JZA80 diff mount upgrades

[clubagreenie]

Whilst fitting the harnesses to the supra (2J N/a) I noticed that the rear crossmember has a large rubber donut with two bolts mounting the diff. To the right (looking from rear) there is another hole with a single bolt hole, unused.

According to Ed's research the TT's/6speeds have heavier duty mounts fitted to both holes. Approximately $140- and can be fitted in about 10 minutes. A worthwhile upgrade to anyones driveline at a reasonable price in an area that's usually overlooked when replacing bushes.

Pics to follow when upgrade performed.

[edwagon]

Great to see some discussion on this much overlooked topic, I need to do this to both my jzz30 (mount both sides) and my jzx91 (only has left hand side mount- same as your jza80).

One of the problems that you may come across is that apart from missing the rubber bush on the right hand side, the subframe is also missing the outer sleeve for the right hand side mount, therefore there will be nowhere for you to fit the new bush into.

you may also find that removing the old bushes requires them to be knocked back out from the front, ie, you may need to drop the diff head and push them out backwards. you may also be able to push them out fowards by knocking them from the rear, but of course they still won't fit out past the diff head!
I doubt that it'd be possible to pull them out from the back, they'll be pressed in place. it would be possible to cut through the outer shell with a hacksaw blade and collapse the outer shell, but in that case I think it'd be easierto just drop the diff!

In any case, sadly, it doesn't look to me like a 10 minute job.

I'm going to jump on the lathe and make up a set for each of my cars (and a sleeve for the missing right hand side mount) and will let you know how i get on with it and any improvement, but in the meantime, anyone else whos done this, you're input would be great!

[ed]

I'm going to jump on the lathe and make up a set for each of my cars (and a sleeve for the missing right hand side mount) and will let you know how i get on with it and any improvement, but in the meantime, anyone else whos done this, you're input would be great!

want to make x2 sets?

[edwagon]

I'll let you know how I get on with them, but yeah, Ive gotta make 2 sets for myself and a third for a mate anyway, so extras shouldn't be a problem.
I havn't designed anything yet, so they might not work out, I don't want to promise anything in case they end up too expensive or don't work or whatever.

As long as you're not in a screaming hurry, and can wait until I can test some out :-)

And theres always genuine ones if mine don't happen! how much did you price them at? and did you have the part numbers?

[edwagon]

Ive had a look and a measure and I will probably use Devcon 80 urethane to pour new mounts. I'll use the original outer shell and bolt holes, with a thick steel ring between them as an extra layer to stiffen and minimise the use of urethane ($!).
I have also seen mounts available which are just solid steel, I know they'd be a bit harsh perhaps, but how bad would it be for the street? The subframe is still rubber mounted, so it would only be changes in torque which it would transfer more harshly. It would certainly stop the diff from moving around! has anyone tried this? - It would be alot easier and cheaper than urethane and reversable if it was too bad.

[ed]

we were considering getting the whole lot hachined out of a chunk of like nylon or something (justin knows the name of the stuff - he spoke to the supplier)

we supply them with a CAD, they machine it.

i was thinking of knocking out the outer metal ring and going back to the bare hole in the x-member. machining up the 2 pieces to fit into these holes from the back of the car, with a shoulder at the rear so they pull down and locate when tightened.

the centre holes would be machined straight into the centre, and havce metal tubular inserts

[edwagon]

I went down that same road when i was making my subframe-body cushions, and buying a billet of nylon big enough and soft enough was bloody expensive, can't remembeer the price offhand but it was enough to put me off the idea!

If you can get it cheaply enough, then it'd be the way to do it IMHO.

I am very tempted to try the solid idea, as can always machine it back out easily and its the cheapest/easiest way to start! just as long as it doesn't break the mounts off the hat....

[clubagreenie]

I'd be worried about solid mounts not so much tearing but at least with the power and harhness of delivery they would receive at some stages deforming the holes. A double steel ring with a say 10mm space poured with urethane (90 is good (same duro as skate wheels(that gives me an idea))) would be stiff while still absorbing.

I spoke to a random plastics shop in chatswood and they can do anything with anything (believe me their displays of pinion/racks in plastic was impresive) including machining nolethane. They had a black polyurethane that come in 900mm stock lengths, and should be large enough to fill the mount hole and the guy seemed positive when described it intended application that it would do the job. 900mm should get at least 3 sets I'd say.

Does anyone have measurements or drawing already?

[edwagon]

A double steel ring with a say 10mm space poured with urethane (90 is good (same duro as skate wheels(that gives me an idea)))

Great!, looks like the double steel ring idea with urethane inserts has been seconded
You reckon that 90 grade would be better than 80? is that grade available in a devcon pack or sim?

And yeah, I have been keeping my eye out for an existing product that we could adapt to suit, the rear subframe cusions that i made used rubber coupling inserts which i found lying around as 'old stock', and worked perfectly. I had to make up an outer adapter ring so they'd fit, but that actually helped the stiffness alot so worked out very well.
Also an existing product has passed QC etc already and don't have to worry about voids in the urethane or wrong mix or whatever. I hadn't thought about load skate wheels- I'll see if I can find anything!

Let us know what a billet of the urethane costs, the quote i got for it looked like a telephone number, but you may be getting looked after alot better than me!

[clubagreenie]

If someone can get the appropriate measurements I'll see what's in the mackay catalogue. Who knows what'll turn up in there.

What's a load skate wheel?, I was talking about skate boards

In hindsight pouring some will still be expensive as new inner/outer shells have to be made, at least for the second mount. I'd rather buy and turn nylon.

Pouring the original 2 bolt mount might be a hassle lining up the inner and outer unless a temporary bridge was welded across until poured.

Need info for sizing people.

[ed]

blagh

i just went and bought one...



cheers
ed

edit - pic will work when ftp client comes back to life

[ed]

fixed.....

[clubagreenie]

MAke a note of the part no. The nob at toyota wouldn't give it to me as a reference for when I called back to order, when I pointed out it would be on the pack it really confused him.

Also FWIW Penrith toyota MUCH cheaper than Castle Hill (>$50) not incl toymods discount.

[ed]

thats a fucker to get in without taking out the whole cross member... which we didnt