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My 40 has always been pretty hungry on leaf spring bushes. I usally only get 3 or so trips out of them before I should replace them. It usally tears the shoulders off on the first trip, and slowly gets worse from there.
I found the purple polly ones the best so far (also tried red poly, and rubber). They now need doing again so I started trying to suss out the hardest/strongest bushes available. Spoke to Dobinsons, who made my custom leaf springs, and he reckons have a go at making some out of Nylon.
The Dobinson guy is confident that the springs will twist to suit, and the lack of moment in the bush shouldn't cause dramas, except possibly limit the travel a little. But my mate thats going to turn them up in a lathe for me really doesn't like the idea of it.
So, what do you blokes thing?
Pic of the front end on full flex to show how things twist up etc.
ISUZUROVER wrote:I wouldn't. At best it will reduce travel and shorten the life of your leaves (by increasing stresses)
The colour of the poly has no bearing on the hardness. Have you tried Super-Pro poly bushes? They are the best I have used.
I am surprised Dobinson's suggested this.
Ahh ok, well the purple ones were Super-Pro's and they have been the best so far.
I don't know how you are getting through bushes in only 3 trips?!?! I have similar amounts of flex on my landie, and my bushes (no-brand poly) have lasted years!
Which bushes are failing? All 3 on each corner? Or just one per corner? are the (custom?) shackles causing issues?
ISUZUROVER wrote:I don't know how you are getting through bushes in only 3 trips?!?! I have similar amounts of flex on my landie, and my bushes (no-brand poly) have lasted years!
Which bushes are failing? All 3 on each corner? Or just one per corner? are the (custom?) shackles causing issues?
Buttom shackle bushes probably are first to go, followed by the upper shackle bushes....pin bushes last much better. As mentioned in the first post, the shoulders get ripped off the bushes first, then I think at full flex the pin pinches the bush against the spring eye and splits it.
Remember the shackle bushes on my model 40 are tiny.
I.D. 15mm
O.D. 25.4mm
So only 5mm walls on them.
Thats crazy....has Dobsons had this issue with other springs they have made??
Even if the geometry of the springs & shackles was way off, you would think you would get alot longer than 3 trips out of the bushes.
It can't hurt to have a go at making your own...if it lasts more than 3 trips your a winner...if not try something else i suppose....
All issues are my responsibility, as Dobinsons made the springs to my specifications. All the geometry is good. Basically the problem is the truck flex's too much for the size of the standard bushes.
Nylon will probably chew out pretty quickly. You'll want a tougher and more rubbery plastic.
If money is no problem, PEEK. Otherwise oil filled nylon will still be a step up from straight nylon. There are a multitude of nice machining bushing/bearing plastics, find a plastics supplier and ask what they've got.
Almost seems like there has to be too much freeplay either between the pin and the bush or between the bush and the spring eye to cause such accelerated wear.
Now seeing as you never had this problem prior to these springs - and the bushes are off the shelf jobs listed for stock 40 and the shackles I assume were on your old springs and are listed by superior for stock 40s - I assume the freeplay will likely be between the OD of the bush and the spring eye seeing as they are custom jobs. Might pay to get some verniers and check out the ID of the spring eyes to rule that out.
Mate, You should try "ACETAL" it's a type of nylon, very hard and we use it on boat lifters as pulleys running stainless cable, lifting 2 to 3 ton, check it out!!
KiwiBacon wrote:Nylon will probably chew out pretty quickly. You'll want a tougher and more rubbery plastic.
If money is no problem, PEEK. Otherwise oil filled nylon will still be a step up from straight nylon. There are a multitude of nice machining bushing/bearing plastics, find a plastics supplier and ask what they've got.
Thanks for the info, will suss out some alternatives when talking to the plastics shop.
RAY185 wrote:Almost seems like there has to be too much freeplay either between the pin and the bush or between the bush and the spring eye to cause such accelerated wear.
Now seeing as you never had this problem prior to these springs - and the bushes are off the shelf jobs listed for stock 40 and the shackles I assume were on your old springs and are listed by superior for stock 40s - I assume the freeplay will likely be between the OD of the bush and the spring eye seeing as they are custom jobs. Might pay to get some verniers and check out the ID of the spring eyes to rule that out.
Well I did have the same problem with the last springs too (also custom dobinsons)....but not as bad. Will check the ID of the spring eyes when I next have the bushes out but to make sure.
the ferret wrote:Mate, You should try "ACETAL" it's a type of nylon, very hard and we use it on boat lifters as pulleys running stainless cable, lifting 2 to 3 ton, check it out!!
could you loosen the spring clamps that are at the shackle end of the spring to maybe let the top leaf twist a little? under compression not sure it would do much though..
toughnut wrote:If the leaves are custom then could you get the main leaves redone to hold larger bushes? Would this be cheaper than replacing bushes every 3 trips?
x2
this is what i would do longer term i'd probably opt for later model sized bushes and springs. its a bit of a job but should get you the results you need.. its like the bush needs more 'fat' to cushion the pin as it twists before it contacts the main spring eye.. with the small bushes it wouldnt be able to twist as much a chop up a bush.
sorry if my typing and shits crap but squinting thru one eye half cut..
x3 the bushes need to be bigger/fatter, try and fine a OEM rubber bush that will do the job, even if you have to change the springs, OEM rubber bushes are very flexible and more hard wearing than anything aftermarket.
Sounds like your bushes need to be more flexible rather than more solid.
GQ 5" coils 35" Muds FOR SALE
98 GU 4500 ST Stock.
The whole problem is caused by making the suspension do what it's not made for.. When a wheel drops into a hole and the other wheel is on a rock, the axle will push the spring to where it wants it regardless, and if you have given it more travel, the tendancy to twist the spring is greater. It can't twist on the axle so it will twist and distort at the spring hanger, this puts severe load onto the sides of the spring eye and inturn onto the bush. The load on the bush and the main leaf of the spring is in tons, not pounds. I would tend to use bronze bushes rather than nylon or as I mentioned before " acetal". It would be great if we could come up with a swivel set up for the front shackles eh?. Other than that, it's coils i'm afraid. cheers.
toughnut wrote:If the leaves are custom then could you get the main leaves redone to hold larger bushes? Would this be cheaper than replacing bushes every 3 trips?
Or is it feasable to use a solid bearing type bush kind of like a rose joint to replace one of the bushes?
I've never had a leaf sprung truck so I really don't know how to get the best out of them. Just throwing these ideas out there for debate.
I was close to upgrading the bush size when ordering the latest set of springs, but couldn't afford it at the time. (Replacing the greasable extended shackles, pins, hangers etc. added up quick). Obviously if I could have my time again, I would have waited the extra month or two and done it properly.
the ferret wrote: It would be great if we could come up with a swivel set up for the front shackles eh?. Other than that, it's coils i'm afraid. cheers.
So what about a solid rose joint type bush? I know that it would be possible but would it make things better or worse? You wouldn't get the sideways movement but you'd still get the flex side of it and if you didn't replace all your poly bushes with it then it wouldn't be too rough. Well not too rough when you're already on leaves.
Hard to tell for sure but from the picture it looks like the leaves may be too long for the application.
If you bushes are flogged out in three trips DO NOT use a harder material.
The bushes are flogging out for a reason, they are getting chopped out due to too much movement. If you put a non compliant bush in there the stress that is being absorbed by the bush (causing it to chop out) will be transfered to the next weakest link and something else will bend or break.
[quote="Uhhohh"]As far as an indecent proposal goes, I'd accept nothing less than $100,000 to tolerate buggery. Any less and it's just not worth the psychological trauma. [/quote]
When I replaced my engine mounts with nylon in the (mostly driven on the street) track setup charade, Everyone told me they would chew out.
I did 50,000 hard kms in them in about 12 months and had no issues. They came out because I was sick of my ears ringing...
mhgill wrote:x3 the bushes need to be bigger/fatter, try and fine a OEM rubber
Sounds like your bushes need to be more flexible rather than more solid.
X2
A lot of work goes into designing bushes.
Too hard and gravel will get trapped and wear out the pins.
Also you need some give to absorb twists and shocks so pins dont break.
tehekho wrote:When I replaced my engine mounts with nylon in the (mostly driven on the street) track setup charade, Everyone told me they would chew out.
I did 50,000 hard kms in them in about 12 months and had no issues. They came out because I was sick of my ears ringing...
You're lucky you didn't crack the mounts off the body.
By the look of your pic the shackle itself is twisted, maybe a bridged shackle (something wleded in place where the bolt currently is) would help stop the shackle from twisting. It will limit travel a little but may save your bushes.
[quote="Harb"]Well I'm guessing that they didn't think everyone would carry on like a big bunch of sooky girls over it like they have........[/quote]
