independent suspension units refurb

  1. pidgeon chit welder sticking metal since 1962

    Have any of you engineers , mechanics or heros sucessfully managed to refurbish a set of small trailer independent suspension units by way of grinding off the square carrier tube and mounting plate and replacing them ?

    I have two pair of units in need of this type refurbishment .

    Today I carefully cut off the crud metal and square retainer tube on one unit . The rubber shock absorbers/ springs are almost " D " shaped .

    I have the replacement metals to hand but am wondering which way will be best to insert the rubbers . I have marked which side it came from and which part is going to be upper most.

    Once I have filed out any manufacturing burrs in the square tubes , made leading edges for the exercise. etc.. the drilled out mounting plate holes assembled it correctly then welded them up with my trusty stick welder ( 5 mm wall thickness ).

    Is it feasiable to clean and use swarfega on the rubbers , insert two on the same side ? . Then compress the rubbers , rotate the square shaft , to see If I can slide the remaining two lubricated rubbers in place . I don't know how easy or difficult this may be.

    Any advice you can offer is most welcome .
    Last edited: Mar 5, 2010
  2. Blackjack Member

    Bristol UK
    Wouldn't use Swarfega, or washing up liquid, or any of the other domestic tyre fitting solutions...

    They all tend to dry and leave the rubber sticky, which doesn't bode well for the life expectancy.

    Swarfega also has mineral oil element in it's make up I believe, and if that's so it will attack certain types of rubber.

    Baby powder. Not dried, and ground up babies, the talc stuff.

    Citreon 2CV's that suffer from heavy steering and dump the steering column in you lap, almost always do so because the steering shaft passes through a rubber grommet in the floor. This can start squeking, and some helpful soul will sprayu it with WD40, which melts the rubber to the shaft and makes the steering so heavy that the top bracket fatigues and tears off.

    The solution there is to lubricate the grommet with baby powder, which lubricates the rubber to metal contact, doesn't dry out, and doesn't attack the rubber.

    Sounds to me like it might be worth a go....
  3. white van man 2

    white van man 2 The 'Rocco Horror Show

    would rubber friendly "personal lubricant" do the job? i've been using it to install suspension bushes for donkey's ears
  4. tigler Expert on the trivial

    Purpose made rubber grease is available.
  5. pidgeon chit welder sticking metal since 1962

    Talcum powder seems the way to go , we still have a full pack from an event that change our lives 8 yrs ago as we never used it on her lower suspension unit.

    How do you draw the rubber down through the square tube when it is along side the 45 degree off set square axle mount ?

    They are very hard , almost D shaped from being compressed from contact on the flats of the axle bar and still quite rust impregnated on the surfaces.

    I have been thinking of making a tube up that will hold one of the rubber profile lengths with a threaded nut at the top to take some 15 mm studding and affixing a sort of plate / retention bracket on the other end that will sit on the open end of the square axle tube. Then feed in the rubber into this " " syringe " after lots of powdering .

    Securely fit the syringe to the square tube and slowly screw in a 15 mm stud that has a thrust button or two where it meets the rubber . So as to try and inject the rubber under fairly high pressure into the cavity .

    Last edited: Mar 6, 2010
    gordon stephenson likes this.
  6. pidgeon chit welder sticking metal since 1962

    I tried to reinsert the suspension rubbers this afternoon , lubed the shaft and tube with silicone rubber grease and eventually managed to insert one rubber . The talcum powder idea was not successful despite de rusting and draw filing the stub arms to a very very smooth in line grain finish

    Either I'm a 17 stone whimp or I need nice soft new 14mm round profile rubber ?????

    Now.... what nomenclature does one give lengths of round rubber suspension insert. ??????

    I have tried all sorts of names but the search engines are leaving me item less.

    (Found lots of S&M clothing and such things though :ashamed: as if :whistle::cool:)

    Do any of you Gals & Guys have any polite suggestions ?
    ( the impolite ones didn't work in the search engines )
  7. Justme

    Justme Member

    Pwllheli Wales
    I think I would look at making a U shaped channel with a lip. Drill holes in the lip & make a thick plate to match. Stack all the bits in the right place & use long bolts to compress it all into the U shape. Once compressed I would stitch weld (giving plenty of time to cool) the base on. You would need to make sure that the lip is strong & wont bend during use. Perhaps use some braces.

    Or similar method but use a U channel that is to tall, fill with the bits, fit a plate that will go inside the U. compress using a vice / clamps, stitch/tack weld the plate in & bend the U over & weld again allowing it to cool.

    With the compression of these things & the shape change that happens to the rubber I doubt you could get them all back in to a sealed tube.
  8. fatfranky Member

    Co. Durham UK
    Just a thought

    If you "pull" the rubbers in they will stretch and therefore the diameter will decrease allowing them to slide into place, once in place they will hopefully return to their original dimensions.

    Perhaps you could tie some fishing line or mig wire ound one end, thread it through and then pull the rubber into place. once in place work the suspension unit back and forth to allow them to re-settle.

    As i say I've never done this, just an idea.


  9. metalspanner

    metalspanner Member

    Haslemere UK
  10. pedrobedro

    pedrobedro Man at Matalan

    CX Derbyshire
    Fill the tube with Sikaflex and shove the axle back in, weld the end then leave it to set :D I don't think they are supposed to be user serviceable items and once they have reached their finite lifespan you replace the whole thing. I wouldn't trust a trailer full of rubble not to break them again.
  11. pidgeon chit welder sticking metal since 1962

    Metal spanner thanks tremendously .. got a bit worried at " Pentonville rubber ":whistle:

    I've visited the site and will be in contact with them .

    My thoughts are 1.5 mtr of 14 .5 mm "cord " looped equally to make a figure of eigth as four legs and then slip over the tube then stretch with a screw thread device and at the same time from the hub end use a purpose made puller to gently pull the tube on over the rubber anbd the square stub end.

    I'll start taking pictures as things progress and when I've done one I'll bung up the full set .

    For I'm ssure there are lots of inde sus units that are getting binned just for the need of a new carriers and rubber inserts.

    A new set of inde sus units will set me back £90 odd plus carriage , so I'm happy to invest at least half that to see if it can be done as I also have a second set already on one of my trailers that's showing sever rust problems.
    Last edited: Mar 21, 2010
  12. metalspanner

    metalspanner Member

    Haslemere UK
    PCW, I cant let ALL my good sites become public knowledge, got to keep a few to myself.
  13. pitmole Member

    Hi, the rubber will have a certain "shore hardness" rating, this will vary the load carrying ability of the unit. 50 shore is reasonably soft for this type of use, 80 would be quite stiff, but probably in the ballpark. We buy a huge amount of axles from indespension for our trailers and think they are made by fitting the 4 rubbers into the outer box with an overhang, then pressing the inner through, trimming the excess,pushing home and capping the end.
  14. pidgeon chit welder sticking metal since 1962

    Pitmole..... I looked at that idea , I gave it a miss .

    I don't have a press and the space between the shoulders of the stub and the retaining square tube is so small I'd have great difficulty doing it " free hand " so to speak .

    I can readily see that pre stretching the cords to reduce things down to a workable diameter is a pre requsite for me . I'll make up a stretcher device for the cord and also a puller clamp to ease the tube over everything .

    Thanks for the shore hardness info , I was going to choose SH 50 but now your input makes me change my mind to go for Sh 80 ( ish )

    Stop press 30 seconds later.....

    Just had a major brain errupting thought ....

    A short dismantable ( two halves bolted together ) tapering square tube collar might just be the way to go , that way I'd get the lead in for the cord and the cord could be kept into the corners , once down face to face , undo the collar ,remove it and draw on the remainder with the puller device
  15. General Lee Member

    Hi pidgeon chit welder, how did you fare out with this? did you manage to refurb one? I am currently fixing a trailer at home and the indespenion units look a little worse for wear as the mounting plates are rotten with rust. So i cut open the worst one to have a look to see if i could just make up one. Bad idea as id say it took some force to put them in there.
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  16. Nivag Member

    I used to work in a shop which made hot cast poyurethane. This can be cast into rods and the rods can be used in "Indespension units". The advantage over rubber is that it is more slippery and easier to install. It also lasts a very long time. I have used box section, then made up my own square centre sections to suit so the rods just slide in with a bit of lube. I belive Brammer (BSL as was) sell PU rod and probably other similar engineering suppliers. Just don't weld near polyurethane as it gives off very nasty fumes.
  17. pidgeon chit welder sticking metal since 1962

    Bear with me if the words etc are mispelt .. I have lost use of my mouse and am using a Bamboo pad & pen .

    I ground out the square tube like you did and took out four Dairylee cheese shaped rubbers.

    I then electric brushed off the square bar to get it shiny and coated it with a wee built of silicone grease to nkeep it that way for a few weeks.

    I contacted several internet based rubber cord suppliers and none of then have replied to my enquiry . I may bite the bullet and end up ordering 1 mtr of 75 shore hard 15 mm cord .. funds have taken a hit this week ..minus £2k out the play fund :(.

    I have procured the square tube and cut it to size , had to wait till Easter to visit a mate who has access to some 4 mm plate and a decent cutter device to get eight mounting plates 6 x 5 1/2 ( enough for two axles )

    He also flatened the plates and champhered the cut edges.

    I've filed through the square tube to get rid of the internal weld seam and champhered a lead in edge on the internal faces to give a bit of lead in.

    Looks like LIDEL or Aldi are selling arc welding rods this week will take a trip to the nearest one as I'm running low on my 8 yr old ones that have been kept in an air tight container with frequently replaced silica gell packs in with them .

    I'll see if funds allow me to buy the cord at the week
    end and rob out my ebay play account into a bank account for it.

    One thing I have decided to do is to only do one side at a time so as to be able to put it back in the correct relationship to the uncut one.. reasoning behind this is that the stubs will have been aged & stressed over the years to run in a certain direction .

    The press for inserting the cords .. been considering stripping down my small 500 mm long 500 mm ish lift hydraulic car trolley jack ( cost £12.00 out of Aldi a few years ago ) and making up a frame as a complete oblong so that I can use all of the frame as a pushing surface to insert the cords .

    I'll be putting a 4 x 200 mm lengths of cord about 100 mm into the now welded on squares & mounting plates then slowly start jacking the stub up onto the tube .. the tube will have a 15 mm bit of square bar at the upper most end to allow for the cords to push through if it occurs.

    My stubs do not have those square plates with the round holes which appear cut in half that are shown in your pictures .. suppose its because my stubs are of a much less rating than yours and not likely to move in and out the tube when cornering and are also not going to be subjected to such a heavy loading as yours. But I will be bunging a bit of bar across stub square bar atthe open end once things are assembled just to ensure they never have the chance to come out .
  18. General Lee Member

    Nivag , i would of welded a replacement mounting plate on but i was afraid i would of melted the rubbers. poyurethane sounds like a good idea does it come in different hardnesses like the rubber above?

    Pidgeon, the square pieces are in fact plastic or nylon. One is in half because it has to split onto the inside of the solid box section- see next to the red rubber grommet. The other is whole and is on the outside of the shaft ( it just got a nick of the grinder oopsie!!!). I think your right about adding a stopper to stop it from popping out I will be adding one of these as well if i get it going.

    Dont think they are rated too much the pcd is 4 x 4'' which i think is around 500kg the bigger rated ones have a bigger pcd as far as i know. I might try and stick the same rubbers into a new box section and mounting plate. Trailer doesnt do that much it was just the fact the plate was rotten and i couldnt weld one on without burning the rubbers inside. But I am still interested to see how you fare out with yours as i might go down that route if it all works out well for you.
  19. pidgeon chit welder sticking metal since 1962

    Last night I sent an email to a company asking to buy 2 mtrs of 14 to 15 mm solid rubber cord shore hardness 75 to 80 ish and have advised them what I want it for ... waiting for reply some time today or tomorrow.
  20. Nivag Member

    Yep, they do hot cast polyurethane in lots of different hardnesses. We typically used 80 to 83 on shore A scale. Look at Jobel Engineering and/or Watts Urethane on Googleweb.