View Full Version : differential

11-26-2010, 08:51 PM
ok to start im a dinosaur when it comes to computer stuff so my typing sux. also a bit of a beginer at fabrication. im planing to build a mini rail or trike that will be dual purpose, with a lot of street time. planning tu use at least a 600cc engine. and i am a tight wad. so im wondering what would be the best starting point for a differential. i am a machinist with acsess to a good welder. would something from a used quad hold up to it? i wanna stay away from car parts cuz of weight concerns. thanx in advance

11-26-2010, 09:21 PM
Welcome Hackncut! There are a couple threads talking about using a BMW differential. That could be a salvage yard part... But there are more vehicles out there that use that style rear end... I think some smaller Honda SUV's have something similar, even a 4wd Ford Escape has a small center section that could be used. the wider you go with a center section, the less travel you will get, unless you keep making your buggy wider, and wider... Hope this helps!


11-27-2010, 11:05 AM
wow i guesse im more of a dinosaur than i thought,cuz i think of parts on cars and just think of those big old cast iron parts from the old V8 days.i was thinking a quad part but then i dont know if it will handle the extra weight and power. the smaller car parts would work great. and the focus is old and common enough that the cost should be right. thanks deranged

11-27-2010, 11:31 AM
Also if you select an SUV type differential as mentioned, lean toward one with larger wheel and tire diameter. This will allow you to select smaller diameter tires and wheels for your build while taking advantage of the gear ratio the manufacturer used to make the larger tires and wheels work well.

In other words, late model vehicles with 20" wheels have relatively low gear ratios. Using a smaller wheel and tire combo for off road makes the gearing even lower, which is good.

11-27-2010, 12:01 PM
thanks hadnt even thought bout that great idea

02-02-2011, 02:55 PM
you can also use a Miata LSD. take it out of the pumpkin housing and take off the ring gear. then bolt up a 52 tooth sprocket and make bearing mounts to hold the LSD. that will work if you want to do CV half shafts or solid axle. this is a pics of just one i found

02-03-2011, 12:24 AM
any additional info on that?

I see where the pic came from. Curious if you have the background story with it.

I can see that working in another application I have in my head.

02-03-2011, 05:13 PM
there is quite a few forums that have done the Sproket/Miata Diff. What else do you want to know

02-03-2011, 06:20 PM
Once nice thing about that setup is that it moves the sprocket off the CV flange. Some spools have the sprocket mated to the back side of the CV and a larger diameter mating surface is better IMO.

05-05-2013, 11:17 AM
I made a drivetrain from an old LSD from an impreza

05-05-2013, 01:45 PM
more pics on that subie diff?

05-06-2013, 03:53 PM
Here it is.
Std rear LSD from a early wrx impreza thee are better helical diff fitted to sti version that are even more enclosed
I just replaced the tapered bearings with std sealed roller bearings and used the Subaru bearing housings fitted into my plates


Also using the drives and part of the outer hubs
Drives are the same length
Outer hubs are 5x100 but I will cut some old wheels to get centres for my atv rims
Machined and welded a flange onto the inner of each drive to carry inboard brakes from the rear of a small motorbike NSr 125 I think using that caliper too

Made a flange to adapt for a 47 tooth sprocket I had but ya could get a special sprocket cut

Capped the diff using 4" exhaust pipe probably should have used stainless in heinsight
Gonna fit a grease nipple for lube
Gonna always loose a bit round the drives but I can live with that


I cut the bearing seats from the old diff housing to weld too the inside of my mounting plates but their not hat tidy so I will machine new ones when I get a chance just for a little extra support on those aluminium bearing carriers

08-05-2013, 01:01 PM
This site is very cool. Its nice to see people that have come to some of the same conclusions. I have a project and its turning out much like that subie rear end. Im using honda accord stuff. Mfactory helical diffs/lsd. I will use the sealed bearings just like nivek's subie and then enclose the diff to hold lube much like niveks and also the custom sproket mounted to the ring gear location. Its so cool to see stuff like this when you have worked it out in your own head then see a site where people are doing that. I will be the only one who knows I didnt copy anyone and came up with this stuff on my own (even though it has been done before) *thumbsup*

Here is the Mfactory helical honda diff. Its a nice little package but has not been tested yet so I cant comment on its abilities yet.

The diff part is about 6"s wide. Should be cool .. great site. :)

Edit: Oh yea ... there is a need to seal between the cv and the diff. Niveks shows how the original seal is mounted in the transmission wall. Well trany fluid is meant to lube the axle and bearing in my set up so I need to seal the axle point. I will make a cup that holds the seal and rotates with the unit, this should add life to the seal because it will only "slide" when the diff has a difference in rotation speed on each wheel. The original setup "slides" the seal with every rotation of the axle.

08-23-2013, 10:57 AM
I'm gathering parts for my '75 Z1 Kawasaki quad project, and these solutions look very impressive. But because I'm not sure where I'll be, I'd like a locking diff or maybe a non-clutch type LS diff. The exposed carrier might still work, but I'll have to find donor from a small 4x4.

I'm sure there's information around here on how to keep sand and dirt out of the bearings. These are a very elegant solutions to the diff and rear brake problem. Very nice indeed.

Edit: looks like the mfactory metal plate diff might be worth looking at. It looks like you can preload the diff to get an adjustable slip. That would be very nice to dial in. I'm sure it's not cheep though.

08-24-2013, 12:21 AM
(Im told) a helical lsd is not like a normal open diff. It doesnt give out on one side. It applies the power to the grip not the slip. It will accomplish this without plates or springs and it is all direct drive through gears.
This is what I have been told...I have looked at cut away views of them but still cant figure it out.

I mistakenly thought the subie one was using sealed bearings , Opps. I see now that the original taper bearings are in the pictures. Im just going to get some large sealed ones and make some 6061 carriers for them. This will keep gunk out of them.

I was looking at Subaru stuff (before I found this site) and just determined that it was to expensive compared to the honda stuff. Honda accord drive line boot to boot 56 bucks and its over 34"s long. The hondas have great little hubs to and they are cheap. The subie stuff is more performance minded and might suit a normal mini rail better because of weight but all the subie parts are more expensive. That I have found.