Spring and damper conversion

cobraboy

cobraboy

Well-Known Member
Following on from the successful anti roll bar upgrade my thoughts turned to springs and dampers.
I have had some very helpful input from guys on here who have trodden this path and my thanks go to them.
The front will use a steel spring seat to which the top of the original spring cup has been welded, over this a 2.25"ID spring will sit and this will seat in a new mount bolted to the original spring cup that has had the bump stop removed.
I do not have the new bump stop size etc figured out yet.
Damping will be by a stock AVO adjustable in the normal location.

The rear is to be custom built AVO coilovers which will take the place of the stock damper with strengthened mounting points.

I have fitted a 9"x 500lb spring as a start.
DSCF4258 (1).JPG
The good thing is I can fit and remove these springs by hand with no compressors and they do not decouple from the spring seats on full droop.
The spring is mounted off centre on the bulkhead to ensure alignment with the bellcrank push rod.
 
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Nice one Mark.
I always thought that might be the case with this kind of setup, bonus of making it much easier and safer to work on.
Did you not want to bolt the seat mount direct to the bulkhead?
Jim
 
Sowen has done a front coil-over set-up that is heading for being copied once the delivery of my Round Tuit is completed.
I will be watchig this thread as well. Happy tinkering.
 
corazon said:
Nice one Mark.
I always thought that might be the case with this kind of setup, bonus of making it much easier and safer to work on.
Did you not want to bolt the seat mount direct to the bulkhead?
Jim
Click to expand...
Jim
I did a mock up with the ali spring seat bolted direct to the bulkhead, but the skin is very thin material with a 55mm void behind to another thin skin to the cars interior.
The only way I could see this working is to insert a spacer tube and through bolt, even then the loading may deform both panels.
This way I am picking up on the original area that the original spring sat on.
The downside is I have 30mm or so less available spring length, I dont see this as a problem as the movement on the bellcrank will not require that much compression of the spring.
The good news is with my chosen ride height the stock damper is exactly mid stroke so at least I can fit a stock adjustable damper and not have to get one custom built.
Mark
 
Hope your testing goes well Mark.
I will make a start on mine when I get my first pay cheque from my new job, no funds currently!
I was thinking about a steel plate to spread the load bolted through and filling the original spring cup diameter area of the bulkhead which the new spring seat would then bolt to..but if the same outcome is achieved it doesn't really matter how does it?
Your idea is nice in that the bulkhead can remain untouched, hope it all goes to plan.
How much lower are you aiming for? I want mine 2.5" lower at the front ideally..
Jim
 
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OK so first road test tonight and I am a happy bunny.
9"x 500lb springs, sill to ground at front ( with rear still up in the air ) = 7" started out at @ 8".
With the rear lowered I expect the sill to ground to be around 6 1/2 " the car looks to be a lot lower at the front.
Two things - having been a Lotus owner for 35 yrs I always keep in mind the Chapman mantra of soft springs, firm damping. On testing tonight the ride is still fairly level through a bend, but on stabbing the brakes hard the front seems to dip and return quickly, I think a bit more damper is req.
Having said that my damper bushes are very soft. I will wait until my new front adjustables turn up before assessing springs again, I don't think they are far out.
And this drive was undertaken without re setting camber or tracking and running loads of negative camber, it still felt good.

I have to break now for a bit as the house needs new bargeboards, but will try to re shim camber and set tracking in between.

I need a bit more to do really !
 
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Wee update.
Found some time to look at the car yesterday, wanted to set camber and tracking in order to go for a drive today.
The Rover has to be the easiest car with which to set camber I have ever worked on. I measured it after fitting the adjustable spring seats and it was 1 deg negative, and astonishingly for such an old car both sides were exactly the same.
The manual says 0 deg for camber.
I slackened off the nuts on the pivot studs and introduced two 3/8" plain washers behind the inner pivot mountings and this brought the camber right to 1/2 deg negative which is what I was aiming for.
I set the toe in to 1/16" and will see how it drives today.
 
Its been a case of 1 step forward 3 steps back, so nothing picture worthy sorry, but now I feel I have turned a corner - turned a corner geddit ?
The spring seats I bought are for a 2.25" spring and when I welded the cap on the end from the original spring cup I left a generous bead of weld for strength as the sleeve is very thin.
This weld meant there was not enough running clearance between the sleeve and the inside of the spring resulting in rubbing issues and clonks as the weld skipped over the coils - not good. The springs were bought primarily to go over the rear coilovers but I trialled them on the fronts, so they will now go on the rears as planned.
I ordered a pair of 9" x 500lb 2.5" ID springs and made up a set of centralising collars to centre the 2.5" spring on the 2.25" seats. These springs have a good clearance to the sleeve and can cope with the arc of the pushrod.
I road tested tonight, still clonks - aargh!
Now for the muppetry award, the clonks were coming from the sh@gged shock bushes - doh ! ( as well as the springs )
So replaced the shock bushes with a better set and at last silent running.
I have to tear this down to fit a better spring adaptor set which I will turn up soon so I can take pics then.
The car drives good, it needs firmer damping but the handling is much more neutral and way less understeery, which is probably due to the negative camber.
 
The car is now nearly how I want it with the new suspension. When I decided to lower and firm up the car what I did not want to do was to lose all the Roverness. I still wanted it to be refined and comfortable, no banging and clattering but with a more modern feel, if that makes sense. Although a barn find my attitude toward the car has been as if I were working on a much nicer example and not to be careful not to ruin it.

This is the 2 1/4" threaded tube with the cap welded on from the old spring cup, it is 135mm tall, any longer and it will interfere with the casting on the top link.
DSCF4254 (1).JPG
This is the adaptor to go from 2 1/4" to 2 1/2" ID springs for clearance inside the spring.
DSCF4251 (1).JPG
This is the fitted position concentric with the pushrod, which is achieved by having the other end of the spring mounted off centre on a mount that can be turned to align the spring.
DSCF4257 (1).JPG
Installed on full droop, still clearance inside the spring and spring still under tension. Spring 9" x 2 1/2" x 500lb.
DSCF4258 (1).JPG
Later I found the rear spring insulators made for an excellent fit behind the front spring mounts at the firewall :)
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Finished up fitted the front dampers.
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The disappointing thing with the front dampers is that they rattle !!!! All the replacements use a bush with a steel sleeve as apposed to the conical bushes that tighten when compressed. I may have to convert these later.
The rear thankfully was much simpler. Dampers fitted with 9" x 2 1/4" x 500lb springs. The springs have been found to be only just long enough and in fact can go coilbound on compression, so will be changed for 10 1/2".
DSCF4274.JPG
The holes in the body and trailing arm had to be opened a little to accommodate the top hat bushes on the dampers. Also the holes in the body were not quite concentric with the shock tower, so when enlarging I tried to centre them. The spring is a tight fit and there is very minor rubbing on the top two coils.
Fitted. The chassis bump stop now removed.
DSCF4276.JPG
I still need to replace the dome rubbers on the front pushrods as one has now given up, this is no big deal as the intall comes apart very easily.
Ride height now 6" sill to ground, and can go higher if needed. Camber re set to 1/2 deg negative.
The car drives very well, it has taken a lot of work to refine it so that there are no nasty side effects, the handling is quite neutral and it corners with very little roll.
If I was building a track weapon I would try 6oolb springs all round, but for now the 500's are nice for the road.
DSCF4279.JPG
 
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I forgot to mention, I am re modelling the wheel arches on this car and at the moment the rear wheel can only be removed by undoing the nuts on the bottom of the rear shock in order to let the trailing arm down low enough. For me this is not an issue as I always carry a few tools and the job is very doable if a puncture occurs.
The alternative is to carry a sealer / inflator as many moderns do.
 
Excellent stuff, you're making nice quick progress :)

What's the open/closed length of the rear coilovers? I take it they are mounted on the standard damper mounting points?

Does it scrape the underside when driving? I'm going to be welding a few sacrificial plates to the bottom of my exhaust since it's been taking a hammering over the last few years :D
 
Thanks Simon
The trouble with the rear dampers is sorting the stroke as you would know. I would have liked to have gone with a longer damper in order to get the wheel off but then the closed length would have been too long for the ride height. I think I am in a good position around mid stroke at a 6" sill to ground height.
The dampers are 14" open, 9 1/2" closed measured from the mounting face of the bushes, having said that they don't quite make 14" open, they are a little shy.

They go into the stock mounts in the body and trailing arm and I welded the bolt in plate to the trailing arm.
I have the stock exhaust at the moment and the middle can hangs a little low, nothing scrapes or rubs either on the road or in the arches.
Cheers

Mark
 
cobraboy said:
The disappointing thing with the front dampers is that they rattle !!!!
Click to expand...

I had a pair of those on Sparky, but they rattled so much, whatever I did, that I eventually took them off and put the old ones back on.

Richard
 
quattro said:
I had a pair of those on Sparky, but they rattled so much, whatever I did, that I eventually took them off and put the old ones back on.

Richard
Click to expand...
Well I have also tried a number of fixes now and after a few miles the rattle is back. Have now cut the eyes off and tomorrow will weld on stock eyes from a set of old shocks.
 
Well I did weld some old eyes cut from original type shocks onto the new AVO units and it has worked, the rattles have gone.
The only remaining job was to change the dome rubbers on the ends of the top link pushrods.
I chose poly for these as they get a beating and I see no reason to stick with rubber. They needed a sanding in order to get them to fit inside my threaded spring seat tubes, but slid on the ends of the pushrods quite easily.
The car is driving well, but desperately needs new tyres, I hope to push the button on wheels next week.
Dome rubber ready to fit.
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Update on rear
For the moment am trialing 10 1/2" x 550lb x 2.25" ID springs on the rear, as the 500lb were a tad soft.
 
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Update on rear
Fitted 10 1/2" x 600lb x 2.25" ID springs today, set dampers to max, much better, getting there now.

Update on rear
Fitted 9" x 850lb x 2.25" ID springs, set dampers to mid way.

Update
Front 8"x 2.5" x 850lb dampers re valved
Rear 9"x 2.25" x 1000lb dampers re valved
 
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