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Post by Ken Nelson on Jan 23, 2021 17:06:28 GMT
After pondering over Martin's radius rod modification method, I decided to modify it one more time to come up with this method of simplifying installation of the radius rod to replace the bushings. I went to a machine shop and had them cut off the front 1/2" stud flush at the start of the 1" tube. They then drilled the tube back 7/8" and threaded the hole for a 1/2-20 UNF Grade 8 bolt. I then plan to insert the rear fitting of the radius rod into the subframe housing, and simply put a 4" long bolt through the metalastik bushing in front and thread it into the radius rod and tighten with lock-tite. I believe this will make it simple to remove and replace the rod without disassembling anything else first.
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Post by enigmas on Jan 23, 2021 22:10:07 GMT
That seems like a straight forward modification Ken.👍 I've not sectioned a radius rod yet but presumed the wall thickness woud be insufficient to create a viable internal thread. It would also be seemingly straight forward to machine a threaded bung and weld it to the tube either internally (press fit), or as an external, slip over fit.
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Post by Ken Nelson on Jan 24, 2021 5:01:20 GMT
Thanks Vince, The threaded 1/2" front bushing sleeve of the radius rod is actually an extension of a 3/4" long bung that Rover pressed into the end of the radius rod tube. The remains of the bung go about 3/4" into the radius rod after the 'bolt' end is cut off. So the bolt I put in is actually threaded into the remains of the bung in the rod. The bung was drilled through fully and threaded with a 1/2-20 UNF tap. In retrospect I could have done all this myself at home. The radius rod is substantial, but perhaps not enough to thread. You'd need an insert of some sort anyway-I just used it as Rover put it together after cutting off the threaded sleeve. I used a 3 1/4" long bolt to go in through the front of the lower link bushing and thread into the front of the bung in the radius rod. It did require a bit of fiddling and jacking the lower link up and down several times to get my bolt aligned straight and screwed into the radius rod. With lower link raised I could aim it straight, but the torsion bar put a lot of tension on it, so I lowered the link to screw the bolt in almost all the way. I'll finally tighten fully when suspension is fully loaded. So far I don't see any reason why this shouldn't hold up fine, but time will tell.
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Post by 3litrekiwi on Jan 24, 2021 9:50:57 GMT
Hi Ken From my investigation, the spigots on each end of the radius rods are brazed into the hollow tube. There looks to be plenty of material for your thread. The only thing I would question is the locking of the bolt into the rod. It will bottom out on the inner tube of the metalistic bush though so it should be ok. The tube in the bush is quite thin walled though so a periodic nip up might be a good idea until you are sure the joint is stable. Alternatively, some high strength loctite on the thread should stop any movement. BMW consider blue loctite sufficient for many fasteners including brake calipers where our Rovers seem to have positive lock tabs everywhere. The rest of our suspension has some form of positive locking, for the most part split pins with some lock nuts.
We are not allowed to do any uncertified mods to suspension over here. The certifying engineers are often not particularly qualified and follow a guide book. A friend of mine is building a Chatterham 7 which is largely to a set of well used plans. He has had to redo most of his suspension parts, slightly thicker material, larger threads and so on. The original design should work as well on NZ roads as it has in the UK but apparently the Low Volume Vehicle Technical Association here disagree. To get my mod certified would cost $650 and there is no guarantee that it would be approved. My calculations give me confidence that the modified arrangement has a good factor of safety.
So I designed my mod so that it is not visibly different to the original unless you really know what you are looking at and no mechanic here is likely to be familiar with a P5.
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Post by enigmas on Jan 24, 2021 10:03:55 GMT
Hi Martin....psst, (in hushed tones) I won't tell anyone either. It'll be our secret.
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Post by Phil Nottingham on Jan 24, 2021 10:42:11 GMT
Very useful mods - Rover should have done this from the outset!
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Post by Ken Nelson on Jan 25, 2021 0:29:24 GMT
Thanks Martin, Vince, and Phil, I'm not telling anyone either. But I will keep an eye on it as suggested.
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