Increasing Chassis Strength

[Yoof]

Thought this topic would be of use to most on here- increasing the strength of the passenger side Mk3 chassis legs, prone to cracking at the joint between the bulkhead and box section (does anyone have pics of a cracked one? I'll add it on here)

Below is what I did to increase the strength of both my Mk1 Legs and Mk3  

Stich Welding of Mk1 Chassis Leg- not done this on my mk3 as it's a road car, mk1 is intended for hard track use (plus andy might drive it   LOL  )


If you're running really stupid spring rates then it's worth stich welding the rear up too, mine started to split slightly on the mk3 after running silly cup car springs, so have done this to the mk1:



Below you can see the stich welding on my mk3 (just the gearbox mount only)




And the rear leg brace:




Usually passenger side leg splits, which is no surprise when you actually look at the differances:





And the Mk1 bracing- more industrial than the mk3, but will have more power and harder suspension set-up:



And if you don't believe me     here's how the professionals do it  







Hope this helps,

Pete

[Nick_S]

[quote pid=22 author=Nick_S date=1204461806]And if you are going the whole hog, then possibility to reinforce the outside of the chassis legs where they join the bulkhead on the inside of the wheel arches.

 

[/quote]

[Andy]

What's the rationale behind doing that Nick?

[Nick_S]

[quote pid=26 author=Andy date=1204469776]What's the rationale behind doing that Nick?[/quote]

If its good enough for ze Germans, it's good enough for me. Extra gusseting round there can't be bad.

[Yoof]

Home of motorsport is England   We're better... lol

It won't hurt to re-enforce that area, but it certainly won't stop a crack propagating between the bulkhead and chassis leg, any minor fracture will grow and grow as it's loaded and unloaded- the plate at the back will just lengthen the time it takes until the leg physically hangs off, it's not a preventative measure in my opinion.

[Nick_S]

Yeah i see your point once a crack starts propagating. I just see that it will help reduce flex/torsion in that area.

[hayesey]

are you going to put one on the inside as well nick?

[Nick_S]

Yeah, already done.

[86C]

If you've ever looked in a proper VW body and chassis manual, they do this when replacing the inner wing sections anyway

[grungeisdead]

would this be worth moving into the FAQ section?

[AlexG40]

Yes!

[gavin.starr]

I cant remember if it was on this club or the ( club polo ) forum that some one was doing a mk2 or mk3 rally prep'ed polo, and that showed all the strengthening points, from the engine bay through to the rear beam ill se if i can find it later. Unless some one knows the one im on about. Im sure it was baby blue in colour.

[hayesey]

That was heg123 on clubpolo..car is,now crashed and dead