Moving Early 240 Diff Backwards!

[Z]

In a spot of bother and hoping you guys can help out...

 

I've spent the day with Dat2kman figuring out the best way to improve the R180 diff/axle set up on the car seeing as I've just completed the S14 gearbox conversion.

 

The problem is that with the early 71, it has the diff located slightly (35mm?) forward. This was later fixed in the 72 models onwards apparently, their diffs were placed further back, positioning the axles in line with the diff, which helped out the old uni axles somewhat. I am sticking with uni axles and it would be best to reposition the diff backwards while other work is going on. So my question is - what is involved in doing this correction to move the diff backwards???

 

Jason had a mustache bar with two doglegs in it which may solve the rear mounting point for the diff, but are there any other factors for the front diff mount perhaps? Dimitri to the rescue maybe

 

I've tried searching on this problem but only came up with this: http://www.viczcar.com/forum/index.php?topic=3770.0

 

Any knowledge/experience on this tricky little curve ball would be appreciated as I'm wanting to get stuck into it!

 

 

[satrat z]

Hey mate , have just done this exact diff move on my 1970 240 after fitting an S14 box, the mustache bar and also the straight brace behind the diff needs to be replaced with the later style curved brace .  I got all the parts off Stew Wilkins as he had supplied a new engine and box.  I also replaced the fwd diff mount with a 73 that I had sitting around. This was recommended by Stew but if you don't have one I am pretty sure it would have lined up with the old style.    Did you use a modified Gearbox cross member ?

[satrat z]

Back again, sorry mate also forgot to mention the restraining strap going over the top of the diff needs to be moved back in to the rear holes so you only get to put one bolt in per side , I have kept an eye on mine and haven't seen any movement with only one bolt either side . If you felt the need to you can weld an extension on the bracket and drill for the fwd hole to fit a second bolt.  Hope that helps.

[Z]

That does help very much satrat z

 

I've been doing some research and http://www.classiczcars.com/forums/thread48143.html (Posts 2 & eight) seem to think you update the front crossmember, get a curved Rear Transverse Link Mount (http://zhome.com/ZCMnL/tech/R200.htm) and then flip the mustache bar around! It all sounds doable but flipping round the mustache bar...really?

 

And this link for all things diff by JMortensen, have referred to this one a bit: http://forums.hybridz.org/topic/49194-differential-cv-lsd-hp-torque-r160-r180-r200-r230-diff-mount/

 

I did get a modified gearbox cross member from SWM and with 300 odd kays so far it seems all good, hope you are having the same experience with yours satrat z. Great info on the alignment for the restraining strap, will have to consider that as well!

[satrat z]

Glad that was of some help, re flipping the mustache bar, maybe that can be done but I swapped the straight bar for the later model bent one. The S14 box is a massive improvement.  Not sure if you have replaced the rear seal in the box? I bought my box from SWM and after installing found that the seal was worn and leaked badly so if you haven't already, it is a good time to do it. Especially now with the diff moved back, the tail shaft bolts are a lot more difficult to access as you have probably found.

I also found the original rubber gear stick boot doesnt fit because  the S14 boot/upper seal that fits tightly around the stick interferes with the early model boot as it hangs down too far so i just used a generic one that fits on top of the tunnel as it is covered by the vinyl boot on the console anyway.

Hope all goes well.

Geoff 

[dat240z]

As above. Id say you need the r200 traverse link and moustace bar. SW Motorsport has high quality diff mounts which can eliminate the need for that old strap....

[Z]

Really appreciate all the feedback fellas.

 

Satrat z I will check the rear gearbox seal, hoping the transmission shop did all that when they recoed the box and fitted the 260 bellhousing. As mentioned above, SWM recommend the later 240 mustache and transverse link. He did say the the front crossmember can be the same but the rubber mount is different.

 

dat240z for the moment I have ordered the SWM front crossmember, which is modified by Stewart to also hold the front diff in place... (same effect as the R/T Mount) and go from there. She ain't cheap...but it is fullproof from all accounts!

 

At the end of the day it seems there is a solution for the early girls, with the forums help and modified parts we should get there!

[dat2kman]

Further to this, i have what i def know is a later 260z moustache bar, that uses the curved type horizontal brace that sits at bottom and behind diff rear cover.

I also have two other moustache bars,

One a flat one, ie no dogleg/kinks, and

One with diglegs/kinks, but,

Niether of these are the same shape as the later 260 moustache!

 

Which is which?

And if Z decides to stick with stock items, i'm happy to let one of the spares go, unless he goes all fancy with the Arizona stuff!!

[Mr Camouflage]

Another thing to watch out for is that since you are keeping the R180, an R200 moustache bar won't work. Different bolt spacing on the R180 vs R200. If I recall correctly.

[dat2kman]

Another thing to watch out for is that since you are keeping the R180, an R200 moustache bar won't work. Different bolt spacing on the R180 vs R200. If I recall correctly.

The two spares i have must be r180 as bolt spacing for rear diff mount is narrower than the one i know is an r200

With the change Nissan made, was it simply just a doglegged moustache, a front of diff to crossmember mount change ( rear offset?), and??

[gilltech]

FWIW an R180 fits in place of a factory 260 R200 installation using longer studs & some spacers - I've done it yrs ago as a temp measure to keep my car mobile until a replacement R200 came available - but not the reverse obviously. I recall having to slot the R200 moustache bar diff rear mounting holes slightly to get the studs through, & that reversing the bar wasn't going to work with the driveshaft.

 

My manual 2-seat 260's R200 moustache bar is slightly dished towards the front of the car, curled ends facing forwards. I also have a spare just the same, which came out of a manual 2+2.

Auto equipped 260's typically came out with R180s, so the bar must be deeper dished?

[Z]

Cheers Gilltech, I've recently heard that you can do that with the R180. But looks like I'm now going R200, albeit kicking and screaming! Really wanted to keep the R180 if I could as I think it can handle my cars power, but it just ain't gonna happen it seems.

[gilltech]

The R180 is lighter than the R200 for starters.

FWIW many many years ago I knew a guy who regularly raced his 240Z in club competition & with R180 & R200 diffs being difficult & expensive from dismantlers back then he just used a succession of R160 diffs (out of 180 or 200Bs I think), at least they were dime-a-dozen therefore cheap & expendible. He just put a new one in every so often! But then his car wasn't modified for much more power.

[PZG302]

If you can keep the R180, keep it. A lot lighter than the R200, and generally cheaper to get different ratios if you need to chase them up.

 

In my car I only ever had 1 R180 let go and that was after a customer rolled the diff over, letting the oil drain out and cleaning te mess up without telling anyone. It did almost 10 laps of Amaroo before going bang.No other problems at all with launching from 3500 for race starts to 6000rpm for hill climb starts to put oon a show.

 

And a cheap easy fix for the diff restraint is a bit of chain over the diff, worked well in my race car.