Furyous
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| posted on 3/3/16 at 05:51 AM |
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Looking for suitable gearbox mounts
I'm looking at making a gearbox mount like the (very!) rough drawing below. Can anyone recommend some suitable rubber mounts?
Blue is the gear box, black is a 3mm plate and chassis brackets. Red are the rubber mounts.
I'm looking for rectangular mounts up to about 50 mm wide, 150 mm long (or 3 in a row at 50 x 50 mm). Height isn't massively critical,
although I don't want them too wobbly. The mounts could be angled on top like in the lower drawing, and I think that would actually be better to
stop sideways movement.
 
Description
I do have a square bobbin here with me for an exhaust which seems a nice size, if a little tall, but I'm not sure if a few exhaust mounts would
be stiff enough?
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HowardB
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| posted on 3/3/16 at 07:14 AM |
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is that for a type 9 rear mount?
If so I bought a HD ford one,. about £10 or something...
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again  and goes zoom)
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Furyous
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| posted on 3/3/16 at 07:40 AM |
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It's for a Mazda MX5 5-speed. It has some M14 holes at the bottom going front-back but they're level with the bottom of the chassis.
Can't lift the gear box any higher and can't have a rubber mount under the gearbox. I did try turning a Type 9 mount 90* a while ago but
it was too narrow to fit onto the Mazda gear box.
I should have clarified that the drawing was looking forward through the transmission tunnel.
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HowardB
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| posted on 3/3/16 at 08:13 AM |
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ok, understood.
Have you tried trelleborg AV, or similar?
boing
hth 
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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mcerd1
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| posted on 3/3/16 at 08:26 AM |
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Have you got some pics of the gearbox in the chassis?
(I've googled for pics but can't see any that sound like your setup - most look like they have more space underneath)
My vote would be for the setup shown at the top of your sketch.
Your engine mounts should be taking care of any twisting loads etc - by making the gearbox mount that can take too much of this sort of load can
actually create extra stress.
The basic principle to avoid over constraining it is to support it at 3 points (because tripods are naturally stable and self aligning) and avoid
having 2 mounts trying to restrain the same direction of movement.
So if the 2 engine mounts acting together can restrain it in nearly all directions and rotations - they only need the gearbox mount to hold its weight
up (and stop it pitching up and down) - any more than this and it can create stress as the different mounts fight each other....
[Edited on 3/3/2016 by mcerd1]
[Edited on 3/3/2016 by mcerd1]
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Smoking Frog
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| posted on 3/3/16 at 10:05 AM |
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quote:
50 mm wide, 150 mm long
Why do you need them so big? Won't a rubber bobbin say 30mm dia each side do. As said it's the engine mounts that take most of
the weight.
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Neville Jones
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| posted on 3/3/16 at 12:07 PM |
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We've been using polyurethane TVR suspension bushes from SuperPro here for engine and gearbox, and even diff mounts, since the late
80's.
They fit into 1 1/4" od x 10g tube.
Done a few MX gearbox rears, just as you require. 5 & 6 speeds are the same.
Cheers,
Nev.
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Adamirish
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| posted on 3/3/16 at 04:39 PM |
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I used these in my mk3 2.0 fiesta conversion. Coped with the power no problem. Albeit it was FWD. cheap to replace too.
https://www.ebay.co.uk/ulk/itm/121575605331
MK Indy 1700 Xflow
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big-vee-twin
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| posted on 3/3/16 at 08:36 PM |
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I did the same and used TVR gear box mount rubbers.
Duratec Engine is fitted, MS2 Extra V3 is assembled and tested, engine running, car now built. IVA passed 26/02/2016
http://www.triangleltd.com
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mark chandler
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| posted on 3/3/16 at 08:57 PM |
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Land Rover Series 2, 2a & 3 Engine and Gearbox Mount NRC2052 277513
Locost and plenty strong enough for bouncing around a field.
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Furyous
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| posted on 3/3/16 at 10:02 PM |
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They don't need to be 50 x 150, that's just how much space I have and I wasn't actually sure what size I could get away with.
Those Fiesta and Land Rover ones look like just what I'm after, thanks.
If I just have one mount on each side, I could bend some 50 x 5 mm bar to shape and bolt it to one of the holes on the gearbox. That seems like a
simple way to do it. Poly bushes would need a bit more fabrication with brackets etc.
I did come across Markymark's Fury build with the RX8 gearbox. The box is a little different but the mounting point is the same. In mine, the
bottom of the gearbox is level with the bottom of the chassis. I don't have any space to lift the box up at all, so I'm not sure
what's different with his.
Again, that's a bit more fabrication than just a bar sitting on some rubber bobbins.
 
Gearbox mount
http://www.locostbuilders.co.uk/forum/4/viewthread.php?tid=160426
Edit:
Here's how I've got it mounted now. It was kind of a temporary thing to get the car moving around. My plan is basically the same but with
rubber mounts on the chassis brackets and the metal plate/bar bent to sit on top.
 
Description
[Edited on 3/3/16 by Furyous]
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DIY Si
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| posted on 8/3/16 at 11:16 AM |
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Whilst I've got the earlier box, and it's mounted a little differently, this may give you some ideas for other options if you need them.
My rubber exhaust bobbins sit inside the bit of cut open box section. This arrangement should work as well if the tubes that bolt to the chassis were
angled down rather than up.
 [url=https://flic.kr/p/oi8BBk]
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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jps
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| posted on 22/1/18 at 02:23 PM |
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quote:
Originally posted by Furyous
Here's how I've got it mounted now. It was kind of a temporary thing to get the car moving around. My plan is basically the same but with
rubber mounts on the chassis brackets and the metal plate/bar bent to sit on top.
Description
[Edited on 3/3/16 by Furyous]
I'm planning to do something very similar - did you finish this off in the end?
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