| Author | Message | ||
     Richard Gray New User Username: mooney1el Post Number: 26 Registered: 08-2016 |
Does anyone happen to know the free length and compressed length of the front coil springs on an R-type. My car, B351SP, needs new springs as the lower coil on the right side is broken. I will do the job safely using Kelly Opfer's factory duplicated tool. Any help will be greatly appreciated.  | ||
| David Gore Moderator Username: david_gore Post Number: 4128 Registered: 04-2003 |
Richard, Christopher Carnley has asked me to post the picture below of his spring compressor: "This is my own version of the tackle as the original was worn to a dangerous extent. From memory, the free spring length is about 18".   | ||
| Richard Gray New User Username: mooney1el Post Number: 27 Registered: 08-2016 |
Thanks David and Christopher. That tool looks like the one that Kelly makes. It might seem expensive but extra safety is required when doing this job. I had a friend who was injured doing a similar job on a Triumph. The spring exited the vehicle with great force and travelled between his legs. He was lucky with just minor injury.  https://www.britishtoolworks.com/product-page/rr-b-epw-front-spring-compressor | ||
| ChristopherCarnley Unregistered guest Posted From: 109.159.182.218 |
Richard, Read Service Bulletin No BB39, found in the Post War Technical Library on this site. You will also require a compression bolt to enable you to remove the damaged spring. For this see the MK VI Workshop Manual, Section "C" Workshop Tools, page 3. You will also need a compression/decompression pot as shown on p4, to compress the replacement spring which along with the blind bolt, is required to refix the spring. Ensure the hole in the top of the suspension cross member is sound or else the hook on the compressor will not engage. (Message approved by david_gore) | ||
| Richard Gray New User Username: mooney1el Post Number: 28 Registered: 08-2016 |
Thanks Christopher. I have read the manual. Kelly's tool comes complete with the compression bolt. I have the appropriate materials in house to create the required compression/decompression pot. I have the production drawing for the spring and using the information on that drawing I have calculated the nominal designed free length. I have also asked Flying Spares for that dimension and their supplier reports that the free length of their supplied after market springs is 12". Since there is facility to use shims, a free length of 12" will suffice for most but is not the designed free length as I calculated.. To try to understand further the data on the drawing, I have also measured the installed length on 5 springs of similar vintage Rolls-Royce or Bentley cars and all suggest that the 6.43" "normal length" shown on the factory drawing is in fact the designed installed length. | ||
| ChristopherCarnley Unregistered guest Posted From: 217.39.245.93 |
Richard, I made a compression " pot" from 2 lengths of 4" wide steel channel section, with holes drilled for the compression bolt and 2 lengths of 14mm HT (8.8)threaded rod. Compressing the spring with an electric spanner is hard work. Then I modified my secondary hydraulic press, but the spring made that groan! C. (Message approved by david_gore) | ||
| Richard Gray New User Username: mooney1el Post Number: 29 Registered: 08-2016 |
I agree, Christopher. If we consider that the spring rate for these springs is 260 lbs/in and we need to compress from 12.75" down to about 4.2" the resulting normal force would be over 2200 lbs. Our pots must be properly designed to safely handle the load and not allow the spring to suddenly exit the fixture. } | ||
| Richard Gray New User Username: mooney1el Post Number: 30 Registered: 08-2016 |
Uh Oh - I made a mistake in a post above. I have verified that the Flying Spares supplier provided springs is indeed the 12.75" as calculated from the data shown on the production drawing. So there should be no issue using those springs should anyone order from them. |
