Leaky Dampers = No Chance of an MoT

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Spacenut
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Leaky Dampers = No Chance of an MoT

Post by Spacenut »

Guess what? After 20 years of standing around, and 5 years of hard use, my rear dampers were leaking. Both of them. So, an easy replacement job, right? Wrong.

My coilover dampers were supplied by SPAX, who in the intervening 25 years have gone bust, and been resurrected again, but unfortunately with a much reduced product inventory. And there's more good news – pin-mount dampers such as mine are no longer available.

Anyway, this is what the old units looked like in situ...

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...And the detail of how the pin-mount interfaces with the chassis...

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Whatever I replaced the SPAX units with would need to use a standard 1/2” bolt fitting at both ends, so I bought a couple of chassis brackets from Demon Tweeks and then took advice from my friend Graham, who has been through this whole business with his Kudos hillclimb racer. Graham advised using AVO dampers, double adjustable (i.e. bump as well as rebound), with spherical joints at each end instead of rubber bushes.

I did a LOT of measuring before ordering the replacements. This was because the position of the top eyelet would shorten the effective length of the coil/damper unit by about 20mm, and I didn't want to run out of ride height adjustment. Eventually I settled on the 17” open/9” closed option, for 1.9” ID springs. Then I waited...

3 weeks passed, and a heavy parcel arrived, also containing a pack of 4 high angle spherical joint spacers for the lower wishbone mountings (originally designed to take bushed fixings). The dampers look fantastic, black painted with red anodised aluminium spring collars, the bottom one complete with a locking screw (nice touch that). The bump and rebound adjusters have blue and red anodised knurled knobs to make adjustment even easier. I arbitrarily selected rebound to face outboard, as I think I will probably need to access this one more often than bump.

Following a well-established ritual, the old damper was removed from the nearside. This is what it looks like off the car...

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I replaced the old rubber top mounts with Poly bushes a few years back, but other than that you can see they are pretty tatty. My rear dampers have 4 clicks of rebound adjustment dialled-in and in spite of the oil leak were still working OK (in fact I had to reset the rebound to zero before I could extend the damper by hand).

I swapped over the main spring and helper spring onto the new damper and doesn't it look smart?

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An abrasive wheel attachment on the angle grinder cleaned up the flat surface of the chassis around the original pin mount hole, and I used an old coach bolt to locate the new bracket ready for welding.

Of course, welding upside down is never much fun, and I had the added complication of freshly painted calipers and gearbox that needed protection from welding sputter (you've seen my welding, right?). So I covered all of the vulnerable areas with rags and dampened them with water just in case. It's amazing how fast an oily rag goes up when a particularly fat blob of molten metal drops on it, ask me how I know. Still, my welding gauntlets came in handy for beating out the flames, and the car was absolutely fine!

After tacking the sides of the bracket into place I removed the coach bolt, zipped up the sides and outside edge and plug-welded through the pin mount hole for good measure. Most of the force through the bracket will be in compression anyway, with only a small proportion in shear.

With a bit of etch primer and some chassis black the end result looks quite presentable...

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With the nearside done I repeated the exercise for the offside damper, and before long the car was back on its wheels again, this time with brand-new, leak-free dampers! Using the longer of my two 325 lb springs (11.5” open length) the spring collar is at its maximum adjustment, so I cannot reduce the ride height, but I do have a spare pair of 10.5” springs of the same rating, for when I get those really fat, tall profile rear tyres for my Compos...

I will almost certainly replace the front dampers as well at some point, but right now they are not leaking so should be OK for an MoT. So fingers crossed, that is all the chassis work done.

Lauren
Last edited by Spacenut on Mon Oct 23, 2017 8:52 pm, edited 2 times in total.

Veesix75
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Re: Leaky Dampers = No Chance of an MoT

Post by Veesix75 »

Great work, the shocks look good.....

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PETROLHEAD
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Re: Leaky Dampers = No Chance of an MoT

Post by PETROLHEAD »

Well its a shame you had to do it, but i think you'll be glad you did anyway.

I fitted the AVO units to my 33 qv, previously on konis, and i love them, i think the build quality and extra adjustment is excellent.

I have learnt over the years however that no matter who makes them, a regular application of grease to the exposed body thread is a must. More recently I use the spray lithium grease for speed and simplicity and its been working well


Good job lauren, and another step closer :D
SHREW

I AM the Law!


Alfasud 1.7-16v, Charade Turbo SR, & The Dirty Diesels - GT Cloverleaf, 159 Ti Sportwagon, Saab 9-3 Sportwagon

Kegsti66
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Re: Leaky Dampers = No Chance of an MoT

Post by Kegsti66 »

I am really looking forward to seeing the "green machine" Lauren.
Great upgrade, and as said, in the scheme of things, you will be glad you have done it. The car will feel all new to you. :D
I am still new to the history of your car and your suspension design is great. Can i ask , is the hub carrier your own design or a modified carrier?
Fantastic.

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Spacenut
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Re: Leaky Dampers = No Chance of an MoT

Post by Spacenut »

Kegsti66 wrote:I am really looking forward to seeing the "green machine" Lauren.
Great upgrade, and as said, in the scheme of things, you will be glad you have done it. The car will feel all new to you. :D
I am still new to the history of your car and your suspension design is great. Can i ask , is the hub carrier your own design or a modified carrier?
Fantastic.
Thanks Keith. It's a long story, but the short version is that the hub carriers and the wishbones came off a Noble 23 sports racer, back in 1991. Lee Noble had designed, constructed and won a race series with his Lotus 23 replica, which used the Alfasud transaxle, front brakes, hubs and driveshafts in a mid-engine configuration. The 23 was out of production by then, but Lee sold me the parts as spares and let me have his geometry drawings as long as I promised not to mass-produce them. As you can see, the hub carriers come with ears so that you can set them up for outboard brakes as well.

I've had to reverse the wishbones in my application, I have a chassis bridge which conveniently combines the gearbox top mount, suspension mountings and roll hoop bracing into one integrated assembly, which also helps to strengthen the area around the engine (boxer of course instead of the Ford twin-cam in the Lotus replica).

The Noble 23 was later manufactured as the Auriga, and the wishbones and hub carriers were still available until quite recently from a company called Mamba Motorsports. The Alfasud front wheel bearings are a straight press-fit into the casting. I had a special tool spark eroded to tighten the multi-faced hub nut up to the prescribed factory torque figure (FT).

Yes, I hear good things about AVO, and unlike my old SPAX units, these shocks can be rebuilt, which should help to protect my investment!

Lauren

Kegsti66
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Re: Leaky Dampers = No Chance of an MoT

Post by Kegsti66 »

Thanks for the education Lauren, what a pedigree your car has.
I re-read your thread after my last post following your interior re-design. You must have spent thousands of hours on your car over the years.
Cheers. :D

junior
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Re: Leaky Dampers = No Chance of an MoT

Post by junior »

Neat job, looks good Lauren, and interesting to hear a bit more of its history. Hope its just as good when it goes down the road. :)

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Spacenut
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Re: Leaky Dampers = No Chance of an MoT

Post by Spacenut »

Kegsti66 wrote:You must have spent thousands of hours on your car over the years.
It feels like thousands but I think it is just hundreds :lol:

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Spacenut
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Re: Leaky Dampers = No Chance of an MoT

Post by Spacenut »

junior wrote:Neat job, looks good Lauren, and interesting to hear a bit more of its history. Hope its just as good when it goes down the road. :)
Thanks Junior, it should be OK I think. One of the best aspects of this build is that I am not working completely in the dark, as the car has been on the road in this form for over 5 years and 22,000 miles. The various tweaks will hopefully just build on that success.

The key breakthroughs to date have been the front and rear suspension rebuild in 2010 and the engine and gearbox re-alignment in 2011. These two modification programmes have pretty much transformed the way the car drives. Who knew that dialling in 2 degrees negative camber on the front would make such a difference on a car with 54% of its mass over the rear wheels?

Lauren

Alfasixnut
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Re: Leaky Dampers = No Chance of an MoT

Post by Alfasixnut »

More progress.....Have you a date in mind for the MoT Lauren?

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Spacenut
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Re: Leaky Dampers = No Chance of an MoT

Post by Spacenut »

Alfasixnut wrote:More progress.....Have you a date in mind for the MoT Lauren?
This year. And that's all I'm saying!!!

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Re: Leaky Dampers = No Chance of an MoT

Post by KevJTD »

Spacenut wrote:
Alfasixnut wrote:More progress.....Have you a date in mind for the MoT Lauren?
This year. And that's all I'm saying!!!

you'll beat both my Lancia projects by some distance I feel Lauren :D

at least you're giving everything a thorough sort through so once back on the road you should get many years trouble free motoring ;)
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Spacenut
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Re: Leaky Dampers = No Chance of an MoT

Post by Spacenut »

Thanks Kev - yes, that's the plan. Although I have recently had a brainwave that could see me swapping out the old engine for the Alfatune sooner than I planned!

Even more work :roll:

Lauren

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PETROLHEAD
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Re: Leaky Dampers = No Chance of an MoT

Post by PETROLHEAD »

Interesting?

Pray tell Lauren?
SHREW

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Alfasud 1.7-16v, Charade Turbo SR, & The Dirty Diesels - GT Cloverleaf, 159 Ti Sportwagon, Saab 9-3 Sportwagon

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Spacenut
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Re: Leaky Dampers = No Chance of an MoT

Post by Spacenut »

petrolhead wrote:Interesting?

Pray tell Lauren?
I didn't want to say anything until the company got back to me, but I have been enquiring about decompression gaskets for a friends heavily-skimmed AMC 390, and I got to thinking - could a similar type of spacer, this time placed between the camshaft carrier and the cylinder head restore the tension on the camshaft belts? The answer is yes. Ferriday Engineering are the people I asked, and they can make spacers in aluminium, engineering plastic or thick paper in any thickness up to 2mm (I need 1.5mm per side to compensate for the skimming of the block and cylinder heads on the Alfatune engine).

With the thicker gasket in place, the cambelt tension is restored, but the corresponding tappet clearance increases by 1.5mm. This can be compensated for in two ways - use the available adjustment in the tappet buckets (if there is enough) or use "top hat" tappet followers 1.5mm thick. For the latter option suitable shims are available for 101 series Alfas, or Ducati motorbikes, which also use 8mm valve stems.

All that Ferriday need is a pattern to work from, even a "brass rubbing" will do, apparently. I was thinking that this approach might be preferable to the larger diameter tensioner pulleys that we were discussing in Fruity Fruitbat's thread the other day...

Anyway, I'm going to make some more measurements and get a quote from Ferriday for a pair of spacers. Watch this space!

Lauren

Alfasixnut
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Re: Leaky Dampers = No Chance of an MoT

Post by Alfasixnut »

Hi Lauren
When I was racing my straight six Alfa, I had re-re profiled cams and could not get the small bucket shims on top of the valve stems in sufficient "thickness" - so I put so I put a discs of stainless steel into the cam bucket followers to take up the clearance. A possible solution for you?

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Spacenut
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Re: Leaky Dampers = No Chance of an MoT

Post by Spacenut »

Alfasixnut wrote:Hi Lauren
When I was racing my straight six Alfa, I had re-re profiled cams and could not get the small bucket shims on top of the valve stems in sufficient "thickness" - so I put so I put a discs of stainless steel into the cam bucket followers to take up the clearance. A possible solution for you?
Yes, quite possibly. Although the tappet followers that I was looking at (Alfaholics, EB Spares etc.) are available in thickness ranging from 1.5mm to 3mm, so should be able to make up the difference. I might even be able to tune it out with the standard Alfasud tappets - although the re-profiled cams mean I can't wind the adjusters out (because the cam lobe base circle is almost the same diameter as the camshaft), I can wind them in.

Very happy with what Ferriday have said so far though. This is what I have been looking for, a proper engineered solution, rather than a bodge!

Lauren

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