Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Two Motors

harlequin2 · 03-23-2011, 11:53 PM

In answer to all of the above, the BMW318 uses a rubber coupling from the gearbox to the front driveshaft. That coupling can handle the power, torque and rpm of the ic engine - and then some! - so I figured it ought to manage the electric motors two.....
I think I mentioned this earlier.
I bought a couple of couplers from a couple of wreckers, plus the one I had already and picked the best ones from all of them. The rubber bit is a disk of about 120mm dia and about 35 mm thick with six holes, each of which has a steel insert. Each side of the coupler is a 3-fingered "spider" with holes in the legs spaced 120 deg apart and 3 x 10mm bolts go through each one. You can see from the picture in my first post how it goes together.
The 2 spiders have central bosses, one splined to fit the gearbox output shaft and the other splined for the drive shaft end.
I cut these splined bosses off two of the spiders and machined some new ones to fit my motor shafts, welded them to the spiders, bored them out to the appropriate shaft sizes and cut keyways also to suit the motor shafts. Did the same with another spider to fit the rear motor output shaft to enable it to connect to the drive shaft.
I think I paid something like $10 each for the extra couplings from the wrecker(s) so it worked out pretty cheap - not counting the lathe, welder etc. I had to send them out to get the keyways cut and that cost more than the couplers!

Look again at my earler pictures and it should all be clear.

03-23-2011, 11:53 PM	#16 (permalink)
harlequin2 EcoModder Join Date: Mar 2010 Location: New Zealand Posts: 181 Thanks: 0 Thanked 33 Times in 20 Posts	In answer to all of the above, the BMW318 uses a rubber coupling from the gearbox to the front driveshaft. That coupling can handle the power, torque and rpm of the ic engine - and then some! - so I figured it ought to manage the electric motors two..... I think I mentioned this earlier. I bought a couple of couplers from a couple of wreckers, plus the one I had already and picked the best ones from all of them. The rubber bit is a disk of about 120mm dia and about 35 mm thick with six holes, each of which has a steel insert. Each side of the coupler is a 3-fingered "spider" with holes in the legs spaced 120 deg apart and 3 x 10mm bolts go through each one. You can see from the picture in my first post how it goes together. The 2 spiders have central bosses, one splined to fit the gearbox output shaft and the other splined for the drive shaft end. I cut these splined bosses off two of the spiders and machined some new ones to fit my motor shafts, welded them to the spiders, bored them out to the appropriate shaft sizes and cut keyways also to suit the motor shafts. Did the same with another spider to fit the rear motor output shaft to enable it to connect to the drive shaft. I think I paid something like $10 each for the extra couplings from the wrecker(s) so it worked out pretty cheap - not counting the lathe, welder etc. I had to send them out to get the keyways cut and that cost more than the couplers! Look again at my earler pictures and it should all be clear. __________________ Sometimes I sits and thinks and sometimes I just sits.