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Re: 80-83 Safari\MQ Patrol H260 Diff Questions

Posted: 22 May 2016 19:24
by Brett Bignoux
HELLO DAVID .
Ok , from your photos , the rear diff you have is from 1982 - 1986 early model SAFARIs . yes the ratio will be 4.875:1 . Yours is the semi full floating type axle .
(your wheel bolts directly onto the side shaft . Later models up to the last four produced in 1990 had the bigger full floating rear axle . The side shafts are about 45mm in diamater . All safari pick-ups with the 2.8 l28 motor came out with 4.875:1 ratios . Station wagons with the l28 came out with a 4.55:1 ratio . The smaller axle was up graded because NISSAN had three or four warranty claims on side shafts breaking . The bigger full floating axle is the same axle that was used on the three tonne NISSAN CABSTAR ! (you can remove the side shaft without taking off the wheel) . Don't worry , your SANI won't break that axle , and it seems like your LSD is still in very good nick , you are lucky !
DAVID , get it fixed and go get out there ! !

Re: 80-83 Safari\MQ Patrol H260 Diff Questions

Posted: 22 May 2016 23:11
by davidvdm
Thanks for the info Brett.

I poked around the diff this morning for a bit, smacked that dust cover ring on the pinion shaft straight as it was all buckled. Pulled the drums off, and found the shoes probably about half worn. Although not dripping wet, there is a fair amount of oil/dust residue inside both drums.

When I put the drums back, I wanted to keep the wheel nuts safe, and while turning them back onto the studs by hand. I managed to push one of the studs back into the drum. The stud is shorter than all the other, and it seems its seating splines portion is smaller, and hence just pushes back. I will have to go find another stud.

Brett, you seem to know these diffs, can you tell me if I can just pull the pinion seal out, replace it, and turn the pinion nut back on. To me it looks like that nut also needs to be replaced, and I presume, torqued very specifically so as not to mess with the pinion preload. Someone else told me that there is a crush washer that needs to be replaced as well.

What is my cheapest route here? I am doing all this on zero budget. I literally pull things apart, and through faith, things come together.

Re: 80-83 Safari\MQ Patrol H260 Diff Questions

Posted: 22 May 2016 23:34
by davidvdm
Brett, you say I won't break that diff, but I was pushing some figures into a spreadsheet the other day. Now I believe you multiply torque through gearing, so not sure what my final figure will be through two transfer cases. Anybody able to work out what torque I will be putting down on the wheels. Not even sure what the TD27 puts out. I get absolutely crazy figures working on a mere 200Nm, so I am not even going to post it, I am sure I am wrong.

But the speed works out to be fairly interesting... At 650RPM engine idle, through 1st gear at 3.321:1, 1st transfer case at 2.02:1, second transfer at 2.074, diff at 4.8, and through my 33" tyres, I end up with a wopping 25,2 meters per minute crawl speed :woo: .... Or have I got that wrong as well.. I hope not. I think I can for to like that :blonde:

Re: 80-83 Safari\MQ Patrol H260 Diff Questions

Posted: 23 May 2016 07:13
by Peter Connan
David, your speed calcs are about right.

For the torque calcs, two items you may not have kept in mind:
1. You need to factor in friction, which is probably upwards of 30% through two transfer cases.
2. Actually, the torque generated by the engine probably becomes meaningless at these gear ratios. Instead traction becomes the limiting factor.

Re: 80-83 Safari\MQ Patrol H260 Diff Questions

Posted: 23 May 2016 08:35
by davidvdm
Peter, I bashed a figure of 200Nm at the flywheel into the spreadsheet, comes out to over 13000Nm on the side shafts to the wheels. Not sure how to calc the 33" tyres into the equation.

If you say we drop 30%, that gives me around 9000Nm driving the wheels. Is that considered the torque at the wheels? Surely not as the wheels diameter or rolling distance would affect the final gearing to the ground.

But as you say, with that type of torque, traction is now the problem. Of coarse, I would like to know what is the next weakest link that is going to break the day I find the traction, and the wheels don't want to turn. I'm understanding that its doubtful the diff is going to break, so I am thinking propshafts. I would prefer it to be a propshaft than a transfer case.

The Safari TC is gear driven, and the portion of the TX10 Hardbody TC I am using to get drive, is also all geared and not running through the chain drive. The chain drive is still there, but only spins the unused forward facing pinion that used to drive the left drop Sani diff.

I kinda have a plan for that drive shaft. I want to see if it will drive a spare aircon compressor I have here to inflate my tyres. But that was just a thought.

Re: 80-83 Safari\MQ Patrol H260 Diff Questions

Posted: 23 May 2016 10:59
by Peter Connan
Torque is torque, and is measured on a shaft. Thus does not consider the wheels/tires at all.

Wbat you are thinking of is "tractive effort". This is calculated by dividing the output torque by the tire effective radius. 227 tons approximately. But i can't see you ever generating that much traction.

My feeling is that the most likely point of failure is the rim or wheel studs, but the propshaft and u-joints are a good possibility as well as they could see up to double their design load.

Re: 80-83 Safari\MQ Patrol H260 Diff Questions

Posted: 23 May 2016 11:22
by Peter Connan
Just for interest's sake, i did the same calcs using Y60 patrol gear ratios. 1st gear 4.556,transfer 2.02 and diff of 4.111.

A torque of 320Nm gets about the same tractive effort. Most of the Patrol engines can exceed that quite easily, so if your 200Nm is not too far off the mark, you shouldn't have too much to worry about.

Working on Michael's claimed 500Nm, you would need 310Nm to reach the same tractive effort.

Re: 80-83 Safari\MQ Patrol H260 Diff Questions

Posted: 23 May 2016 11:49
by Michael
Peter Connan wrote:Working on Michael's claimed 500Nm, you would need 310Nm to reach the same tractive effort.
Ek is bly jy het die woord "claimed" ingegooi, ek is ook maar skepties oor dit :lol:

Re: 80-83 Safari\MQ Patrol H260 Diff Questions

Posted: 23 May 2016 12:25
by JoshJ
Michael wrote:
Peter Connan wrote:Working on Michael's claimed 500Nm, you would need 310Nm to reach the same tractive effort.
Ek is bly jy het die woord "claimed" ingegooi, ek is ook maar skepties oor dit :lol:

Jys die enigste ou wat se tyres meer rook gemaak het teen koos se klip op as hulle xhausts :lol:
Dinki dis te ver af nie.....

Re: 80-83 Safari\MQ Patrol H260 Diff Questions

Posted: 23 May 2016 12:57
by offroadbiker
:lol: :lol: QQQ :lol: :lol: