408 front subframe / crossmember removal

[dwomby]

Originally Posted by Kevin H

David,
>
>

Another spot where the V8 cars are notorious for rust is around the top mounting points for the rear shock absorbers. Which is even harder to see!

Kevin

Thanks for that tip - I'll take a good look there.

David

[Thomas591]

Hi David,

as I replaced all the screws on the front axle, I made a list of them. Maybe this will help:

Quant Description Dimension lenght

8 Hex Screw 1/4-28 1/2
2 Hex Screw 1/2-20 1 1/4
4 Hex Screw 3/8-24 1
16 Hex Screw 3/8-24 1
10 Hex Screw 3/8-24 1
6 Hex Screw 5/16-24 3/4
8 Hex Screw 5/16-24 1


This is for my 411 S5, I do not know if earlier cars used BSF screws instead.

Regards

Thomas

[dwomby]

Thank you, Thomas.

It seems, from the parts book, that nearly every nut and bolt on my 408 suspension is BSF. I can get those here in the US from a few suppliers but I would have thought several of the fasteners could be safely replaced with UNF Fine Thread equivalents.

E.g. the bolts holding the upper ball joint between the upper wishbones are listed as 1/2" BSF. So I may investigate using 1/2-20 Grade 8 to replace those. Provided the unthreaded portion of the UNF bolt is the same diameter as the BSF one, it should work. I'd be interested in peoples' opinions on that.

David

[Kevin H]

Originally Posted by Thomas591

This is for my 411 S5, I do not know if earlier cars used BSF screws instead.

Thomas,
I'm pretty sure on my 411 S5 they were all still BSF.
Regards,
Kevin

[Kevin H]

David,
I thought this may be useful/interesting - it's a strength test comparison between BSF and UNF
https://reports.aerade.cranfield.ac....=1&isAllowed=y


Kevin

[dwomby]

Thanks, Kevin. I think the UNF will be fine in most locations.

You may be interested to see my progress dismantling. I have done a bit each day for several days. Tomorrow, I hope to get the tubular cage out from the front of the car and the lower wishbones off. The upper wishbones are being a pain and may have to be removed after the crossmember comes out to get better access. I think I'll leave the oil cooler attached but hang it from the metal work

David

[Kevin H]

Originally Posted by dwomby

You may be interested to see my progress dismantling.

Definitely!

The upper wishbones are being a pain and may have to be removed after the crossmember comes out to get better access.

The bolts which go through the bushes in the wishbones are probably seized with rust. They were on my 411. It's very hard to tell until you go to remove them!

Thankfully on the 411 the fulcrum bracket arrangment and the way the wishbones are fixed to the crossmember is a little different, which makes it easier to get them out.

Good luck and please keep the photos coming!
Kevin

[Thomas591]

On my car definetly not. On the front subframe there was not a single BSF bolt. I collected all the original screws and measured them, then bought new ones. all UNF. Very strange...

I found a few BSf bolts on the rear axle and its suspension. But even the studs for the swingarm housings were UNF.

Originally Posted by Kevin H

Thomas,
I'm pretty sure on my 411 S5 they were all still BSF.
Regards,
Kevin

[Kevin H]

Originally Posted by Thomas591

On my car definetly not. On the front subframe there was not a single BSF bolt. I collected all the original screws and measured them, then bought new ones. all UNF. Very strange...

I found a few BSf bolts on the rear axle and its suspension. But even the studs for the swingarm housings were UNF.

Well now you have got me wondering Thomas Maybe I am making assumptions! It was 20 years ago and I must admit I didn't measure every nut or bolt, and some of the work was done by a third party. I'll have to go back and look at what he supplied and what I bought from Bristol. I know for sure that the "thin turret nuts" that secure the upper wishbones to the crossmember were bought from Bristol and they were 1/2" BSF.

I was given the impression by Bristol at the time that many suspension parts carried through from the 407, 408 & 409 to the 410 and 411 (and probably the 412). Certainly many of the parts I bought from Bristol for my 411 had 407-409 part numbers.

Is it possible your car had already had restoration work done and someone had already replaced most the BSF nuts and bolts with UNF?

Regards,
Kevin

[Thomas591]

Darn! You got me… I was a bit over-enthusiastic in my statement „not a single BSF“. Yes the thin turret nuts are definitely BSF. I had these nuts glass-blasted and zink plated, so these were not on my list. Sorry for that..

Regards

Thomas

Originally Posted by Kevin H

Well now you have got me wondering Thomas Maybe I am making assumptions! It was 20 years ago and I must admit I didn't measure every nut or bolt, and some of the work was done by a third party. I'll have to go back and look at what he supplied and what I bought from Bristol. I know for sure that the "thin turret nuts" that secure the upper wishbones to the crossmember were bought from Bristol and they were 1/2" BSF.

I was given the impression by Bristol at the time that many suspension parts carried through from the 407, 408 & 409 to the 410 and 411 (and probably the 412). Certainly many of the parts I bought from Bristol for my 411 had 407-409 part numbers.

Is it possible your car had already had restoration work done and someone had already replaced most the BSF nuts and bolts with UNF?

Regards,
Kevin

[dwomby]

Just to let you know I am stalled for a bit trying to work out how to remove the overtightened, hard to access and oddly shallow bolts holding the crossmember to the front of the main chassis rails. We have guests for a few days too so I won't be touching the car until next week.

David