having chassis repowder coated, something I overlooked.

 

I only became aware of possible issues when I found a thread about the diff mounting helicoils.

 

I am thinking about adding bracing in same place as yours but have it so they are bolted in via rivnuts? 

 

Is it the actual lower diff mounts that fracture? If so I have another possible idea for that....

 

Having said that I never suffered any issues when I did use it last, and that was with Yokohama A048R (soft compound) and a tall 1st gear Quaife box. So quite a load on the rear end as opposed to a short (standard (ish) sort of 1st gear) which would have been easier to break traction and reduce stress....

 

This is my logic anyway?!?!??

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Dave Eastwood (Gadgetman) - Club Secretary

Historically, it’s been some of the box section tubes making up the diff cage that have suffered, the lower ones, running from to rear in particular. If you look at later, stronger chassis, you’ll see the square tubes originally used are now beefier rectangular section tubes. (As well as the additional bracing).

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Dan Ingram

Mine had cracked where the lower tube meets the chassis. As Dave says on the newer models the sqaure box section has been replaced with a larger rectangular box section. I might have got away with just repairing it but it seems to daft not to try and stop it happening again while it's stripped down.

 

I'll get a M12 kit ordered and sort the diff. I'm not messing about with those studs.

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Dan Ingram

Helicoiling the diff casing worked a treat, thanks guys.

 

Can't fit it yet though as a I b*****red one of the bushes reaming it out to 12mm 🙄

 

 

20210223_130357575_iOS.jpg

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Glen_I

@Dan Ingram I think I have at least 1 (brand new) metalastic bush that I can thrown in the post if you want, it will only end up getting carefully stored away for the rest of eternity!

 

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Dan Ingram
43 minutes ago, Glen_I said:

@Dan Ingram I think I have at least 1 (brand new) metalastic bush that I can thrown in the post if you want, it will only end up getting carefully stored away for the rest of eternity!

 

 

Thanks for the offer. Fortunately I have a spare one as they came in a pack of 5 for some reason.

 

I need a new reamer as mine is knackered and then I can fit them and mount the diff.

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Glen_I

Just a thought, but is the 5th bush you have for the diff stabilizer/torque reaction bracket?

 

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Dan Ingram
1 hour ago, Glen_I said:

Just a thought, but is the 5th bush you have for the diff stabilizer/torque reaction bracket?

 


It is yes. That one is ok though so I’m not changing it. The only reason I’ve changed the main ones is because I removed the old ones when I was straightening the chassis and welding new bits in. The heat melted the rubber.

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Glen_I

Gotcha, well if you need another spare if things go pear shape let me know and I will chuck it in the post.

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  • 2 weeks later...

Just reading this post I notice the difference between mega chassis design, ie I'm presuming that it's a car engined car mega model rather than a bike engined car as the bike ones a Freelander diff with a different looking diff cage and extra brace brackets.

Also you circled the lower wishbone mounting lug where it broke... How is the diff responsible for breaking that? Wouldn't it be the suspension stresses?

If adding braces... Make sure you can actually get the diff in and out! It's tight fit

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