Engine adaptor plate. How thick ?

[Smallfry]

As title. making an adaptor plate to couple the wrong gearbox, to a wrong engine. I see most commercially available ones are made of alloy, and are usually quite thick, but apart from the weight, whats wrong with steel ? It is a LOT cheaper, and more readily available.

Any reasons NOT to use it ? Engine block is iron, and gearbox is alloy, as are a lot of OE fitments

Difference between the two units is about 100mm diameter, so about 50mm each side, so if made from steel, how thick ?

Is 6mm thick enough, so as not to distort, or would thicker be better, 8 or 10mm ?

I need to make up 35mm thickness in total, but at least 25mm needs to be a "simple" spacer, rather than an adaptor, which I could make up from segments if necessary.

 

[dan.taylor.1]

How much power/torque is in the equation? How is the engine and box mounted, will the joint be stressed or literally just holding the 2 apart.

Also are you planning to thread the adapter, or use bolts and nuts with through holes? If threading it ideally it wants to be at least the diameter of the thread thick with steel, 1.5x with ally I believe.

 

[fizzy]

If the bolts are pretty hefty and there are a good number I doubt it matters much.

 

[fizzy]

Here is a steel one - they say good for up to 1200bhp.
Doesn't look that thick. Perhaps 6 or 8mm?

SR20DET to 350Z Gearbox Adapter

This is the Protuner Nissan SR20DET to 350Z Gearbox adapter kit it is the best Gearbox solution for high power SR20 engines. Our plate makes the strong and refined 6 speed 350Z gearbox bolt up to the SR20 engine. The 350Z gearbox is superior to the SR20 RB25 and 300zx in both strength and shift...

protuner.co.uk

 

[hotponyshoes]

Is a suitable piece of steel actually cheaper?

When you get to 35mm of thickness a piece of alloy plate will probably be flat enough to use 'as is'
Most of the lumps of steel you'll see floating about cheap might well need a bit of work (which is fine if you've got the capability)

Also, a bit of alloy that size can be sent via carrier. Steel is a pallet.

 

[DAPPH]

I suspect it will be a controlling factor as to the thickness of the plate .. how far will the spigot still engage in the flywheel once it is in place ?

If there is a clutch , will the clutch release bearing thickness affect things . I had to grind a lot off my 1303 Beetle's bearing off when I put a VW combi 1700 engine in it.

 

[Smallfry]

How much power/torque is in the equation? How is the engine and box mounted, will the joint be stressed or literally just holding the 2 apart.

Also are you planning to thread the adapter, or use bolts and nuts with through holes? If threading it ideally it wants to be at least the diameter of the thread thick with steel, 1.5x with ally I believe.

Engine produces about 350lbs/ft, and weighs 244kg. The mountings are more or less in the centre of the engine, so is reasonably balanced. Gearbox weighs 62kg, and has mountings at the rear, so is nose heavy.

The adaptor plate bit bolts to the engine with four M12 bolts. The other part, which will be alloy I think, is effectively a bellhousing extension will bolt right through the adaptor, and will have nuts fitted, all except one, which is at the top of the bellhousing, which is under compression anyway. The sump is cast alloy, and will also be bolted to the adaptor.

 

[Smallfry]

Is a suitable piece of steel actually cheaper?

When you get to 35mm of thickness a piece of alloy plate will probably be flat enough to use 'as is'
Most of the lumps of steel you'll see floating about cheap might well need a bit of work (which is fine if you've got the capability)

Also, a bit of alloy that size can be sent via carrier. Steel is a pallet.

There are two elements to this as described earlier. I will be using alloy for the thicker bit. It is just the adaptor part I am thinking about here.

A 35mm thick alloy plate will be expensive and will need a lot of milling work, which I am trying to avoid. In the highly likely event that I will cock it up, it will be an expensive experiment.

 

[Smallfry]

I suspect it will be a controlling factor as to the thickness of the plate .. how far will the spigot still engage in the flywheel once it is in place ?

If there is a clutch , will the clutch release bearing thickness affect things . I had to grind a lot off my 1303 Beetle's bearing off when I put a VW combi 1700 engine in it.

I can accommodate the different thickness, I have worked out all the variables already so should be OK.

I have already adapted a different flywheel, with a clutch to suit. I cannot buy a ready made adaptor kit for what I am doing, and besides, they are rather too much money, and also, there is no challenge in buying one, so why would you ?

 

[Kram]

A 35mm thick alloy plate will be expensive and will need a lot of milling work, which I am trying to avoid. In the highly likely event that I will cock it up, it will be an expensive experiment.

Perhaps it can be cast in alu? Are you able to make up a wooden form?
Sand casting can be economical atleast, if DIY and recycling, but requires a bit of dry space to work.

For something like this you can recycle alu wheels or enging casings, which are both, usually a decent grade - tho try not to mix sources - similar wheels, or engine cases of the same model/manufacturer and era.

 

[Smallfry]

Perhaps it can be cast in alu? Are you able to make up a wooden form?
Sand casting can be economical atleast, if DIY and recycling, but requires a bit of dry space to work.

For something like this you can recycle alu wheels or enging casings, which are both, usually a decent grade - tho try not to mix sources - similar wheels, or engine cases of the same model/manufacturer and era.

Its an interesting idea. I had not thought of that TBH. Maybe a bit more effort than I wanted to make though. I used to make furniture, so making a form is no problem at all.
No idea how I would go about melting the ally though, and by the time I have bought everything to do it, would probably be less money and hassle to pay someone to cast it.

 

[Agroshield]

Have you considered getting it laser or water-jet cut? At the least, the postage cost could be cheaper as the whole ring in the middle stays with the cutter and is never carried in the postie's bag. Put some location features on it so you can clamp squarely onto the mill, make all the necessary holes in it and then mill away those extra pieces at the end.

 

[8ob]

As title. making an adaptor plate to couple the wrong gearbox, to a wrong engine.
I need to make up 35mm thickness in total, but at least 25mm needs to be a "simple" spacer, rather than an adaptor, which I could make up from segments if necessary.

Its worth trawling the internet for hole/dowel data off the engine and the bellhousing. With that info you stand a good chance of getting alignment correct, correct dowel locations of both are critical.

Bob

 

[hotponyshoes]

There are two elements to this as described earlier. I will be using alloy for the thicker bit. It is just the adaptor part I am thinking about here.

A 35mm thick alloy plate will be expensive and will need a lot of milling work, which I am trying to avoid. In the highly likely event that I will cock it up, it will be an expensive experiment.

It would make sense to choose the size to suit then?
25mm Alloy and 10mm steel.
10mm would be overkill in terms of strength and weight but probably a lot easier than trying to calculate exactly what you need and going with 6.8mm steel then fi ding or machining alloy to 28.2mm for example.

What's the overall size you need? I might have some alloy to suit..

 

[Smallfry]

Have you considered getting it laser or water-jet cut? At the least, the postage cost could be cheaper as the whole ring in the middle stays with the cutter and is never carried in the postie's bag. Put some location features on it so you can clamp squarely onto the mill, make all the necessary holes in it and then mill away those extra pieces at the end.

Yes, getting it laser cut would be ideal, and save many hours of work with a junior hacksaw and my blunt files selection

I understand that cannot do it by using a paper/cardboard/ wooden template, and need a DWG or DXF file. I have no clue at all how to do this, and have a learning block when it comes to this sort of thing anyway.

I will do as Bob suggests, and continue to look on the internet for them, but unsurprisingly it seems those that have them, do not want to divulge.

 

[Smallfry]

Its worth trawling the internet for hole/dowel data off the engine and the bellhousing. With that info you stand a good chance of getting alignment correct, correct dowel locations of both are critical.

Bob

I have tried this, without success at the moment. I assume they overlay the patterns for this sort of thing ?

I do have a method to get the location dowels something like right though. I have the automatic transmission bellhousings from both the engine, and the gearbox. Most autoboxes are located via a nice concentric to crankshaft hole in the bellhousing. So, by tacking a machined steel tube, which I already have to the middle of the plate, I can then slide each bellhousing in turn over the tube, and transfer punch the locations into the plate. Not CNC accurate I know, but near enough for me.

 

[GRW]

It's not the same but.... the forces will be considerable, so just as food for thought..
When mating big industrial alternators to engines the rotor coupling disc that mates/bolts to the flywheel - even on stuff around 500hp & which is the only connection between all that engine grunt and the rotor... can be a single disc of about 3mm steel, with 6/8 bolts in the centre (rotor boss connection) and about 12 bolts around the periphery (flywheel connection).
On that basis I'd think that a static steel adapter plate of 8mm thickness firmly bolted between an engine block and a gearbox bell housing to be very strong indeed.

 

[Morrisman]

6mm will be ample. I’ve not made adaptor plates but I’ve done a couple of front motor plates for V8s with no problems, and driven on worse roads than we get in the U.K. This one handled 300hp with nary a problem.

Keeping an adaptor flat shouldn’t be a problem, once it’s bolted tight to the engine block.

 

[Morrisman]

It's not the same but.... the forces will be considerable, so just as food for thought..
When mating big industrial alternators to engines the rotor coupling disc that mates/bolts to the flywheel - even on stuff around 500hp & which is the only connection between all that engine grunt and the rotor... can be a single disc of about 3mm steel, with 6/8 bolts in the centre (rotor boss connection) and about 12 bolts around the periphery (flywheel connection).
On that basis I'd think that a static steel adapter plate of 8mm thickness firmly bolted between an engine block and a gearbox bell housing to be very strong indeed.

The flex plate for most all V8 cars with automatic transmissions is 1/16” steel, with just 3 x 5/16” perimeter bolts to connect to the torque converter.

 

[Smallfry]

It would make sense to choose the size to suit then?
25mm Alloy and 10mm steel.
10mm would be overkill in terms of strength and weight but probably a lot easier than trying to calculate exactly what you need and going with 6.8mm steel then fi ding or machining alloy to 28.2mm for example.

What's the overall size you need? I might have some alloy to suit..

I am thinking exactly the same regarding the thicknesses now 10mm for the steel, and 25mm for the alloy.

The 25mm thick alloy ideally, because of the shape, which is not exactly circular, would be a 450mm X 410mm, but I COULD get with a disc, 425mm diameter, with a 340mm concentric hole in the middle.

Would be great if you have something that I could buy, you may even keep the offcut from the centre !!