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

Hi Bob,
Sounds good, from what you found the KP's should be OK. Let us know how you get on with the springs. Just curious, is Mulfab supplying matching rebound springs and will you end up with the zero preload as per PJB's advice on Morganatica?
Cheers J

Agree with everything about the tyres. I'm also intrigued to see how much they are contributing to the front end characteristis I've been getting.

I cannot imagine they don't have a part to play and I guess pressures will be another round of experimentation after they've been replaced.

Hello J, I'm going to keep my fingers crossed regarding the KP / Bush scenario, but as I say remain open minded regarding stiction on my car until proven one way or the other.

I've also had a couple of excellent off group posts about KP / Bush history and the effects of what wears first and how, so I have a couple of other factors to take into account. There is a line of theory that suggests (providing the bushes are OK) changing to Hard Chrome KP's whilst in pieces is a worthwhile option on it's own. This is easy but it's success depends of course on the state of the bushes. It seems that the KP wears a lot faster than the bush which is at odds when compared to normal practice. But then these are Morgans so.............?

Mulfab were really helpful on the phone yesterday. They don't stock the shortened rebound springs and were not over excited about fitting them to a road car. Having read PJB's notes a couple of times now he does make a compelling case for their fitment - but they have to be just the right length or you could actually make things worse. Very sobering because I've had enough of "worse" with the 180lb springs.

I need to continue reading PJB's stuff and fully mentally assimilate the content. I keep saying to my wife I'm not overly stupid - just slow.

Fitting shortened rebounds would be an easy option on reassembly and too good an opportunity to miss, but they have to make things better. One things for sure though - you can't protect that rebound spring area enough from what the road throws at it.

Cheers, Bob

Hi Bob, given your proximity to Mogsport/Mulfab I would be tempted to entrust your car into their capable hands for some front end fettling.

Hi Bob,
Interesting that Mulfab are not keen on the shorter rebound springs. Did he say why? I cant see what the drawback would be. (altough that doensnt say there cant be any) Maybe a little more body roll? Should not be a problem, especially on a road car. All I can say is it came standard on my roadster and works fine, feels better than the Plus 4 I had before. Personally I would not change the KP's without changing the bushes. I would want them reamed to a perfect match and no chance of sand embedded in the old bushes ginding on the new KP's. Just MHO. All these variables and decisions, isnt it great to own a Morgan? I just cant imagine e.g. Audi drivers having this kinds of fun. J

Sorry to be harping on this rebound spring issue Just realised, maybe the reason against shorter rebound springs is the risk of bumping on extension (as the tire goes into a hole).
The solution is maybe not a shorter rebound spring but a shorter (softer) main spring that sags just enough in static condition to keep the preload off the rebound. Shortened upper springs to give 1" lowered ride height in combination with with standard rebound springs might give this. Standard length upper springs plus the bearings probably result in preload on the rebounds. Unless someone can give you the exact details it will be a case of trial and (hopefully no) error.
Cheers J

Yes, always a possibility of course and very tempting: the downside is I lose the chance to learn a bit more about the front suspension if I let someone else do it.

There's nothing I plan to do that isn't reversible and it does now seem to be well trodden path, but if my expectations are not met then yes, always a consideration.

I wouldn't want the rebounds to be too 'slack'- it's not proper engineering is it? The suspension movement is limited anyway, so I guess that the stub separates from the rebound spring on full bump, but not by much. Mulfab bearings use shorter mains and there is a comparison picture on my kingpin thread. The rebounds are compressed when fitted, I would say maybe a quarter/half inch. I know that because my leather gaiters which were cut to fit unfitted rebounds had to be trimmed to fit when fitted. My original rebounds were slightly shorter than the replacements which I put down to 'wear'. The obvious solution to de-loading the rebounds is to make up some spacers to fit between the lower tube bracket and the bottom plate. You can nip up the bottom plate until the rebound is just compressing then measure the required thickness. You may need slightly longer nuts & bolts, and you would have to put spacer washers between the kingpin and bottom plate. The limit of the spacer depth will be the safe useable length of the threaded part of the bottom of the kingpin. Alternatively with the right measurement you could space the top of the kingpin from the upper cross tube as there's quite a bit of thread on the top bolt.

JJW, I may be paraphrasing a bit here but from Mulfab it was essentialy do the shortened rebound spring on a race car (maybe) but not really worth the call on a road car. That's my recollection of that part of the conversation and I do apologise if I am misquoting. It would appear there are many respected authorities on this, each holding different views.

The purist in me agrees with not doing KP's without the bushes, the pragmatist says think it through before throwing the idea away. It all comes back to the state of the bushes in every way and as they seem (strangely) to be more hardy than the KP's there seems little point in creating scrap and work for the sake of it. But I haven't seen or inspected mine yet so I don't even have an opinion, let alone any data on which to act. It just seems an idea to be worthy of thought. I have access to an aerospace metrology unit where bores are measured to far greater accuracy than we require for our KP bushes. I think a little measurement might come in handy here when I have the stubs off the car.

I'm also advised no one has yet had to replace Hardened Chrome KP's because of wear - just the opposite to the mild steel factory efforts: unless of course anyone knows differently in which case the mileages would be interesting.

As you say - many variables. You're never stuck for something to think about when you own a Morgan.

Bob

The kingpins in 05 were stainless Bob. Not sure when they changed to stainless though. For a brief period before 05 they tried "Nylon" bushes. (Not really Nylon, but some new fangled synthetic which didn't work).

The problem I have with re-bushing is that the bushes fit perfectly round the new pins before being pressed into place. Pressing-in distorts them to the extent that they must be reamered, but the only way a tube can distort is to go out of round, so I reckon the act of pressing in introduces a bigger gap between bush & pin on opposing faces. Plus the fact that I'm not convinced that they line up properly in the stub.