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

408 Re-assembling the front subframe and suspension

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Old 19-10-23, 07:58 PM
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Default 408 Re-assembling the front subframe and suspension

This is to carry on the story from here that got as far as removing everything and the front subframe returning from the welder.: 408 front subframe / crossmember removal

With cooler weather finally here in central Florida, I have restarted work.

I am refreshing the major parts of the suspension that will be reused: the control arms/wishbones, springs and the steering box and idler. So far the lower control arms and springs have been scraped, sanded, treated with phosphoric acid, primed and sprayed black. The new spring pans have been primed and the first side painted black too. I ran out of paint after that. They spring pans will get their other side painted when I do the upper control arms.

The upper control arms need to have some holes enlarged and rethreaded for the bump stops so they will be painted after the machine shop does that. The big subframe and antiroll bar also need painting but will be done last minute when everything else is ready as the subframe needs to be removed again to paint it. I reinstalled it temporarily when I left the car for the summer to help ensure the frame rails were not spread part by the engine's weight.

David
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File Type: jpg Repainting bits (18) (Copy).jpg (155.0 KB, 28 views)
File Type: jpg Repainting bits (16) (Copy).jpg (172.0 KB, 22 views)
File Type: jpg Repainting bits (17) (Copy).jpg (83.5 KB, 22 views)
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Old 14-11-23, 06:58 PM
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This has been stalled for a while as the upper control arm bushings would just not go into the control arms. Graeme Payne eventually worked out what was going on for me. He discovered that he had two slightly different designs of the 407/408 upper control arms in stock. They both had the same part number cast into them but the hole for the bushings on one kind were 1" and the other kind was 1.05". The bushings are ~1.06". So the bushings would probably be perfect for the cars with the 1.05" design of control arms but my car's control arms are all the 1" ones and there's no way those 1.06" bushings were ever going in. I mangled 2 badly trying to squeeze them in there. IMHO that was pretty poor practice of Bristol to make any change like that and not change the part number.

I used the better of the two bushings left that were not totally mangled by my previous attempts to fit them. I fitted it on a section of 1/2" threaded rod and put the rod in the chuck of an electric drill. The drill was rigidly mounted horizontally in my trusty, 40+ year old Black and Decker Workmate. Then, turning the bushing with the drill, I sanded it down using a sanding block fitted with 150 grit wet and dry until I got the overall diameter down from 1 1/16" to 1 1/32". I had frozen the bushing but it actually seemed to sand better as it warmed up.

It still needed a good greasing and a lot of pressure from the table vice but it's in!

The 4 replacement bushings arrived in customs in New York today. So they will probably be here this week and will then get the same treatment but I may use 220 grit to sand a bit more cautiously.

David
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File Type: jpg lower control arm bushings 3.jpg (97.8 KB, 17 views)
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Old 17-11-23, 10:09 PM
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The replacement bushings arrived this morning. I sanded them down a bit and they are now installed.

The front subframe is now out of the car again ready to be painted black. Then I start putting everything back together.

David
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Old 18-11-23, 10:11 AM
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Good job. I took the front subframe out of a 411 once, but it was a parts car so I had the luxury of knowing it was never going back in!
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Old 03-12-23, 08:40 PM
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Default 408 Upper control arm fit problems

I am trying to instal the upper control arms (aka wishbones). I am working on the left side of the car first.

First I installed the Fulcrum Brackets but they are only loosely fastened and free to move left and right.

Then I installed the rear control arm with a temporary bolt but with all its washers correctly positioned. It is torqued to spec.. In this picture you can see the key washers that position and hold the bushings. They are the ones between the bushing and the outer edge of the subframe on the right and between it and the fulcrum bracket on the left. Squeezing the bushing and two washers into that gap was tight but doable.

I cannot find any way to install the front control arm and its washers. I'll attach a photo of the end of the control arm showing the washers.

The distance between the outer edges of the large washers is 2 7/12". The maximum width of the space those must fit into, between the front edge of the subframe and the fulcrum bracket, is 2 5/32". There's no way I can compress this to fit.

The rubber of the bushings sticks out noticeably further than the inner metal tubes. This seems a natural consequence of the bushing being squeezed in the middle. Would it be OK to cut that excess rubber off - flush with the metal tube inside? Or is it protruding necessary to engage tightly with the washers? Any ideas, please?

David
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File Type: jpg upper control arm new left 2.jpg (97.3 KB, 21 views)
File Type: jpg Upper control arms new left front.jpg (156.8 KB, 20 views)

Last edited by dwomby; 04-12-23 at 12:16 AM.
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Old 22-12-23, 12:19 PM
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Apologies for not responding sooner - I'd imagine you've made the decision by now!
I can't remember precisely from when we did the front suspension on mine but I do recall there was a lot of trimming required on some of the bushes.
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Old 14-02-24, 11:24 PM
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Job finally done. The repaired front subframe and rebuilt suspension and steering are in. I won't detail the trials and tribulations but it was a long hard slog. I haven't wired up the electric power steering unit yet but the car is on the road again after 15 months. Needs a tune up and a wash though!

Thanks to all who helped along the way, with apologies to names that I overlook, - Graeme Payne, Thomas Willig, Per Blomquist, Geoff Kingston, Mark Coleman and especially to John Tullett whose guidance and encouragement were essential.

Someday I will document the whole process but for now I just want to enjoy the car for a while.

David
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Old 19-02-24, 01:20 PM
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Excellent news - well done - the time seems to have passed remarkably quickly!
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