well all u may know me from my car being on this forum a few times. i drive a green 71 datsun 1200 coupe. Equiped with a ka24e with 45 webers, zx traney, 510 wagon rear diff with truck 4:38 gears. well.. i upgraded to a ka24de 16 valve with the early cams. pull hard up to 7 to 7500 rpm. ran 13.6 with no traction with slicks. when i did get traction with slicks i ran 13.2 and then BROKE MY AXLE ONCE AGAIN... hmm i have lost count. for my car only weighing in at 1655 man it sure breaks axles. I have a welded spider gear setup and it just is not holding up to this STOKE ka24de with 50mm mikunis. I need a stronger rear end. This means i must do a back half or 4 link setup with adjustable coil springs i presume. I hate having teh car down and not being able to attend a event because of a axle. What im gettin at is, does anyone have any sugestions on what route i should go ? ford 8.8 ? gm 8.5 ? 8 1/4 ? i mean i obviously have to get it shortend and custom axels most likely the 4 x 4.5 so i can still run my nissan wheels when i must. its hard to find out and see pics of 1200s that have been through this same process. im planning on runing 26x10x15 on it .. 15 inch rim 10 wide and 26 tall. I have a 2004 ford f-150 v6 heritage lsd rear dsic rear end at my shop from a totaled truck of ours .. but people say that rear end is to big and i can suffer power loss. well just let me know if u guys have any feedback or what not. thanks

RICH

The 510 wagon rear diff has 23 spline axle that are 24mm diameter. These are very small for the torque you are putting through them.
Try modifying the rear from an 80's 200SX V6 to fit, as these are more than adequate with 29 spline 30mm diameter axles. These axles are used behind 300 hp V6 VG30 engines regulary in rally trim.

i don't see how a diff can cost you power.

people go on about strong and heavy diffs adding weight and killing 1/4m times. but the trouble is, a strong and lightweight diff doesn't put enough weight over the back wheels to get traction - so the benefit of low weight is offset by no traction andyou're back to square one. at least with a strong and heavy diff (ala nine inch) you get the bonus of traction AND an unbreakable diff.

i'd go the diff you mentioned if you have it just "laying around".

You also have to consider how much power it takes to get the heavier diff assembly (gears and axles) spinning. The lighter the internals, the less effort it will take to get the whole lot turning.

As an example, a very good friend just had an experimental tailshaft made for his car. It's an all aluminium tailshaft, wrapped in carbon fibre, and weighs half of what the original tailshaft weighed - the difference in engine response and acceleration was quite noticable in the car - and the lap times were quicker.

no denying that at all - less intertial resistance means the engine can use it's power elsewhere.

but a heavy gearset / tailshaft / whatever wont COST you power, it just moves it from the wheels to the heavy rotational items.

funnily enough, you'll still record the same power at the wheels with or without a lightweight drivetrain item(s).

I wonder if the axles where removed before welding???
If not, could the heat from welding the spider gears have
anealed the axles????

I must strongly disagree that adding weight to the rear of the car is good.
Weight transfer..yes...but just weight no!!!!!!!
There are better ways of improving traction without adding large amounts of extra weight.

It may not COST you power on a dyno, but in real life, in makes the car slower....wether it be cicuits or drag racing.

Also, the diff is unsprung weight.....which is even worse than body weight.....keeping unsprung weight down to a minimum is key. The extent that my mate has gone to, to reduce the weight of his diff in the sprinter is incredible, but it is significantly lighter than a standard sprinter diff.....and it also helped the car turn quick lap times. It also broke at the last race meeting , after 12 months of hard racing, and a fair amount of testing. He is now considering going to a full spool set-up - which is stronger, and also lighter I believe.

I would stay away from a Ford 9 inch. Strong, yes, but it will also cost you 3% more power to turn than say, another unnamed rearend that uses 12 bolts to hold the ring gear on. The 9 inch meshes the pinion low on the ring gear, bad for friction.

yeah lightweight is cheap horsepower. but horsepower is useless if you can't get it to the ground!

the thing is, it's wheelspinning with slicks - so something is wrong with the weight transfer. a set of 90/10 shocks might do the trick up front, but they're plain horrible to drive with.

i mean, ANY diff will prob be heavier than the one you have in there - so it's just a matter of how much heavier. the 9in will be about 55-60kg more than a hilux / BW rear end - depending if you run gearsets or a full spool.

if it were my car, i'd choose the commodore / skyline BW and fit up a 4.5ish detroit locker. i'd keep the std leaves and just run a 2link / trampbar rear end instead.

but that's just my o-pinion....pardon the pun

Nice Pun Pro!

You hit the nail on the head..... something is wrong with the weight transfer. And when he gets the weight transfer right, and the rear end hooks up, it will put even more stress on the axles.....

There has to be a balance though.....and the balance is simple (to me anyway) - make it as light as possible, but still reliable. Sometimes it can take some trial and error to find this balance.