Reply With QuoteFurther Figures for above post.
YarnMaster
I found this modification for LT230's on the web site for Ashcroft Transmissions. It was included with the instructions for installing their crawler gears into an LT230 transfer case. The page has gone now, along with the crawler gears, which were not as popular as their underdrive add-on.
The final drive gears for high and low range, do not have rolling bearings. They employ hardened steel, plain bearings. This is possible because the driven gear (for the range selected) rotates with the centre differential shaft. The other (non-driven) gear does rotate, relative to the centre differential shaft, but the radial load is small.
Because of backlash between the teeth of the selector sleeve, small movements do occur between the driven gear and centre differential shaft. Good lubrication between the mating surfaces is necessary to avoid wear and fretting corrosion.
The modifications detailed here, improve oil flow to the high and low range, final drive gears.
The LT230 gear case, the rear output shaft and the sleeve inside the high range final drive gear must be stripped out for the modifications.
The modifications to the gear case are described first.
'Figure 1' (below) is a cross section drawing through the final drive gear and centre differential assembly.
There are two oil holes through the rear of the case where the rear output/speedo housing fits. The 6.5 mm hole at the 6 o'clock position, should be plugged by tapping the hole to M8 (see 'Figure 2' below) and fitting a grub screw. The 8.5 mm hole at the 12 o'clock position, should be drilled out to 12 mm and angled upward at approx 45 degrees (see 'Figure 3' below).
The enlarged upper hole feeds more oil into the rear housing, and by plugging the lower hole, the oil level is increased so it will return to the main case through the final drive gear and centre differential assembly.
Now that more oil can be fed to the rear housing, we need to modify the rear output shaft to create a gap for oil to flow between the output shaft and the hollow centre differential shaft (see 'Figure 4', '5' and '6' below).
'Figure 7' shows the modified rear output shaft and the new dimensions of the modified features. The outside diameter and width of the shoulder are reduced. The material is removed from the front side (right side in the figures below) of the shoulder and blended into the fillet radius.
'Figure 8' and '9' show the modifications to the sleeve that fits inside the high range final drive gear. The diameter of the shoulder is reduced and a flat machined on one side.
That completes the modifications to the components of the lT230.
The patches that look like stain marks on the centre differential shaft in 'Figure 5' and the sleeve in 'Figure 9' are light fretting corrosion.
The straight cut (spur) gear in these photographs is a low range crawler gear from Max-drive Engineering. The standard low range gear has helical teeth.
Be careful when assembling the final drive gears on the centre differential shaft. The selector hub (not shown in the photographs) for late LT230's, has a chamfer on one side of the bore, be sure to assemble the selector hub with the chamfer towards the low range gear or the high gear will bind.
YarnMaster
Further Figures for above post.
ChatterBox
Cheers Bushy..good mod for the next time I have the tranny out
Moderator
Nice post, thanks John.
Hopefully this will be archived by the mods.
Another t/case mod that can be done involves replacing the four intermediate thrust washers which are 3mm thick with Maxi-Drive ones which vary in thickness between 4mm to 2mm to move the high range gear closer to the slider. This enables an extra 1mm of dog engagement.
1mm may not sound like much, but it's a 25% increase in dog engagement and can prevent the thing jumping out of high range
YarnMaster
SubscriberJohn;
Would this be a DIY job do you reckon, I'd like to have a Crack at installing crawler Gears, but does it require any special tools?
Last edited by Disco_owner; 28th October 2007 at 02:50 PM.
YarnMaster
My post was not about installing crawler gears, nor are these mods necessary if installing crawler gears.Originally Posted by Disco_owner
No special tools are required to install Maxi-drive crawler gears.
For clearance from the larger diameter of the final drive gear, it is necessary to grind away some material from some bosses/webs inside the case and from one side of the shaft for the selector fork.
Some LT230's need another drain hole drilled and tapped to relocate the magnetic drain plug away from the low range final drive gear.
A lathe is required to carry out the lubrication mods detailed in the above posts. The shaft and sleeve are hardened and difficult to machine with normal tools. Perhaps some ceramic tips would be ok. In my case an angle grinder was used while the parts were spun in a lathe. A 1mm disc was used to cut the flat on the sleeve.
YarnMaster
That mod sound like it would be for an LT95 transfer case?
Moderator
could be.
It's in my Maxi catalogue lumped in with all the rest of the LT230 stuff so just assumed.....
I've only been into my LT230 to do the input shaft seal and inter shaft O ring.
Last edited by rick130; 29th October 2007 at 11:11 AM.
I have dug this thread up rather than start another.
My LT230 has dropped the rear bearing on the intermediate shaft from what appears to be oil starvation.
LT85 Santana 5 speed & LT230
I'll have another search around for any more ideas.
ForumSage
Bump for a great thread. John, do you have any details on cross drilling the imput gear for the early lt230s that dont have it?
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