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We are going to work on making a high volume of these to keep the price as low as possible. I make more selling Powerflex but this is a much better product so I'd rather help get this out to market than make loads of profit.
Right guys, after few more requests, I'm looking at some dogbone bushes, I wasn't going to because there's a lot of them available, but after chatting with a few people about the vibrations levels and the thread last month about the same I know I can offer something far less harsh.
However, the only local car I have is that 1.4 Clio I was testing the first mount on, and it looks like there's some difference between that and the larger engine mounts (just going by part numbers - it may be as simple as the larger engine cars have stiffer mounts?) and apparently between ph1 and ph2 mounts?
Anyone got definitive answers?
I got the one from Oss (thanks!) and a new cheapo ebay one - pressed the bushes out, etc - unfortunately there seems to be a fair variation in size between the two - the holes aren't very round in either and the cheapo is 1mm bigger on the small end and between a 1mm smaller and 1mm bigger on the large one, depending where you measure.
Good news is the bush design I wanted to use on the large end will work okay with that, bad news is the design for the small end probably won't push in without fettling housings, it's far too rigid - so I might have to rework that, I'm still going to prototype one as planned first though and I'll look at accommodating size variations after some NVH testing.
Ran a few more deflection tests and tweaked things to keep the overall shape similar to a Renault OE bush for radial loads, and thinned the bush down but increased the insert size to keep the axial/twisting forces more in line with the renault design (keeps all the harsh vibrations suppressed when you get any misalignment, which is where most poly bushes are terrible):
Then beefed up the bridges as much as possible (basically stiffening it when you get on/off throttle) until they start getting to the point of little return for more harshness.
Got a prototype running atm, see how it goes.
Spent a bit of time working out toolpaths and pricing, and depending on what I have to do with the smaller mount (still working on that one), should work out cheaper than the Powerflex ones too.
Okay, the original plan for the small end using a spherical bearing isn't going to work - too much variation in housing sizes - so back to plan B and polybush it, should have a prototype ready for testing next week.
Right, got everything where I'm happy, bar a few tweaks I want to make for ease of fitting + cosmetics. poly both ends now, oversized aluminium inserts similar to the OE bush, to spread the stress over a wide area on the polyurethane and also allow for full bolt clamping torque just the same as the Renault specs, without any worry of squashing the bushes or distorting the inserts:
I've tweaked things so they can more easily be fitted by a vice or some clamps now, whilst still retaining similar preload levels.
@OssPoop has kindly agreed to letting me test it vs the uprated lower mount he's already running as a back to back, I'd also like to test it on someone's car with a relatively new standard lower mount if someone local wouldn't mind volunteering their car for a test run - all the simulations in the world aren't worth an hour on the car
Okay, @dCi_rep sent me a nice pack full of used mounts this morning, which I've cleaned up and measured up - the good news is, the sizes are all well within what the bush design will cope with for preload variation, so I don't need to make any changes. In fact I could probably slacken things off a little on tolerances but I cba
I can also see just how much they suffer with the small bush getting knocked out - the big bush is perfect on one even though the small end is dead, and it's pretty similar on another one too. But then again it's so much stiffer than the large bush and with so little area, that's expected, fortunately what I'm using in the small end is about 3x tougher than the OE compound, and has more lateral support.
Anyway, looking at that, I may offer the two bushes seperately - that would give people a nice cheap option just to refurb the mounts you have if just the small end bush is shot, with a decent replacement part, without being a massive amount stiffer any thoughts on that, or would you be more likely just to buy the kit of two + inserts anyway if you were taking the mount off?
I still need to get around to checking fitment and some quick testing, but me and @OssPoop keep missing each other at the moment
An as a slight aside, if anyone wants a look at the mounts, and/or the exhaust mounts that KAM are now stocking, then they'll be on display at a stand next month at the TCT manufacturing show in the NEC - along with a few other parts for different models, engine mounts, wishbone bushes, subframe mountings, balljoint boots, etc, etc - you may or may not catch me personally as I won't be at the stand for long.