Ben D

no need for someone to design a 40 spline part if you are running a Z31T rear end, Ross at Moidern Motorsports www.modern-motorsports.com has already got the design, and they have been tried and tested.

Don't any of the S12 owners in the world have RSX gazelles they are doing up ? It would be a real shame to junk the crank - you guys just can't find them over there.

Hi guys, I still have one good FJ20 ET crankshaft in the USA being copied at Crower, and since I no longer need it, and Crower are finished with it, I want to see it go to a good home. It will be first in best dressed. E-mail me at ben@digsfish.com with your offer and your address and I'll get it sent to you and we can work out how you'll pay me later. I will not let Crower destroy the crank, they are too rare , surely someones needs a spare FJ20 crank over there in the US of A ? Ben D

Radial ball bearings have pretty consistent decription numbers for them as used by manufacturers such as NSK, Nachii etc. A 6007 series bearing has the right dimensions (62 mm OD, 35 mm ID), load and speed ratings to accomodate the part produced by Ross, however if there is enough interest in the part I think he will end up developing and marketing a complete kit including bearing and seal as well as companion flange and of course the stub axle itself. Over to you Ross and Modern Motorsports !

PS, There will be nothing metalurgically wrong with the 27 spline MM stubs that broke - they just have limits like all other parts, and the design of the neck down means they will always break at the end of the spline as the spline itself acts as a serration whenever an axle is necked down like that. The part simply breaks at the weakest point and there is nothing you can do about it except either A. cease the brutish launch behaviour or B. go to a stronger part. Personally, I always like to go to the strongest part available.....

Hi guys, I read this one with much interest. Welcome to the world of heavy duty stub axles. I worked on this with Ross at Modern Motorsports over a year back now after consistently breaking numerous stub axles in my little 4 cylinder S12 gazelle, which while only 2 litres, was running into the 9s at over 147 mph. The S12 gazelle RSX uses OEM R200 CLSD with suspension/crossmember which is identical to Z31 T 300 ZX. What I learned with this car is as follows: 1. stock 27 spline Z31 stub axles are good for a few 10 second passes before failure using a manual gearbox. With an auto I expect they'd last a lot longer. 2. make the 27 spline piece out of good material (4340, 300M, 2767 tool steel) and they will get you into the mid nines at 1.4 to 60 ft before they break with a manual box. Expect 8 to 10 passes out of them if you 60 ft into the high 1.30s. 3. the only solution is to increase the axle cross sectional area, which is possible by running a bigger bearing OD on the inner bearing to remove the neck down in the stock Z31 stub. 4. Ross at Modern motorsports has developed these for the Z31 stub axle and it is a 40 spline unit with matching companion flange which fits into Z31s if you use an inner bearing with a 35 mm ID (OD remains 62 mm) and the appropriate oil seal. 5. The part description for the inner bearing is 6007, the new oil seal to suit the companion flange is a 48 mm ID, 62 mm OD, haven't got the part numnber on me at the moment. Ross has manufactured these and I have tested the prototypes and can report they are good to at least 1.33 sec 60 foots and 9.12 &154 mph in my little 4 banger beast. In fact, its possible to hang the wheels in the air a fair ways with these parts. They should get you guys well into the 8's I would think. I attach pics of the pieces- the big stub is on the left. I also attach pics of what they can do for your car.

PS when the halfshaft broke, the car still drove down and back on the LSD (which is shimmed pretty tight), and since it broke where it did, the CV boot held it in alignment so it damaged nothing. Lucky I suppose.

I've broken one half shaft, I'm using a Z31T IRS with stock Z31 T shafts with a manual gearbox, and if the halfshafts break, they break on the launch. However if you can preload the driveline a little, they seem to hang in there, its the inertia shock of the clutch dump which does it. Furtunately you're doing 0 mph when it happens. They break at the root of the outer CV spline car in my experience, but I have only broken 1 so far, and this set I have in there now has done 25 x 9 sec runs and a best of 9.12 with 1.33 to 60 ft, so they are impressive for stock pieces. I've said to myself if I break another one, it is time to go to either a GTR style half shaft and CV (bigger splines), and/or get a set made from 300M. With both bigger CVs and the 300M shaft, I would say mid 8's would be attainable and reliable with my combo (would need more power then)....

shes certainly doing a great job for Canada. World class. Maybe we should change the name of this thread to something more appropriate ???

1983-85 S12 RSX Gazelle/silvia and 1983-85 DR30 RS turbo and DR30 RSX (intercooled - late model "iron mask") I have FJ20ET in my 510 too, nice swap, but the engine makes it a little nose heavy, and its a tight fit around the steering box for Left hand drive cars. I reckon if you bought a DR30 or S12 RSX, keep the whole car and you won't be disappointed, as they already have R200 LSDs, 5 speed, big 4 wheel disc brakes etc. and aren't too much heaver than a 510.

I ran the car on the street with the GT35R and a tight turbine housing (0.82), I found it spooled about as well as an old T3/4 hybrid I had on a previous car, so I reckon they are definitely streetable . They don't pull like a bigblock from 2000 rpm (they are only 2 litres after all), but from 3500 on you have to hold on. So compared to other cars with similar performance, the GT35R is definitely on the small side. It would boogie with a 88-94 mm compressor on it I'd reckon......... All the FJ20s are twin cam 16 valve, they are simply so old that Nissan was not using the D suffix for their motors back then in the early 80's. Today, nissan would call the turbo variant as FJ20DET. But the comparison between FJ and L is correct, they were both around at the same time., though the L was a late 60's design and the FJ a late 70's early 80's design.

Thanks for the support Guys. It does show what can be done with the Z31T rear end. For those who asked, I'll give it a wheel alignment (looks like the toe /camber moved a bit after that second launch) and will tighten up the LSD a bit more then back for the nationals and jamboree. On a prepped track we should be able to get the power down in the higher gears and we'll see what she will do then. Still running the small street turbo and mild cams, though I'm not sure what I'd do with the extra power anyway if we upgraded either again. Yes, the FJ is a great old motor - they appear to have the edge over SR20 and are at least equal to 4G63 mitsubishi in some areas. I'm running stock block, crank, inlet manifold etc., so they are great packages out of the factory. Pity they stopped making them 20 years ago...... Ben

some videos thanks to the blokes at Gunnamotorsports at http://www.gunnamotorsport.com/vids/willowbank-update/GUNNA-Gazelle-190706.wmv and http://www.gunnamotorsport.com/vids/willowbank-update/GUNNA-N13-190706.wmv

Just thought I'd let you blokes know that I got my S12 gazelle down to a test n tune the other night here in Australia and we put down a 9.12 @ 153.4 mph. Specs on the car include factory fitted 2 litre 4 cyl FJ20 ET engine, little street cams and turbo (garrett GT35R), 5 speed manual out of a R33 GTS-T and stock R200 LSD and Z31 T half shafts. The good bits are the Link G2 ECU and the modern motorsports Z31 stub axle upgrade. All glass etc. still in the car and 2600 lb weight. The air was good so the second pass of the night we turned it up to see if there was an 8 in it, but got into a wheelstand situation and had to get out of it and back on for a 9.7 at 151. Then the last pass of the evening the track went away and we could'nt get the power down. Updated the timeslips section - I guess it might get up the noses of the 6 cyl and V8 guys to have the little 4 cylinder up there, but hey its a factory car with a factory fitted engine , factory fitted Z31 equivalent rear end, factory driveline configuration with the manual stick shift, so I guess its OK to post it here ? Ben

Just wanting to let those who are interested in bulletproof stub axles know that modern motorsports has developed a 40 spline stub axle to suit Z31 turbo, with a 5 x 114.3 mm pcd on the flange and a fine 40 spline axle which is much stronger than 280 Z or even Z31 turbo stubs. I have tested these in a manual car and thay are fine for high 9 second passes with 60 fts in the 1.42 zone. I'm not sure how they translate to 280 Z or earlier models, but the basic design of the stub is virtually identical, so I'm sure if you provide the bearing numbers and other relevant dimensions Ross at modern motorsports can help you out. http://www.modern-motorsports.com/catalog/default.php

Why bother for a custom aluminium shaft if a 350 Z carbon shaft fits my car ? I'd prefer carbon up to a certain price premium as my understanding is (more knowledgeable authorities can correct me if I'm wrong) carbon shafts will be lighter while at the same time absorbing more shock loads than either an aluminium or steel shaft. However, looks like the 350 Z shaft is too long - 1321 mm c/c for manuals and 1283 mm c/c for autos, but no info as yet on whether the 350Z runs the big spline output shaft in the gearbox like Z32 TTs and R34 GT-T. Does anyone know this info ?

Hello guys, I'm interested in the carbon fibre driveshaft from the latest Z as a potential upgrade. Can anyone provide me with the following specs of a 350 Z driveshaft ? Length (both overall and centre to centre of the universal joints), shaft diameter, transmission yoke specs (diameter of trans output shaft and spline count) and rear uni/ flange specs. My car runs all Z32 300 ZX TT bits in the yoke and differential flange area, but runs a custom length single piece shaft that is 925 mm c/c of the uni joints. its a steel 3.5 " diameter shaft that weighs a ton - if I could get a 350 Z shaft to fit I'd save probably 20 pounds of reciprocating weight and pick up both ET and MPH, as well as cushion the driveline a bit on the launch..... Thanks Ben

Ok, sounds like the Z31 300 ZX semi trailing arm rear end has an advantage over earlier designs in that when we break stub axles, the brake caliper keeps the wheel on (the disc can't escape past the brake pads!) and you just coast down the track on one wheel power if you only break 1 stub, or get pushed back if you break both. I've done both, and driving down on one wheel is the least embarrassing and most fun, provided your diff isn't locked up and puts you in the wall. Thats why I like to shim my LSDs up tight, but not weld them, as its safer that way if something else breaks. Anyway, we've done a bit of R&D at modern motorsports and reckon the 35 mm, 33/35 spline stub axle option for Z31 300 ZX rear ends is a goer. If anyone is running this semitrailing arm rear end and is sick of changing out the stubs, drop modern motorsports sales@modern-motorsports.com or me ben@digsfish.com a line for more details. I plan to run deeper in the 9's with these units in a manual car, so I'll post feedback on them if anyone wants to sit back and watch developments. Cheers Ben D

Hope these pics are of some use to folks. Cheers, Rob Rob, Great pics. I'm stuck with a Z31 300ZXT trailing arm at present and can't see how I'd shoehorn a Z32 TT rear hub in there, and then again still running the R200 means you could only really run an Z32 CV on the outer, the inner CV needs to suit R200. I honestly can't tell you when the R200, half shafts and CVs begin to break on a Z31 T , I've only broken stub axles to date. Those other bits are surprisingly strong...

I've seen some low 10 sec skylines break axles, and when i went to inspect them from memory I counted 31 splines, but this was a visual inspection of brooken pieces in the pits and I didn't have anything on hand to measure or record what I was seeing. Still waiting for word from Modern motorsports re: development of a 35 spline stub axle upgrade from the 27 spline 4340 item they have for Z31 300ZXT. They may well be able to develop a bulletproof stub axle from 300M alloy, but I would need a group buy to get the price down to around $1K US for the set. I guess too much to ask that others need to spend this amount on their Z31 or earlier Z rear ends ?

Hey guys, I own a S12 RSX gazelle with FJ20 ET engine. Stumbled onto this forum while looking for stub axle solutions to some problems I am having in that area. Just to provide a bit of friendly rivalry between the 4 cylinder boys and others in this excellent and diverse forum, I direct you to the timeslips area . I'm sure you'll note that 4 cylinders rule the roost here for the moment...... It'll be a red rag to a bull for the 6 and 8 cylinder people, but the S12 with the 2 litre 4 cylinder is up there for the moment keeping them honest.

Jamie, Sounds like you're putting together a nice combo. I'm pretty sure that in an early Z what you have there will run into the 9's pretty easy, you'll simply end up adding boost until you do. My car is also a street car, though once they insist on the roll cage, harnesses and parachute etc., you don't tend to do too much street driving. I like using the IRS for drags, they provide good handling and are easy to tune once you work out a few tricks on how to control camber change (especially in the Z31 rear end set up my car has). I too prefer keeping the manual box and the IRS as its pure and keeps the character of the cars pretty much intact, rather than them becoming just another race car with a 4 link and auto trans. I run the RB25 DET box after breaking the output shafts from a few RB20 DET boxes. The 2.5 litre unit is certainly tough inside - do you know the ratios you have in that gear set ? Their stock 3.3 first gear seems Ok for drags with a 26 inch tall tyre and a 4.1 rear end. If I were you I'd run the twin plate clutch first then use the triple only if required, as besides being nicer for street use a bit of slip on the launch cushions the driveline a bit and also provides a better 60 ft with less chance of bogging in (especially with a 3.7 rear end). I run an ET street and reckon with a slick on a sticky track you'll need every bit of the Z32 TT stuff in the stub axle area - though it looks like from their design they dispense with the bits I am breaking. The only thing I don't like about the R230 is the 3.7 ratio. If you have a lower number than a 3.3 first gear in your gearbox you'll find launching difficult I would think. For lots of drag racing, I think even the stock 32 spline Z32 shafts will eventually give up in stock form, but I guess the moser bits will be made from 4340 and therefore would be much stronger ? Sounds like I should get a hold of some Z32TT half shafts and have a look - can you provide the diameter of the shaft and splines for comparison with R200 ?

Interesting info Jamie, Forgive me if I ask a stupid question, but from what I gather from your message below is that you're planning to run a Z32 TT hub and half shaft in an early Z, - does this mean you need to run the R230 and custom shortened half shafts, or do the Moser axle shafts suit R200 on the inner CV and Z32 on the outer ??? S15 200sx owner, I can officially assure you that the R180 and, more specifically, the half shafts and stub axles associated with it, will definitely be the weak links in your drive train. In my 2800 lb car with manual trans, the R200 stock bits are good for 30 or 40 mid/low 10 sec quarters with a DOT slick on poor tracks 1.6 to 60 ft), proabably wouldn't last near as long on a sticky track, and from what I have seen of the R180's , they're good for low 11's only. Dunno how these equate to road racing , but for drags I have found the aforementioned parameters to be pretty close.