Ventilated discs for KE70

[altezzaclub]

So, hunting around the wrecker checking on projects, I came across one of these-  A Daihatsu Move.

The reason it doesn't have a disc or hub on that side is because I have them on the bonnet of a nearby car..

 

They are unusual because the disc mounts on the back of the hub, like a RWD, while nearly all FWD put it on the front of the hub so the wheel bolts it into place.

You can see the diameter is bigger by 16mm, or 8mm of radius.  The swept area is MUCH bigger, 30mm out to 40mm is a lot.

The hole in the middle is 6mm larger (FWD!) so we'd need a 3mm wall spacer to center it.

The bolt holes are 2mm out, so that would need a little filing.

The setback from the front mounting face goes from 30 to 37 or so, and we can only steal a little of that back.  The disc thickness around the hub is only 7mm on a KE70 and 8mm on the Move, so we'd take a mm off that.

The caliper mounting holes are15mm closer together, so new mounts would need to be welded onto the KE70 backing plate.

The alternative would be to swap the whole plate over from the Move, but that enormouse FWD hole in the middle means the 4 Move boltholes run into the edge when you re-drill for a KE70. Either way it needs a bit of welding for caliper fit. The KE70 holes aren't symmetrical, their pattern is very strange.

 

..and that is as far as I've got. I don't think I can any check more without doing something about mounting it and seeing if it fits on the strut and if it clears a 13" stock wheel. 

 

Anyone with a lathe want to knock up a pair of rings to center the disc?  If it fits with a centering ring on the disc and another on the Move backing plate, it would be a very cheap and simple conversion to ventilated discs for stock KE70s, so you can set up a production run later! 

 

So, do we need this?  Are stock brakes fine? The keen people with fat wallets can go to coilovers and Brembos, others can get Corona/Celica stuff, but I figure the current suspension and steering is nice without adding too much unsprung weight.

 

Edited October 8, 2017 by altezzaclub

[altezzaclub]

Ok, back to the wrecker today- I took the backing plates off and fitted the Move plate & caliper to the KE70. Fits fine, but the center hole needs spacing down to the KE70 hub diameter.

Fitting the disc showed everything cleared, although without the spacer ring its not held in exactly the right place.

Then I put a Rolla wheel over it. Seems the different thickness & larger diameter gets taken up no problem.

OK, so its good enough to think about the machining involved. The 3mm spacer ring for the disc to hub is simple, as is the central ring for the bolts on the backing plate.  Moving the four boltholes 2mm in the hub to match the disc... not so simple.  The correct way to do it would be to fill the holes in the hub with weld and re-drill them, or fill the holes in the disc and re-drill then re-thread them partway into the spacer disc.

Really, its a simple conversion compared to many!

[LittleRedSpirit]

Can you order new rotors un drilled and have a brake shop drill them correctly?  Have you done a control F check on the DBA catalogue to see if theres other slightly sweeter options?  Maybe something has the right pcd?

[ke70dave]

just remember that im pretty sure the same diameter vented disc is not going to improve braking, it will just help with cooling when you start pushing them hard. 

I always wondered how far you could go on standard KE brakes, high temp fluid, high temp pads, air ducting via a hole in back of the backing plate. 

Interesting find none the less, I think the DBA catalogue trawling is the way to go. If the tophat is different height you can probably put some spacers between the caliper and caliper bracket. though you want to be careful doing that, changes the moment force on the caliper bracket. 

 

 

[altezzaclub]

The swept area is noticeably bigger, the KE70 is quite inefficient with how much pad area they use, so I expect they will stop much better.

Trawled the DBA, nothing much of a better fit, the change from rear-mounting the disc on the hub to front-mounting stops a lot of good diameters. There is a Suzuki Swift down there that was my original choice, I might pop that apart and check it.  Mind you, hot day today, shorts & T-shirt, snow forecast tomorrow..

[altezzaclub]

Well, the boss at Great Western Wreckers, an absolute gem if ever I came across one, loaned me both brake setups. Then the light-bulb went off in my head!

The Girl attends trade shows sporadically, selling Tiertime UP Mini 3D printers for 3D Printing Systems Lts, one of which is beside her desk..  So it took me  a morning to learn how to use an online CAD program enough to draw the two spacers needed and off we went this afternoon-

The machine started with this-

It produced this...

Which fitted perfectly to centralise the disc to the hub.

They need the mounting holes re-drilled.   So copy the plastic ring to steel, weld it in place and re-drill.

The backing plate spacer is drawn up, but I have to wait until after DOTA-time to get it printed!

 

 

[LittleRedSpirit]

Well this thread just jumped into the future.  Woolshed needs its own 3d printer!  lol.  Awesome.

[altezzaclub]

OK, bit the bullet and saw my local engineer. He copied the spacers into steel and I went back to the wrecker to get the other side, and actually pay for the parts I'd borrowed!

The engineer welded the big one into the Move backing plate-

and I slotted the hub holes a mm so it all fits on his spacer here.

Now I can drill the holes in the Move backing plate to suit the KE70 strut and try it all!

So far $50 for the Move parts and $180 at the engineer.

 

[altezzaclub]

Well, I've certainly had bigger headaches!  The backing plate has an obvious place to sit due to the indent for the LCA, and then it can be rotated forwards or backwards to suit the mounting holes. The center hole of the spacer was a half-mm too small, perfect to file out and get a perfectly tight fit located onto the stub axle. The 4 bolt holes were a best-guess and drilled to 8mm then filed to 10mm to get them exactly where they needed to be. One hole has an overlap, but not in a direction that is important.

After the first side I made a paper template so the other side was easy.

On the strut there wouldn't be 5thou of movement in rotation, and zero laterally.

With the enginering finished it was a matter of assembly. The hub and disc went on-

Then the calipers-The biggest pain appeared now. I went to swap the brake hoses but the hard-line 10mm fitting on the chassis end rounded itself off in my brake spanner. They sieze in there after a decade. I had to keep the KE70 lines and change the caliper, so much swearing and brake fluid everywhere!

It lines up perfectly in all dimensions, very surprising really! The wheel clears fine too-

So there you have it, back on its wheels with the brakes bled, but I can't drive it as I'm halfway through doing the alloy radiator conversion! The pedal may go down a tad more, hard to say without driving it, but it should as the Move has larger pistons.

The Move caliper & pads (new) weigh 3.2Kg, the KE70 caliper & pads (worn out) weighed 2.4Kg.

The Move disc on a KE70 hub weighs 11.55Kg, the KE70 setup is 10.85.

So we've added 1.5Kg to each side.. a nuisance, but hopefully not noticeable.

I even scored a set of almost-new pads, a swap for the KE70 ones that were down to their last few mm!

Edited October 8, 2017 by altezzaclub

[altezzaclub]

Well, drove it around the town this morning, no change in normal driving. The pedal has a good feel, doesn't go down a noticeable amount, but if you lean on the pedal the response is sharper. It will get a tryout when I go up to Walcha next.  Find yourself a Daihatsu Move!