Hi

I have a suspicion that i'm running coil over springs that are too stiff.

Its a book 1600GT Xflow locost built fairly light (500-525kg) but with the 275kg (front)/175kg (rear) springs it gives a bone jarring ride, even with the Gaz dampers set at their lowest setting.

Does anyone have any softer springs 9 or 10 inch long that I could borrow/buy to see if this improves the ride quality?

Many thanks

Gary (Reading, Berks)

what tyre sizes, and pressures are you using?

185/60 R13 tyres, i've tried running them as low as 20psi.

I'd go lower still with tyre pressure.

I ran between 16-18 psi on my MK Indy. Any more pressure and the car skipped about a fair bit.

2.0 Pinto engine, Type 9 gearbox, around 650kg IIRC.

I think this shows that i'm only using roughly 1/2 to 2/3 of the available travel.


Rear damper compression

I've checked and the springs don't go coil bound.

My car uses 300lb front springs and 150lb rear , it rides fine with no jarring at all since it was set up at Pro comp . They raised the rear spring seats which improved things no end .

HI Gary,

like yours mine is a std book locost using a xflow, (540kgs fully wet and with me in it) the front springs sound quite high, I was struggling like you so I swapped mine from the back and the 300lb never moved, so I sought advice on here and was told 160lb at the front was good enough. Ive had to wind those up a little bit so maybe go for 170lb instead if your going for brand new ones, or just something around there if you can find second hand ones that you can then pre load if needed.

On my car, I can press down the front (just) and the same with the rear. I am also running tyre pressures of 18lb front and back, it does crash down pot holes and rough roads, but so do the best of sevens while we're on Sunday run outs.

Jason

[Edited on 23/7/22 by Deckman001]

Gaz shocks are awful things on kit cars, they are too hard.

Been there done that, get some Protechs and you'll notice a massive difference.

You could ask on the Robin Hood site, Rhocar, the early ones used 170 1.9s which were too hard. Gave mine away I’m afraid, got some 120s but they’ll be too soft for your setup.

Gosh, everyone is different! My Haynes ended up with 300lb front and 225lb rear with 16 - 18 lb tyre pressures - 195/50 x 15. Perfect, a friend with a Civic type R said it was much more comfortable than their car! On the Haynes the shocks are angled quite a bit, perhaps on others they are more vertical giving a harder response?

Do all of the suspension arms rotate freely around the crush tubes? No point in trying anything else if they don’t! A lot of cars use crush tube the are too short causing the suspension arms to bind which doesn’t help the ride. Do a search on here for crush tube issues. Easy enough to test by disconnecting the out ball joints one at a time then checking each arm rotates under its own weight with the inner bolts tight, if they don’t just slacken the inner bolts a couple of turns and retry . If using one piece metallastic type bushes it won’t apply
I think the best thing and money spent I did with my car was to get the suspension set up properly by Procomp who know what they are talking about. Before the suspension bottomed out which probably what is causing the bone jarring ride? Raising the rear (150lb springs) stopped all the jarring , the 150lb springs were borderline , stronger may have been better but I’m now happy with the ride and handling

quote:

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Originally posted by CosKev3
Gaz shocks are awful things on kit cars, they are too hard.

Been there done that, get some Protechs and you'll notice a massive difference.

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Gary,

I have a set of original Robin Hood 2B 'Green' springs on rusty Zimmerride coilovers you would be welcome to try if they might be any use? Sorry I don't know the specs but if you are interested I'll have another go at disassembly to at least confirm open lengths.

I'm near Newbury.

Chris

I think the 2B green ones are around the 300lb mark, the earlier monocoque ones were red.

Wow, didn't expect that!


Corroded crush tube

I decided to strip the rear suspension and found all the stainless steel crush tubes in pretty much the same state as the one in the photo above.

Whats most surprising is that the car has covered less than 2000 miles and only been out in the wet once.

Cleaned and reassembled with silicone grease but really need something more tacky to apply around where the bushes meet the brackets to try and stop water ingress in the future....any suggestions?

Probably mild steel?

You can buy stainless ones off Ebay

Pretty sure they're stainless.

Must be a poo grade if the cars only seen rain once!

Did you check that the suspension arms moved freely before assembling the suspension?

Thanks for all the advice guys.

Yes, the arms moved freely even after the bolts were tightened. I’ve road tested the car now and the ride is back to as good as when the car was first built, so I’m happy that the rear spring rate is probably ok so will leave as is.

The stainless steel crush tubes/bushes/trailing arms were bought as a kit from a reputable 7 dealer so I’m a bit disappointed they corroded as easily and to the extent they did. Hopefully the replacements will last longer as I can’t see any way of effectively waterproofing these areas of the rear suspension.

Try a magnet on the crush tubes next time you get chance.

MK used to supply mild steel crush tubes,hence loads of people that didn't realise poly bushes need regreasing snapping wishbones as the crush tubes expanded so much with rust the bushes went solid.