eps steering rack.... delvin into the deep!

[havoc]

I can't answer even the simplest of your questions let alone the problems you've solved to get it to this stage, power to the Steampunk. 😂😂😂

Seconded. Absolutely bowled over by your persistence there Mr Sutherland!

[britlude]

next up, the 2 gears i ordered have arrived..... i bought 2 just in case of disasters, but only need one.... there have been several reports of the plastic gears losing a tooth or two from the guys in the US...

so made a quick split jig to hold it on the lathe.....

IMG_20190314_172925 by jon sutherland, on Flickr


and soon it was looking a bit more like the plastic original....

IMG_20190314_174100 by jon sutherland, on Flickr


now..... i ordered a 0.5mod 60tooth brass cog, knowing there would be a slight discrepancy with diameters... the one on the input spline is exactly the same size..... so i know the designers know what a standard mod pitch is!

IMG_20190314_175002 by jon sutherland, on Flickr


and the original plastic measures....

IMG_20190314_175015 by jon sutherland, on Flickr

so 0.6ish mm smaller.... it's still 60 tooth, and the tooth form isn't obviously damaged, but it might have had wear over the last 26 years, but not so sure.... this isn't an issue at the splined shaft side, as there was loads of backlash,





so that gets reduced nicely...



however the sensor side is too tight to fit the gear...

so the plastic gear is loose on one side, and meshing nicely on the other, so it was made small then? so slightly off pitch - ok for a less backlash mesh, but then loads the other side??? ok, thanks, make it easy why don't you!!!


soooo... a slight tweak required to get it in, the sensor gear has to move over a little.... a quick desolder and file....

IMG_20190314_182413 by jon sutherland, on Flickr

literally less than half a mm to correct....the position was tweaked toward the original position to get the mesh better.... now it has a little adjustment!


so once put back in, all is well...

IMG_20190314_183035 by jon sutherland, on Flickr

oh, and drilled some holes in the gear, just cos i could!





now on the subject of 'why didn't you use standard parts when you design this stuff', the steering rack end bush on a eps rack.... the steering rack main shaft is 24mm diameter, so a 24mm inside diameter bush, approx 25mm long, and the outside diameter of that bush appears to be 26mm (haven't taken it out yet)

your standard steel backed industry size bush, meaning you can have oilite, ptfe, teflon or even more exotic options, is 24mm inside diameter (tick), 25mm long (tick) and 27mm diameter, 27mm! 1mm bigger!!!!

[ozon02]

I think you should not duplicate the American guys idea and improve Japanese engineers. If your plastic wheel had all teeth. Why ... ask Kaz, he'll explain to you.
Stiffening the structure in a place where the unevenness of the road is directly transferred to the material is not a good idea.

[bbvnsx]

If you go to the USA rack repair website and click on their services, they divide 91-96 and 97+ NSX. By looking on their description I was under the impression Honda changed the torque sensor on 97+ cars... and that Honda eliminated the plastic wheel on 97+ cars... but did Honda change to metalic wheel or a complete different torque sensor? :-/

I think you should not duplicate the American guys idea and improve Japanese engineers. If your plastic wheel had all teeth. Why ... ask Kaz, he'll explain to you.
Stiffening the structure in a place where the unevenness of the road is directly transferred to the material is not a good idea.

[goldnsx]

Just a sidenote and not of any relevance at all: but regarding the costs of a new unit and the complicated repair I'm pretty glad to have a manual steering gearbox (which is reliable except for one bushing). The EPS is simply not needed in an NSX. Question: I've never run across it but would it be possilbe to throw the EPS out and install a much cheaper manual gearbox instead?

Great effort on the repair though.

[britlude]

1. the gear, nylon or otherwise, is on the steering wheel side of things, so isn't in quite such a harsh environment, having a damper, in the shape of the driver, attached. however there are various documented cases of the gear teeth breaking, both with d1guy in US and KSP in japan.... add to that, my rack being 26-27 years old, so don't want to trust the old nylon gear.... and as i had it all apart anyway.... and honda not supplying any internal rack parts....


courtesy of KSP..... https://minkara.carview.co.jp/userid...og/c991096/p3/

2. yes the EPS steering rack changed with the NA2 update, the NSX getting a new steering torque sensor and control ecu..

3. the eps, as far as i know, is the same steering ratio, so all you have to do is remove the motor components and it's exactly the same as a manual rack anyway.... however, i'm sure you can just delete it and fit a manual rack if you have the urge.... tho the EPS does make slow speed maneuverability easier, and the assist is speed dependant, so once you get moving it doesn't assist anyway!

[ozon02]

ok Jonathan, you convinced me - I am ordering from you an enlarged bearing (to 36mm) and gear (bronze?or brassing?) for future

I love my EPS
1. I was invited to the *** Fest in Poland last year. Connected to Track Day. I met a friend from NSX 92. We decided to exchange cars (mine is Acura 96)
2. my feelings about non-EPS:
92 used on the track definitely better - more responce from road
92 on the high way road - ok, I did 130 km
92 in Town - unacceptable
3. a colleague's feelings about the EPS
96 used on the track - unacceptably poor feeling (it was a 1.5 km track - not the Nurburgring Nordschleife, a bit similar to the Nurburg GP) - it's worth adding that last year's friend won the second place in the Polish cars' GP to 2 liters of capacity on Honda S2000
96 on the road Approx
96 in Town much better than 92
...... and because I'm not "fast and furious" I think it's better to have an EPS and the costs of repair are acceptable