Outer Limits 4x4 Board

just found this in the archives


Rainbow warrior (pat) wrote:

Actually the easiest way if your going to change bearboxes is either use a MQ Patrol remote transfer case or just an MQ 5speed & transfer.
Third is always the weak point with a Holden conversion, you should get the syncro rings background to stop it popping out.

can any one explain this to me. i'm about to do a quick tart up on a series box that is jumping out of third and fourth. This sounds like a good mod.

you will find that it will be end play that causes a gear box to jump out of gear. and and once that starts it takes the the edge off the little doovas ( cant remember the name of them right now) that the sincro ring uses to match the speeds of the gears for a smooth shift. once the doovas are warn and theres excesice end play it will jump out of gear on deceleration. but mostly its the endplay thats the cause. if you want i can find the corect name of the doovas. i hope this is of help

thanks for the info - i know what you meen by doovas
i've got some synchro hubs and bits lying around which were out of an old smashed box. you can clearly see were they shag out. I was hoping to modify these with the "background mod" (whatever that is) and use them in a tightarse rebuild.

I have heard of backgrinding but have never known exactly what it was or needed to do it. If the teeth on the synchro HUB (not ring - only 1st/2nd on the SIII box have synchro rings) and the gears are good then it will be fine. New synchro hubs are not very expensive and still seem reasonable quality (unlike a lot of other series gearbox parts).

Often the biggest problem is the bush that 2nd and 3rd gears run on. It almost always breaks into 2 pieces and then wears down and moves around a lot. Another common problem is if the mainshaft bearings are worn or the mainshaft nut isn't tight - then the mainshaft moves backwards and forwards in 3rd. If you hold the gear lever in 3rd and go on and off the accelerator does the gear lever move noticeably?

thanks ben,
i wouldn't say that in third gear the stick moves much under throttle. it jumps out when engine braking down hill. fourth jumps out all the farken time. did 2000k's over christmas like this. its ok as long as every 3 mins you back off on the accelerator and nudge the stick back a bit.

wondering if rebuilding these boxes is a waste of time or can they be done up to be reasonably strong? i'm thinking polished turd, but a few guys on the old lre forum were running them behind v8's and tdi's

still don't know wether the back grinding mod is to bring back worn synchro hubs to servicable condition or a mod to stop them been damaged ? hoping the former as i dont want to fork out $$$ on crap.

Some one must know about this, i've heard talk about it in a few places. Does rainbow warrior still look into this rover section, or did you guys piss him off too much in the nissan v rover thread? he will know

I have rebuilt (and broken) quite a few IIA boxes in my time (IMO a bit stronger than a SIII).

Apart from the box being weak to start with, the biggest problem these days is getting good quality parts - genuine gears aren't available anymore, and although you CAN get some that are decent quality, picking the good from the bad are a problem. I had a layshaft first gear strip 3 teeth when it was less than 6 months old, ripped them right out at the root. It was obvious they were made from cheap metal and then over(case)hardened to compensate. The replacement gears seem to be holding up OK though.

The SIII boxes tend to have more problems. A mate with a worked 2.25 (he was an engine builder and it was bored and stroked with about 10:1 compression - really went like hell) got sick of rebuilding his box every 3-6 months and bought a Stage 1 V8.

But on the other hand, another mate with a SIIA 109 with a retrofitted V8 went quite a long time before the layshaft of his IIA box broke (usually the weakest point).

IMO it is probably not worth doing the "backgrinding". Usually by the time one of my boxes has started jumping out of gear the teeth on the synchro hub are so worn there is almost nothing left. As I said in the last post - the synchro hubs are usually OK quality - and only about $80. Just check it will engage before putting the box together - the tolerances on some of them are not great - and it usually takes a couple of weeks of driving for a new one to bed in - changes can be a bit stiff before that.

If you want to stick with a series box, I would find a good (cheap) IIA one and rebuild it (if you can live with double-clutching 1st and 2nd). You can also fit your bellhousing and input gears to the IIA box so that you don't have to change the clutch). If you do this, make sure you get a later model box with the step in the layshaft properly radiused. I have this layshaft in mine and have given the box a very hard life and it is one of the few parts I haven't broken.

If you are gentle on it I think a good series box can handle a holden engine with no problems. But if you can get a better box (ZF, R380, any truck box, etc) and do a conversion cheap I would probably go for it.

Just remembered you probably have the 6-cylinder box - there are a few differences, including the mainshaft and bellhousing, but not 100% sure. The overall strength is the same as the 4cyl box though.

can

Hi...tuppence-worth from me here.......This thread took me back a few years..!!

Whilst in NZ (..as an 'impoverished' ag student..!!) twenty-something years ago, I graduated from a 2.3 PA Vauxhall-engined '51 S1 to a tidy little '57 S1 88" Safari that had an H-series Monaro 186-S (..the one with the 'lumpy' cam, two-barrel carb & h/c Yella-Terra type head.)

Lovely road engine, absolute bugger in a riverbed.....unless it was doing +2000 rpm.....& I got it because the previous owner got fed up with its hunger for 3rd gear & ability to wring the neck of a synchro-unit as soon as he reached for the key...

..AND....of course, you can put those synchro rings in arse-about-face, which Holdens have an uncanny ability to detect......& destroy..!!

My mate who helped me fix it up told me I'd never be able to afford to fuel AND fix it told me to be nice to it & if I wanted to 'play' with it, to just get it rolling gradually, & it would take more aggressive throttle the faster it happened to be 'rolling'....

Well, this worked....I had it for 18 months before returning here & it was as good as gold. (..Hydraulic-ed out the reverse idler bush instead, but never broke the forward cogs, diffs or shafts.....)

And I never missed a chance to give the odd RS2000 or Charger a run for it at the lights now & then, & it would squeak the tyres in 3rd....considering they were a set of 33" Wide Climbers, it was a bit risky..

But it was a bloody nice little truck & I miss it even now.....

(..It had a Fairey overdrive in it too...now that hated the Holden, 'cos they are really meant to be an economy tool, so they don't like being asked to transfer low-speed engine torque , high-speed overrun braking, & they really don't like raw 'grunt' either...as they are made with bits of Rover 2000 car 'box, its not really surprising...)

Oh, & if you have'nt already done it.......worth heaving out that fibre cam wheel in the engine.....fit the alloy option..!!

I had the 'cardboard' one go in the Landie, AND when I borrowed a mate's GTR Torana ..which had a 161-S in it.. (40,000 miles really is a bit short a life for vital components..!!)

This one takes me back to my child hood too Nick I remember that the Land Rovers that were used for Roo shooting were run mainly in 3rd gear, The end result was that the box nearly always jumped out of 3rd gear. The solution was quite simple and easy we use to knock a hole in the dash and run a piece of no 8 fencing wire through it and put a loop in the wire so you could wrap it around the gear lever and hold it in gear.
Problem solved. It was stuff like this caused the bent that I have for Land Rovers, this along with the fact that a 2.25 litre petrol 88 inch Land Rover could pull a 12 Tonne trailer easier than the 4 Litre Nissan Patrol of the time.