Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Roadster rear suspension fail

Well done Peter, as access to that is a bit of a sod

S1's didn't have an anti tramp and so long as you didn't prat about with a racing start from the lights I never had a problem - personally I think a Mog should be driven with what I call 'mechanical understanding & sympathy' as the engineering is somewhat old school

I found both ends of the ATB a real pain to access, especially as I didn't really know what I was looking for. I did a lot of searching online (although frustratingly you'd be amazed how much stuff there is for "Anti-Trump"). I found that the best illustration is in Dave Wellings' excellent book, showing both bars on a Roadster 3.7, early in the build before annoying other bits get in the way ! As suggested previously by Richard, you can really only get to the saddle block in situ with the ATB removed. And it would have been much easier at the front end if I had removed the driver's seat. I should also have spent an extra fiver and an extra hour to go to a charity shop, and buy a tee-shirt and pair of shorts that wouldn't have mattered if I'd got grease and oil on them. Drat ! Anyhow I'm looking forward to getting it back together, not having the springs wind-up, and also not hearing the knocking.

L of the W, I'm with Cooperman In that hard starts or launch as they seem to refer to it these days is the only time you would really get the springs winding up! If you drive it like a scolded cat, and why shouldn't you if that's your bent! this won't move the springs too much when in forward motion. However one ATB ie. one on one side of the car will unbalance the car quite a bit if you get any distortion in the Springs whatsoever as this will induce some level of rear steer effect coupled with a height difference between wheel and body either side of the car. I have always thought that the fitting of just one ATB was a ridiculous solution to spring damping by MMC. You may be correct in that the battery cage prohibited MMC fitting the other sides ATB as no doubt all the Cassis' out back had the mountings in place for the battery. You could have a word with Cain at Wolf Performance, he sells ATB's and I'm sure he will offer good advice but for me, well I think I'd take the ATB off if I could only have one and have a balanced car, I'd like to also see if just having the one would allow the potential spring wind up to find the weak spot and in fact cause the unsupported side to cause a greater level of wind up to that spring.

Now that's a different and helpful perspective. I've never done any "wheel-spin" starts with the Roadster, although after the clonking had started (due to the detached ATB waggling up and down and hitting the floorboards) I did pull away sharpish from a junction and had felt a strange wallowy sensation. That would've been tramping I guess. I did have a look, and I'd say there's room beside the battery to install another ATB on the nearside.

Interestingly, you say "However one ATB, i.e. one on one side of the car, will unbalance the car quite a bit if you get any distortion in the springs whatsoever, as this will induce some level of rear steer effect coupled with a height difference between wheel and body either side of the car. I have always thought that the fitting of just one ATB was a ridiculous solution to spring damping by MMC".

In the car's history file, in Nov 2012 at 9K miles / 4 years old, a respected specialist dealer commented (after a service): "it was discovered that the rear offside is 1/2 inch lower than the nearside". I have always attributed a slight difference to spring sag, but I wonder if that's what this was all about.....

Fitting one anti-tramp bar is patently ridiculous and only the MMC could come up with such a "design"

You don't have to indulge in violent acceleration to induce distortion in the rear springs and one ATB will cause an uneven amount from one side to the other. In general terms a leaf spring is compromised by it's need to both perform the springing function and also locate the rear axle. In higher power applications it's usual to use other means to locate the axle, the most basic being anti-tramp bars and more advanced using multi link arrangements etc.

Here are a couple of videos showing the Morgan suspension. The first fitted with one ATB, the second fitted with two.

Or better still two trailing arms each side plus diagonal panhard rod to control axle. Coil springs allow drive torque to be separated from suspension medium.

Many thanks for posting these videos, quite scary really. I may just invest in a simple Go-Pro type camera and rig it up on my car to see what's going on. When all else fails, I may further investigate the SSL 5-link solution, but so far have been unable to justify the cost.

My two cents. If I remember correctly, installing the second ATB in my S3 3.0 Roadster Sport didn't just have advantages in terms of the driving experience. I wrote earlier in this thread that the car gained so much control with two ATBs that I even removed the Panhard rod again. (Perhaps the workshop had not installed the retrofitted Panhard rod with the correct geometry, because every time there was a vertical bump in the road, the PR translated the force into a horizontal movement that was extremely uncomfortable for my back. I didn't have this problem with my P4SS, where the PR was factory-fitted).

Now back to the ATB. As has been said here, these ATBs are extremely heavy. And two of them have, in my humble opinion, changed the car in two negative ways. 1. The car became noticeably sluggish and lost some of its fantastic agility. 2. With two ATBs, everything was more controlled, but also less fun and somehow more sluggish. The willingness to turn into corners was less enjoyable in my subjective perception.
What I didn't realise at the time was the possibility of changing the leaf springs, as I have now done with my 4/4 with the 4-seater leaf springs. If I were in the position to optimise a roadster again, I would do without both ATBs (because one is nonsense and my Roadster Sports always drove in a slightly slanted line across the road when accelerating sportily). But I would install reinforced leaf springs. For a while, there were some that were designed asymmetrically to prevent winding, but I have no experience with them... whether they were OK or too flexible overall.

To be honest, one of the reasons I switched to a 4/4 was because it's such a wonderful driving experience with 145 hp and an unladen weight of 800 kg, because none of my optimisations added even 1 kg, and because I don't have to take any measures to harness the power of a roadster with additional linkages and corsets.
So, bottom line, I would leave out the ATBs, never accelerate from a standstill because it rapes the car, and maybe use different leaf springs, or maybe not, if yours aren't sagging after all these years, if they feel strong enough and if you drive sensibly.
Another tip... I would definitely try it out without ATBs, at least on a trial basis, to see how it drives before you spend any money on any parts. You might be positively impressed by the new driving experience when the car really drives straight ahead when accelerating.
By the way, the video above refers to the 270 bhp of the 3.7 Roadster and it's not as dramatic with 220 bhp and less torque.

Some good wisdom there Heinz, thanks. I particularly like "I would definitely try it out without ATBs, at least on a trial basis, to see how it drives before you spend any money on any parts. You might be positively impressed by the new driving experience". So I'm going to put the removed rear shelf, carpet, and trim pieces back in place, and go out for a drive "ATB-less".

Also, I may have overstated the weight aspect. I checked: 1.1kg for my detached one. That's the same as say a bottle of wine, a cricket bat, a pair of shoes, or 1.5 litres of petrol -- all commonly-found items in a Mog.....

Haha, yes, you are right!
One thought, perhaps was my feel that it drives more sluggish because it could be that the ATBs not only do what they are supposed to do, namely prevent the spring from winding up, but that they also somewhat impede the actual spring function and the spring is somewhat dampened in its up and down movement so that the spring no longer responds as finely. It's just a thought and other members know more about these causal relationships.