3rd member swap

[scott]

i trashed an axle and exploded the spiders on my rear axle. i'm looking at a couple of 3rd members out of a range rover classic that look pretty much like the iia's. they use the same gasket which says the bolt pattern is the same. if the distance from the drive flange to the gasket suface is the same and the distance from the gasket surface to the center of the gear that fits the axle is the same, can anyone think of why they couldn't be swapped?

[Leslie]

You can put RRC/Disco/Def 3rd's into a Series. Been done before many times.

Thing is, your Series has 4.7 gears, the RRC is a 3.54.... so, while you might do better at cruising speeds, it'll be harder for the 2.25 to get you there, and off-road, you won't have the lower gearing.....

FWIW...

[a109]

You can put RRC/Disco/Def 3rd's into a Series. Been done before many times.

Thing is, your Series has 4.7 gears, the RRC is a 3.54.... so, while you might do better at cruising speeds, it'll be harder for the 2.25 to get you there, and off-road, you won't have the lower gearing.....

FWIW...

You also will have to replace both diffs as the ratios would otherwise be different.
John

[yorker]

you can swap the RR diffs in, if they are 24 spline you can get upgraded series shafts for them too from Jim at Series trek. If you want to use 4.7 ring and pinion you should be able to swap those in to the RR diffs. Later RR diffs use different bearings (metric vs imperial)than series diffs but if you swap it all together it should work. This is a common swap in the UK. You might need a spacer for the ring gear to make it fit the 3.54 RR carrier because the 3.54 is thicker than the 4.7 ring gear. Those spacers are like $10 or so IIRC GBR has them.

[scott]

thanks all. yes i bought 2 knowing i might have to do the front. i was hoping to swap the ring & pinon so i coud keep the low end. can any of you guys id the critical measurement, how exact will i have to shim the 4.7 serries iia ring when i replace the rrc 3.5. for me the best part of owning a rove is nothing is exact, just get it close and it'll run

[yorker]

I have one of those spacers I can measure for you. I think it was like .1" but that is just a guess, I'll get back to youy tomorrow or tonight

BTW You can buy those spacers from ashcroft too.

http://www.ashcroft-transmissions.co.uk/part_7.html

also BP has them:http://www.britishpacific.com/landro...RBlockers.html

AB:

http://www.roverparts.com/Parts_Accessories/Differentials.cfm

The real way to go would be to get 24 spline 3rd members from a 94 disco and do the swap with a set of the HD 24 spline axles. Later you could get a truetrac or detroit as well.

[scott]

oh yea! that who be a sweet set up and is it's what i want eventually, but i'm getting these 2 rrc 3rd mbrs delivered for less that $150. a bud gave me his spare 10 splines. not too bad, 2 hrs of fun in the dirt and it only cost me $150 (plus another after the holidays to replace the borrowed axles) and about three hrs of knuckle bang'n. are you sayig that there's only one size shim, 0.1 in?

[yorker]

Yeah there is only one size shim, any of those spacers from the above sources should work. Might need longer bolts too depending on the age of the RR diffs you got.

[a109]

thanks all. yes i bought 2 knowing i might have to do the front. i was hoping to swap the ring & pinon so i coud keep the low end. can any of you guys id the critical measurement, how exact will i have to shim the 4.7 serries iia ring when i replace the rrc 3.5. for me the best part of owning a rove is nothing is exact, just get it close and it'll run

You'll only need to shim for pinion height since the ring is freely adjustable side to side.

John

[scott]

you're scar'n me now. i was thinking of using my oringinal 3rd member leaving the pinion gear where it is. i was going to pull and swap the spider gears and the thing that holds 'em. i figured all i'd have to do is pull the ring gear off the rrc's and put my iia ring gear with the 0.1" spacer i just ordered and drop it back into my original 3rd mbr housing. am i not on track here?

[J!m]

Both the ring and pinion may need to be shimmed; it depends on the ring gear and carrier used. The ARB requires a ring gear spacer for the series trucks, but the pinion stays in stock location (the ring is the same diameter)

If the ring gear diameter changes, the pinion may need a shim.

Remember, the ring and pinion both have to be changed, and they should always be kept as a matched set. I have heard stories of people changing the ring gear only, and that is not a good situation...

Maybe I'm missundestanding the point here?

[a109]

you're scar'n me now. i was thinking of using my oringinal 3rd member leaving the pinion gear where it is. i was going to pull and swap the spider gears and the thing that holds 'em. i figured all i'd have to do is pull the ring gear off the rrc's and put my iia ring gear with the 0.1" spacer i just ordered and drop it back into my original 3rd mbr housing. am i not on track here?

In this case where you are simply changing the carrier you likely won't have to change the pinion height since the relationship to the ring won't change.
Sise to side adjustment likely will still be needed if the the two carriers will probably be of different thickness
John

[scott]

jim & john thanks. the fear is gone. i'm leaving the pinion in the casing, swap'n the carrier and spiders as a whole. putting on the rrc carrier my old ring (using a ring spacer to make up the difference between a rrc ring and a iia ring). doing this, it's only the carrier side to side that i need to watch. this thread would have been alot shorter if you guys would have just stopped by the garage with some beer.

[J!m]

Um, yeah, but YOU have to provide the beer... This may be why no one stopped by???

[scott]

here's an update on the mashing together of a rrc and iia 3rd mbr. 1st the rrd, about a 1990, will bolt right onto a '64 rover. but the rrc 3rd mbrs have 2 short comings. 1- no fill plug and 2- a 3.53:1 gear ratio. I got 2 rrc 3rd mbrs pretty dang cheap off e-bay. the damage to my originals was one spider destroyed, the spider shaft snapped and the spider carrier marred. my plan was to bolt my ring gear to the rrc's spider carrier and drop it back into my iia 3rd mbr casing. dang it did work. the spider carriers are not interchangabe. their bearings' id and od are differrent. so i had to put my pinion gear into the rrc's casing and put the rrc spider carrier fitted with a iia ring gear and a .10" spacer back into the rrc casing. the iia pinion fit by removing a few shims between the inner and outer pinion bearings and using both the rrc and the iia outer pinion bearing washers that go on between the outer bearing and the flange. i also used a iia pinion seal on the rrc's casing. i hope it's oil tight. so what i have now is a rrc 3rd mbr with a 4.71:1 gear ratio to bolt onto my series iia. i still have no fill port so my plan tomorrow is to bolt on the rrc 3rd mbr, jack up on side of my truck and pour 3 qrts of gear oil into the outer end of the axle housing before putting in the axle. oh yea,i almost forgot, copious amounts of beer had to be consumed throughout the dis an reassembly process