Your assistance in designing a tranny cross member

[oldeskewltoy]

One of my "pet" projects is FINALLY coming to fruition.......

The J160 6 speed transmission that was fitted to the IS200("G" powered) and the Altezza("S" powered), I am now fitting to my AE71




Above is a LEEN adapter mounted to the J160, below is a view of the J160 with its original cast end/bell, and a similar view with the LEEN adapter




I did a number of measurements....

Length of LEEN J160 to shifter cup



and the floor of the car. I used the metal plate of the engine to measure the body length needed, and I got VERY lucky....

The reinforcement that runs across the floor was about 3/8" shy of the length to the transmission's shifter cup.... I get to keep the reinforcement!

Floor before and after alteration....



.... and the actual floor measurement




Feeling confident that my lengths will be good, I proceed to check clearance for the J160 selector rod - it operates out of the back of the transmission, and "sits" under the shifter cup.



I get lucky here too, the floor is shaped similarly to the reinforrcement member I've saved, a small radius cut should allow more than enough clearance for the selector rod.


So now that the car seems ready, and the transmission seems ready... the one final part to engineer is the rear transmission cross member and how it is shaped.


Here is the T50, and the J160 with their own respective mounts......



They are completely different........ different lengths, and depths......

(limit on photos reached continued in next posting)

[oldeskewltoy]

Remove the cast aluminum cross member and if you are "visual", you see the rubber mount begins to describe the mount IT wants....







So I go with it, and let it design itself






Once the design is done, I have a friend build me a prototype....




NOT exactly what I wanted... WAAAY too chunky


Prototype 2 is a far better match to my desire





Once the trans is attached to the engine... we raise the J160 into place......



It looks pretty good here.....



..... and here....




.... and here!

[oldeskewltoy]

The rough installed views so far........






In the above view the new cross member needs a bit further shaping... on the right side you see a marker drawn triangle, this area needs to be removed for speedo cable clearance. The lines drawn is my current idea for reinforcement - plates will be added along the long drawn lines to reinforce the plate in two planes - along the flat that mounts to the body, as well as the reinforcing the drop.

The final unit has not yet been finished/finalized. I've posted here to hear simple ideas on reinforcing that new cross member, and if mine are inadequate.... So let me hear what you have to say............

[oldeskewltoy]

[thechuckster]

Nice gear stick position - hands fall off the steer wheel right onto the gear stick. Out of interest, in the pics above what gear is it in? And what length of throw do you get from the stock J160 box?

Nice to see the cross member not have welds at the bends

It just needs some triangulation across the upper bend so it wont bend when twisted around the drive-line axis. You could probably add some lightness to it with a hole saw?

[oldeskewltoy]

Nice gear stick position - hands fall off the steer wheel right onto the gear stick. Out of interest, in the pics above what gear is it in? And what length of throw do you get from the stock J160 box?

Nice to see the cross member not have welds at the bends

It just needs some triangulation across the upper bend so it wont bend when twisted around the drive-line axis. You could probably add some lightness to it with a hole saw?

it is in neutral.

the throws are about 3 1/2" from neutral position to any gear - as measured from the top of the shift knob

[oldeskewltoy]

Usind CAD(cardboard aided design), I further refine the design to offer additional structural support

[SHEPPO3930]

that will be more than strong enough... as long as you replace the cardboard with some steel :-P

[wagonist]

See how the original cross member has a bent edge all the way around?
I'd suggest an additional pracing going around the edge of the plate to the outside of the holes, but still have the cardboard shapes as is (you may be able to delete the brace across from the top then).
there's still a chance of the plate bending from the mounting point onto the car.

[oldeskewltoy]

Here is the finished cross member.... the welding is only fair in appearance, but there is plenty of penetration. You can kinda get the idea of the shape, and the reinforcement

[wagonist]

Is there another gusset plate to be welded on where you're holding it with the pliers? It's shown on you cardboard mock up.

Don't forget that the gearbox is putting downward force on this setup. You've accounted for any bending caused by moving the gearbox mount forward so they're not in line with the bolts on the car, but you've only slightly accounted for any bending across the car.

The plate isn't that thick.
If it was my car, I'd be welding another plate across where the other cardboard piece was, and also some sideways gussets plates between the mounting point on the car.

Any cushioning of movement due to engine movement or rough ground should be taken up by the rubber bushes, not the cross member.

[Supra967]

+5 points for expert use of CAD tools, -2 points welds, -2 points ignoring CAD layout and missing extra stiffener. Net result is positive so should be fine

[4th surf]

Now aside from nice shifter position and mounting what have you done in respect of driveline angles? You can build the nicest crossmember ever but the sign of a good conversion is there is no vibration at speed on the first drive

[oldeskewltoy]

The design with the gusset going across the back was excessive.... Colin Chapman wouldn't approve Believe me this is more than adequate in strength.

Now aside from nice shifter position and mounting what have you done in respect of driveline angles? You can build the nicest crossmember ever but the sign of a good conversion is there is no vibration at speed on the first drive

My design for the mount was based on keeping the output shafts in similar positions.



I'm retaining the 2 piece driveshaft... I'm having it rebuilt, balanced, and a new carrier bearing installed. The Supra (W5x) shaft I'm using will only need to be shortened by 3/8"

[oldeskewltoy]

still waiting on the driveshaft - should be ready later today.... for now.......