Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Workshop Note - Bump Stop assists

Odd answer! It does not seem to address the issue of a rear suspension bottoming out more frequently over time

For decades, Morgan trads come straight from the Factory with bump stops. For example, look under the hoop that anchors your dampers. See the thick piece of ruer. As well, if you have the right dampers, (I prefer RUTHERFORD AVOs). they are internally bump stopped.

You probably missed or lack some home basic on suspension. I DO try to make GoMoG stuff as simple as possible..but some times I miss that mark. My apologies.

David, b]All suspensions system must deal with a basic reality [/b] They can only operate within the maximum extension and compression space the car design gives them. This is.called "suspension travel". With trad Morgans, that space is VERY limited..tthough happily, the famous flexing frame adds a large of suspension assistance..unquantifiable and different for each example. So the suspension setup must be in perfect form to give you the ride Morgan became famous for. The car must be suspended between the sprung and unsprung weight precisely. Sagging prevents that.

As springs age, they sag. As they sag, they bias off the perfect suspended position at rest and they begin to bottom out more often when used. This happens on the driver's side first, as many of us drive alone without the benefit of SWATSW (she who adds to sprung weight). It is worse for LHD Morgans as the Factory left the battery (and other items) in RHD sites.The LHD's batteries is wrongly on the left of the car adding to the driver's weight, that side's leaf spring prejudice and handling.

So adjustable bumps merely make a Morgan's preciously small travel space, smaller. And this will get worse over timeas the springs continue sagging, the new bumps stops are ever adjusted and ever closes the precious suspension travel.

Beware of the GoMoG Law of Good Drivers. Good drivers unconsciously adjust to the incremental encroachment of car wear and/or faults. Eventually, they adjust to a car not worth driving. Sadly, by the time, many are into the I-paid-for-one-I-fit-the-thingie-so-it-MUST-be-great.:( The rest of you should search out replacement leaf springs as every other automobile does in the same circumstances.)

Lorne (aka GoMoG)
[u][/u]

Roger's item transformed my last 4/4 which was not suffering from spring sag. They are a brilliant addition. Clearly the gomog comments reflect the opinion of someone who hasn't tried them.
Nick

You are correct. My 2014 4/4 came with a rubber bump stop on the hoop designed to impact the diff casing. When first inspected, it had never contacted the diff - even though I had experienced loud crashing as the springs hit the frame and the tool tray was hit by the diff casing. I fitted a second one to double the thickness when I changed the springs (Mulfab 4 seater 4 leaf). The new springs made a huge difference to things. I suspect I was a victim of a poor batch of factory springs. Sadly, the crashing bottoming out was not completely eliminated. The design simply doesn’t fit in recent cars with the plastic tool tray.

I fitted Roger’s spring assisters / bump stops recently and adjusted them as advised. The crashing finally stopped - even with a full load of touring luggage.

Have now driven a few thousand miles with Rogers bumpstops on board. Delighted with their intended function and performance.

HI Chris. Interested in this stuff? I had the your experience with leaf springs...4 times with my UK Morgan and once with my first Plus 8. No problem EVER with my last remaining Plus 8. Because of the UK experience those 4 sets were changer in a period from 2005 to 2007 and I only used that mog for a couple of months in the Spring and Fall.I would go out on a trip, and Kevin Vernon, my partner in crime at that time, would be appalled how much the rear had dropped each time after his installation of another set of spanking new Factory springs (Kevin, Mike Duncan and John Worrall looked after the UK c=car while I was back in Canada)

I do not count two of my leafs spring replacements. The cars involved were old when I got them and the leafs and the rest of the cars had not been perfectly cared for. When Morgans are not used, left on the ground (not stands) for long periods, or the leafs are not dealt with properly, they rust and when the car is finally used, they crack. (ugh) I finally cured the problem with the help of Morgan mates by buying outside the Morgan network. Is it still a hidden secret that that Morgan ran into a long batch of lousy leaf springs from a different suppliers? Is this a taboo subject? Luckily I have the old 5 leaf springs on my current mog, and they have not dropped in 19 years!

So no wonder Roger thought the problem was inherent! But he tried and I admire that a LOT. I do so wish there were more like him! Being right is not as important as trying. Am I strange in that I instantly toss anything that doesn't work and improve the car or make it simpler? In a nutshell, vehicle leaf springs are not supposed to sag that quickly and if they do, like every other well cared for car, they are replaced when they do.. The increasing banging and crashing is merely a symptom. This "solution" makes a crash into a "thud" which, though less disconcerting, will happen more often as the adjustable bump stump HAS TO to invade the available precious suspension travel to work. And each adjustment, invades that space more. Theoretically, there will come a day when the car, at rest, will sit on the bump stop.

The major problem here, is not merely the long line a bum or inconsistent leaf springs(sometime from late 2002) but where to find reliable replacements NOW for the huge fleet out there that need them! I see some suppliers offering super stiff springs that will kill an older back in no time and are grounds for divorce .Avoid them. Any suggestions welcome. I get asked for people looking for new leaf springs every day. I could use some help finding some for trad Morgans. I have some feelers out there..and Downunder, as the distances make trucking more prevalent and trucks still use leaf springs..If anyone wants to help, I believe I have pinned down the spring rates with some guru types.

Lorne

This is exactly my experience too. My springs (4-leaf supplied by Peter Mulberry) are absolutely fine, they haven't sagged at all since they were fitted. The bump stops do exactly what they are intended to do (which is not to compensate for knackered springs) and I'm delighted with them.

Thank you Lorne for sharing your perspective

I hope you don’t mind but I feel I should fact check the gomog comments below.




If TM is the British forum referred to I’m not aware of any recommendation to use these devices as a fix for degraded sagging leaf springs, to the contrary, one of my previous comment on the subject below a couple of years ago. Its also stressed in the assembly instructions not to be fitted with sagging springs. Unfortunately some cars suffer from bottoming even with new springs and don’t necessarily exhibit any sign of sagging.






I apologize if perhaps you have been misled by the term “bump stop” that is often used. These are not conventional bump stops. As DaveW says they are more akin to spring assists, hence the name of the thread. The conical elastomer stops function as supplementary adjustable progressive springs that under some circumstances might improve comfort and safety. If you were to drive a car with these fitted you might notice the subtle feel of the elastomer at the end of the suspension travel. The leaf springs appear to be more tolerant to body impact or the shock of the diff hitting the pad under the hoop when these are fitted.


Posted before but here is the force/deflection profile for each stop which may or may not be of interest.

If one's dampers are bottoming out, then they are of the wrong stroke length. The bump stops in AVOs are there to protect the dampers in extremis not to form part of the normal suspension operation. It is important that the stroke length of the damper rod is greater than the suspension travel for the suspension to work properly.

This was explained to me by suspension expert Peter Ballard and confirmed by Kevin Vernon. The damper needs to be able to go shorter than the minimum suspension travel and extend longer than the maximum. AVOs are great dampers, and the Morgan versions come in 3 stroke lengths as standard. Kevin and I measured them and realised that the way my car was set up, none were appropriate.

Fortunately Tim Ayres was able to get a set of custom AVOs made for me at no additional cost and I'm very glad I did.

Why did my car not suit the stock stroke lengths? Not sure, but it's more than a bit non-standard. Terry Foxen chassis, Rutter rear hoop, Mulberry anti-tramps, Panhard rod and 4-leaf springs. For a factory standard car I bet one of the stock dampers would be fine.

Given your experience with having to be explained several times how springs in parallel work, this comes across as an unbelievably patronising thing to say, especially when you consider the experience and technical knowledge of the people you are replying to.

I appreciate your comments refer to leaf springs Tim but with coil suspension it is the damper's that limit travel, on full stretch at least and maybe full compression to avoid coil bind and/or physical contact with some part of vehicle. Given such the damper stroke does play a very important part of suspension travel.