408 With Negative Camber

[jeff02740]

Has anyone had a problem with negative camber on their v8 cars?
I noticed that the camber was negative, I have since replaced all wishbone bushings and cleaned everything up. There is no play in the ball joints and everything is tight. Still have negative camber especially on left front. Any suggestions?

[AndrewA]

Is it a lot out?
I went to great lengths to get it spot on on mine and got hold of some camber shims from Bristol Classic Car Parts. They call them caster shims but they don't do anything to the caster!

[jeff02740]

Right side is close, about a half degree, but left side is 2 degrees negative camber.

[Kevin H]

The 408 was originally set up with:
Toe-in 1/8 inch
Camber angle 0 degrees
Castor angle 1 degree nominal

Ten years ago I wrote the following in another discussion thread - I'm pretty sure the information came from Brian Marelli who was head of the service dept.

The 411 was originally set up with zero camber and generally speaking it is not adjustable. At least not without disassembly of the front suspension and drilling new holes for the fulcrum brackets, which are bolted to the front crossmember and govern the camber. Castor is 1 degree and "toe in" one eight of an inch.

I believe there was very little difference between the 408 - 411 suspension.

[AndrewA]

The camber is adjustable by using shims plates behind the top joints.
They were developed as some of the new top joints are thinner and need shims to make them the same size as the old ones. You can go a little way using the standard bolts - if you're packing them out a long way then you'll need longer bolts. It's really a job for an alignment shop IMHO as it's trial and error - shim it , measure it, go again etc
Hope this helps.

[jeff02740]

Thank you for your response, but I think you are talking about the shims (washers) that are used with the 1/2 inch bolts on the inner top wishbones that pivot on the subframe and plates that are bolted to the subframe. To my knowledge, those shims do indeed adjust the caster, be it ever so slightly. Other than elongating the 1/2 inch holes on the subframe and moving the inner mounting plates, which are attached by 4 bolts to the subframe, I see no way of adjusting camber. Seeing that this is set from the factory, I do not understand how it could go out of adjustment.

[AndrewA]

You're right - have just looked at diagram again - apologies.
As regards the cause I can only think of potholes or kerbs.

[Kevin H]

Originally Posted by jeff02740

....Other than elongating the 1/2 inch holes on the subframe and moving the inner mounting plates, which are attached by 4 bolts to the subframe, I see no way of adjusting camber. Seeing that this is set from the factory, I do not understand how it could go out of adjustment.

jeff02740, I believe the "inner mounting plates" you refer to are what Bristol call the "fulcrum brackets" which you can see numbered 2&3 in this diagram .

In the diagram it's hard to see why the fulcrum brackets are required, given the neat holes in the subframe which the 'upper wishbone bolts' pass through (see Resources - Front suspension wishbones ).

However, in some cars I believe those holes in the subframe are in fact elongated. I think they are on my 411 but I can't find the photos from when the front end was rebuilt 20 years ago.

If your subframes do not have elongated holes, it is hard to see how the camber could change. Maybe it's always been like that.

[jeff02740]

Thank you for your response, the fulcrum brackets are required to support the inner part of the 1/2 inch diameter bolt that goes through the wishbone and bushing. I have had it apart and the holes are not elongated. You may be correct when you state that it could have been that way from the start. I am new to Bristols and have no idea what their quality control was back in the day.

[Kevin H]

jeff02740, another thing that just came to mind is that the flexible part of wishbone bushes could be badly deteriorated. That would affect the camber.

[Kevin H]

Originally Posted by jeff02740

Thank you for your response, the fulcrum brackets are required to support the inner part of the 1/2 inch diameter bolt that goes through the wishbone and bushing.

Yes, of course!

These are hand built cars so every one is set up individually. When we were dismantling the front suspension on my 411, the service manager at Bristol suggested we take great care to label all the parts so that no parts were swapped from one side to the other on re-assembly.

[jeff02740]

When I disassembled, I did one side at a time as not to get parts mixed up, old bushings were pressed out, wishbones sandblasted and inspected, painted and new bushings pressed in. All went together fine with no play anywhere. I did not remove the ball joints from the king pins as they were tight with no noticeable play.

[Kevin H]

jeff02740, I didn't mean to suggest that you had made a mistake - I didn't realise that you had completely disassembled the front suspension - but at some time in the car's history it might have been dismantled before.

It's interesting that you could press the bushes out, they usually have to be cut out. Do you know the history of the car?

Edit/PS: i'm thinking that if the bushes pressed out easily then it is likely they had already been replaced at some stage.

[DODD]

jeff02740

It’s very interesting that the camber angle on each side of the car is slightly different.

When I removed the bushes from the wishbones of my 410, they all had to be cut and drilled out using a core drill at a slow speed before being pushed out with force. The new bushes were pressed in using the appropriate lubricant, with what I also considered to be a lot of force.

Whilst the front suspension of the 408 to 411 is very similar, it’s not exactly the same. There are some subtle modifications as the models progressed.

It’s my opinion that slightly elongating the 4No. holes in the chassis or the fulcrum bracket which accept fixing bolts for the fulcrum brackets to the chassis, will not seriously effect the camber angle as the outer part of the upper wishbone fixings in the chassis are set and not adjustable (and must not be elongated). Elongating the holes in the brackets should only be considered if the wishbone fulcrum bracket holes don’t line up with those in the chassis; If the wishbone bracket fixing holes and the holes in the chassis aren’t in line, the upper wishbone bushes will be slightly in twist. I hope I have described that properly and it makes sense.

I also wish to note the holes as shown in the diagram in Kevin’s posting are elongated in a direction along the length of the bracket; holes in that position will only slightly effect the caster angle. The hole would need to be elongated at 90 degs to that shown, to affect the camber.

Presumably, the part numbers will be stamped in the castings on your wishbones, have you checked they are for your model?

Again in Kevin’s posting whereby he refers “resources front wishbone” the diagram therein is somewhat different from my 410. The lower wishbone where it connects with the lower suspension joint on the hub is a completely different design. It may also have had the bushing modified at the same time. If your lower wishbones have been replaced with those from a different model, this may effect the camber.

Other areas to check, if you haven’t already done so, are the wheel bearings and the stub axle. Have you checked the ride height on each side of the car, also the coil springs and dampers?

One last point and please don’t take any offence but the car is over 50 years old and may have suffered some corrosion or even been involved in a bump in its life, which will have been repaired but left the chassis with a slight twist, this may result in the differing camber angles.

As I noted earlier, this is only my opinion.

Regards

Brian

[Kevin H]

I found some photos from when my 411 S5 front suspension was restored in 2001. You can see in one of the images that the holes in the crossmember subframe which the upper wishbone bolts go through to are in fact elongated (I believe this is original).

In the other picture you can see that the fulcrum brackets are quite different to the 408 and run in the opposite direction. Therefore drilling new holes in the fulcrum bracket on the 411 S5 will affect the camber. Obviously this is not the case on the 408.

I note that on the Parts List there are three different pairs of fulcrum bracket parts numbers!

[Kevin H]

jeff02740

When you did the work on your front suspension was the sloping distance piece on top of the spring still there and the rubber spring seat?

On later cars there is also a steel washer between the two (which is well worth adding). See photo here.

[DODD]

Kevin

Thanks for the photos attached to your posting. I have been trawling through some of my photos from when I refurbished the front suspension on my early 410, with power steering. The two holes in the crossmember subframe do appear to be elongated, though I don’t remember them being so.

I would have thought with the forces involved in moderate to heavy driving, the two 1/2” fixing bolts to the upper wishbone where they pass through the elongated holes, would move. Therefore, I have to stand corrected on that point but I still can’t understand the logic, hopefully someone will enlighten me.

The fulcrum brackets on my early 410 (power steering) are exactly the same as per your second photo, 411 S5; perhaps the elongation of the holes in question only relate to cars with power steering.

Brian

[Kevin H]

Brian,
I also thought the fulcrum brackets appeared to be flimsy considering their purpose when the holes in the crossmember are elongated. However, my knowledge of the forces at work in a suspension system is minimal.

I was also wondering whether coil spring length could affect the camber.



Kevin

[jeff02740]

Kevin and Brian
Thank you for your input, I do not know the complete history of the car, but I do know that the bushings that I replaced had been done at least once before. The car’s ride height is the same left to right and yes, the angled spring seats were both intact and in good condition. With respect to elongating the holes in the subframe, I guess that could be done, but new fulcrum brackets would have to be fabricated because the bushings would now be cocked and there is no room to relocate the brackets.
At this point I think I am going to run the car as it is, but if I do at some future date disassemble it again, I will address it by elongating the holes and making new fulcrum brackets.
Thanks,
Jeff

[DODD]

Kevin,

When I was rebuilding my suspension, the 4No. Bolts, 1/4” BSF securing the fulcrum brackets to the crossmember, in my opinion, appeared to be small for the job in hand. I upgraded these bolts to 5/16” BSF. They fitted in position very well with the flat side of the hex head neatly positioned close to the vertical section of the fulcrum bracket.

I can’t give you a definitive answer to the length of the coil springs affecting the camber angle but as the upper and lower wishbones are in a fixed position on the crossmember, albeit in a pivotal position and the outer extremities of the wishbones are secured to the hub, again in a fixed position; my initial thoughts are no BUT as the four fixing points are not triangulated, there has to be a degree of camber movement when the wishbones are raised or lowered. In fact I went to my 410 and roughly checked the camber angle with a spirit level on both front wheels and they were near enough when the car was sitting on the garage floor. I then raised the front of the car to confirm my suspicions and as expected the camber angle changed quite a bit. My thoughts are that if the coil springs are too long, short, over or under strength, that can have an affect the camber angle.

When refurbishing my front suspension, I decided to renew the springs without having the existing ones tested for compression, despite them being the correct length. Once fitted they made a noticeable difference to the cars stance and handling.

Another thought on the elongated holes in the crossmember: my car had and still does have the standard washers fitted as per item 3 in the parts list. I would have thought Bristol would have used friction washers in place of those specified, this would have reduced the risk of the camber angle being pushed out of line due to the “occasional” potholes on our roads here in the UK!

Brian