All on my ownsome…

There’s still no chassis here, so I’ve been getting on with other things. i did phone up the powder coating company on Friday afternoon when it became apparent that I might be able to get over to Soham. However, there was no answer so I guess they’d gone home early. Either that or they’ve gone out of business taking my chassis with them… 🙁

Here’s something though, in that I’ve finally finished the rear brakes. The new taps I ordered arrived and I was able to properly  cut the threads. I did have an experiment using helicoils but, for some reason, I didn’t feel confident about it. All the same, I’ll keep the helicoiled part as a spare.

That photo above is unique in that the bolts holding the ally block to the upright are actually locktited in position. That is, they’re the first bolts that I’ve done up intending them to remain where they are. Up to now I’ve been assembling and disassembling. Hopefully from now on I’ll be able to concentrate a bit more on the former.

One thing I did manage to do on Friday was to call into the lasercutting place and pick up the parts for my diff mountings, having decided that perhaps the hardboard versions weren’t going to work properly. These ones are made from 6082/T6 aluminium which is rather beefier. Actually, they were amazingly cheap really in that this lot cost me about £70 which is pretty good considering that 6082 is of the most expensive aluminium alloys.

Obviously, I need something to hold the diff bearings in those plates and some time ago I designed a couple of plates to do the job. This picture is exported from the CAD system so as to expose things to your withering gaze. I’ve rendered the mounting plate itself as a wireframe so that you can see the two bearing support plates and the bearing itself.

So, I went to Mackays and bought some big slices of a socking great 5″ diameter aluminium bar and set about them with the lathe. After a goodly while, and a lot of swarf I’d exposed the parts in the next photo. As you can see I’ve yet to drill the holes through the plates that will bolt them and the mounting plate all together but that shouldn’t be too difficult, especially as I’ve got the laser cut plate as a template. The only problem is that I’ve become a bit sensitive about the quality of taps and I don’t have a particularly super-duper set of M8 taps so I’ll order those before bolting this together.

One minor issue is going to be getting the bearings onto the diff itself. They appear to be pretty tight interference fit and I’m going to have to make some sort of press-arrangement to fit them together. In fact, I should probably put some thought into how I’d take them apart as well, although a pair of large screwdrivers might well suffice.

By the way, those two 20mm holes in the mounting plates are for access to the bolts that retain the sprocket on the diff, many thanks to Adrian for pointing out that I’d need these before I actually ordered the laser-cut plates.

8 thoughts on “All on my ownsome…”

  1. Progress is looking good. as for your helicoil repair for your caliper moints it should be stronger than the all aluminium one on two counts. the effective diameter of the taped hole in the aluminum is larger giving more surface area on the softer metal. And the bolt is screwing in to a steel thread so less damage to the thread caused by the milling action of the bolt as it is tightened. of course this is also dependant on how much “meat” is left around the hole. some machines are Helicoiled from new. due to the strength required on the casting threads.
    As for your diff bearings instalation should be easy if you heat them first. in the oven 180deg C gas mark 4. and just throw them on before you get court! just one point. are you clamping the bearing on both sides to the plates? which would mean putting the clamping plate on before the bearing. but may make dissassembly difficut. if the plates are stiff enough the inner could be bored to slide over the bearing after bolting up. there shudn’t be too much in the way of side loads, so one plate should be able to take the thrust.

    1. Yeah, I know that people say the helicoils are superior to the bare material. Never believed it though… 🙂

      I did wonder about heating up the bearings, problem is I’m not sure it’s fair to the lubricant that’s buried inside the sealed bearings. Currently, there is an inner shoulder for the bearing to sit against. I did wonder about removing it, but I think it’ll be OK without. As you say though, that means I’ll need to put the mounts on before the bearing.

  2. Hi Tim
    Just signed up, my first comment, but I am following your build closely as I am also very interested in the J15(current name?)to use as a track day car.
    Just a comment for consideration. Do you suppose there may be a concern with stripping out the alum threads in you alloy blocks due to heat build up? the alum alloy blocks will be directly heat sinking the caliper/disk heat and alum becomes mallable at around 450 deg C. Plus the alum expansion rate may pull the threads out. You may need to undertorque to allow for expansion. I have noticed a similar set up on a DSR(can not find link). But the builder used steel as he believed the alum would be a problem when hot.
    Looking forward to your completion and track test and how the J15 will compare to the Fury. Your Fury is the perfect yardstick to compare, Proven car and driver.
    Thanks for your build log of this car.


    1. I don’t think there’s a problem with stripping the threads, purely because these mounting blocks are always made with lumps of aluminium and I’ve never had a problem before. The ally blocks I started with are specifically sold for this purpose after all, and the pre-made ones I bought for the front brakes are also aluminium.



  3. the ally mounting blocks will conduct the heat away faster than the steel bolts will conduct. so temperature should not be a problem it’s the disk that sees most of the heat as the caliper is insulated with the pads. if the caliper was getting that hot. then i’d worry about the seals.
    warming the bearing is recomended practice. if you are unsure then warm up gently till it drops on. the ludricant will be ok. i’ve had bearings smoking before and had no ill efects. it is after all a lowish speed bearing. it’s explaing the smell and the greasy finger marks the the other half thats hard!

  4. No withering glances from me. I am enjoying every minute. Actually I am getting a bit worried about your professionalism. I remember the glory days of the eiffel tower of steering column!

    I hope you are having fun with it,


  5. Tim Helicoils are fine they were developed for the aerospace industry.
    The bearings should be fine with a bit of even heating. Bearing companies sell bearing heaters as it is the best way to fit bearings without loading the races.
    If you want to make removing the bearing covers easier and less bodge prone you could drill and tap a couple holes in the cover so that to remove the cover you screw a bolt into each hole and jack the cover off against the diff mounting plates. This is fairly standard on things like water pump bodies.

    1. Ah, that’s a good idea! In fact, I’m already planning on drilling and tapping holes in the inside retaining plate. So, I couldyank the bearing off by just pushing some longer screws in there, and putting some sort of anvil behind for them to press on. Nice one!


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