Bristol Cars - Owners and Enthusiasts Forum  

Go Back   Bristol Cars - Owners and Enthusiasts Forum > Bristol Forums > 8 & 10 cyl Bristol cars

8 & 10 cyl Bristol cars Type 407 onwards - restoration, repair, maintenance etc

408 front subframe / crossmember removal

Reply
 
Thread Tools Search this Thread Display Modes
  #1 (permalink)  
Old 20-01-23, 11:00 PM
Member
 
Join Date: Oct 2014
Location: Florida / Nova Scotia
Posts: 201
Default 408 front subframe / crossmember removal

I need to get my front subframe out for repair. Anybody done this on a V8 car? I am really looking for advice on any issues or tips on doing this. A lot towards the end of the list will have to be done from under the car.

I am thinking it goes something like this:
  • remove bumper and apron
  • remove undertray and decking bearing the builders plate at the front of the engine compartment
  • remove electric fans
  • drain coolant and remove radiator
  • disconnect and plug brake lines
  • remove shocks
  • remove springs (extremely carefully!!!)
  • probably will remove wishbones while I am there
  • disconnect steering (any advice on how to do this wanted especially, please)
  • Remove tubular frame supporting front bodywork
  • remove bolts attaching subframe to each side of wheelwell bodywork
  • remove bolts attaching subframe to the front ends of the frame rails and lower.

Have I missed anything? Any obvious pitfalls? I know proper shops often cut and reweld that front tubular framework but I really hope to avoid that.

Any advice will be appreciated.

Thanks

David
Reply With Quote
  #2 (permalink)  
Old 22-01-23, 01:39 PM
Member
 
Join Date: Mar 2021
Location: Norderstedt Germany
Posts: 68
Default

Hi David,

I think you got it pretty well sorted. I just did this job about 8 weeks ago.

My advice:

Take photos of everything, specially about the position of the washers on the wishbone mountings. Don’t mix them up, put them in labeled plastic bags.

To remove the steering is straightforward. First, while the subframe is still in place , remove the steering arm from the steering box. Everything else is really logical.

No need to cut and weld anything, at least on the 411.(sorry, but in my opinion someone who does this „cutting and welding“ is just to lazy to do a good job).

While doing this subframe removal I suggest that you inspect and if necessary replace all metalastic bushes etc. I send all parts to be bead blasted and repainted. You will never be able to access all the parts so easily again.

After finishing don‘t forget to have the track aligned.

I have attached some pictures of the job I have done.

Regards

Thomas
.
Reply With Quote
  #3 (permalink)  
Old 22-01-23, 02:31 PM
Member
 
Join Date: Oct 2014
Location: Florida / Nova Scotia
Posts: 201
Default

Quote:
Originally Posted by Thomas591 View Post
Hi David,

I think you got it pretty well sorted. I just did this job about 8 weeks ago.
>
>
>
Thomas, thank you for your informative reply. It's very reassuring to know I am on the right track.

David
Reply With Quote
  #4 (permalink)  
Old 22-01-23, 09:55 PM
Member
 
Join Date: Jul 2008
Location: woodhouse australia
Posts: 231
Default

Thomas a great job. I noticed the Spax Shock Absorber do you also have them on the rear of the car ? I would much appreciate the numbers of both and any experience you have had with them. Did you consider Koni and would you have a listing on those as well. My 411 has aftermarket gas units on the back which you pump up with compressed air to compensate for the disconnected self levelling system. You unfortunately need to pump them up regularly as they do not hold pressure very well.

Regards Peter Dowdle
Reply With Quote
  #5 (permalink)  
Old 22-01-23, 10:49 PM
Member
 
Join Date: Oct 2014
Location: Florida / Nova Scotia
Posts: 201
Default

Thomas, to help me plan, do you have any estimate of that crossmember's weight, please?

David
Reply With Quote
  #6 (permalink)  
Old 23-01-23, 06:54 AM
Member
 
Join Date: Mar 2021
Location: Norderstedt Germany
Posts: 68
Default

Hi David,

I would estimate that the bare crossmember, without any suspension or steering components, weights around 25-30 Kg. I was just about able to carry it all by myself, but preferred a helping hand to put it on the workbench.

Regards

Thomas
Reply With Quote
  #7 (permalink)  
Old 23-01-23, 06:56 AM
Member
 
Join Date: Mar 2021
Location: Norderstedt Germany
Posts: 68
Default

Hi Peter,

I have no experience on the Spax units, as the car is still lacking it’s drive train. The part numbers can be found in my parts list in the resource section.
Yes, I fitted new Spax shocks also to the rear.

Regards

Thomas

Quote:
Originally Posted by peter dowdle View Post
Thomas a great job. I noticed the Spax Shock Absorber do you also have them on the rear of the car ? I would much appreciate the numbers of both and any experience you have had with them. Did you consider Koni and would you have a listing on those as well. My 411 has aftermarket gas units on the back which you pump up with compressed air to compensate for the disconnected self levelling system. You unfortunately need to pump them up regularly as they do not hold pressure very well.

Regards Peter Dowdle
Reply With Quote
  #8 (permalink)  
Old 23-01-23, 11:02 AM
Member
 
Join Date: Oct 2014
Location: Florida / Nova Scotia
Posts: 201
Default

Thank you, Thomas.

David
Reply With Quote
  #9 (permalink)  
Old 24-01-23, 01:15 AM
Member
 
Join Date: May 2008
Location: Melbourne, Australia
Posts: 1,146
Default

David,
While you have got the suspension disassembled I suggest you examine the bolt holes in spring seat pans for stress cracks.

I would also recommend that you mark the fulcrum brackets and scribe their position on the crossmember before removal

Assuming the suspension hasn't been rebuilt in the recent past, the wedge/distance pieces which sit on top of the springs may need replacing along with the steel and rubber rings used to isolate the coil springs.

Bristol Cars Services recommended using new turret nuts when re-fitting the wishbones (they are a special half-height turret nut).

I wrote a few posts about my experience with the front suspension which you might find helpful V8 front suspension

Regards,

Kevin
Reply With Quote
  #10 (permalink)  
Old 24-01-23, 02:37 AM
Member
 
Join Date: Oct 2014
Location: Florida / Nova Scotia
Posts: 201
Default

Thanks, Kevin. All helpful except the flat area where the fulcrum brackets sit is rusted away. That's why the whole subframe has to come out for repair. Odd place to have rusted but that's the way it is.

I made a start stripping the parts today. Righthand shock and spring are out. I will check the pans as you suggest.

David
Reply With Quote
  #11 (permalink)  
Old 24-01-23, 02:44 PM
Member
 
Join Date: Oct 2014
Location: Florida / Nova Scotia
Posts: 201
Default

Here's a picture of the rusted area on my subframe.

David
Attached Images
File Type: jpg 408 front suspension 11-26-22 (6) (Copy).jpg (83.9 KB, 21 views)
Reply With Quote
  #12 (permalink)  
Old 24-01-23, 05:02 PM
Member
 
Join Date: Mar 2021
Location: Norderstedt Germany
Posts: 68
Default

I can confirm this! After sandblasting the spring pans, one had rust damage and both had stress cracks as described. I cut out all damage and reinforced the spring pans with new material on the stress points.

Regards

Thomas

Quote:
Originally Posted by Kevin H View Post
David,
While you have got the suspension disassembled I suggest you examine the bolt holes in spring seat pans for stress cracks.

I would also recommend that you mark the fulcrum brackets and scribe their position on the crossmember before removal

Assuming the suspension hasn't been rebuilt in the recent past, the wedge/distance pieces which sit on top of the springs may need replacing along with the steel and rubber rings used to isolate the coil springs.

Bristol Cars Services recommended using new turret nuts when re-fitting the wishbones (they are a special half-height turret nut).

I wrote a few posts about my experience with the front suspension which you might find helpful V8 front suspension

Regards,

Kevin
Reply With Quote
  #13 (permalink)  
Old 24-01-23, 07:24 PM
Member
 
Join Date: Oct 2014
Location: Florida / Nova Scotia
Posts: 201
Default

I took the second spring out today.

I looked at the spring pans. They need proper cleanup that may reveal cracks but I could see no sign of any today. Amazingly, the lower spring seats both seem to be reusable. The upper wedges and spring seats are just not there at all. I do have new ones to fit when I reassemble.

Try as I might, I could not get the spring pan to lower staying parallel to the wishbones (see pic) but it came down ok anyway.

I know the Spax part numbers for shocks but can anybody identify this Koni that was fitted?

David
Attached Images
File Type: jpg 4. Spring pans (Copy).jpg (124.9 KB, 15 views)
File Type: jpg 5 Left shock (Copy).jpg (111.7 KB, 13 views)
File Type: jpg 2 Left spring in process (Copy).jpg (79.8 KB, 14 views)

Last edited by dwomby; 24-01-23 at 07:32 PM.
Reply With Quote
  #14 (permalink)  
Old 24-01-23, 07:52 PM
Member
 
Join Date: Mar 2021
Location: Norderstedt Germany
Posts: 68
Default

Hi David,

My 411S5 was equipped with the same Koni shock absorbers. Maybe it is still the original, factory fitted, shock. I searched the internet today, but could not find any reference about Bristol and Koni shocks.

Looking at your spring pan, I can see some corrosion around the center hole. Get it sandblasted and then repair it. The spring pan is made from a two layer steel material and moisture can penetrate between the two steel layers.

Regards

Thomas



Quote:
Originally Posted by dwomby View Post
I took the second spring out today.

I looked at the spring pans. They need proper cleanup that may reveal cracks but I could see no sign of any today. Amazingly, the lower spring seats both seem to be reusable. The upper wedges and spring seats are just not there at all. I do have new ones to fit when I reassemble.

Try as I might, I could not get the spring pan to lower staying parallel to the wishbones (see pic) but it came down ok anyway.

I know the Spax part numbers for shocks but can anybody identify this Koni that was fitted?

David
Reply With Quote
  #15 (permalink)  
Old 25-01-23, 05:16 AM
Member
 
Join Date: May 2008
Location: Melbourne, Australia
Posts: 1,146
Default

Quote:
Originally Posted by dwomby View Post
Here's a picture of the rusted area on my subframe.

David
Wow, that's pretty serious corrosion!

Quote:
Try as I might, I could not get the spring pan to lower staying parallel to the wishbones (see pic) but it came down ok anyway.
Probably because the wedge distance pieces were missing, so there would be more pressure on one side of the spring.

Assuming the surviving lower spring seats are made of the same material as the upper wedge distance pieces, (they would have been orignally), then it is likely they have been replaced at some stage.

Do you know much about the history of the car?


Kevin
Reply With Quote
  #16 (permalink)  
Old 25-01-23, 05:16 PM
Member
 
Join Date: Oct 2014
Location: Florida / Nova Scotia
Posts: 201
Default

Quote:
Originally Posted by Kevin H View Post
Wow, that's pretty serious corrosion!
>
>
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

Last edited by dwomby; 25-01-23 at 05:38 PM.
Reply With Quote
  #17 (permalink)  
Old 27-01-23, 04:41 AM
Member
 
Join Date: May 2008
Location: Melbourne, Australia
Posts: 1,146
Default

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
Reply With Quote
  #18 (permalink)  
Old 27-01-23, 10:46 AM
Member
 
Join Date: Oct 2014
Location: Florida / Nova Scotia
Posts: 201
Default

Quote:
Originally Posted by Kevin H View Post
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
Reply With Quote
  #19 (permalink)  
Old 28-01-23, 10:01 AM
Member
 
Join Date: Mar 2021
Location: Norderstedt Germany
Posts: 68
Default

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
Reply With Quote
  #20 (permalink)  
Old 28-01-23, 12:55 PM
Member
 
Join Date: Oct 2014
Location: Florida / Nova Scotia
Posts: 201
Default

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
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


All times are GMT. The time now is 08:17 AM.


This is the live site

Search Engine Friendly URLs by vBSEO 3.6.0 PL2