Adapter plate design considerations

PradoTDI

Veteran Member
Joined
Sep 25, 2020
Location
MT
TDI
1991 Toyota LandCruiser LJ78 with ALH Swap
Looking for input on design consideration for building a custom adapter plate to bolt my ALH back up to my Toyota R150f transmission. I am in the process of replacing a poorly made adapter plate with excessive runout that ruined my clutch, input shaft bearing and pilot bushing. Was going to get a whole new adapter kit, but price and lead time have prompted me to explore having one custom made. I have had a precision 3D scan made of my spare bell housing and transmission case to get the bolt pattern and transmission centerline and have started drawing up an adapter plate.

I have seen suggestions to make adapter plates that have provisions for an additional motor mount, but my motor and transmission both are fairly well balanced on their respective mounts. I'm not sure how necessary that would be, but would welcome input.

My previous adapter plate did not incorporate the engine oil pan bolt locations, but I have seen others that do. I can definitely see the benefit to having more mounting points, but I am undecided if it makes sense to "capture" the oil pan. It would make it much more of a chore to remove it if I ever have to dig into the bottom end of the engine.

I will be using the factory VW and Toyota dowel pins to center the engine and transmission to the adapter plate, and the new plate will be the same thickness as the old one so I can resurface and reuse my current flywheel. My original adapter kit used a collar fitted to the Toyota throwout bearing to extend it a bit to make proper contact with the pressure plate. I would like to be able to just use a stock throwout bearing, but don't see a good way to do that without running into starter engagement issues or having the clutch fork run out of travel.

If there's anything else I should consider or incorporate into my design I would greatly appreciate input. Hoping to get a drawing finalized so I can run it by the machinist soon.
 

PickleRick

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Joined
Nov 29, 2017
Location
Greenville sc
TDI
05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
For my set up I opted for a 2pc 2 inch thick design to help the tandem pump clear the firewall.

The only gripes I had about my adapter purchased from Diesel conversion specialist were: no provisions for oil pan bolts. Quick work with a side grinder solved that. Not pretty but if you're under my rig complaining about my work you should probably start with my welds.

The other is it doesn't clock. Wasnt an issue in my case but for some this would be less ideal.

I like that I run a stock 3.0 Toyota stater. It's in stock at most auto stores if I need one. Since it made the back of the motor look like a a 3.0 v6 it enabled me to run a larger 3.4 flywheel and clutch. If I wanted to spend the cash I could have run the some 40 lbs I think lce flywheel. I don't have issues with vibes so I didn't.

The only rig I've seen that that bell mounted motor mounts was an fj40. Short wheel base and a little 10ish inch long 3 speed transmission. The r150r is very long.



If I was running 400-500 or more ft lbs of torque I can see wanting an extra set of mounts. Since I'm making well less of that I've had no issues with the stock set up of mounts. I can see it being very handy with high power rigs and/or those with huge tires and dual gear boxes.
 
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PradoTDI

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Joined
Sep 25, 2020
Location
MT
TDI
1991 Toyota LandCruiser LJ78 with ALH Swap
I'm going to be using a 1/2" thick single piece plate at a ~15-17º angle so I can retain my current motor and transmission mount locations, as well as maintaining the same position on all my coolant, intake and hydraulic hoses.

I currently run a 3.4 V6 Toyota starter, cold weather 1.8kW option and will be retaining that as well.

Thanks for the confirmation on adapter plate motor mounts, that is pretty much what I was thinking as well. Going to be adding in a few extra bolts on the transmission side, possibly the oil pan bolts as well. When you say no provision for oil pan bolts, were there no holes or no clearance to access the bolt heads? If I go with oil pan bolts they will be inaccessible with the transmission installed.
 

PickleRick

Veteran Member
Joined
Nov 29, 2017
Location
Greenville sc
TDI
05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
There was no clearance to access the rear oil pan bolts with the engine adapter installed. I sent pics to DCS as that's something I'd remedy if I was them. No idea if they cared.
 

PradoTDI

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Joined
Sep 25, 2020
Location
MT
TDI
1991 Toyota LandCruiser LJ78 with ALH Swap
Another thing I have been pondering is some kind of corrosion protection for the adapter plate. It will be mild steel and therefore prone to rusting and the hardware seizing in the threads. My old adapter was electroplated in yellow zinc and held up fairly well, but I don't have local access to electroplating facilities and shipping would likely be cost prohibitive.
 

PickleRick

Veteran Member
Joined
Nov 29, 2017
Location
Greenville sc
TDI
05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
Could you powder coat? Will likely scratch up as you install and remove the adapter but I suppose it's better than nothing
 

03Golfer

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Apr 8, 2020
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Canada
TDI
03 Golf, 92 Toyota swap (ongoing)
Just curious why you're concerned about rust when cast iron has been used for engine blocks for years? Don't get me wrong, powder coat or plating would be nice, but I'd throw some rustoleum on there and grease the bolts on install.
 

PickleRick

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Joined
Nov 29, 2017
Location
Greenville sc
TDI
05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
He's in Canada...they treat the frozen white stuff up there quite often
 

03Golfer

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Apr 8, 2020
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Canada
TDI
03 Golf, 92 Toyota swap (ongoing)
Me too... I'm more concerned about corrosion on my aluminum adapter plate than I would be with steel
 

PickleRick

Veteran Member
Joined
Nov 29, 2017
Location
Greenville sc
TDI
05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
You'll find plenty of unpainted aluminum on marine applications. From window frames to 60 plus ft masts. You won't find any unpainted steel as it will rust overnight.
 

PradoTDI

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Joined
Sep 25, 2020
Location
MT
TDI
1991 Toyota LandCruiser LJ78 with ALH Swap
I’m not quite in Canada, but not too far south. We get our fair share of magnesium chloride on the roads in the winter and stuff tends to rust pretty quickly. Mostly I’d be concerned about the aluminum bellhousing mounting to a bare steel plate. Paint is probably the best option, was thinking about either a cold galvanizing zinc paint with top coat or something like Master Series Silver with top coat.
 

PradoTDI

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Joined
Sep 25, 2020
Location
MT
TDI
1991 Toyota LandCruiser LJ78 with ALH Swap
Getting close to having a design I can take to the laser cutter and then the machinist. I'm planning on water jet cutting a test plate from some 1/4" polycarbonate sheet I have just to confirm all the bolt holes line up properly before I start in on the steel version.
 

PradoTDI

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Joined
Sep 25, 2020
Location
MT
TDI
1991 Toyota LandCruiser LJ78 with ALH Swap
Design phase complete, manufacturing phase has begun! The part is laser cut and currently at the machinist getting the rest of the holes punched in it.
 
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