Ew350 gearbox fixing

[Neilj]

Sorting all my boxes that make up a ew350 hopefully.Does anyone know what size and thread are the bolts that hold the gearbox to the frame please.

[EW-Ron]

I was just looking into that, having sourced a better gearbox.

They are 3/8"  diam and 1 & 7/16" long and 20 tpi.
That should correspond to BSF. ?
(unless its coarse cycle thread 20 tpi, although BSF nuts fit, if a little rough)

Its stamped DK on the head, although stamping is a little unclear,  unless you have it correctly orientated.
Looks like they need washers, although these were fitted without.

[Neilj]

Thanks measure my frame bracket at 1 inch that only leaves 7/16 without a washer in the gearbox.Stuck a bit of wire in the gearbox thread and that’s an inch deep recon you could use 1 1/2 or even 1 3/4 with a washer👍

[EW-Ron]

These bolts seem reluctant to go in to their full 1" length of thread.
I need to look into this.

If they didn't have that DK stamped on their head I'd have thought that maybe
they weren't quite correct in some way ...

You wouldn't want them to bottom out though, thats a recipe for breaking something ?

[cardan]

99% of applications like this would use studs screwed (once) into the alloy casing, then nuts to fasten the gearbox in place. Did the EW really use bolts?

Leon

[EW-Ron]

Don't know.

My EW came with bolts, with DK stamped into the heads of them.
And the spare gearbox I bought came with nothing.
And another stray box I've sighted had nothing.
And the OP here doesn't have studs.

So I'd say we are coming to a consensus here.

All that I've seen appeared to have a few problems with the threads.
And the reason that most makers fitted studs !!?

I'll contemplate if the gearbox could actually be removed if studs were fitted,
they'd be pretty long-ish and there is not a lot of room above ?

[Neilj]

Funny got a copy of the ew350 parts book in gearbox it lists studs and nuts with no size.you ever taken a gearbox apart to put new bearings in? Took the side plate off mine the kick start arm flew around and what a mess inside 90 odd year burnt grease and a few bits of what look like broken plastic.mine is marked DD low ratio for competition apparently.

[EW-Ron]

Funny got a copy of the ew350 parts book

Aha ! Solves that then.
I've been searching for that for a while now, last seen about 3 house moves ago.

I have had the box apart, don't recall the finer detail.
Kick start springs are always a challenge.
This new box will need inspecting, if nothing else.
Aside from actually finding/making some studs.

Is liquid grease the recommended lubricant. ?
Is just the end cover enamelled black ?

[Doug]

The 350EW gearbox went through at least three iterations. The first mounted on a flat platform and the case has four individual column legs. The next version jointed the columns on each side into a pair of mounting curbs. In 1927 the frame was altered and the transmission had a plate anchorage that clasped the frame tubes. The spares list I have dates March 1927 and covers the plate anchorage style. That uses bolts (#7741-2). Maybe the earlier style used studs and nut? However the -2 suffix to the part number indicates that the bolt has already gone through two revisions.

-Doug

[Neilj]

Looked up the grease and it’s fairly widely available on eBay and yes as far as I can see only the end plate was black.i painted mine with satin heat resistant looks ok,but it might look nice in high gloss??.If anyone has photo,s of the internals of a gearbox whilst coming apart or drawings this would help.mine has 2 parallel posts for fixing.

[Doug]

Only pic I have is this one of a 600EW (actually F28). Very similar to the 350 EW and I think share some components in common. Longer main shaft however to suit the larger offset for the primary chain.



The combined main shaft, lay shaft, and shifting glut come out together. May need to warm the cases to release the grip on the ball bearing races.

-Doug

[Odd Bob 66]

Mine has the second style of mounting, bolts up through the frame with the mounting bosses joined as two pairs. Definitely bolts, not studs. First reg'd Jan '27, but wouldn't know manufacture date. I would guess late '26 for the '27 season. It has the later two-pipe oil pump set-up. (Thanks Doug, your article on the pump was very helpful!)

Cheer, Paul.

[EW-Ron]

However the -2 suffix to the part number indicates that the bolt has already gone through two revisions.

Could the 2nd version have just been bolts instead of the studs, we wonder ?
I've just seen too many boxes without any studs.
And they're not the sort of thing you'd just remove ??

[Wilfr]

I wouldn't care too much for originality with a detail like this.
If the box can be taken out of the frame with studs fitted, and that is studs long enough to fit a decent nut on the end I would always prefer studs to bolts. And I would Loctite them in. A bolt turning under the load increasing while tightening will always wear out the thread in soft aluminium much quicker than a stud which does not turn.
Cheers
Wilfried

[Odd Bob 66]

Completely agree. If I have to remove my gearbox at any time I will be replacing the bolts with studs. (Although suspect these will be a special pitch, and need to be made to suit !)

Cheers, Paul.

[Daren W Australia]

Hi worked on 4 EW gearboxes yesterday all have bolts no thread damage at all, 2 came out of bikes 2 from spares I'm sure it would be a pain if they had studs they would not have fitted past the seat tube and rear guard. As my bikes are 95 years old I think I will stick to bolts. Ta Daren









[Attachments converted to linked images. 29Nov21 -Doug, Admin]

[Odd Bob 66]

Thanks Daren.
Hadn't thought about clearance on the way out, although I would have eventually!
There's a reason for everything!
If I could just get my wheels built, and fix the magneto drive, and then ride the thing, and then worry about the things are actually a problem, I will have moved along a bit!
Cheers, Paul

[cardan]

If I could just get my wheels built...

If you weren't on the other side of the world you could bring your wheels around this afternoon and fit them tomorrow! Is it just lacing and truing, or is there a bigger problem?

Re the gearbox bolts: are the threads into the aluminium, or is the gearbox case - like the racing bikes in 1920s - fitted with cast-in steel or brass inserts? The idea of screwing mounting bolts straight into the aluminium is a bit cheap.

Cheers

Leon

[Doug]

The EW gearboxes do not have steel or bronze inserts, but they did use approximately 3x diameter or maybe a little more thread engagement in the aluminum, presumably to compensate for the softer metal.

-Doug

[cardan]

Oh well, keep the threads clean, use some lubricant, and do the bolts up tight but not too tight!

Leon

[Doug]

Leon,

There is a built-in tourque limiter for the bolts. Too tight and the cast aluminum clamping plate fractures! That is if it is a 1927 and onward EW.

-Doug

[Daren W Australia]

Hi Neil asked me for a how, too this is what I did to check inside my EW gearbox.

Remove all ¼” nuts including the one on the back of the bolt but don’t pull out the bolt see red arrow as it is attached to the clock spring, also leave kick start lever attached. Use kick start lever as a handle the cover it should come of easy.

Next undo counter sunk screw, leave the sprockets on slide cover off the kick start ratchet will go through the cover.
Undo the sprockets (I used a rattle gun) tap the shafts out using a plastic hammer if you are lucky all the rollers will stay in the housing, I didn’t remove the gear selector just tilted the gearset a little to give access.

It takes about 10 mins to disassemble and about 20 to refit as I was only checking to make sure they were complete and working in the future I will sort bearings and lube them
.
The cush drive was fun to put back together any hints?? I sat it on a socket clamped it to the bench until I could fit the nut. Is there a spanner to do this job?

Ta Daren

Ps photo would not load I will send it to Doug K


[Image attached.  11Jul21 -Doug, Admin]