MadaboutKitcars

Good morning all, Hope everyone is doing well. I know this topic has come up before but hope you dont mind answering it again, I am starting to put my rear suspension together and would like to know what rear springs people are have used. I am using the e36 suspension and I know I have seen people talk about cutting the original springs and then some saying they used lowered ones. I have original ones and the adjusting nut does not fit in the top. Any help here would be much appriciated with what to use and best place to get them.

Thanks

Glen

Glen,

I sent my original e30 rear springs to Marlin to be modified:

They chopped the top couple of turns off, and collapsed one to create a new seat.




At the time, I think the charged me about £15 to do it.

Hi Glen,

I spoke with Mark at Marlin about the rear springs for the E36. He tells me he doesn't know yet what springs to use.
He is currently building an E36 based sportster for a customer and told me that once he has sorted out the corner weights and ride height he will let me know what springs he is using. His plan is to have the car finished in the spring (didn't say what year) so we should know then.

But I've already got my 'fall back 'position with a local motorsports company.......!!

Nigel

Thanks chaps, that would be great to know what Marlin are planning, appriciate it if you could let me know when you hear anything. I too have a fall back plan with a friend of mine who has a rally prep and specialist car business (Qprep.co.uk Plug Plug) Difficult to work out ride heights etc until its on its wheels. Thanks again

Spring

Hi all, hope you are well, I have spoken to Marlin about sending them my rear springs to cut to length and they told me they are not doing that anymore. So I have to go to plan B, do it yourself!!! can anyone tell me what length they are cut down to.

Thanks G

Glen,

I spoke with Mark at Marlin earlier in the week about the rear springs. He hasn't progressed to the stage where the Sportster he is building is off the build stands so doesn't yet know the spring rate and length for the current model. Tim may be able to help though. I think he's the only forum regular that has got that far with an E36.

Nigel.

I think Mark must be suffering amnesia or has maybe decided that shortening the original road springs is not such a good idea. The purple colour Marlin Sportster demonstrator (with no windscreen) that was around at Easter 2004 was an e36 based car.


Marlin Sportster by marlinpeter, on Flickr


I can’t really comment on an e36 build but on my e30 build, rather than asking Marlin to shorten the originals, I used some aftermarket springs sold for lowering. There are a few different makes around and quite a strong aftermarket for BMW fans that want to lower their cars.
Mine were made by Apex and turned out to be the right height and spring rate (according to Track developments). I picked up mine on eBay second hand and after a quick wash under the tap looked brand new so had not seen many road miles.

They are yellow and you can see one in this shot....

Bar fitted

There are a lot of new ones on eBay but second-hand ones do come up from time to time. (BTW eBay's daily automatic search feature is really handy for finding things like this)
Might be worth one of you trying this route as a quick and inexpensive step to get you on the road?

...peter

Mines an E36 and I shortened my own springs using excessive heat. It passed the SVA at the time but then failed an MOT the following year. I got some standard lowering springs for mine off ebay at the time but the ride height has gone up quite a bit. My problem was that the shorter springs were in danger of "falling out" when the car was jacked up so the MOT man said they could come loose over bumps.
Sorry but I haven't got a picture to hand...

Thanks Andy, just one question if you used lowering springs how did you make them fit at the top as the ones I have will not accomodate the adjusting nut that marlin supply.

Thanks

ummm.... I haven't got an adjusting nut... or if I have I've not put it together properly!

The top of my spring literally fits round the bottom of the roll bar tubing...

Andy

I was somewhat horrified at the original suggestion of collapsing springs, I tried lowering springs but they were to high.

I ended up using some E30 coil overs, can't see why a similar solution wouldn't work for E36 based suspension as the damper connections points a pretty similar:

I went a visit to get more parts from Marlin a few years ago and got round to talking about the rear springs. They had a set of cut down springs and suggest they should be match to cortina seat (see picture attached).

Has anybody an opinion on these springs for use on the rear

http://www.merlinmotorsport.co.uk/COILOVER-SPRINGS-FAULKNERS-2.25-I.D.-6-inch-Open-Length/c12_13_130_131/index.html?page=3

I was looking at them earlier and although they are designed for coil overs they not only will probably fit the current spring top/bottom mounts but also look very similar in size/style to the prototype ones Mark showed me on the as yet still on the ramp M3 sportster down at the factory.

I was wondering if anyone could give me a length and poundage rating to go on. I was assuming I could take my final estimate for the overall car weight (1200kg loaded) and divide by 4 (assuming 50/50 distribution). I may be missing the point somewhere.

I was thinking 2.25 ID 6" long 600lb at £22 each

They are pretty cheap so if they only do till IVA time they'll probably be worth a shot and if I can get the right ones they could have a life post IVA too.

No experience, but it looks like worth a try. It's probably what Mark is doing anyway. I think my car weighs about 750kg unloaded. Somewhere there is a thread on rear springs?

I think Robin (Martinclan) is our spring calculation expert.....

Your loaded weight estimates feel about right which makes me think a bit about the front springs that marlin supplied me with 300lbs stamped on them.

But then I've have absolutely no idea how to work out spring rates....................

Weight bias on mine is towards the rear but only by a few %

750Kg!! I'd assumed the 800Kg quoted by Marlin was a optimistic target. So if we assume 750 + two people at 100Kg and a full tank of fuel we're closer to 1000Kg meaning 250Kg(500lb) per corner.

I'm not convinced that the force quoted on these springs is the weight they will support but either the force they'll exert at full compression or the force per unit length of compression (ie. the rate).

If that's so then after one inch the 500lb spring will give 5" and push up at 500lb and after 2" be pushing up at 1000lb.

Nigel, if I'm right about this then your 300lb springs compressed by 2" in the coilover would be giving 600lb at rest which should be pretty firm.

Search for another thread called 'Rear Springs' started in March 2006.
Lots of food for thought.....

here we go

http://www.madabout-kitcars.com/forum/showthread.php?t=551

I'd forgotten to take into account the lever effect of the spring being inboard from the wheel too.

on the initial height side I guess there is also a little over an inch of adjustment in the top plates of the E36 car so we only have to get to within an inch of the right length

Yes that's the one!

The key quote is from Stuart who had his car set up at Track Developments.....(his car is an e30 based Sportster)

"I took the Sportster to Track developments near Castle Combe. I still have standard springs in the back and Marlin supplied on front coilovers. He recommended the following after doing corner weights and a lot of measurements of the vehicle.

quote:Hi Again Stuart

I have managed to get some more info. At last I have found the formula I needed. Before I was transposing from Metric units and getting conflicting results.

Your choice is :- for comfort go with 250 Front and 260 rear. This would still be stiffer than a family saloon.
For a more sporting set up try 280 Front and 300 rear.
end:"

So I think your suggestion of 600lbs would be too hard. My Apex springs are 291lbs.

Hi Morton
Without meaning to be rude I think you are using the wrong site for your queries. The majority of contributers to this site are building Marlin sports cars and if not actually building they are interested in the type and therefore most of the posts relate to the Marlin. In case you don't know, the Marlin is a kit car produced in Crediton, Devon, UK

Sorton, Patrick thinks this persons is a spammer if you see his other thread, I would agree with Patrick