Enfield 1996 frame reinforcements

Bodywork, Engine Mounting, Frames, Sub Frames, Forks, Suspension etc..

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Sphere
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Enfield 1996 frame reinforcements

Post by Sphere » Thu Apr 09, 2009 2:20 pm

Is it necessary to add reinforcements to the Enfield frame if you want to mount a diesel? There's nasty stories about frame cracks, but I'm not sure about their validity/cause. It would be nice to do welding to the frame before powdercoating :lol:
'92 Enfield + Hatz 1B40: street legal, weld up stainless exhaust, check engine rpm and change final drive sprocket.

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Re: Enfield 1996 frame reinforcements

Post by Sphere » Thu Apr 09, 2009 2:34 pm

On the German Enfield wiki there is a mention of using an Audi absorber in the frame mounted to the cylinder head:

http://www.enfield-wiki.de/index.php/Flatterd%E4mpfer
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Flatterdampfer.jpg
'92 Enfield + Hatz 1B40: street legal, weld up stainless exhaust, check engine rpm and change final drive sprocket.

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Re: Enfield 1996 frame reinforcements

Post by Diesel Dave » Thu Apr 09, 2009 8:32 pm

Cool idea,

A bit of overkill on the shocker size!

An old Enfield rear with the spring removed might be more descreet.

Dave

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Re: Enfield 1996 frame reinforcements

Post by Anorak_ian » Sun Apr 12, 2009 9:46 am

I thought it was only the rocking motion of twin engines that caused this problem?

Maybe this is a bit of hysteria.

The bike in the pic has a single cylinder engine, a bit like yours Dave, how many miles have you done and have you spotted any frame problems?

For twins, I'm wondering if welding a thick steel plate running from the underneath of the backbone, back of the head stock, and down the down tube would do the job?

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Re: Enfield 1996 frame reinforcements

Post by arnaud » Sun Apr 12, 2009 1:56 pm

As you might recall, i wrote here some stuff about it.
Be sure that the subframe is capable of giving the same rigidness as the engine original does.
I made the mistake to forget about the connection of the 2 lower plates under the gearbox which originally are bolted to the rear of the engine. The frame was bending and solely supporting onto the bracket between the 2 rear frame tubes.
I mentioned this so others do not have to make the same mistake!

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Re: Enfield 1996 frame reinforcements

Post by Diesel Dave » Sun Apr 12, 2009 3:45 pm

I've had no frame issues in 92,000 miles apart from wearing out 2 centre stands and 3 sets of bottom engine plates and 2 sets of top ones.

Over time the holes get enlarged and the studs get a wear groove that allows the engine to move more.

This might have been due to not using a head steady until 2007, so the engine could rock.

At rebuild time I'll ream out the mounting holes in the frame to an accurate round size and turn up interference fit studs. I'm considering adding an additional set of lower engine plates so I'll have a 4 bar ladder and doubling up the triangular top plates. This will create a much stiffer connection and 'lock' up the frame better.

Dave

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Re: Enfield 1996 frame reinforcements

Post by Sphere » Sun Apr 12, 2009 6:34 pm

I've studied pics on the web of the altmann conversion and andrew's conversion, and it would seem their subframe is *not* bolted to the frame (at the back), just to the gearbox. I can't imagine cast aluminium (of the gearbox) is strong enough for that.
'92 Enfield + Hatz 1B40: street legal, weld up stainless exhaust, check engine rpm and change final drive sprocket.

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Re: Enfield 1996 frame reinforcements

Post by Diesel Dave » Sun Apr 12, 2009 7:19 pm

The gearbox does carry most of the strain of the engine.

Even on the Mighty 700cc Interceptors the system was the same albeit with a strengthening plate behind the gearbox but this was on the open Brit frames that did not have the upper gearbox mountings (triangular plates)

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Re: Enfield 1996 frame reinforcements

Post by Sphere » Sun Apr 12, 2009 8:43 pm

So you are saying, don't worry...
Diesel Dave wrote:The gearbox does carry most of the strain of the engine.

Even on the Mighty 700cc Interceptors the system was the same albeit with a strengthening plate behind the gearbox but this was on the open Brit frames that did not have the upper gearbox mountings (triangular plates)
But, what is the "top one"? Top engine plate? What does your subframe look like :? It surprises me you haven't experienced wear at the gearbox, but I don't mind :lol:
Diesel Dave wrote:I've had no frame issues in 92,000 miles apart from wearing out 2 centre stands and 3 sets of bottom engine plates and 2 sets of top ones.
'92 Enfield + Hatz 1B40: street legal, weld up stainless exhaust, check engine rpm and change final drive sprocket.

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Re: Enfield 1996 frame reinforcements

Post by Diesel Dave » Sun Apr 12, 2009 9:39 pm

Here's the top plates I was trying to describe - the triangular ones:

Image

This is the later brit frame, there is no 'down tube' to the top of the gearbox as on the earlier frame used by the Indian factory.

Image

Dave

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