3A Rear Wheel Arches

[rthomas69]

I'm in the process of building a 3a which was started but not progressed very far & then stood for 15+ years before me obtaining it.

I've just refurbished the rear beam,suspension, rear disc conversion etc & have noticed that now it's all back together that the rear wheels sit towards the back of the arches by about 20mm & it looks like the only way to correct this is to move the whole rear beam etc forward. Did anyone else have a similar issue? If so did you just re-drill the mounting holes further forward?

[Guest 2b cruising]

Does it make that much difference.

You didn't notice it before or during stripdown.

Maybe it is because you have just built back up as it was and it sticks out obvious to you.

I can't speak for the 3a but the 2b chassis were made by eye.

When you buy the 2b kit it is not an assembly project, even the makers say it is a full engineering job.

3a came before the 2b so I can only see that being worse and not better.

[Snapperpaul]

I did not have this issue but do have a large gap top of arch to tyre ( not as much as a 2b but still bothers) to change this I would need to raise the forward beam mounts up in a fabricated box then redo the front as front would now be to high

 

In your case the critical mounting points are the beam mounts under the seats which are thick metal plates that can be moved with just drilling new bolt holes

I would strengthen the floor and also the boot floor where the Diff mount bolts as these flex

 

[Snapperpaul]

[cb750]

I don't have this issue. My wheels are within 5-10 mm on the front/rear gaps and looks OK. When you cut the front of the rear wings to fit to the monocoque sides the amount of material removed will alter the gaps as the wing twists and alters the gaps when you push it against the side to mount it. It took me some time and repeated cutting until I could get the gaps looking right.

[rthomas69]

I'll take a photo tonight (got similar gap above the wheel as yours Paul looking at the photo's you sent me)

I think it's one of those things that if I don't correct it now it will bug the hell out of me in the future.

As per your previous advice Paul I have already strengthened the boot floor/diff mount & tied it all in with the roll bar & triangulated seat belt mounts.

It looks like I'll be re-drilling the mounting points & moving them forward (also means a mod to the seat base frames where I've been 'creative' around the beam mounts).

On the plus side it will give me a bit more propshaft engagement into the gearbox (doesn't look far enough in to me).

[Snapperpaul]

Should be about 1" of shaft showing can be more but not to much less

[rthomas69]

I've had another look & have taken some photos.

Wheel arch gap looks like it is about 20mm out.

If I move it forward 20mm the rubber mounting bush will just about touch the folded angle that runs from side to side, so just about ok.

However the inner suspension arm mounting points are only about 10mm from the back of the tub so would only allow that much movement.

Prop also looks like it should be a further 20mm further in looking at the clean part sticking out the back of the gearbox.

[cb750]

Mine looks nothing like that. The wheel is more central and the top gap looks narrower. I have tried to upload a photo but can't due to the size limit for photos when posting direct and photobucket is playing up at the moment

[cb750]

Photobucket has just started working so will see if this works!

 

[cb750]

Just been underneath and had a look at my beam position and it's in the same position as yours. The inner suspension arm bush mounts are close to the bodywork as well. It looks very much like there is something wrong with the wings?

[Snapperpaul]

Looks to me that you forward arch lip at the bottom is to high

Mine is level with the floor

This would swing the whole arch down

Then to increase gap at the rear just push out the arch and use a ½ square tube to support

Tricky Dicky used the stainless stone guards to hold the front of the arch in place

[rthomas69]

I'll have a go at 'persuading' the arch into a better position tonight.

[theduck]

Is it on the ground in that photo? If so my rear end is far lower! I think it's mine that's wrong though...

[rthomas69]

Is it on the ground in that photo? If so my rear end is far lower! I think it's mine that's wrong though...t

It's on axle stands although I gave a jack under the wheel lifting it slightly off the stand, so it's pretty much how it sits on the ground, It will sit slightly when everything else is fitted, a full tank of fuel (& my lardy ar$e in it)