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

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

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

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.

Definitely!

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

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

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

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

Progress. After many days of soaking the offending bolts with PB Blaster (penetrant), the 18 bolts holding the crossmember to the front of the frame rails have all been loosened ready for removal. The steering U-Joint has been disconnected from the steering box and the tubular frame ahead of the crossmember is all loosened up too.

One challenge remains before I try to actually remove the crossmember: there are bolts holding the inner fender wall to the top of the crossmember and, so far, I haven't got any of them out. There are 4 each side on the 408 (I think later cars only had 3) and they are partially hidden by a large ridge on the top of the crossbeam. It makes getting a socket on there impossible. So I will have to put a wrench there and use the socket inside except the clearances by the manifolds don't leave room for a socket there either on the rear two bolts each side! I attempted to cut the head off one bolt but I was trying to be sure I didn't cut the metal the bolt passes through and didn't cut far enough in so I cut the head, not the threaded neck!!!!

I think I'll be able to do it with help and a neighbour has offered to assist later this week.

David

Hi David,

I used an angle grinder with a thin disc to grind off the heads. Don’t worry about the sheet metal of the inner fenders a lot, when you have the front crossmember out you will anyway clean and repaint them .. :)
Regards

Thomas

Yes, I may well end up doing similar.

David

In the end, I did grind off those bolts holding the fender wall to the crossbeam.

The front crossbeam is now completely detached from the chassis and body of the car but is still not removed.

The pic below shows the problem: I can't get the u-joint off the splined end of the steering column. It has to come out as the u-joint is inside the crossbeam and the hole the steering column passes through is too small for the U-joint to go through to take it out of there. I have removed the clamping bolts on both ends of the u-joint and the steering box end slides freely. The steering column end will not shift. Applying leverage just pulls the whole steering column down towards the steering box by about 1/2". I have applied PB Blaster penetrant, I have applied heat (albeit with only a small propane torch) and I have hammered a chisel in there (many, many times) but it won't separate from the column splines.

Any suggestions, please? I am considering just cutting the column to get it out but will have to check what would be entailed in repairing it and what parts may be needed and available.

David

Success!!!!!

I applied the propane torch for 30 minutes today. Then after some levering with a pickle fork, the spines came clear of the u-joint. Thanks for all the advice that got me to this point.

Here's the suspension subframe/crossbeam out of the car!!!!! Once I have dismantled the steering and upper wishbones, it will go to the welder for repair of the rusted out areas.

David

Well done David!
That was quite a job! Must be very satisfying to get the subframe off. In some ways it's fortunate that you are restoring everything because it means get the angle grinder out if need be.

Looking forward to seeing how you tackle the Wishbone Challenge :-)

When you get the wishbones off, in the past I wrote a post about getting to bushes out.

Probably don't need to tell you this, but make sure you clearly mark the wishbones arms so they can be re-assembled exactly where they were orignally.

Kevin

Thanks, Kevin. It's going to be a long process getting this repaired and reassembled....................................... ............

David

The subframe is back from the welder!!!!

The first pic shows the worst of the rusted area after the frame had been in an acid bath. The second shows the same area. The control arms are just being test-fitted.

The plan is eventually to paint this black but I am leaving for Nova Scotia very soon and won't be back until September. So, for now, I will temporarily bolt the subframe back in 'as is' to ensure the main chassis rails don't spread apart under the weight of the engine during the summer. The engine has been supported while the subframe has been out. So it should bolt straight back in but we'll see how it goes!!!!!

David