Thread: LT95 intermediate shaft bearing upgrade

Originally Posted by uninformed

ok so whats the "pitch" on the new 6 speed in the "puma" powerd defenders?

Don't know, but being a Ford design and not an LT (Leyland Transmission) the model of the box would probably not be described by the shaft pitch.
Wagoo.

interested to know why this is not worth doing???

Originally Posted by Vern

interested to know why this is not worth doing???

As 85 County mentioned, the std needle roller bearings were not really a problem.It was the bronze thrusts that burnt out, mainly the 2, one each side of the low range intermediate gear, because it spins so much faster than the other gears on the intermediate gear cluster(around twice the speed of the engine when in high range top gear).
Taper roller bearings if not kept adjusted eventually develop end and radial float which compromises gear tooth contact.The early LT230 transfercases had needle roller bearings and bronze thrusts, but because the intermediate gear cluster was one piece it only spun at relatively low speed, and these t/cases tended to last a very long time. I don't know why they went to taper roller bearings on the later LT230Ts. A cheaper more elegant solution for the LT95 IMO is to change these bronze thrusts for needle roller thrust bearings.I've seen such a modification on a high mileage transmission that came in for reconditioning a few years back, and the intermediate gear assembly was about the only component that didn't need any attention.
Wagoo.

Bill with your idea of running needle roller thrusts does in involve much machining?
From what I can see a Torrington FNT-5070 is the same dimensions as the original thrusts 50x70x3 mm
These are the dimensions on the net are these just a simple swap or do you need to machine the gears and change the pear washers
The dimensions of the FNT-5070 are exclusive of the thrust washers so could you machine the pear washers and then use the 1 mm thrust washers and run the FNT-5070 on the gear surface provided they were in good condition
All that being said the maximum speed for these thrusts according to Torrinton is 6000 rpm
If you look at the worst case a County or Stage 1 with 1.336:1 high range the speed would exceed 6000 rpm at 110 kmh

Originally Posted by djam1

Bill with your idea of running needle roller thrusts does in involve much machining?
From what I can see a Torrington FNT-5070 is the same dimensions as the original thrusts 50x70x3 mm
These are the dimensions on the net are these just a simple swap or do you need to machine the gears and change the pear washers
The dimensions of the FNT-5070 are exclusive of the thrust washers so could you machine the pear washers and then use the 1 mm thrust washers and run the FNT-5070 on the gear surface provided they were in good condition
All that being said the maximum speed for these thrusts according to Torrinton is 6000 rpm
If you look at the worst case a County or Stage 1 with 1.336:1 high range the speed would exceed 6000 rpm at 110 kmh

Djam,The example I mentioned earlier replaced all the bronze thrusts with the Torringtons.On each end they ran directly against the slimmed down pair shape washer, and the gears were faced to allow room for a Torrington washer, which IIRC was thicker than 1mm. I would probably only do the low range gear and leave the bronze washers on the other gears.
When the low range gear is spinning at around twice engne or output shaft rpm it is not under any real load, so based on the condition of this example the actual no load rpm limit of the bearings appear to be adequate.Even at no load the heat build up of the low range gear rubbing on the bronze thrust can turn the gear blue and the thrust black. I've heard that in UK offroad racing, where low range isn't needed, some vehicle builders used to grind the teeth off a scrap low range gear and use it as a spacer so that it didn't generate heat.
Wagoo.

Looks like the Torrington thrusts and washers would add up to about 5 mm so you would need to gain a total of 8 mm if you did all 4 maybe your idea of doing 2 would make it easier.
I tried to source some today and I was told that they may not be capable of taking the load.
Not sure to be honest

Originally Posted by djam1

Looks like the Torrington thrusts and washers would add up to about 5 mm so you would need to gain a total of 8 mm if you did all 4 maybe your idea of doing 2 would make it easier.
I tried to source some today and I was told that they may not be capable of taking the load.
Not sure to be honest

I feel that engineering specs on some components including bearings may be a bit on the conservative side, possibly calculated for industrial applications at 100% duty cycle. I recall many years ago when I first had the idea of making my own portal reduction hubs, I thought about using roller chain drive instead of spur gears. I went to a power transmission specialistwith all the facts and figures re engine power, overal gear ratios, desired sprocket diameters etc.
When the engineer did his calculations by the book he reckoned that I would need a multiplex chain and sprockets at least 6'' wide.I couldn't accomodate this width and didn't know any better so elected for gears instead.A few years later the Agrover was built in the UK on Landrover 110 basis had chain drive portals with chain around 1'' wide.IMO the power transmission engineer was being overly conservative.
Wagoo.

Originally Posted by wagoo

I feel that engineering specs on some components including bearings may be a bit on the conservative side, possibly calculated for industrial applications at 100% duty cycle. I recall many years ago when I first had the idea of making my own portal reduction hubs, I thought about using roller chain drive instead of spur gears. I went to a power transmission specialistwith all the facts and figures re engine power, overal gear ratios, desired sprocket diameters etc.
When the engineer did his calculations by the book he reckoned that I would need a multiplex chain at least 6'' wide.I couldn't accomodate this width and didn't know any better so elected for gears instead.A few years later the Agrover was built in the UK on Landrover 110 basis had chain drive portals with chain around 1'' wide.IMO the power transmission engineer was being overly conservative.
Wagoo.

You got that right Wagoo, he would've been using factors of 4 or 5 due to the 'vehicle' application, and personel etc being in near vicinity maybe?. This, as you know, can blow sensible design parameters out the window.

Multiplex drives can be very hard wearing and surprisingly strong, but at 1" I believe they possibly wouldn't have lasted all that long.

I will be happy to be corrected on this, but I still believe the TR design of the intermediate shaft is still a better upgrade. The torrington thrusts are very good at supporting huge lateral thrust loads, and the needle rollers and the shear diameter of the intermediate shaft in the LT95 makes them extremely strong IMO, But I still believe the addition of Taper rollers either side of each gear will be enough to remove the issues of end thrust wear and subsequent failures. I have an oil temp gauge on my LT95 transfer case, before I fitted the TR's I saw 100degrees while towing 1.5t at highish speeds in 40degree ambient temps (with a very torquey 4BD1T and 33" tyres etc), so that means the bronze thrusts would've been way in excess of that. Consequently they lasted only that trip, and the gear thrust surfaces were so heat cracked that they were discarded.
Since the upgrade, higher loads have been towed and seldom does the oil temp reach 80dgrees now.
The shaft deflection I agree could become a concern at some point, but after 80,000km and loads of hard work, no particles, noises, or endfloat etc has been detected.

I believe the TR conversion is worthwhile in my case.

JC