Datsun Roadster complete rear end

[JonnyCanuck]

I happened to find a guy sort of locally selling off a pile of Roadster parts.

Currently trying to get some photos/parts numbers from anything off the 2 x complete rear ends he has. Hoping one might be a LSD diff. But, knowing little about 510s still and nothing about roadsters, it's a bit of a roll of the dice.

He's asking ~$400 CAD for the complete rear end, but without being able to get there in person, or get decent photos it's impossible to know if it is an LSD or not. He does know it is from a 68-70 car, but so far searching hasn't netted me any results on the specifics of which car/year got which rear end.

Did all Roadsters get LSDs? Or what it an upgrade/option. If I can get the fellow to do the 'turn the axle' thing, then great, but it is via kijiji at the moment, and responce has been slow... (feel like kijij is not his strong suit.)

Curious is anyone happens to know offhand. If not LSD, then not worth the time, and I will stay one wheel peel...

[icehouse]

It was not a factory, it was a option. If it's a true LSD I'd take it for 400 Canadian bucks.

[JonnyCanuck]

It was not a factory, it was a option. If it's a true LSD I'd take it for 400 Canadian bucks.

I will write and see if he has a moment to turn one of the axles, parts listing *does* indicate it is an LSD, but it's in my hometown, and my Dad can go take a look for me, and pick it up if so. It's a 5 hour drive, so I'm not just going to jaunt up and take a look.

$400 Canadian pesos is totally worth it , I would think (and worth, what... pocket change in USD?)... Numbers seem to indicate that even if it is the short of the two Roadster rear ends, that between wider tires, and maybe wheel spacers, it could be a direct swap. Looks like axle size and spline count won't be correct to just swap the pumpkin.

I suppose if it wasn't going to work out in that regard, there is still a market for those LSDs and I could at least sell it on at no loss, and maybe some gain, tho I'm not trying to game the guy, just maybe get two wheel traction in the 'goon.

Cheers!

[datzenmike]

Standard 3.889 but optional 4.11 gears and/or LSD.


I get the Roadster H-190 as being 6" narrower WMS to WMS than the 510 goon. No idea if the leaf springs are mounted in same position on the axle as the goon. Not really even a close swap.

The Roadster side gears are the same spline as the 510 goon so the goon axles will fit if you swap the 3rd member into the goon.

Not worth the effort unless LSD and then do you really have a straight line traction problem with a goon???? LSDs are terribly over rated and come with their own disadvantages.

[JonnyCanuck]

Yes, thanks.

Further reading suggests I had the different roadster rear ends mixed up. The one I thought was correct was ~1.5" shorter overall? I can't see finding any way to swap in a 6" shorter rear end, no.

I'm principally looking for the LSD becuase while I don't plan on wild power for the old goon, I would think the car will be the most fun on anything that is not a straight line.... What are the purported shortcomings of an LSD in this application? I have some concerns about moving from a vehicle that has AWD and a rear LSD to one that will spin a single wheel and lose traction. It seems like an inexpensive insurance policy?

May turn out I don't need it, and I can always go back to the open diff. Easy enough if the axles are correct, and it is just the 3rd member/pumpkin that needs swapping. Looking closer, it appears that if it is an LSD it may have a sale value a great deal more than $400 CAD, so I wouldn't stand to lose anything?

[JonnyCanuck]

Whelp...

Gentleman was kind enough to confirm what the photos he sent along suggested, wrong bolt pattern for an H190, so it is very likely the H165.
And while it isn't a perfect test, turning one side forward rotates the opposite axle in the opposite direction, so most likely not an LSD.

Thanks very much for the assistance tho! Fella had someone coming to possibly take the entire parts lot he had stored up, which would have included the rear ends. I was really hoping to figure it out before that happened.

One wheel peel it is.

[datzenmike]

LSD. Both tires are forced to turn at same speed. Depending on break away torque it can be overcome and clutches forced to slip to turn sharp corners but at all other times other than straight ahead driving, rear wheels are trying to turn at different speeds and your tires will wear more with one. Some wear is just an aceptible cost of doing business with an LSD. Tire 'chirping' and slight wheel hop while turning tight turns may also be noticed.

LSD cars will tend to under steer or plough into corners more than an open differential.

LSD cars are harder to recover from during over steer conditions because the wheels are trying to turn at different speeds but are restricted from this. 10X worse on ice or snow. The one with the most traction (usually the faster outer) will try to force the slower inner to turn at the same speed. Ever watch U tube where cars leaving a car show light up the tires and get out of shape and they go side to side and plough into the curb? or at a drag strip where they get slightly out of shape off the line and end up in the wall? and you say to yourself hell I could have steered out of that. Not so easy when the rear end is fighting your steering input.

LSDs are great on level straight ahead where traction is needed. Try taking off on an icy side sloping road with an LSD and it will spin both tires and the ass end will head right for the ditch every time.

The thing to do is beware of an LSDs propensities and practice driving them. Know what the limitations are and avoid those situations.

[JonnyCanuck]

Thanks Mike,

Clear and concise. I think I am used to LSDs with a lot more 'slip' in them than described above. So perhaps just much less track oriented types, or some other permutation that allows them to be more daily driver friendly.

Maybe I'll just try to get some seat time in a similar car with an LSD and see what it feels like before trying to chase one down for the wagon, which from everything I've read is a difficult task. Leave well enough alone with the wagon until I've had the chance to find it's limits somewhere safe.

[Pjackb]

Hey Johnny, a few points ,

I see you're in St-Catherines so you're most likely talking to Pat about this , Nice guy by the way,

he's had it up for sale for a number of years and it's definitely NOT an LSD but a stock open diff from a 1600 Roadster with a 3.9 final ratio. and his price at 400$ is a little high for the condition I've seen.

All roadsters came with H190 differential only , with 3.7 for the 2000 and 3.9 for the 1600s my understanding however is that the axle size and the number of splines is unique to the roadster.

changing the gears in the roadster for a 510 wagon 3.5:1 is a really sought after modification and if you decide to change yours I'll buy it from you

[datzenmike]

The H-190 Roadster side gears are the same 23 spline as the 510 wagon, so will take the wagon axles.

The side gears in the H-190 Roadster with LSD are different (because LSD) It's not clear if the spline count is also different.

[JonnyCanuck]

Hey Johnny, a few points ,

I see you're in St-Catherines so you're most likely talking to Pat about this , Nice guy by the way,

he's had it up for sale for a number of years and it's definitely NOT an LSD but a stock open diff from a 1600 Roadster with a 3.9 final ratio. and his price at 400$ is a little high for the condition I've seen.

All roadsters came with H190 differential only , with 3.7 for the 2000 and 3.9 for the 1600s my understanding however is that the axle size and the number of splines is unique to the roadster.

Thanks Pjackb. I wonder what it is that he has then, since from the literature I was able to find the shape and bolt pattern look like the H165. Ah well. In any case, it does not appear to be LSD, so I'm going to take a pass on the whole thing.
I do live in St. Catharines at the moment, but this rear end is in my hometown 5+ hours away, so I don't know Pat, but if he has an old Datsun and is in the area, I'm sure I'd like to meet him and chat cars.

I'll leave well enough alone with the wagon for the foreseeable future. It was really just the idea of finding an LSD diff for $400 plus the price of maybe having axles made up that was appealing. Without that as an option, I am sure the stock stuff will be just fine for the L20b that is in there...

Thanks to all for the quick response, and the information. Much appreciated finding that here, after chasing down info other places, and looking at 70s vintage parts listings. Those things can get you there, but it certainly isn't all kinds of fun.

Cheers!