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Post by 3litrekiwi on Aug 4, 2020 7:35:22 GMT
My car passed it's WoF yesterday but the mechanic told me that the radius rod bushes will need replacing soon. I have done a search and read the many tales of the hours of quality time I may be able to enjoy doing this job.
looking at the setup it looks like if the radius rod were a two piece design with a high tensile stud to match the threaded ends and a tube with bushes pressed into the ends or even a solid bar drilled and machined to replace the original, it should be possible to remove the rod without any other dismantling.
Can anyone tell me why this wouldn't work, other than the posible compliance requirement for the mod. I am assuming the bush through the bottom wishbone can be pushed in from the front after the assembly is in place.
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Post by Phil Nottingham on Aug 4, 2020 8:39:57 GMT
Rover adopted the cheapest and lightest option - the lack of suitable easy servicing arrangements is a poor idea. I think your method would work well. I would think a solid bar may be better or perhaps a clamped sliding sleeve over a divided rod? A removable bracket on the subframe could also be done instead
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Post by Sam Bee on Aug 4, 2020 9:37:44 GMT
The removable bracket on the sub-frame is a better engineering solution and avoids any compliance issues with altering the design. Good idea Phil, bit of lateral thinking.
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Post by Ken Nelson on Aug 4, 2020 17:52:17 GMT
Having recently removed, re-bushed, and replaced the radius rod on my P5 I can heartily testify that ANY other option that doesn't require taking the entire front assembly to bits would be very welcome!
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Post by stirlingmg on Aug 4, 2020 18:52:04 GMT
Aye but you’ll probably only have to do it the once
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Post by 3litrekiwi on Aug 4, 2020 19:42:04 GMT
I had considered that replacing the bushes is probably a one off for the car if it isn't a daily driver. To me the trade off is what seems like many hours working on the suspension against a few hours working on the lathe. If the bushes do ever fail then the replacement would be quick and easy. One of the themes that I have read here is that modern rubber parts don't seem to last as well as the originals so this may be a more frequent job.
I will source a spare and make a pair as described. That way if I cut the original and find a problem I will be able to strip the rest down and follow the standard process. If the job goes to plan I will share the drawings. Our warrant of fitness is a six monthly check so there is no rush to get the job done.
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Post by stirlingmg on Aug 4, 2020 20:11:41 GMT
You have a point, modern repro rubber parts are just nothing like the oe stuff. I have however got some NOS ones for my car, so hopefully oil leaks permitting, they should outlast my ownership
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Post by djm16 on Aug 4, 2020 23:44:07 GMT
If I ever have to do the B$%^stds again, I will use PU bushes.
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Post by enigmas on Aug 4, 2020 23:51:14 GMT
The Factory system does last well if there is no oil constantly dripping on the bushes. The original power steering box being the culprit here. Fix that and the bushes last for decades. The PS of my MK3 coupe had no bush erosion issues. I replaced the DS rear radius bushes 3 times though every 2 to 3 years prior to having the power steering box professionally modified to permanently end the constant (factory) weep from the pitman shaft. This was in 2007. It has never leaked since it was repaired. Poly bushes on the top wishbones are a durable replacement if fitted correctly. They function like a bearing not a rubber bush so the method of fitting and operation is substantially different. My ZB MG Magnette runs a similar system. The primary difference between that and the P5 rear support (where the radius rod pivots) is that it is bolted to the frame and thus removable.
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Post by Ken Nelson on Aug 5, 2020 13:59:08 GMT
How lovely it would have been to see that removable mount staring back at me when I looked up at that spot on my Rover. I still find myself dreaming about it sometimes at night. It would have been nice to also have had a ready made polyurethane set of all the front bushes available to buy off the shelf.
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Post by Phil Nottingham on Aug 5, 2020 16:24:08 GMT
The new radius rod rear bushes (from whatever source) do not last in regular use. One on our coupe I did 10 years ago has just split. It is not contaminated by oil either. I have done this job a number of times now on various P5s but its a lot of hassle for a couple of rubber rings!
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Post by 3litrekiwi on Aug 24, 2020 10:11:05 GMT
Here's where I'm up to:
I'll get a metre of 4140 round bar for the stud tomorrow, I have a mate building a Lotus 7 replica who had some leftover 2.4mm wall 1" tube and I thought that if the tube section with the locking nut is placed in the gap , the stud should be able to be pushed through the metalastic bush. If I measure the length of the 1/2" section at the rear and make a gauge to set the length, the stud can be locked in position with a C spanner.
Once the rod is in place only we who know exactly what the original rods look like would notice the round lock nut.
Once again if anyone can see a flaw in my thinking I would be keen on some advice. I have sourced a spare which is in reasonable condition other than the front end being stamped "Back".
Cheers
Martin
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Post by johnwp5bcoupe on Aug 24, 2020 11:46:39 GMT
Here's where I'm up to: I'll get a metre of 4140 round bar for the stud tomorrow, I have a mate building a Lotus 7 replica who had some leftover 2.4mm wall 1" tube and I thought that if the tube section with the locking nut is placed in the gap , the stud should be able to be pushed through the metalastic bush. If I measure the length of the 1/2" sextion at the rear and make a gauge to set the length, the stud can be locked in position with a C spanner. Once the rod is in place only we who know exactly what the original rods look like would notice the round lock nut. Once again if anyone can see a flaw in my thinking I would be keen on some advice. I have sourced a spare which is in reasonable condition other than the front end being stamped "Back". Cheers Martin
Busy doing aa similar thing for Phil at the moment using the OEM tube would have to be 7/8 UNF.
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Post by 3litrekiwi on Aug 24, 2020 20:38:41 GMT
If you look at my sketch John, the 9/16 thread is into a bush that I plan on pressing into the tube and possibly plug welding into place. That way the stud should be removable through the metalastic bush at a later date if need be. This could also be done with the original however not having cut one up I don't know how far into the tube the spigot goes. I would have thought at least 1" so should still be feasible. There wouldn't be room for a lock nut unless a bit were machined off each end to allow for the length of the nut. Alternatively some stud lock on the thread would work but might be risky on assembly if it went off before final adjustments were made.
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Post by johnwp5bcoupe on Aug 24, 2020 20:52:51 GMT
If you look at my sketch John, the 9/16 thread is into a bush that I plan on pressing into the tube and possibly plug welding into place. That way the stud should be removable through the metalastic bush at a later date if need be. This could also be done with the original however not having cut one up I don't know how far into the tube the spigot goes. I would have thought at least 1" so should still be feasible. There wouldn't be room for a lock nut unless a bit were machined off each end to allow for the length of the nut. Alternatively some stud lock on the thread would work but might be risky on assembly if it went off before final adjustments were made. Got that Martin I'm tackling the problem a different way same solution yes the spigots go into the tube 1" and are brazed.
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Post by 3litrekiwi on Aug 25, 2020 6:09:50 GMT
Hi John
How are you tackling this?
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Post by johnwp5bcoupe on Aug 25, 2020 11:23:26 GMT
Hi John How are you tackling this?
Hi Martin until I am sure what I am doing will work I feel it's a bit pointless! I have a couple of ideas and when tested I will put them on here
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Post by Ken Nelson on Aug 25, 2020 19:37:43 GMT
Looking forward to further developments and picture of finished project!
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Post by 3litrekiwi on Sept 25, 2020 8:41:47 GMT
Plan A isn't going to work. I got a spare radius rod that had "back" stamped on the end without the little pip. I had a look under the left hand side of my car and assumed that as the pip on that rod was to the back that that indicated orientation. I thought that the person who marked up the spare had made a mistake, seems not. On receipt of my rubber bits I realised that the rod orientation is around the other way. On my car the current setup is that the rod on the drivers side has the pip to the front and the left to the back. And yet these have the same part number. So with the 9/16 diameter at the rear end of the rod my original design won't work however I drew up another design today and have made one prototype rod this afternoon. Tomorrow I will turn the studs. Attachment DeletedAttachment DeletedThe longer head is due to recycling the slightly shorter tubes that were going to have a lock nut. That won't be necessary now. I've put a 10 degree taper inside the head of the insert so that once the stud is in place it can be locked into place with the 7/16 thread inside the rear spigot. The studs will have a matching 10 degree taper where the stud transitions from 1/2 - 7/16. The rubber bits from Wadhams look like some sort of urethane. One concern I have is that the rear "doughnut" bushes are going to be a bit difficult to compress to get the rod outers in, time will tell..... Cheers Martin
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Post by Ken Nelson on Sept 25, 2020 22:43:22 GMT
So if I understand you correctly I assume you will have a 13.52" long 1" hollow tube with a central solid 1/2"rod that runs the full length of the distance with a 1/2 UNF thread at one end and a shouldered down 7/16" UNF thread at the other end ? Then you will put the distance tube in place and push the solid rod through from the front to the back and secure the nuts?
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Post by 3litrekiwi on Sept 26, 2020 2:52:27 GMT
Yes, that's the plan. The rods were finished today, I've used the step down as a taper to lock the stud into place which seems to work quite well. The extra bit of shoulder due to my initial design not working was actually useful as the 10 degree taper locks up quite tight. A double nut on the 1/2" thread and a 7/8 spanner on the flats cracks it loose ok.
It may be some time before I fit them as the old bushes are not too bad in my opinion. The Warrant of Fitness mechanic disagrees though so some time between now and February when the next WoF is due they will go in. (Either as a 1 hour job as planned or as a traditional strip down if I have not considered something.)
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Post by 3litrekiwi on Dec 22, 2020 8:20:48 GMT
Job done, pity it didn't need doing but the two piece radius rods do work and it was a three hour job for one side once I worked out what to do.
I really struggle with incompetent mechanics doing warrant of fitness checks (MoT). Recently I took my daily driver for a check and it failed with a quote for $2100 to replace the brake pads all round, rotors on the front and radius arm bushes. E39's have two options for standard pad profiles so I pulled the pads to check that I was buying the right ones only to find that there was 7mm left on the front and 8mm left on the rears. The rotors were all well within the wear limit. The radius arm bushes did need doing so $70 and a couple of hours of my time had the job done. After discussing the brakes the mechanic conceeded they were fine.
My recent check on the P5 required the drivers side radius rod bushes, same wheel bearing needed the play reduced and the idler arm bushes replaced for next time.
I repacked the wheel bearing and reset that, no problem.
I removed the ball joints from the idler arm and couldn't feel any play. With a dial indicator in the centre hole in the end of the shaft, 4 thou movement. Hard to see how this needs work.
The front radius rod bush had a bit of slight damage to the rear shoulder, otherwise fine and the rubber was in good condition. The rears were perfect. I thought about arguing that one too however having made the new rods I thought I might as well see if the idea would work.
So out with the sabre saw and remove the old rod. Getting the front bush out was a bit of work due to the bush being in such good condition.
Fitting the new rod proved to be a bit harder than I anticipated however by fitting a bolt and aluminium sleeve to the rear end to compress the new bush the new rod almost fit in the gap however it pushed the new front metalastic bush back out of the arm.
I removed two of the three bolts that hold the pivot bush housing at the end of the torsion bar and put my portapower between the radius rod rear mount and the lower ball joint housing, basically along side the radius rod. This allowed me to get the new rod onto position without pushing the bushing out of centre.
The long stud was a bit tight to slide in due to the slight misalignment of the front bush and the hollow rod. A bit of twisting and tapping got the stud into place and threaded into position. This allowed the front nut to be tightened and the front bush locked into place. In hindsight I probably could have tried to either raise or lower the jack under the suspension arm to improve the alignment.
Portapower off, rear bush fitted, torsion bar bush mount bolts replaced and job done.
If I need to do the other side at some point I think two hours will be enough time. Overall pretty happy with the job. If anyone is interested I will post the final drawings.
Cheers
Martin
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Post by enigmas on Dec 22, 2020 9:02:01 GMT
Congratulations on your 'radius rod modification' work Martin. Yes do post your drawings, I'm sure they'll be invaluable to the fettlers and fabricators on the forum...including yours truly. As an aside, if I ever decide to pull the complete subframe from the car (minus engine and trans) I'd definitely make the rear radius rod pivot support removable as per my ZB Magnette.
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Post by Ken Nelson on Dec 25, 2020 18:22:32 GMT
Congratulations also Martin, and yes, any drawings or pictures would be of interest. I found that I could not get the rear of the radius rod to fit into the mount far enough using the 2 new bushings from Wadhams. But my old bushings both actually looked fine, so I used one old bushing (those were thinner) and one new rubber bushing and then it would fit in OK. Hopefully they both will last without problems.
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Post by 3litrekiwi on Jan 1, 2021 21:26:36 GMT
Here are the drawings. The tube I used was 2.4mm wall thickness, the original is 3.2. I have dome some calculations on the buckling load for the lighter tube but suggest that the drawings be used as a guide and the heaviest wall tubing available used. The tube I used was seamless drawn and with the stud down the centre I am confident the overall assembly is stronger than the original.
The buckling load for the rod assuming the length between the bushes is 280mm and ignoring the support of the stud, is 39.3kN which is just a bit over 4000kg. Also assuming an 80/20 weight distribution under braking on a dry road, the force required to lock the front tyres would be somewhere in the region of 4.4kN or 450kg. So my feeling is that this rod has a safety factor of around 9.
Cheers
Martin
Looks like the only way to attach a .pdf is as a download.
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