EdWills

I only mentioned the possibility that the "9 inch" referred to the size of the rear brakes, as I never considered that someone would attempt to fit a very wide rear end to a Lotus or Caterham Seven. On so many occasions (including by my better half), there is always someone to prove me wrong! The Ford 9 inch rear axle is apparently up there in quality, build and desirability. It was used from 1957 to 1986 on Ford passenger cars and trucks. Jegs.com notes that it is 57.25 inches to 68 inches wide (doesn't mention if this is from flange to flange?), and only a few axles in the range could be shortened (these were mostly early 1970s axles as many later axle shafts had tapered ends). 1973 and later had 5 on 5 bolt circle (which the car pictured at the beginning of this post doesn't have). I found the attached photo in the Chris Rees book "Caterham Sevens" showing how wrong I can be. Graham Arnold, who was Sales Manager of Lotus, also published a book on the Lotus range of cars. In a similar vein, he published a photo of a Lotus Elan sporting very wide rear wheel arches and wide rear track, noting on the caption for the photo - "Please Don't".

I realize that the "Ford 9 inch" diff/axle assembly is a strong and robust unit used in Mustangs and the like, but coincidentally the final batches of rear axles that Caterham sourced from the Ford Mk. 2 RS2000 Escort series of rear wheel drive cars had 9 inch diameter rear brakes as opposed to the 8 inch (by 1-1/2" wide) on the original Escort axles that Lotus used on the few 2-1/2s and all of the Series 3 cars (the Series 4 also had 9 inch rear drum brakes). The 4-1/4 pitch for the wheel studs stayed the same as previous, but the Caterham cars now had 9 inch front discs and 9 inch rear drums.

Hi Scott. According to Tony Weale in his book "Lotus Seven". the first Marina/Ital axle. (81 spec.) was fitted to chassis 4002 TC R M in 1980. The first Mk 1 RS1600 axle was fitted in 1977 to 3601 TC R S, and the first Mk. 2 RS 1600 axle also in 1977. Weale adds the info in the indices section on page 236. Author Chris Rees also confirms 1980 for the Marina/Ital but has different dates for the Escort series (1975 and 1978). First long cockpit Weale advises 1981, Rees advises 1982. The V.I.N/serial numbers on the cars correspond with both authors, but the dates are off. Cheers, W.

Hi Both. Yes, that was what I was attempting to add (the correct web address that is!) - thank you. I guess the only part that appealed to me was the author's information on shocks and springs, and some of his calculations. Agreed it is more for track than road, and he did go heavier on his springs as suggested by Caterham and Redline for racing purposes. I should have specified his information only on the road spring poundages, as it agreed with others who had measured them. Cheers, W.

Hi Pethier - thank you. Yes I found it a tad difficult to find what I was looking for on the site once I found it again. The main point of the article I found was that the writer advised that the spring rates on original Lotus Seven Series 2 and 3s, was 105 lbs. for the front springs and 75 lbs. for the rears. As MV8 notes, this is about as small and light as you can get. Bearing in mind however that the Seven - as originally designed and built - was much lighter (1000 lbs plus or minus?) than the current Caterham cars of course. When Lotus built the one-off Seven S show car, the weight was increased quite dramatically, and the twin-cam cars were just as heavy. DSK advised that for a Lotus Seven twin-cam, spring rates should have been increased by 10% on the front from original, although they quoted that the front springs on a standard Seven were about 85 lbs. Mick Lincoln of the original Redline Components, advised that the rates were 105 lbs F, 75 lbs. rear. I have a chart sent to me by a gentleman who was originally on this forum, listing sizes and spring rates for the Seven Series 1 and 2 (plus the Lotus 11 Series 1 and 2). It seems that rates varied quite a bit during the years of manufacture of these cars and the way the cars were used. W.

Try 'Lotus Seven Eugene', then on the opening page click on 'modifications'. The car owner provides info on the work he did on the new car after a bad crash to the first one. I should have done my homework before just placing a web address on this forum. Duh! W

Apologies. Please see my reply to MV8 above. W

Hi MV8. My apologies. 'Iamscotticus' advised me that the web site I quoted leads to a forum not the page I originally saw and bookmarked on my computer.. When I google searched for 'Lotus Seven springs and dampers', a site popped up titled 'Eugene' and the web location was simply the address www.7-dna.com. I am not sure how best to locate the pages I found, but the web site owner provided some helpful information on his car. Great advice again MV8, thank you. W.

Getting back to the original question regarding springs for a Lotus Seven, there is a very good article on the web at: http://7-dna.com regarding the springs and dampers on the writer's car called 'Eugene'. He mentions the original spring rates that Lotus chose for the fronts and rears. David Kaplan of DSK advised in one of his publications on springs and dampers for a Seven that the springs manufactured for Lotus Seven Series 2 and 3s were not very reliable and would lose tension. Even Lotus in a letter to me admitted that the springs on my car were probably sagging badly (which they were) due to a less than optimal oil pan clearance. The Eugene owner has done some great research into this subject, and is worth a look at his site. W.

Hi Scott. According to a news release quite some time ago by Dave Bean (when he was still with us), he noted that the metal composition of the replacement crankshafts (SCAT) for the Crossflow - after Ford had discontinued casting them - was akin to steel. He detailed the metal composition, and I've searched for the bulletin, but so far cannot locate it. The Ivey crankshaft possibly comes from a different production facility, but should also be of a better quality than the original Ford unit and Ivey balances the units and sells direct or through Pegasus I believe. Some (most?) of the replacement Crossflow cranks are manufactured in China, but their metal processing is equal to, or in some cases now, better than original. You can get forged steel cranks from the U.K., but naturally they are expensive. The problem with the cranks in Formula Fords for example, is that the flywheel is often exposed at the bottom of the bell housing, and off-road excursions could result in the flywheel hitting the curbing (a very momentary sudden stop?) with the engine still trying to turn, putting extreme stress on the crankshaft. They didn't last very long this way. Otherwise the original cranks and the latest ones are good for their application. Note: This last piece of information is according to various engine tuners detailing the cranks in books and articles that I have. Many early U.K. engine tuners suggested that steel main caps should be fitted to the blocks for racing purposes, but the new block that you have has the beefed up caps and stronger bolts, so these should be more than sufficient. One engine tuner advised that you could safely rev an engine with a steel crank fitted, quite a bit higher than the recommended maximum for the original Ford crank, but this should need to take into consideration the balance of both the crank, the flywheel, and the clutch cover. The older rounded mains caps of the 2737E were not as strong as the replacement square caps.

John. This from the Calgary Herald March 2/2025. Most appropriate

Also John, when they've filled in some of the potholes. I used to drive up to Edmonton using a rental car as I didn't want my personal vehicle being damaged by the roads to and from Calgary and Edmonton. Calgary is now suffering from poor maintenance on our major ring road, and vehicle repairs for many motorists are becoming the norm due to bad paving and snow plough damage. It's what you get living in a northern climate with freeze/thaw conditions, but the city sure takes its sweet time to fill in the holes in the spring when the weather improves. W.

If you can find a set, DSK manufactured a very good quality set of springs for autocross use with 125 pound fronts, and 90 pound rears. This would not be too extreme for road use on a Seven. W

Hi. Would a farm tractor dealership be of use? Many of the farm tractor manufacturers such as Massey Ferguson, John Deere etc., produced silencers in imperial sizes that look like your unit, and they may have the right size for the Seven. Your unit certainly looks original. I found a company in the U.K. that produces an oval silencer identical to the unit used on the original Series 3 (not the later round one used on the Twin Cam and Caterham models with the leg protector fitted). They sell the stainless steel cover, imperial size tubes for welding to the cover, wire wool, internal baffle and fibreglass to pack inside the silencer, all as separate items. A round silencer similar to yours is also available. See: http://www.jetex.co.uk. I have used this company, and found them very helpful. Hope this helps.

Hi John. Glad to hear that Dave Bean came through for you. If anyone else needs springs or dampers for a Seven, you can check at: https://www.anglocanadianlotus7.ca and click on "Lotus Seven Series 2 and 3 Dampers (Shocks) and Springs". There is a spring manufacturer mentioned who produces springs for Avo shocks. I haven't checked to see if the supplier is still in business, but an email may confirm if springs are still available. Lotus (Colin Chapman) deliberately kept poundages low for the Lotus Seven. The original Redline company advised that for track work, the spring rates could be drastically increased at the front, but with the state of some of our Alberta roads and highways, the ride - with heavy poundages - would probably shake out any of the fillings in your teeth. 75 or 80 lbs. rears seems to be a good option... W.