Talk Morgan Forums Morgan Sports Cars Morgan Plus Four, Supersport & Plus Six (CX & CXV Generation Vehicles) Plus Fours suspension

I would have thought the adaptor plates would use taper seats. Oversize holes don't matter then. I often get called out with my Land Rover at tyre shops when one or other guy tells me I've fitted wheel nuts the wrong way around. I say nothing and just grin until they realise nuts are double taper

Yes. That was my original worry. But it is not being used on the splines of course. Then same data sheets and the classic Jaguar Community convinced me I was wrong. Loctite makes nothing that comes to mind that is irreversible. And logically speaking, how many times does one remove a splined shaft?!!! Even with my mileage on my two splined hubbed Morgans, I have never done so!

And I believe you both did not examine the release temperature of this stuff. IT IS 250C. After all, we all use Loctite in some format or should. You gentlemen did not check out the release temperatures for the most common Loctites and compare them with this treatment? Two of the most common Loctites have a HIGHER release point. The people at Loctite are not nuts (PUN!!!)[/b]

LOCTITE RED = 260C
LOCTITE GREEN = 260C
[LOCTITE BLUE = 160C

Lastly, as I suggested, it is something the MMC can check out far easier than an owners' forum can. Many of us are aware that the current owners of the MMC desert rally race 1979/80 Plus 8s. Their very capable race preparer can check this option easily. (Drying is 15-20 minutes and full cure time is 24 hours.) Great PR for them. I wouldn't pass it up. though there is often a priority difference between owners and current Management.

L.

P.S. Added later. That being said, it is why I listed cures in an order of preference. The biggest concern from a point of view of cost, would be whether the splines have been prejudiced and if so, whether that is to an non-repairable extent.,

I was in MMC yesterday raking the car for a job. I asked about the rear "clunk". They use a heavy duty grease". ". I put graphile on when replacing the wheels. The tip they gave was put sone on the inner end of the wheel hub so it gets pushed inwards as the wheel slides on. I do that anyway, plus a small amount on the leading edge of the splines on the hub. I'll delve more on Friday when picking the car up. I'll ask which brand grease they use. I might be cheeky and take a small tub to get a "sample"!
There quite a few Supersports going through production. Looks like sales are decent.

Went to Lifes today and followed Morgans instuctions re greasing the splines with a graphite grease, in fact we applied a very high temp resistant grease which is used on wind turbines and designed for and very capable of dealing with a salty marine envionment. The wheel spinners were really tight (much tighter than Matt would normally tighten upto),. what we found was plenty of grease already packed on the splines, the adaptor plate nuts were tight,. There was no noticeable wear on the splines or the inside of the wheels. So he was a little head scrathing as to Morgan's suggested packing grease in that area recommendation, as on my car that wasn't an apparent and obvious issue.

Matt then checked the diff and he felt there was more tolerance/ some play there, enought to cause a slight clunk, which is most likely what I'm hearing. The only solution he thought that might help would be a much heavier diff oil, which I will talk to Morgan about.

Great drive there and back, the Morgan really handles well and can get a move on when necessary, far too easy to get a little carried away and still doing high 40 mpg...............one of the best Morgan drives I've had in years.

John, Roadsters have a friction modifier in their diff oil to partly stop clunks in the LSD. I know I changed mine every 25k as the oil seemed to get tired. It could also be oil level I guess. I don't think the CX has an LSD but have no idea of the oil needed.

Maybe it is also the UJs?

Could well be the UJ's, Matt was very busy, so we didn't have too much time to investigate beyond the greasing of the splines, I'll get it checked out in October when the car is back in Malvern for a service.But certainly on my car it wasn't an issue with the wheel splines or adaptor plate. (so far anyway)

Interestingly, he had replaced a set of early CX brake calipers all round, as they were thought to be inefficient and struggling, with a later design set, just a slight difference in the hydraulic hose connection was necessary. Just over £1500 for the parts and then labour on top, apparently much better feel all round. I must admit I do find the current brake feel a little dead on the pedal, they bite ok but no real feel as to what is happening eg close to locking up. They certainly felt better after the brake fuild change in December, but don't inspire real confidence, they stop you, but thats about it. May need to start to save my pennies up.

Done a little more research and AI came up with these potential areas for further investigation. I based the search on my car being a 2022 car, but equally applies to other years.


On the 2022 Morgan Plus 4 (CX-generation), isolating a drivetrain clonk with physical slop points to three highly probable areas: the main input flange/pinion nut, the differential mounting bushings, or—a classic Morgan quirk—the wheel hub splines themselves.
Because your car utilizes a BMW modern powertrain (B48 engine paired with a ZF 8-speed auto or 6-speed manual) housed insideMorgan's bonded aluminum chassis, you can narrow down the issue by checking these components in order
A worn propeller shaft universal joint (UJ) or excessive backlash in the BMW-sourced rear differential is causing the clonking and drivetrain slop in your 2022 Morgan Plus 4. Because the CX-generation platform uses a modern aluminum chassis and tightly packaged drivetrain, diagnosing and fixing this requires a specific approach.

Diagnostic Steps

Next Steps for Diagnostic Check

To narrow it down before turning a wrench: Jack up the rear end safely and secure it on stands. Grab one rear tire and rotate it back and forth.If the wheel moves a fraction of an inch but the brake rotor/hub does not move, it is a spline/wheel clamping issue.If the hub rotates but you hear a distinct click coming from the exact front face of the differential where the driveshaft enters, it is the BMW input pinion loose/backlash issue.Are you running wire wheels or alloy wheels on your Plus 4? If you can confirm whether the clonk happens exactly when letting the clutch out/putting the auto into gear, or if it happens over bumps, will tell you exactly which bolt or spline to target first.

Isolate the UJs:

Raise the car safely on a drive-on ramp or lift so the suspension is under normal load. Grab the propeller shaft and twist it firmly back and forth while watching the universal joints. Any visible movement or "slop" within the joint cups confirms a failed UJ.Check the Differential Backlash: Hold the input flange of the rear differential still and try to rotate the rear wheels. A tiny amount of play is normal, but excessive rotational free-play accompanied by a sharp metallic click means the internal gear backlash needs adjustment or rebuilding.Inspect the Center Support Bearing: Check the rubber housing around the driveshaft center support bearing (if equipped) for tears or degradation, which can also mimic a bad UJ clonk.



More detailed areas to investigate.

Morgan's bonded aluminum chassis, you can narrow down the issue by checking these components in order:

1. The BMW Differential Pinion Flange NutModern BMW-sourced differentials are highly susceptible to a specific "input clonk".The Issue: The large nut securing the input flange (where the propeller shaft mates to the front of the differential) can slightly back off or lose its factory preload. This introduces tiny amounts of back-and-forth rotational slop before the gears actually mesh, resulting in a sharp metallic "clonk" every time you accelerate or decelerate.

The Fix:
The propeller shaft must be unbolted from the diff flange. The central pinion nut must be checked, treated with high-strength thread locker (like Loctite 648), and torqued back to precise factory specification to restore internal preload.

2. Differential Mounting Bushings & BoltsThe CX-platform places immense torque load on the mounts holding the differential casing to the aluminum chassis frame.
The Issue:
If the front or rear differential mounting bolts back off even slightly, or if the rubber isolation bushings wear down, the entire differential casing will physically twist under load. This causing a heavy thud or "clonking" sound directly under the rear package shelf.

The Fix:

Safely raise the car and check all main differential mounting bolts. Use a pry bar to check for excessive vertical deflection in the rubber mounts.

3. Wire Wheel Splines (The False Differential Clonk)If your Plus 4 is fitted with traditional wire wheels, a notorious Morgan characteristic is for dry splines to perfectly mimic a failing differential or propeller shaft.
The Issue:
If the wheel splines or the conical contact taper at the back of the hub are dry or insufficiently tightened, the wheel will microscopically slip on the hub when you pull away or brake. The sound telegraphs straight down the half-shafts, making it sound identical to a broken differential.

The Fix
:
Remove the rear wheels completely. Scrupulously clean away old grit from the hub and wheel splines. Apply a generous layer of high-quality graphite or copper grease to the splines and the conical seating taper, reinstall, and tighten the spinners firmly using a proper dead-blow mallet. Many owners discover this entirely cures their drivetrain clonk.

It seems more sensible than MSCC. If you clean the splines watch out they can be very sharp so wear gloves.

Matt went over the splines carefully with his fingers, he could see no wear, or slant or edge to the splines indicating wear, The reason I took it to Mat is he deals with these things on a daily basis. He did note that with the taper on the spline, the wheels need to be pushed on quite tight or you would feel some movement.

I read your posts with interest, John.

I have experienced this issue from very early on in the ownership of my 2022 P4. Although the issues related to clonking in my case relate to the splined output shafts and wheel hubs (or so I was told), I am suspicious now, having read your detailed post, that there is much more going on.

Having undertaken research into the right grease (high temperature molybdenum infused grease) for the splined shaft/hub, which certainly seems to have quietened down the immediate clonking, there is no doubt that accelerating and decelerating at modest urban driving speeds, the drive and transmission are best described as 'jerky'. It is far from smooth and requires gentle throttle application to avoid excessive jerkiness and an in cabin audible clonk.

My big question related to all this though is why this isn't being picked up when the cars are serviced? I have mentioned it every time my car has gone in and been informed it was down to the splines of the wire wheels / shafts. I suspect now that this isn't the real root cause, a contributory factor yes, but the whole story, no.

Finally, and back to the original question raised in this post. I have experienced a seriously bad squeaking noise from the suspension struts. This has manifested since having Nitron's fitted, which hugely improve handling and ride quality. My suspicion was that the bearing surfaces between the bolts and suspension bushes were running dry. This has now been confirmed and is being widely reported by cars with Nitron retrofit. It seems that the bolts and bushes require re-greasing when the car is serviced. Just something to bear in mind if considering Nitron's. Inconvenient yes, but still worth it.