engine and drivetrain How much power can the rear end take?

[lelio]

so these number's represent the engine's with EVERYTHING on them. transmissions, manifolds etc.

my hoist scale only reads within 25lbs or so

nissan: ~650lb

bmw: ~575lb

so much for weight loss.

i blame it on the transmission. the nissan has a power steering pump and turbo that the m10 doesnt, but those cant add that much. if you look at the m10's little 4 speed next to the sr20's it looks tiny. do the 5 speed converted ones wiegh much more?

when i get into preparing the sr20 ill weigh the engine and transmission seperate and get a better idea of where the weight is.

[winstontj]

If I were you I'd keep the Nissan transmission just because it's designed to be together. The 5-spd gearbox isn't much heavier than the 4... but it is a little heavier. Maybe 20lbs max. The other thing to think about is you won't be needing that power steering pump AND if you take your battery and put it in the trunk then you're even.

POST SOME PICTURES!!!!!!

[lelio]

so, almost a year later and Im finally getting around to this part. so i thought id bump this thread in case anyone came up with anything since last time. or if M20Curtis has broken the latest one he was talking about.

I found a used Nissan Viscous LSD that would work fine except its about 3 inches wider than the stock BMW one (i have a feeling this would be the case with most stronger Diffs), which would mean i would have to find some short axles with flanges on both sides that i would make adapter plates for. which is proving kind of difficult to find and will no doubt get expensive if i do.

im torn because it would be so easy to just use a BMW LSD and have the custom drive shaft made, but im not building this car to drive it gently.

perhaps someone knows of a decent shop that works on BMW diffs ? i could talk to them and see what kind of options there are for similar size diffs, even if i have to spend a bit of money to have one rebuilt special.

or if anyone knows a good shop that i can talk to about getting short/custom axles.

[winstontj]

I think that you can put an e30 diff into your car with short money. Also take apart one of your axals and take a look. You **MIGHT** be able to just have a machine shop cut down the splines and shorten them up. Possibly just cut the splines in further? 3" isn't that much when you divide by 4 (shortening up .75" on either end of either axal).

Other than that I'd look to put an e30 subframe, diff, trailing arms, etc. all in the back of your car.

[lelio]

thanks for the advice, Ive been lazy about updating, but i actually found a solution, kind of similar to what you suggested.

I put in the nissan VLSD. took the bmw axles apart, cut an inch out of the middle of one and 2 inches out of the other, Because the diff's input is off center. then i put them in a lathe and put a 1/4 inch hole exactly in the center of each cut off end, put a good chamfer all around while i was at it. then i connected the ends together with a 1/4 inch pin and took them to someone who is a much better welder than i am to weld them together perfectly straight and centered. (perfectly meaning within about .005").

if that doesn't make sense i have some pictures on the shop pc, If I work on the car tomorrow ill get them all together and post some here.

then I replaced 2 cv joints that looked a little doubtful but kept 2 that looked good (I was planning to replace them all regardless but turned out to be harder to find and more expensive than thought. ). I made 2 adapter plates that bolt up to the bmw's cv joint on one side and the nissan diff's output flanges on the other.

mounting the diff was a little hairy too, I had to cut into the very front of the trunk a bit and add a support bar that goes from the bottom of each strut tower and ties in with the little bit of stuctural sheet metal there too. ill be welding in a little sheet metal to pretty it up soon. that was for the back bolts on the diff, the front ones got an adapter plate to bolt onto the subframe.

Also i got lucky and the drive shaft from a 240sx fit in perfectly with no modification. I just had to weld in a mount for the support bearing. so drive train has been 100% completed as of a month or 2 ago

Im currently working on rebuilding the the transmission tunnel and firewall. after that will be the roll cage which i hope to tie into my diff support bar.

Im gonna really try to get on this pictures thing, there's so much i haven't put on the journal.

[winstontj]

Pictures or ban!!!

Hope this makes sense... If you take your normal cage and run a standard rear X it should be fine. An easy way to deal with the rear towers is to run a tube straight between the two - then take another and make a stretched V going from the tower, down to the top of the diff, back up to the tower.

The other thing is don't forget about the little straps that go from the subframe carrier bushings to the forward chasis. (the things about a foot long) they can be beefed up and tied in to your cage as well.

Is the Nissan driveshaft a two part? Would love to see how fitted the diff into the subframe... I'm about to put an e30 diff into an e21 and I know that it won't fit. I've been told I need to cut into the trunk floor to make it work properly. Did you need to do anything to the subframe or just the chasis (trunk) floor?

[lelio]

The Nissan drive shaft was a 2 part. much shorter than 02's but the Nissan transmission was a lot longer so it came out just right.

nissan diff with part of driveshaft;

and you can see the second piece and how it connects to the trans in these 2;

I almost got away with 0 modification the the subframe but in the end i had to shave about a square inch of sheet metal off or the diff wouldn't align straight.

a better pic of the adapter plates and before i knew i would have to take that notch out. ;

and here's the ugliest part, the trunk hack;

I was hoping to do something like the v bar you described. and just have it attach to the same spot the rear x bar of the cage attaches to the strut tower on either side. or have the v bars attach directly to the bottom of the x bar. i definitely need to do something since as you can see i lost a lot of structure there.

ill also be laying in sheet metal to try and pretty it up some and ill have to rebuild part of the gas tank mounting which was kinda rusting away anyway.

basically what i had to was make a plate that mounted to the back of the nissan diff, weld it to the the plate that org diff bolts to,

cutout the structure that the plate mounts to, attach those together through the bushings then hold the whole assembly in the car in the right position while i welded the structure (trimmed to fit) back into the car (slightly further back, up higher and to the left) with the use of that square piece of tubing.

I cant find the pics of the axles being assembled, but i have a few of the finished product at least.

you can also see the adapter plate i made for the diff on the left.

[pkbinplano]

Hey I have a brand new Nissan 350z diff. It's a 3.3 lsd and for an automatic. It's the complete diff. Email me if interested and for pics

[peteinjp]

Very cool project. I'm looking forward to seeing your blog updated. Let us know when you have posted the new pics.

Just curious- having to go to all the trouble to weld the shafts together why didn't you use the Nissan cv on the inside thus avoiding the need for the adapter?

[lelio]

your right about the axle's. It didnt occur to me because i didnt have any nissan axles. but i probably could have gone to a junkyard and got some and welded together a hybrid bmw/nissan axle shaft, it would've been a little less work.

oh well. this works too.