LT230s what to do?

[Bush65]

...someone on outerlimits uses one in a racing discovery i think to good effect. only issue was keeping it cool enough, which proved to be quite a big issue i think. one that was resolved, however. i'm sure if you do a search for tf727 or a727 there you might find some threads.

It is missleading to state only issue was keeping it cool enough.

He spent a lot of time and money on the best available modifications to make the 727 stronger and more reliable. Although it had substantial custom coolers, he still experienced frequent failures (nearly each event).

There is a lot of drag racing experience with mods for the strength of 727's, but the duration of these events is minute compared to the races that he was competing in with the defender.

Success only came when the cooling and oil capacity was greatly increased (multiple large coolers), but by then it was very strong for a 727.

Edit: search for posts by discokid on outerlimits.

[will_warne]

LT230 can take a lot more torque than that - remember engine torque is multiplied by gearing in the gearbox (minus mechanical losses).

Regarding naming conventions:

LT stands for Leyland Transmission. When there was a Leyland group, the convention was to name gearboxes and transfer cases with the LT prefix, followed by the centre distance (in mm) between the mainshaft and layshaft for gearboxes or the centre distance between the input and output for transfer cases.

The LT85 was designed by Santana, for Leyland, when they were affiliated.

The R380 was designed after the demise of Leyland. The R prefix stands for Rover, and 380 is rated torque in Newton metres.

The weakest part of the LT230 is the 2 piece cross pins in the centre diff. There are aftermarket one piece cross pins (Macnamarra in Aus for example) which overcome this. Same problem with the LT95 centre diff.

Early LT230 had needle rollers in the intermediate shaft assembly. These are not as strong as the later versions, which have taper roller bearings. Same problem with the LT95, which has a similar intermediate shaft assy, if you push them, the needle roller thrust bearings fail. In Aus, there was a taper roller conversion for the army LT95, but I don't know of any conversion for LT230's.

Apparently, the gearing in LT230's has changed from time to time. When I ordered a 30% reduction gear conversion for my LT230, I remarked to Mal Storey about how low the pressure angle was for the LT230 gears. He said that they have changed the pressure angle and also the helix angle over the years.

In the early days of involute gearing (before gear tooth generating, cutting machines), the pressure angle was 14 degrees, but this was mostly replaced by 20 deg (with gear tooth generating cutters) and 25 deg has often been used many years when higher strength is required. The main downside of higher pressure angle is noise if the tooth profile and tooth to tooth accuracy are not of a high standard. The other downside of higher pressure angle is greater tooth separating forces, but should not be a design problem.

I have not had anything to do with the so called LT230Q (quiet gearing) transfer cases. From pics, diagrams that I have seen (could be unreliable), it appears to me that Rover have used a larger number of smaller teeth for some (maybe all) the gears. Although it will help to reduce noise, the strength will definitely suffer, if this is the the case. I suspect (again from pics I have seen), that this (more small teeth) also contributed to the reported (unsubstantiated) weakness of the 80% reduction gears that Dave Ashcroft had for a short time.

I would stay well clear of LT230Q if you want strength, unless someone can confirm otherwise.

John, IIRC the Q gears use a differant cutting method developed by Ford which makes gears much quieter and became available to Land Rover after the take over. As far as comparitive strength you'd have to ask Ashcrorts but I don't believe it suffers.

I've been told by Ashcrofts that the crawler gearset you're refering to was withdrawn due to lack of demand (people wanted underdrrives) and due to the failier of 2 units fitted to the same vehicle (very large tyres and large bhp) which was due to the small size of the teeth. I know of 3 forum members using these gearsets (Robhybrid, Tangoman and Ced) and none of them have had issues with them even though one of them had to have their LT230 rebuilt after running it dry.

[MECCANO]

I've not heard of any breaking, they seem to be one component that LR got right and the only upgrade I've heard of (gearing changes aside) is a one-piece diff spider for them.

ive got a broken one, its a mr wuffles special

[honitonhobbit]

i'm using a 4L80e

Never mind mate - spares are available if you are lucky. Once you have cut your teeth on this one you could get a decent box that is easy to mate a T box to...

[pugwash]

yeah it's a bit of pity it's so badly under engineered what with being the overdrive successor to the TH400- it's not supposed to be a box that needs repairing- it's only good for 900lb/ft so i'm hoping a days off roading won't totally destroy it! anyway you can get all the bits you need shipped next day from the US and they're not exactly expensive! makes ZF boxes look hideously expensive- and their are at least 2 guys in the UK who rebuild them for the drag scene- i could even get out and learn how to myself!

can't say that i'm having too many problems mating the box to the t-box at the moment- i'll let you know how i get on though.

[TomG]

yeah it's a bit of pity it's so badly under engineered what with being the overdrive successor to the TH400- it's not supposed to be a box that needs repairing- it's only good for 900lb/ft so i'm hoping a days off roading won't totally destroy it! anyway you can get all the bits you need shipped next day from the US and they're not exactly expensive! makes ZF boxes look hideously expensive- and their are at least 2 guys in the UK who rebuild them for the drag scene- i could even get out and learn how to myself!

can't say that i'm having too many problems mating the box to the t-box at the moment- i'll let you know how i get on though.

Kinda going OT here but very interested to hear more about this conversion. Been reading the threads on the weaknesses with / uprating the ZF4HP22 and am interested in alternative options.

Whats the 4L80e like for fit in a LR? I've heard some American autoboxes are physically bigger and have issues with propshaft clearance?

Alternatively, does anyone do a aftermarket controller for working the solenoid shifting on the HP24 box? (Megasquirt principle for autoboxes?) there seems to be a few HP24s coming up on ebay now. I realise the HP22 can be rebuild with HP24 internals but this is pretty expensive.

[orange rover]

found this on the ashcroft site

http://www.ashcroft-transmissions.co.uk/part_18.html (scroll all the way down to "2.8 International engine to ZF auto")

have enquired, was told that the hp 24 would be compatible with a rrc shifter. but if the are solenoid operated, how would that work?

[honitonhobbit]

Jim,

I wrote a really witty, informative reply. It looked good, was proven in it's accuracy and was even gramatically sound. Then I though "It's '07, I am 41 in 6 weeks time, why bother?"

Good luck with the project mate - all the best and Happy New Year

[ashtrans]

found this on the ashcroft site

http://www.ashcroft-transmissions.co.uk/part_18.html (scroll all the way down to "2.8 International engine to ZF auto")

have enquired, was told that the hp 24 would be compatible with a rrc shifter. but if the are solenoid operated, how would that work?

Hi,

when we make a heavy duty ZF we use the stronger internals from the 4HP24 but use the 4HP22 casing and hydraulic control unit so we don't use the electronics,

Dave

[Lewis]

John, IIRC the Q gears use a differant cutting method developed by Ford which makes gears much quieter and became available to Land Rover after the take over. As far as comparitive strength you'd have to ask Ashcrorts but I don't believe it suffers.

Does anyone know when the LT230Q was released? Because AFAIK Ford bought Land Rover in mid-march 2000, assuming rather unusual haste from Land Rovers typically lackadaisical development engineers this wouldnt see LT230Q developed untill late 2000/early 2001 ready for 2002 model year updates sometime around August 2001.

Was the LT230Q available before mid-2001 or are my above assumptions correct?

[Bush65]

John, IIRC the Q gears use a differant cutting method developed by Ford which makes gears much quieter and became available to Land Rover after the take over. As far as comparitive strength you'd have to ask Ashcrorts but I don't believe it suffers...

I'm aware of some of the statements about cutting methods. I have not seen anything of a technical nature on this method.

Looking back over a poor quality pic of Q gears, I stand by my conclusion that they apparently have more, smaller teeth compared to the LT230T. If this is the case, then I can not believe the LT230Q is anywhere near as strong as an LT230T.

Unless someone has better information (as I said, I have no experience with the LT230Q), I will keep an open mind on this, but assume Rover has sacrificed strength for reduced noise.

I used to have a lot to do with gear design and cutting, but have not kept up to date with any advances in cutting technology. I doubt there have been any quantum leaps.

Gear noise is generated by errors in conjugate action, caused by tooth profile and pitch errors, or distortion (bending and twisting) of the teeth or pinion shaft.

These errors and distortion also lead to increased dynamic loads and reduction in strength.

A quality number is used in gear design for this reason. For the usual quality numbers achieved by good generating gear cutters and gear grinders, the tolerances are very small. Higher quality numbers increase the strength rating, reduce noise and cost much more to manufacture.

When designing gears, it is necessary to determine whether a tooth profile modification is necessary - usually tip interference due to deflection of the tooth

For large gear face widths, it is common to cut the pinion with camber in the teeth to compensate for the bending deflection and torsional deflection.

When I was involved with ore grinding mills, we used arrays of infrared sensors to contantly monitor gear tooth contact across the width of the gears.