It is beautiful

Hey D, loving the M16A.

Here goes nothing, this will probably confuse you rather than give you a picture of whats going on.

The symptom is a violent vibration through the whole car when you back off the power or when you cruise up to 80km and back off to just coast. It gets worse if you put the clutch in and roll at 80km and is also very bad coasting in 5th.

Through process of elimination and coountless hours off looking we have narrowed it down to the tail shaft. Had the car up on stands in gear and it just doesn't look right. With the car on all fours I have too much play up and down where the tail shaft slides over the output shaft on the box.

The shaft could be too short. So I un-bolt it from the diff and slide it in and the play becomes acceptable, I slide a touch further and it hits webbing on the box. I then notice witness marks on the very front yoke and the grease nipple has worn down where it has contacted the gearbox. Its hitting as the suspension travels and diff kicks up.

You really need to know what a sierra box is like. There is a large section for the gear selector the sits above the output shaft. So a good 6 or 8 inches of shaft along with the uni's spin under the gear selector.

So i'm thinking the shaft is too short and causing vibration. Sierra's run a remote transfer case with a short shaft thats bolts to a flange on the transfer case. The short shaft and box must have little clearnce as there is very minimal movement. Its not coping with normal suspenion travel.

Whats your thoughts?
Do you have any idea what I just posted? because I don't

2 piece shaft?

Its sounds like the uni doesnt let the tailshaft move up and down freely.
You will need to take it to a diff place they should be able to rectify
the issue or let you know how to solve it. you might need a two piece
tailshaft (the shortest section from the box) with the support then having
the longest part to the diff.
I remember Ford escorts having a similar issue when I went to a single
tailshaft from the two piece one supported one.

Datsun 1200 utes with long body use a 2-piece tailshaft. Maybe you could adapt that. The center bearing is the same as Nissan D21/D22 Navara pickup.

Tailshaft

Yeah thanks boys, thats what I was thinking. Or, I could just use the RingR and a w50 or w55 and be done with it.

I honestly would prefer a worldclass BW T5 Gav, only because the W55 (not 50 its a diff box)
and w59 are the only ones avail at the moment from late hi-lux and some chinese copies.
These boxes have like 3.9 or 4.3 first gear which is useless.
The t5 box has racing close ratio kit for 1200usd and it has a choice of 2.6 or 2.8 first
as far as i recall that would be the ultimate box compared to the W series Toyota cost of
8000aud for the close ratio gearset.
I know 1200usd is a lot to fork out on top of a $250 falcon box, but the auto vitara bellhousing
has the same depth as the T5 box and would cost less than your custom dizzie to adapt.
You would need a new tunnel again though for those boxes so it might be worthwhile to
try a 2 piece tailshaft (as DDs pic shows) where you can keep it and just change the input shaft on the
short one to the box rear for another box later on.

I would like your view on the sierra box ratios? whats the first gear like? does it run
out of revvs quickly or have some other gears wrongly spaced?

With my engine I forgot to mention to anyone interested
I also have the coilpacks and top cover.

isnt the idea with the suzi engines to have an engine thats still light, kinda going backwards if you use a T5 or W series as you dont need the strength and they arent really a light gearbox

An extra 10kg in the middle is still better than 25kg extra from an A series engine.
As I discored in Simon comprehensive T5 bible it only weighs 35kg and that with a
suzuki engine is still better than a 42kg 71 series gearbox matched to a cast iron engine.
If the suzuki gbox weighs 7kgs less than a T5 it still costs a fortune to rebuild or get
parts for as it only handles less than 120hp.

It all adds up for sure. Gav is maybe already aware of is shortcomings as the suzuki
sierra box was internally designed/made for kei sized engines and never intended
for a twin cam gti motor. It marginally accepts a 1.3 8v engine so anything over
120hp is quickly the end of them and they are a sought after box in the suzuki
community due to this issue. The jimny box is a better unit with improved synchros
and strength to suit a the whole range of M series capacities 1.3-1.8.
But has no easy way to adapt to a G series.
In todays major adaption to FWD vehicles anything RWD is a challenge for unique
conversions yet its good to know there are options out there for improvements.

Gav, there is also the option of a 30kg rwd 626 and 929 box but needs the bell
cut and shut which can only be done by a specialist. As mentioned earlier the
mazda box is a factory close(r) ratio setup favored by NA rotary guys over the years.
I say closer as its not exactly close but good enough compared to the rest.

Without running down the 1/4 I think the ratio's are good in the sierra box. 1st gear is ok which was my main concern. Still haven't been able to give to much punishment so time will tell. If they only handle 120hp, I don't know how long it will last. I must add that they have no speedo drive.

Im confused, I thouht the RingR was only to adapt a w series box. Will T fit aswell? The 626/929 sounds good but I wouldn't know where to start looking to get bell housing done.

I think im going to try a two piece shaft and start my stock pile of boxes.