undertray

[ERIC BAYLISS]

Just another question, can any one please tell me if the gearbox undertray is the same on a B/ham as other models. at the moment I have got a gearbox but no undertray or engine.thanks eric

[ERIC BAYLISS]

As there are no replies ,I take it as nobody knows, only I don’t want to buy one for a pre B/ham if its not going to fit eric

[scott596]

Hi Eric as far as I know the early long frame flyers that had the straight back crankcase used a different shaped undertray that had a tapering section into the bottom of the crankcase, I think the gearbox was set back a bit further, wether the rear mounts were any further back I don`t remember but as the rear clamps were moveable this would not be a problem, but the early trays did not have the large hollow bolts at the back like the post war/ Brum trays, so if you see a tray with 3/8″ holes at the back it wont be any good for a Brum Scott. Alan Noakes. scottworkshop@hotmail.co.uk

[PaulR]

Dear Eric, Geoff Case is the man to contact re Birmingham Scotts, Regards

[Oldguy]

Just found this topic and would like to ask the following, what undertray should be fitted to a 1938 Flyer?

The one I have has the 5/8 holes for the hollow bolts at the rear, the problem is that to fit the clamps I have to spring the frame with a pry bar due to the tray being hard against the lower tube.
The tray rubs against both lower tubes even without any inner clamps, so something seems wrong, this also impacts on the gap at the frame rear.
I should also add that the tray looks rather new when cleaned.
Mike.

[Geoff Case]

Hi Eric, Post war Shipley Scotts and the Birmingham model use the same under tray. Not sure ,but I think some pre war bikes have this tray too. I will ask my expert Graham G. and get back to you.

[BRIAN MARSHALL]

From about 1929 to 1972 the same tray will fit Flyer, Rep, Sprint Special, Clubman, etc..
Brian

[Oldguy]

Thanks Brian, that is what I needed to know. Will crack on with what I have.
Mike.

[BRIAN MARSHALL]

It shouldn’t be fouling the frame tubes ! Can you measure the full width of the tray over the rear lugs, and the distance between the frame rear lugs, so that I can compare with trays and frames here ?
Brian

[Oldguy]

When clamped in position,it does not foul obviously, the width across the tray lugs is 8-1/8″ which seems to be a “correct” measurement if we accept “whole” numbers.
Without the inner clamps it rubs on the frame rails.
The rear spindle lugs are now 5/16″ (8 mm for the young’uns) apart, was 3/16 max before fitting the tray.
Also the rear spindle nut now needs much more force to tighten which is understandable given the extra spread and shorter run.
So, being used to younger machines from the 50’s, is this normal?
I have always been taught that if you have to use force to fit anything, then investigate and question.
Hence this post! 😳

Mike.

[Oldguy]

Brian, my apologies, the original distance measured from the inside edges of the rear frame lugs, was 7.860″ which I assume should be a nominal 7.875″
This was the “at rest” position with no tray present, the frame was quite flexible.
With the tray in position the inside measurement is now 8.015 and somewhat more rigid.
I hope this helps.
Mike.

[Geoff Case]

Hi Eric, Graham G confirms Brian”s info that under trays from 1929 to the last of the Brums are compatible. The other tray used on scotts was longer from an earlier period . At a Scott Rally some years ago I saw a bronze? under tray for sale, looked just the job until I picked it up, It weighed a ton!

[BRIAN MARSHALL]

Mike, I have just measured a couple of gearbox trays and frames. The trays are both 8 + 1/8″ inches across the rear mounting lugs, like yours, so it sounds as if your frame is a bit distorted. Both the frames I measured are 7+5/8″ between the rear axle slots, which is a bit LESS than yours, so I’m more than a bit puzzled…. Are your rear frame members perfectly straight ?
Brian

[Oldguy]

Brian, that I will have to check, visually it all seems symmetrical with nowt to draw the eye.
The rear lug dimensions that you give sit square nicely with the book measurement across the rear wheel nuts of 7.687″.
It all looks a little odd!
I am beginning to wonder if the poor old girl used to have a sidecar fitted, that could have put all sorts of stresses into the frame.

Thank you for your input on this, I will get the measuring sticks out tomorrow to see if there is an obvious discrepancy.

Mike.

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