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Front spring sizes

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My 7 has SD1 front struts and custom springs. It looks like the springs are so big they rub on the inner wing panels under some conditions.

I may need to rework these for smaller springs and the obvious route is to go back to the stock size even though i would use uprated springs.

I may even consider a coil over set but those seem a lot smaller.

Anyone got the outside diameter of the standard springs and free and loaded length.

I can refit a standard top mount but need to asses how much i need to change on the lower spring platform.


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I modified SD1 front strut assemblies and rear axle to fit a 7 many years ago.

The front springs are cut down standard SD1 finished length circa 250mm.

This is shorter than the full extension of the strut so a restraint was fitted on the lower support pan to keep the spring correctly located.

The diameter of the standard spring looks to be around 150mm overall diameter.

I never got to use it on the road but the car sat ok with no obvious fouling issues.

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Thanks David.

Im not having much luck on this.

I found some info on the TR7 springs:- 13.88" (350mm) free length, 7.5" (190mm) installed, 5.5" (142mm) OD. For uprated springs around 160lb/inch the free length should reduce to 10" (250mm). Can't find an internal diameter for the lower end though.

The SD1 struts have an OD of 2.25" (need to check this) but thats means you can't use standard coil overs as they assume the spring internal diameter is 2.25". The standard TR7 strut should be the normal 2". The std TR7 top mount can cope with a spring with ID 3.75" with a new rubber. I assume the standard spring internal is 4.5". So does have to be changed for coil overs.

My SD1 springs seem to have an OD of 6.25" (160mm) which is part of the problem. The other thing is that the SD1 lower pan is offset from the strut axis so it moves nearer the body when the wheels turn. My SD1 springs are supposedly 200Lb and only 8" long (200mm) free length.

Interestingly im looking at using rear springs as the data i can find on the standard TR7 has 166lb/ft, 10.2" free, 8" mounted (but would be different on the front). Just need to find some diameter info. Otherwise this could be a cheap option.

Im thinking I may cut the SD1 lower pan down, fit uprated TR7 springs (or rears) with new top seats and shim the bottom of the spring to get the height.

Any info greatly apreciated.



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Your SD1 200 lb springs seem really short. I presume 200lb rate is not standard.

From memory I had to cut  quite a bit off the length of mine and they are currently 250mm!

At the time of me playing around with my mods I did come across details of instances where the SD1 lower spring pan was cut off and a new spring pan repositioned and welded on.  This may be the route for you to take?

I also have what I believe are a pair of rear SD1 springs. Similar gauge springs to the fronts but 140mm overall diameter at 340mm overall length.

Any use to you?

Good luck.


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I think the SD1 rear springs would be to long.

For info:- The inside of the tower is 190mm wide. My springs are 160 diameter so there should be 15mm clearance each side. On the front there is a reinforcing member that attaches to the inner wing. This is tapered but extends into the turret space by as much as 20mm - its dificult to compare to the spring. This is part of my problem. Incidently this doesn't apear in Rimmers online catalogue - or the rear one - and i couldn't see them in online pictures. Not sure if everyone has these.

I also see that my 1st free coil is not concentric with the spring axis - looks like under load it will extend 5mm further.

Also because the spring axis is not concentric to the strut the spring moves off centre when the wheel turns.

The SD1 mount has an OD of 115mm so you can't fit a TR7 spring pad. I would have to change the mount aswell.

I also noticed that the lower pan is hitting the corner of the turret. Must be on full lock. I have the front quite low at present - hence the short springs. The pan is wider than the spring.

So to keep the cost down im going to grind 5mm off the front reinforcement. Fit the springs the other way up so the top is concentric and try and align the spring so its doesn't hit the reinforcement. If i cant find a simple way to make a spacer and raise the front about 10 mm i may cut the sides off the lower spring pan to clear the turret. The spacer has to ensure the spring doesn't move sideways off the pan.


Other info that may be of use to others:-

The SD1 mount has a bearing inside. It sits above the circumference of the mount so the top spring pad has a raised centre to match. I can see on one of mine there has been contact between the pad and the circumference. Since the circumference is fixed it has worn the pad, this would also make the steering heavy. I will fit a washer as a shim to ensure clearance.

The SD1 top pad is angled to match the offset bottom. The SD1 strut is 51mm diameter - i measured it. So you can use the standard coil over conversion parts. You can also fit a TR7 spring and it would sit on the lower seat pan. The pan has a taper down to the strut so it would sit OK and probably about 10mm lower than the SD1 spring. Lengths would probably be wrong though.

SD1 spring pad allows for 15" wheels. I can't tell if its the same height as a TR7 pad though.










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