408 front subframe / crossmember removal

[dwomby]

Originally Posted by Kevin H

Wow, that's pretty serious corrosion!
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Do you know much about the history of the car?


Kevin

Yes, that rust is bad and in a strange place. John Tullett says it must be from mud sat there for a long time. It's actually hard to see in there which is why I think it has been undiscovered over the years. I only found it investigating the upper spring supports and even then only by accident.

The car is 408 Mk1 7023. Its history from leaving the factory to c.1990 is unknown to me. It was sat with no engine and transmission when Tony Crook took a prospective buyer to see it at somebody's house. The buyer was an Air Force Chaplain whom I have spoken to. He had the body restored and repainted in the UK in 1991. The work was not done by SLJ but they acted as project managers and I have various reports they sent on the restoration. The owner then brought the car with him when he moved to the Minnesota in 1992 and had a later 360 engine fitted with a period correct 727 gearbox.

The chaplain sold the car, I think around 2000, and it seems it had 2 other owners before me. It was in West Virginia in 2001. I bought the car here in Florida from a gentleman who had it from 2009. He did a lot of restoration on the brakes but not the springs, etc..

I suspect the rust was missed in the 1991 restoration but it could be from salt in Minnesota. So far, there doesn't seem to be any other rusty area to the frame or this subframe but I will keep checking and there may be more visible once the subframe is out.

David

[Kevin H]

David,
It is odd that the rust is only in one spot, however it is an area that could hold some water if there was mud there and particularly if the car was parked across a slope. Add salt to the scenario and it could do some serious damage over time. Of course once the rust takes hold it would just get worse every time the car was driven in wet weather.

I once lent someone a trailer who left it with inches of wet sand sitting in it for six months or more. It had almost completely rusted through the bottom of the trailer.

Anyway, it's good that you found it and can now restore it.

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

[dwomby]

Originally Posted by Kevin H

David,
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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

[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