Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Plus 8 Front Springs

I wouldn't let aerospace metrology any where near a Mog, you will only frighten your self stick with a boxwood rule and a mark one eyeball

Dave, I am advised that "The Factory used mild steel pins until 2004".

It ties in with your 05 stainless KP's statement.

Not as frightening as 180lb springs on the road though...........

Why is it not proper engineering Dave? From what I have seen "normal" suspension systems (involving coilovers) dont even have a rebound spring. Negative travel is only limited by the damper with a (usually hydraulic) bump-stop system. If you need 1/2" travel to get the pre-load off the rebound springs, you have 1/2" of falling rate suspension, in the area of travel you use the most. I think the set up on my (MkIII) roadster is preferable. Cheers J

It’s hard to envisage what’s really going on dynamically with sliding stubs. I appreciate the view of rising rate for the initial half inch, but this must be viewed in the context of the main spring rate. Without actual data I can only speculate, but the effect of the rebound spring as it reaches full extension from half an inch compression isn’t straight line – it will reduce rapidly to zero. Equally the main spring on compression will rise rapidly from zero. Given that the main spring will be significantly harder to compress, then I’m unconvinced that the outcome of a shorter rebound spring will have much of an effect. Leaving ‘slackness’ between the stub and the rebound spring means that the initial downward movement of the stub is without resistance followed by ‘sudden’ resistance when it engages with the spring. I think that when cornering, this is not ideal for the inside wheel. This is just my hypothesis!
It would be interesting to experiment with spacers on the bottom plate to put this to the test, but that would be very time consuming. I have no problem with front end bobbing on 4 clicks and 25psi.

Also just remembered that I read somewhere that the front ride height can be increased by fitting shorter rebound springs - it allows the main spring to expand further so pushing down the stub axle relative to the kingpin.

A few notes to close off this thread and the odd photo where appropriate. I’ll not go through everything as the procedure has been so ably documented by DaveW in his “How to…..” but I have one or two observations that may help others. In summary my 2001 car now has:-

• New 140lb mainsprings
• New rebound springs
• New hard chrome kingpins
• Upper torque reaction bars
• Mulfab steering bearings

with the work being spread over two fairly solid days. It wasn’t exactly planned to last that long but things come along to trip you up and contrive to confuse so 2 days it turned out to be.

DAY 1
To get started a pic of the Mulfab wheel nut spanner in action. This tool was new to me, picked up from Mulfab and what a delight it turned out to be. No more hammering with that short spanner, no more near misses with the wheel rim when the spanner breaks loose, no more bloodied fingers: money well spent.

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I generally followed Dave’s methodology and used the eMog “safe” method of spring withdrawal and it worked without incident. The photo shows the calliper and rotor already off with the 8mm threaded rod in place ready to start unwinding. It took maybe an hour to get to this point including raising the car, making coffee and messing with the garage iPod.

A 13mm ratchet spanner is essential for this bit unless you want to be there spanner twiddling all day. I had 12 and 14mm so guess why it took so long? By day two I’d acquired a 13mm, but it still took all day for reasons I’ll go into later. With the springs released the whole pillar assembly was loose and could be lifted out. There was no need to withdraw the KP from underneath as I had imagined. This may have been easier to lift out as my 180lb springs turned out to be a strange length.

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Those of a nervous disposition may want to skip this bit. The pic below shows the new spring in the “home adapted” spring compressor.

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Note the life preserving safety feature: but even with the sf I still didn’t feel entirely at ease with this contraption and am not proud of it, but when you’re stuck, you’re stuck – and I certainly was, as that new spring would not go back into the car without some degree of compression!

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I was fitting the Mulfab bearing and new springs came as part of the kit. They were etched on the top face “140-1” so 140lb and 1 inch shorter to allow for the thickness of the blue bearing housing. Strangely, my old 180lb springs were supplied to the previous owner of my car by Brands Hatch Morgan also as being 1” shorter so work that one out if you can.



Once under compression a couple of cable ties were applied and the compressed spring removed from the clamp, transferred to the car and assembled. This actually took several attempts as cable ties are pretty near useless for this, sliding their way around the spring until they don’t have any work to do. Only solution is to work as quickly as possible or find another way to do it.

I think there’s a significant manufacturing and marketing opportunity waiting for someone who can design and make a compressor that works. It would make the job so much easier (and safer!)

On the advice of another member I had decided to change the KP’s to Hard Chrome as a precaution. When extracted the old pin measured 0.997” dia at the “road end” to 1.000” higher up. The bushes measured 1.003” dia to 1.002” at the “mouth end”: so some minor wear although the bottom of the pins did show signs of a little pitting visible in the pix below. When I slid the new pin (1.000”) into the stub axle on the bench it felt as close to a size for size fit as you could get and still have it move, so I have no worries about not changing the bushes.

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This pic shows the thicker coil dia on the 180’s: no wonder the ride was harsh. I would urge anyone contemplating 180’s for the road not to do it.



Getting the top of the stub axle lined up with the dust cover took an inordinate amount of time, as did the KP into the rubber rebound stop, but now we have the driver’s side reassembled and more or less complete. The AVO’s are turned as shown as the adjuster obscures the grease nipple when facing inwards. Still adjustable with the wheels on though.

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Time to finish for the day and have one for the tonsils.

DAY 2

The anticipation of “I’ve done it once so this should be easy” soon evaporated. The passenger side fought me almost every inch of the way. Pix are scarce today as things got a bit fraught.

I didn’t start until 10:00am (there’s over confidence for a start) and had the first taste of things to come with the track rod end nut just turning the tapered joint rather than unscrewing so had to get a bit inventive to solve that. The brake calliper removal was straightforward so I thought things were picking up – then came the hub / brake disc removal and after removing the nut and washer it wouldn’t budge.

The right hand side had come off easily with no more than finger pressure so this was a shock. Light tapping with a rubber hammer turned into heavy whacking with a rubber hammer and still nothing. The hub pullers I have were nowhere near large enough for this so in the end I removed the stub axle with the hub / disc still attached (a heavy and awkward assembly).

Next to make me sweat was the top kingpin bolt which wouldn’t break free of the kingpin – all it did was rotate the pin and there was no way of locking it. I then reasoned that as I was installing new pins anyway the old pin was sacrificial. Luckily, because the old springs are shorter, there was enough room to get the jaws of a 12” Stilson wrench in at the top and biting into the pin, so with a tube extension on the breaker bar and pulling on the Stilson I got the pin to hold still.

So everything was locked off and I pulled and pulled and………….. nothing. The bolt would not move. I think we’ve all had these moments so it was a good time to go in for lunch and have a think about it – but thought I may as well leave the bolt surrounded by Plus-Gas as there was just a slight chance some might find it’s way in despite the almost impossibility of it getting to the thread.

Over lunch I thought that again as the pin was no longer required the only option was going to be taking an angle grinder to it – the question was where to cut as the pin itself was covered by the dust cover and the top half of the stub axle so this plan was fraught with danger (not to mention the fact that the spring was in the way and the risk of fire with all that underseal under there).

I really didn’t fancy the grinder option so parked it and pondered some more. With one last shot of desperation I squirted some more Plus Gas on the top bolt, gave it a few minutes and pulled and………………… the thing moved. Tried again and it moved a bit more, then another and another. With the bolt removed I could see from the thread that the Plus-Gas had done it’s job and melted the rust into a slurry. Interesting as to why there should have been this difference left to right? The RH top bolt had come off without a problem. Kerbside vs roadside perhaps?

The whole spring / pin / hub / brake rotor assembly was now lifted out and was a heavyish assembly. It was a case of degrease (stay well clear of the wheel bearing), clean up, re-paint etc and get ready for reinstallation. Even with the hub / rotor on the bench I couldn’t persuade the rotor to part from the stub axle, but as the bearings felt OK decided to leave it for another day and reinstall as is. I shall now try and source a suitably sized puller / extractor so I can remove it on the car at a later date and inspect the wheel bearings as I’d done on the other side.

Bush measurements were similar to the other side at 1.004”, with the pin coming in at 0.998” so some wear but not enough to be concerned over.
Reassembly time and alignment of the pin into the dust cover did seem marginally easier this time, as did the pin into rubber rebound stop so that the top bolt could go in. I think I may have adjusted my methodology slightly based on doing the other side first as this part was definitely a little easier.

I include the pic below to emphasise the importance of running with some form of rebound spring gaiter. What you can see is the brand new shiny hard chrome king pin sticking out of the bottom, soon to get it’s first serious wipe of moly grease from the sliding axle and become a magnet for all of the dust and grit thrown up by the road. This will then turn into a fairly aggressive grinding paste which will delight in attacking bush and pin alike. And it’s a pain to clean off once it starts. Making a gaiter isn’t difficult………………………

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CONCLUSION

I made a few mistakes along the way and had to go back and undo them which I shouldn’t make if I do this job again. There isn’t two days work here.

The low points were:-

1. Not having a ratchet spanner to help lower the rebound spring. This would have saved me more than an hour when winding those barrel nuts up and down!

2. A mainspring compressor would have saved time also, especially now I’ve thought it through as it would have made the alignment issues (dust cover and kingpin) so much easier and quicker. Getting the kingpin top bolt thread started would have been easier too!

3. Not being able to get the passenger side hub off. I spent about an hour and a half before giving up. I need to revisit this now and make an extractor to fit.

4. Passenger side king pin top bolt rusted in. Very, very time consuming. Plus-Gas to the rescue again.

Other than the above it was really quite straight forward. As others may have remarked the job is not difficult, just a bit laborious when you have to improvise because you don’t have the right tool.

Driving Impressions

SPRINGS

The ride is now so different as to feel like a different car – so I now have something more or less stock (which was the kick off point for the whole exercise). It is now something that could be made to work a little better as opposed to a rock hard lump of a car that wouldn’t respond to anything. In the short distance travelled yesterday afternoon (35 miles) I experienced the car absorbing the lumps and bumps of the road (still passing a few on, but in a softer manner and more controllable) and generally making for a pleasant ride rather than just being a bone shaker. A very slight oscillation from the front at times but gone is the nodding donkey characteristic. I shall see how much of the oscillation effect can be tuned out with the AVO dampers that now have a chance of doing some work. They’re on quite a soft setting (2 clicks) at present.


STEERING BEARINGS

If I accept that the ride quality changes were predictable (going back to near stock) then this has to be the absolute star of the piece. No more Herculean effort turning the wheel. Even at standstill there is a notable difference, and when the car gets underway the steering becomes very manageable in a light and easy way that I didn’t think possible on this car.
The car also feels more responsive on the road now that the steering is lighter although this may be a combination of the spring mods and bearings.

The negative effects of steering shimmy or vagueness just haven’t materialised. The steering is rock steady with no wandering or the wheel flicking side to side. I would recommend this to anyone as a mod on it’s own – it’s just unfortunate that you have to strip the sliding pillars to do it. But I now have no damper blades to grease!

TORQUE REACTION BARS

First impressions are I can tell no difference – but that’s not surprising. They cost less than £40 a pair and I considered that whilst I was doing this other stuff I may as well fit them anyway.

There must be a surprising amount of stress and attempted movement in that area: nuts I’d checked for tightness a year ago were no longer quite as tight as they should have been. At least the upper bar now spreads the load a bit and theoretically this area is a lot stiffer and stronger than before. Does it matter? Probably not, but theory says it should – so at least I have a phsycological comfort!

FURTHER WORK?

I now have 2 surplus rebound springs sitting on my bench that could be shortened and fitted to the car to explore the Peter Ballard “Shortened Rebound Spring” theory as supported by many.
Free spring length is 89mm, compressed on the car is 74mm. Will removing 15mm be worthwhile? I’m cautious as both Simon at Mulfab and Tim Ayres said they do it on 4/4’s but wouldn’t bother on a Plus 8.

Something to think about………… and time for new tires.

Congrats with the result, enjoy the new ride, and thanks for the great post.
cheers J

Well done Bob - a great job!!!