Series 3 Chassis Reinforcements?

[Guest Dave U]

A few years ago there was a series of posts about some cracks on Series 3 chassis. I have a Series 3 stainless tub and would like to weld on some reinforcements or gussets to prevent these issues.

 

Does anyone have information on where the cracking occurred, and what reinforcements were adequate?

 

Thanks

David Ulicki

[Big Jim]

The "channel" that houses the front suspension, where it's welded to the side panels is a major point where the welds crack, also put a "strap" over the top of the joint (you can just see it in the photo)

Where the top wishbone pivots in the "channel" can both wear and crack (mine did). I've made plates with threaded bosses on, that I've rivited to the original "channel" because at the time I couldn't get it to a s/s welder.

It's been fine for the last 3 years anyway!

[Guest Dave U]

OK-- The area in your photo looks a bit different on the version I have. (New Series 3a, with outboard coil-over and RH fabricated upper/lower arms.)

 

In the spot with the strap, my tub already has a bent sheet metal angle welded on there. I am thinking that this top angle is OK as-is.

 

 

The weld that joins the large boxy upper cross channel to the sides is on the inside corner, on the INSIDE of the tub. This weld is visible from inside the engine-bay. In your photo this weld appears to be on an inside corner on the OUTSIDE of the tub.

 

Also—the riveted plates in your photo seem like a good idea. Did you add two plates, one on the rear of the cross channel on each side? Or are there four? Front/Back of the channel, both left/right sides? How thick is the material?

 

I looked at this area on my tub and RH has already welded a reinforcing piece in. The cross-channel box is made from 1mm thick material. The reinforcement appears to be about 2mm. Total thickness is about 3mm. It is SS sheet bent to fit just inside the cross channel. It runs along the inside up the front, across the top to the back, and down the back side. It is about 5-6 in wide. The outboard edges are spot-tacked and the inboard vertical edges are welded into a corner joint.

 

Please see photo, and see if you think this is OK, or needs reinforcing to be as solid as yours.

 

Also—

On the Dave Andrews site, he mentions adding a box-section to reinforce the differential mounts. Can you add any insight to this??

 

Thanks

David Ulicki

[Big Jim]

there is a plate on the back side of the rear-most "flange" and another one inside the front flange.

I first measured the amount of spacer that I needed for castor (behind the front flange) then using 3mm plate & about 9mm spacer welded on, reamed out to suit the spindle, this went inside the front flange.

I still have a nylon washer either end of the wishbone, so at the rear flange, I made again with 3mm plate, this reamed to suit the spindle, but now with a 13mm thick boss, tapped to suit the thread on the spindle, welded onto the plate. (use the spindle to make sure that it's all lined up before welding together.)

So now I have about 13mm of metal supporting the front of the spindle, and 55mm with another 13mm of thread supporting the rear. There's a nut acting as a locknut on the back of the spindle, and a nylock nut & large s/s washer on the front. so the spindle can't turn at all.

note that I had to have new spindles machined as longer ones were needed.

also note that the wishbone now has a grease nipple fitted.