R32 Gtr Diff & Cradle Into Gtst While Keeping Abs

[THENIG]

Car is a R32 with RB25 engine & gearbox putting out around 230rwkw.

One Rear diff cradle bushing is shagged (leaking grease), causing visible contact marks where it is hitting chassis rail and audible knocking over bumps.

Car has factory ABS which i want to retain, it is my daily drive & i want to keep the car as safe and drivable as a daily as possible.

Option 1: Install pineapples or solid alloy bushes over all four worn bushes. Easily done but may cause rear end misalignment (if installed by me) and may increase NVH. Still doesn't fix diff single spinning or backlash.

Option 2: Drop rear end use hole saw and/or oxy to cut/burn old bushes out. Hacksaw metal casings of bushes to remove & then press in new bushes (may need a press to do this).

All this seems like a heap of work & possible problems along the way, which may mean not getting the rear end back in in one day, & without access to a workshop that is open over the weekend to possibly press new bushes it is the least favorable option, especially after reading about horror stories of how much effort it is to replace all four.

Option 3: I have been toying with the idea of shimming the standard diff and getting it rebuilt with new bearings, i have been quoted around $600 but car will have to be off the road for a few days while I send the diff off. For the same price I have a complete r32 GTR rear end which i hope to swap over with minimum fuss once i get everything sorted. Can't really afford to have car off the road during the week and this seems to be the least messing about at first glance (other than pineapples of course).

GTR cradle came with everything minus the attessa stuff, springs& struts, rear calipers & discs.

I also have a pair of GTR rear coliovers so i don't have to swap over the hubs. The plan was to just unbolt calipers and hang them off the guards with wire while the HICAS lines are disconnected, remove exhaust & rear sway bar, drop the whole rear end, swap the four bolt flange with gtr 6 bolt (i think) over between the two diffs (using large gear puller to remove both :see pic below). Hopefully it will press back on using standard tools. (advice needed)

Upon closer inspection of the GTR rear end sitting in my garage I have noticed a few things that may cause trouble, i thought I would ask for advice before I start pulling things apart.

ABS sensor on Gtst diff is in different position to GTR diff I think.

Gtst seems to be built into the 'nose' of the diff (circled in green) whereas the GTR diff has a sensor for each wheel (see red circled).

Are the two ABS systems compatible or do these sensors have something to do with GTR 4wd system?

It also seems that gtst diff with ABS is slightly longer and GTR diff measured roughly from rear cover plate to flange.

Pic below shows GTR yoke/flange, which seems to be longer that Gtst one (see pic still fitted to the car )

Do I have anything to worry about or is this going make the conversion impossible to do if i want to retain ABS??

If that is ok then my next concern is the GTR cradle bushes themselves.

Gtr diff cradle bushes stick out compared to pictures of what the Gts ones do. I have read that there may not be enough thread to tighten up after i do the swap.

Can i cut the 2cm of steel off that protrudes out of the bush with a hacksaw or should i get them swapped with aftermarket polyurethane ones designed for gts?

This option is not too bad if i don't have to worry about anything else because I can take the whole gtr rear end to a shop to get them pressed in before i start pulling apart my car.

I am aware that the diff ratios are different & will probably cause my speedo to read high. Is this correct?

I have two non ABS gtst diff laying around that I can use for parts but I wouldn't attempt doing this myself on a saturday arvo in my garage knowing that the car has to be back together by the end of the weekend.

Any advice on the easiest way to do this with my limited spanner turning abilites would be greatly appreciated

Cheers

Rob

[Duncan]

Hey rob, good researching.

I am not sure of the possible diff ratio differences. GTR is 4.1 so if you can confirm 33 GTST that will tell you how much the speed will be out by. But.

You should keep your gts diff and bolt it into the gtr subframe. Just check the mounting points are all the same. This way you keep the right yoke, driveshafts and ABS fitting. Alternatively you can fit the GTR's diff centre into your casing which keeps you ABS but you will have to change to GTR driveshafts. But as you said you would need a few days off the road for a shop to do that.

Very good idea to get the cradle bushes down before you start. They are 20yo and rooted so it will be worse than current unless you do something.

You may find that most or all of the control arm bushes in the GTR cradle need replacing. I recently saw superpro do a "rear cradle" bush set for GTR for about $700. It is expensive but worth considering it will be a big improvement.

Check the ball joints where the hicas arms bolt onto the hub before using the GTR cradle. Most of them are rooted and there are a couple of hundred $$ ea from nissan to replace. Also much easier to replace with subframe out and a press.

One other option to consider....give it to a workshop for 2 days, get them to do your diff rebuild and subframe bushes, take their courtesy car and just pay. You knuckles will thank you.

[THENIG]

Thanks for the quick reply Duncan,

Engine & box were from a S1 R33gtst if thats what you were asking re: diff ratio. Also i vaguely remember the mechanic who did most of the mechanical work telling me that when they got the tailshaft modified with the correct yoke, it had to be made a little shorter than usual 25 conversions because of the ABS diff.

My question;

This superpro 'rear cradle' bush set you speak of, is it similar to this?? I found it on ebay a few weeks ago, ebay

I have thought about keeping the Gtst diff casing and swapping it with the GTR centre, but can i still use the GTR subframe & suspension/hubs?

Would I use the crown & pinion wheel from the GTR diff if mine has bad backlash or are there other things in the diff that dictates this?

I will check the ball joints to see if they need replacing before i do the sums to see if this is still financially worth all the trouble.

in a perfect world the extra length of the GTR 6 bolt flange to the tailshaft (see 4th pic) would be exactly the same increase in length as ABS sensor on the Gtst diff compared to a non abs diff. But, this would mean that all the other people who have done this swap before with non-abs 32's did something else i don't know about. I really need to go get the other gtst diff i have in storage and compare everything side by side. Even then the chances that the electrical side of the ABS sensors being compatible are even fewer.

I may have to consider dropping it off at a workshop and saving my knuckles if thats the only way of getting the best of both worlds, just need to figure out when i have the time, i have been burnt too many times in the past from workshops promising two days and taking two weeks, then the more you push the higher the bill gets.

Hey rob, good researching.

I am not sure of the possible diff ratio differences. GTR is 4.1 so if you can confirm 33 GTST that will tell you how much the speed will be out by. But.

You should keep your gts diff and bolt it into the gtr subframe. Just check the mounting points are all the same. This way you keep the right yoke, driveshafts and ABS fitting. Alternatively you can fit the GTR's diff centre into your casing which keeps you ABS but you will have to change to GTR driveshafts. But as you said you would need a few days off the road for a shop to do that.

Very good idea to get the cradle bushes down before you start. They are 20yo and rooted so it will be worse than current unless you do something.

You may find that most or all of the control arm bushes in the GTR cradle need replacing. I recently saw superpro do a "rear cradle" bush set for GTR for about $700. It is expensive but worth considering it will be a big improvement.

Check the ball joints where the hicas arms bolt onto the hub before using the GTR cradle. Most of them are rooted and there are a couple of hundred $$ ea from nissan to replace. Also much easier to replace with subframe out and a press.

One other option to consider....give it to a workshop for 2 days, get them to do your diff rebuild and subframe bushes, take their courtesy car and just pay. You knuckles will thank you.

[Beer Baron]

i would do the GTR diff into the GTST housing option duncan mentioned. so GTR cradle, GTR hubs, GTR rear dampers, GTR driveshafts, GTST diff housing (if you can fit it to the GTR subframe from memory they mound differently?), GTST yoke, GTR centre inside it.

the reason is the GTST diff is pretty crap being viscous lsd. even shimmed up they are unpredictable and still pretty crap. the GTR centre on the other hand is proper 2 way mech clutch pack type lsd diff. and with a new set of plates in it and shimmed up properly they are as good as any mech lsd really.

[wlspn]

Interested to hear how you go as I'm looking at GTR diff, driveshafts, rear hubs, etc for my R32 GTS25T as well.

As a side-note, backlash is determined by shims behind pinion & either side of centre. So even a rooted c/w & pinion can have good backlash. Just normally causes a period noise (e.g. noise at a certain speed)

If you want centre preload, pinion preload, backlash, etc set correctly I would take it to a shop...

[THENIG]

Ok thanks BB,

Say i swap the gtst diff housing over and keep the rest of the components GTR, I may have to find out if I can use the cover off the GTR diff to bolt it into the GTR cradle.

Two more questions:

Will the GTR subframe bushes need swapping with gts ones or do I just need to cut the ends off them to make them fit with enough thread sticking out the other side to tighten them up?

Also I i have the GTR diff centre apart, i may aswell replace the clutch packs while i am at it. How much should i budget on spending and from where?

Cheers in advance to anyone that can confirm this info

Rob

i would do the GTR diff into the GTST housing option duncan mentioned. so GTR cradle, GTR hubs, GTR rear dampers, GTR driveshafts, GTST diff housing (if you can fit it to the GTR subframe from memory they mound differently?), GTST yoke, GTR centre inside it.

the reason is the GTST diff is pretty crap being viscous lsd. even shimmed up they are unpredictable and still pretty crap. the GTR centre on the other hand is proper 2 way mech clutch pack type lsd diff. and with a new set of plates in it and shimmed up properly they are as good as any mech lsd really.

[sr_ceffy]

yes you can just cut the protruding steel sleeves of the cradle bushes and the r33 diff should bolt into the gtr cradle you could but the gtr diff would be the better option but your abs would need to be removed maybe? or im notsure but can you mount your single sensor to just one of the axle sensor mounts on the gtr diff not sure if that would work or not but you could try it

[THENIG]

Interested to hear how you go as I'm looking at GTR diff, driveshafts, rear hubs, etc for my R32 GTS25T as well.

As a side-note, backlash is determined by shims behind pinion & either side of centre. So even a rooted c/w & pinion can have good backlash. Just normally causes a period noise (e.g. noise at a certain speed)

If you want centre preload, pinion preload, backlash, etc set correctly I would take it to a shop...

I will let you know how i go but if i chicken out, put it in the too hard basket and end up selling it all keep an eye out in this thread, i will post a link.

i will deff take it to a shop if i crack it open, still looking for any info on re: replacement clutch plates for the gtr diff.

Also i think i will cut down the bushes as opposed to replaceing them at this stage, they still seem pretty soft with no cracks yet, not sure how long they will stay that way though.

[THENIG]

Ok, so I have decided to swap the R200 centre out of the GTR diff into the GTSt housing with the ABS sensor on pinion output (?).

I pulled the diff centre out of the housing on saturday, wasn't too hard, still haven't decided whether I am going to keep the GTR crown & pinion wheel or the GTSt (4.3 vs 4.11 i think could be the other way round).

Not too sure how i am going to remove the pinion gear if I do want to keep the GTR ratio, 1/2" socket set I have is too small to remove the bolt. Need to find bigger socket set.

Now I need to know if the clutch plates are worn, not too confident in pulling the centre apart myself, diff oil seemed very clean, there wasn't much metal on the magnetic plug, but this wouldn't mean much.

Still have no idea other than nissan to find a replacement set. I need a new gasket too for the rear cover. Any idea what they are worth?

Since my car is still on the road for now, I also need to confirm whether the 6 bolt GTR half shafts (?) will fit in the gtst housing before i pull my car apart, I will need to do some more searching.

Another thing I only just noticed was that the HICAS lines on the GTR cradle i bought have been crimped, wondering if they did this just to keep the lines in good nick whilst is was in storage or the previous owner did it to eliminate the HICAS, I would have thought the you needed to lock the rack with bushes or fit lock bar to stop the rear steering from floating round?

If the rear rack was hydraulically sealed by crimping the lines would the rack still move?

[bumpstopbrawler26]

You should put your gtr centre into your old diff housing, and use the crown wheel off your old diff.

That way your ratio will be the same, and you will still have your abs sensor where it needs to be, and you'll have the good lsd.

Then, use the gtr axles and hubs. The axles are bigger and the hubs are alloy which means they are less unsprung weight. You will need to use all the gtr arms.

Your diff will fit into the gtr cradle as long as you use the rear cover plate off the original diff, and also use the original front diff mounts too, as the gtr had big rubber mounts on there's.

PM me if you need any more info., I've done a lot of work with diff's and rear end setups.

Thanks, Scotty

[THENIG]

You should put your gtr centre into your old diff housing, and use the crown wheel off your old diff.

That way your ratio will be the same, and you will still have your abs sensor where it needs to be, and you'll have the good lsd.

Then, use the gtr axles and hubs. The axles are bigger and the hubs are alloy which means they are less unsprung weight. You will need to use all the gtr arms.

Your diff will fit into the gtr cradle as long as you use the rear cover plate off the original diff, and also use the original front diff mounts too, as the gtr had big rubber mounts on there's.

PM me if you need any more info., I've done a lot of work with diff's and rear end setups.

Thanks, Scotty

Thanks Scotty, you have answered all of my concerns, what you have described is exactly what I am planning to do. Now I don't have to worry too much about things not going to plan.

Now I just have to do a bit of searching as to what value I have to torque the crown wheel and caps down to, I have a real reason to use my deflection beam torque wrench that I have been itching to use.

I am guessing that I can just use the orange gasket sealer to seal the rear cover instead of trying to find a gasket off the shelf, unless anyone recommends otherwise.

[THENIG]

Ok, jump finished the subframe swap & got it all back together, dropped the rear subframe out last monday, took the gtst diff into a place down the road from my work to swap the centres.

They removed the old vicious centre out, opened up the GTR centre to have a look if the plates were worn, decided they still had plenty of meat in them(place seemed to have had lots of experience with nissan diffs, in particular patrols that use very similar centres, time will tell i suppose), gave them all a scuff to get rid of the glaze on them apparently,

shimmed up the centre a bit to allow for the wear in the plates, swapped the gtst pinion gear over, slapped it all back together, filled it with oil & some friction modifier (don't know what the hell it is but the diff guy swears by it).

While I had the rear end out i ditched the hicas, bought the lock bar from ISC, gave it a scuff & a coat of matt black before I bolted it onto the subframe.

Tried installing the Justjap HICAS loop kit I also just bought onto the rear solenoid (seemed the logical place to put it, no instructions came with it) but it was about 12mm too long when fitted onto one of the fittings on the solenoid. Maybe its meant to go somewhere in the engine bay, but I thought it would be better to use the loop running under the car for PS cooling. Anyway, ended up finding a loop with the exact fittings that came off GTR cradle, its not a permanent fix but it should work fine for now until I find out where the JJR loop is meant to go.

Didn't need to cut the standard GTR subframe bushes down, there was just enough thread sticking out to get the nuts on, it seems like there is a bit of a gap between subframe & chassis because of the gtr bushes having a metal collar that protrudes 20mm, not 100% convinced that this is a good thing.

Just took the car for a spin to get it booked in for a wheel alignment, diff feels soo much better, just a slight chatter at slow turning speeds when under throttle, no 'clonk clonk clonk' like an aftermarket 2way, boths wheels hook up very cleanly now.

Rear end feels less squirmy and even though I haven't give it the full beans launch, it seems to have fixed some of the axle tramp that was always there before. (could also have something to do with different rear shocks & springs also).

Only concern is ABS light comes on after I start the car and move a few metres up the road, brake pedal feels very soft now also which is a bit worrying.

Anyway overall a success I think, considering I have never tackled anything like this in my garage before.

I have some leftover bits and pieces that I will be trying to get rid off if anyone needs it.

old gtst subframe with all suspension & hub pieces (no diff).

Bits & pieces of GTR & Gtst diff including gtst vicious centre, gtst rear diff cover

gtr diff casing with ABS sensors & loom,

GTR crown & pinion gears,

hicas rack with lines,

Nismo 4 way adjustable Gtst rear shocks & springs.

JJR hicas loop

Prolly some other stuff I have forgotten about too.

You should put your gtr centre into your old diff housing, and use the crown wheel off your old diff.

That way your ratio will be the same, and you will still have your abs sensor where it needs to be, and you'll have the good lsd.

Then, use the gtr axles and hubs. The axles are bigger and the hubs are alloy which means they are less unsprung weight. You will need to use all the gtr arms.

Your diff will fit into the gtr cradle as long as you use the rear cover plate off the original diff, and also use the original front diff mounts too, as the gtr had big rubber mounts on there's.

PM me if you need any more info., I've done a lot of work with diff's and rear end setups.

Thanks, Scotty