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Ring & pinion choice


upnover4x4
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I was looking for your opinions on what route to take on choice of ring & pinion (R&P). I blew my 3.54 R&P up this weekend taking my diff pan with it. Im running fedimas which measure 36". The gearing has been thrown running these. Now Im going to be fitting arbs F&R when rectifying the damage but at a predicament about my choice in R&P. I was thinking of fitting an underdrive at a later date but Im undecided about whether to stick with the 3.54 R&P & get the underdrive or to go for a 4.75 R&P & not bother getting the underdrive. I do realise that other gearing ratios are avalable but the are not much cheaper than the 4.75.The cost of the 4,75 R&Ps are about £280 & I'm finding this quite difficult to justify, but bearing in mind that an underdrive costs around £2000.

The vehicles primarily used for challenge events & driving days & doesnt really get used on the road much. If I go with the 4.75R&P, I understand it option isnt an underdrive or have the same capabilities as but will the newer reduced gearing be suffice to justify the outlay of an underdrive.

Thanks Adrian

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I have KAM 4.75's on my RRC 4sp Auto with 35" creepy crawlers and find them a tiny bit lowly geared.(I had been competing with them for three years before I trashes my challenge truck after a roll and was forced to scrapped it so all the parts went onto my RRC)

but its fantastic control in low ratio and in High it is about 8mph slow at 70mph on the clock.

4.1 may be a better option

Also I was told Ashcroft is very reasonable for R&P at the moment.

Its undoutably a much cheaper alternative than the under drive and if you do the gearing first the fit a under-drive later it will be much much more affective

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If you fit the Under drive you won't need to alter the R&Ps at all

and you get the best of all worlds running 36s/33s winch assist driving controlled descents

bluddy superb piece of kit

How do you find it on the road? Do you find you need to change down for the hills more often or is it tolorable

Ade

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upnover, do you know the history of the r&p you were running? Who built up the diff? What mileage had it done? I ask because the 3.54 is a much stronger natural design than either the 4.11 or 4.75. The aftermarket r&p's tend to be made of better materials negating the difference slightly but if you're after ultimate strength then stay 3.54 and get the diff pegged. Even pegging may be a bit OTT on 3.54's unless you're pushing big power or you're very hard on your truck.

I went through this a while ago and the decision I went with was 3.54's (pegged), a 1.667 transferbox and an underdrive (hooked up to an Ashcroft built HD autobox and 2.8 TGV). It got a bit of use before I ripped the truck apart to use it as a donor for something new but the drivetrain won't be changed. IMHO its spot on and gives you high range, 2 low ranges (one that's very similar to the gearing with 4.75's in low range) and a crawler ratio that's stunning. Its much more expensive than r&p's but spend it once spend it right......

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upnover, do you know the history of the r&p you were running? Who built up the diff? What mileage had it done? I ask because the 3.54 is a much stronger natural design than either the 4.11 or 4.75. The aftermarket r&p's tend to be made of better materials negating the difference slightly but if you're after ultimate strength then stay 3.54 and get the diff pegged. Even pegging may be a bit OTT on 3.54's unless you're pushing big power or you're very hard on your truck.

I went through this a while ago and the decision I went with was 3.54's (pegged), a 1.667 transferbox and an underdrive (hooked up to an Ashcroft built HD autobox and 2.8 TGV). It got a bit of use before I ripped the truck apart to use it as a donor for something new but the drivetrain won't be changed. IMHO its spot on and gives you high range, 2 low ranges (one that's very similar to the gearing with 4.75's in low range) and a crawler ratio that's stunning. Its much more expensive than r&p's but spend it once spend it right......

The axles were purchased from a friend of white90's that are td5 axles. Age & mileage unknown. They were in excellent condition with negligible backlash. They have only been on the truck about a month prior to the explosion & the fedimas were only fitted last week.

My thought as to why the diff exploded...Well I had jacked up the vehicle to fit & clearance the new tyres. Due to having dislocating suspension I had fitted the axle limiting strap to lift the truck. What I had forgot to do was remove the strap for yesterdays challenge! Now assuming that the suspension was doing what it was supposed to be doing in relation to the ground I tried to straddle a obsticle. Not quite having the ground contact I thought I had I blipped the throttle to climb the bank & the tyre gripped a raised root! I cant help but think would the damage have happened had I removed the strap. Yes the tyres a new to me but I not a particlary aggressive driver. Usually slow & consistant.

With reference the 3.54 r&p, I was chatting to Crown diffs today & he claimed that the 3.54s available on the market are basically rear directional r&ps which can & are fitted to front axles. This he said is what landrover do from the factory and thus due to the faces being machined to be directional make up for a weaker front axle. Is this the case?. What he did say was that the lower ratios that he sells are directional & come as matched pairs ie front & rear & can only be fitted in their respective postion.

I dont have any issue with refitting 3.54s. These were probably going to be my first choice as I really did want to fit underdrive, I just thought that I might be able to achieve a lower ratio without the cost of underdrive.The cost of fitting 3.54s is significantly cheaper but I dont want to be in the same position again shelling out on what could be a lesser quality r&p. The cost of a built locker with 3.54s is £658inc as opposed to £928inc for a 4.75r&p. 2xr&ps at £300 quid is a big chunk toward an underdrive.

As you said I dont want to make a costly mistake twice I just want to get it right first time...or as near as possible

Thanks Adrian

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Guest WALFY

If I'm reading your post correctly you're saying the R&P's are 300 an axle? If that is correct I'm almost sure that Ashcrofts are cheaper than that. Got to be worth a call, even if it's only for honest advice. When I got my ARB's from them I got them to fit them into my diffs. That way I knew they were being fitted correctly. With the right amount of backlash

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Been using Ashcroft 4,11 R&P`s for a couple of years now , they have been fine , stripped out and checked every 3rd event and no signs of strain or damage whatsoever , And it was the fedimas that made me do it . Gearing was terrible before .

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If you fit the Under drive you won't need to alter the R&Ps at all

and you get the best of all worlds running 36s/33s winch assist driving controlled descents

bluddy superb piece of kit

I don't what to get into this argument again but

I still struggle understand this

how can you put up with the gearing in high ratio on the road my RRC and my 90 before on 34"/35" tyres within reason the engine revs and gears work as they were designed to by Land Rover . I can drive my Rangie on its 35" tyres and if I need to overtake or get into a sticky situation and need to accelerate hard up a slip road on to motorway traffic etc I can. before I changed the gearing my auto box wouldn't change into 4th gear until I was doing at least 85mph, as you can imagine it was a little andysocial to drive :unsure: . shurly your 5 speed box must feel under powered due to its over gearing on the road driving to events.

Also I put my car trailer on the back with a defender racer on it and as you would expect from a Rangy I could barely feel it was there. could you put a 3ton load on the back and the gearing work properly

post-312-1208197425_thumb.jpg

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If I'm reading your post correctly you're saying the R&P's are 300 an axle? If that is correct I'm almost sure that Ashcrofts are cheaper than that. Got to be worth a call, even if it's only for honest advice. When I got my ARB's from them I got them to fit them into my diffs. That way I knew they were being fitted correctly. With the right amount of backlash

Yeah correct! I had to sit down after he told me. I checked ashcroft & they want £275+vat for 4.75s. With vat thats £323 each. 4.1s are quite a bit cheaper. You can justify the cost of pegging going for these as they are £80 quid +vat cheaper.

With regards diff pegging, Im running a 200tdi which is getting the pump adjustments carried out soon, not exactly a 300bhp motor, not likely to ever come close to it so is it worth pegging.

Adrian

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Guest WALFY

When I had my ARB's fitted the only ratio I contemplated was 4.11. Seen a few trucks running this and it seems to work for them, Ciderman, Stumpy2268 and Jst (I think) and their trucks perform well. And only 195 +VAT a lot better than 4.75's

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I don't what to get into this argument again but

I still struggle understand this

how can you put up with the gearing in high ratio on the road my RRC and my 90 before on 34"/35" tyres within reason the engine revs and gears work as they were designed to by Land Rover . I can drive my Rangie on its 35" tyres and if I need to overtake or get into a sticky situation and need to accelerate hard up a slip road on to motorway traffic etc I can. before I changed the gearing my auto box wouldn't change into 4th gear until I was doing at least 85mph, as you can imagine it was a little andysocial to drive :unsure: . shurly your 5 speed box must feel under powered due to its over gearing on the road driving to events.

Also I put my car trailer on the back with a defender racer on it and as you would expect from a Rangy I could barely feel it was there. could you put a 3ton load on the back and the gearing work properly

post-312-1208197425_thumb.jpg

Jules, I'd agree with you as I had basically the same gearing as Tony before I went auto - on 35's 5th gear was overdrive only. However, the defender transfer box is quite a bit lower in high than the one in your RR.

Also, Tony (like me) also runs/ran 255x85r16 BFG MT's and standard gearing works really well with these. As Tony doesn't/didn't do many road miles on Simex its less of a problem.

Adrian, Speak to Ashcrofts. They may well do you a deal on the diff rebuilds if you get an underdrive too. You're right about the cut of the r&p's - its standard practice. As the front 'should' see less load and is a weaker axle anyway due to the shaft diameters / lengths it should rarely cause problems. I prefer having not having a reverse cut front diff just for the spares issue.

As far as pegging goes, failiers of r&p's on propperly built diffs are rare on Tdi's. That said, there's no harm in doing it as it will give you peace of mind.

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I don't what to get into this argument again but

I still struggle understand this

how can you put up with the gearing in high ratio on the road my RRC and my 90 before on 34"/35" tyres within reason the engine revs and gears work as they were designed to by Land Rover . I can drive my Rangie on its 35" tyres and if I need to overtake or get into a sticky situation and need to accelerate hard up a slip road on to motorway traffic etc I can. before I changed the gearing my auto box wouldn't change into 4th gear until I was doing at least 85mph, as you can imagine it was a little andysocial to drive :unsure: . shurly your 5 speed box must feel under powered due to its over gearing on the road driving to events.

Also I put my car trailer on the back with a defender racer on it and as you would expect from a Rangy I could barely feel it was there. could you put a 3ton load on the back and the gearing work properly

post-312-1208197425_thumb.jpg

I just drive the vehicle at normal speeds suited to its size/shape rather than like a racing car which it isn't

I drove it tonight 110miles with a trailer and 5th is still useable and the car drove fine, hills and all,

simex on BTW.

I have had a 2 ton load on the back and as it is a TDI and not a 4.2V8 yes I knew it was there alright, still the gearing works properly for the tyre mix I have

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I just drive the vehicle at normal speeds suited to its size/shape rather than like a racing car which it isn't

I drove it tonight 110miles with a trailer and 5th is still useable and the car drove fine, hills and all,

simex on BTW.

I have had a 2 ton load on the back and as it is a TDI and not a 4.2V8 yes I knew it was there alright, still the gearing works properly for the tyre mix I have

Will said it with your transfure box and I forgot if you run 255's as well from time to time if you lowered your diff's it would become massively slow on the road so what you have is the best set up as you run a second set of wheels.

I'm too lazy to change boots around :lol:

4.1's would be an general improvment I feel

My truck is 4.7's this was grate on simex but a little low on the maxxis

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With reference the 3.54 r&p, I was chatting to Crown diffs today & he claimed that the 3.54s available on the market are basically rear directional r&ps which can & are fitted to front axles. This he said is what landrover do from the factory and thus due to the faces being machined to be directional make up for a weaker front axle. Is this the case?. What he did say was that the lower ratios that he sells are directional & come as matched pairs ie front & rear & can only be fitted in their respective postion.

From personal experience most front differential failures occurr when reversing up hill,out of a hole or when snatch recovering other vehicles in reverse gear. When driving forward in high torque situations such as climbing steep gradients or heavy pulling, weight transfer to the rear axle reduces the strain on the front drive components relative to the rears. For this reason I believe that the concept of''Handed'' ring and pinions is based on a false premise, and that standard cut gears front and rear are the optimum arrangement. Generally a ring and pinion is only around 70% as strong when driving on the coast side of the teeth.IMO it should be arranged that the strongest side of the teeth should be under load when driving forward for the rear diff and when driving backwards for the front diff. Toyota LandCruisers very rarely broke front differentials until the introduction of the reverse cut ring and pinions on the 80 series. Admittedly these diffs werealso smaller than their predecessors, but that's only part of the reason, and again most failures occurred in reverse.

Bill.

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Will, Thanks for the advice on chatting to ashcroft about soting a deal out.They said they would do quite a good deal on 2 arbs built diffs with pegging & 4.1s. Waits about 2-3weeks but will give me time to sort out the remedial work.

Having lost all my oil I suppose the will mean the wheel bearings will need replacing?! Drove about 20miles home. No trailer unfortunately. On inspection plant wheels blown to bits & few teeth missing off the C&P.

Does any body know where I can get the heavy duty weld on diff pans at a reasonable price? Been quoted between 80-90quid. If I could get the pipe caps I would rather make them up myself.

Adrian

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Having lost all my oil I suppose the will mean the wheel bearings will need replacing?! Drove about 20miles home. No trailer unfortunately. On inspection plant wheels blown to

Have a look and see - a lot will depend on how well greased the bearings were and what state they were in. The trick with bearings is use genuine bearings, stub axles and seals - I would change axle oil after every event or every other play day plus whip off the drive flanges to check what they looked like inside, adjust the bearings and pop some more grease in there. Even with narrow hubs I reckon I got 2 years out of bearings and I wasn't kind to them:

Will_Wading.jpg

Will_climb.jpg

Web_IMG_0229.jpg

They must have been taken over about 2 and a half years and I think I was using the same rear bearings and went throught one set of fronts ;)

Oh, and Ashcrofts do 4.11 r&p's - you get one more tooth on the pinion than with 4.1s B)

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Does any body know where I can get the heavy duty weld on diff pans at a reasonable price? Been quoted between 80-90quid. If I could get the pipe caps I would rather make them up myself.

Adrian

Exact Fabrication do them for £50 inc VAT but I didn't have much success in managing to purchase one a few months back.

Ended up getting one from Steve Parker Land Rovers - £80 inc VAT.

More here: http://forums.lr4x4.com/index.php?showtopic=13705

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Guest WALFY

James Same as me. Like I said I only contemplated 4.11 as I had seen them in other trucks out and about, hence I wasn't sure about yours. It's never out and about. But couldn't justify the extra money on top of all the other goodies I got from Ashcrofts

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