Need help w/ datsun 5 speed

[heavy85]

Just got my 240Z this week (shipped in from Cali) and discovered an unexpected issue with the tranny. Basically it grinds a little going into second gear from first but 3-5 are fine - oh yeah it's got a 5 speed of some vintage which I dont know. The other thing is it's nearly impossible to downshift into either second or first when the car is moving at all. My initial thought is the synchro's or something in the tranny is shot. Supposedly there was $1500 dumped into the tranny to build it for autocrossing but....maybe I just got screwed. So my question is twofold - first is there anything I can do or check prior to just swapping in a new tranny and secondly is there a difference in early datsun 5 speeds. Someone I work with has a 5 speed sitting in his garage collecting dust and I could probably get it but should I be looking for something specific? Last thing it's got a new clutch (again supposedly) that seems to work fine.

 

I tried searching on here but the new site must not be working right because I can't get it to find anything.

 

Thanks

Cameron

[260DET]

For the 240 IIRC there were two types of 5 speeds. Up to mid 71 they had the close ratio box with a flanged output shaft. After that they had the wider ratio box with a recessed splined output shaft. So if your tailshaft has a bolt on flange at the front you have the earlier box.

 

It does sound like your syncros are buggered. Depends on the general condition of the box as to if it would be worthwhile rebuilding or not. And there is only one real way of finding that out...........

[heavy85]

Thanks - I have yet to jack it up and see what's all underneath (I was trying to fix my jack tonight so I could do just that but no luck) but at least it'll be easy to tell what I have. Is there, in general, an advantage from one box to the other? I assume the earlier box being close ratio would be better - that's assuming you can hit 60 in second but that depends on a lot more than just the tranny. By the way, how hard is it to repair a manual trans? I've rebuilt an engine and do all other auto repairs but never actually opened up a trans to see what's inside.

 

By the way what do used 5 speeds go for anyway?

 

Thanks

Cameron

[j260z]

sounds like your second gear synchro is gone. first gear usually is tough to shift into while moving anyway. as for working on my own tranny, i'm very mechanically inclined but don't have all the tools to do it right. i'd rather remove the tranny and take it in than try to explain why i'm bringing in a lot of pieces for them to re-assemble.

[JMortensen]

If you have a Comp trans, or a roadster 5 speed with the steel synchros, then check this out:

 

http://hybridz.org/nuke/index.php?name=PNphpBB2&file=viewtopic&t=31024

 

If it is just a regular brass synchro 5 speed, then any transmission shop could do it for you, or you can buy a kit and do it yourself. The Porsche synchros are a PITA, so I would suggest taking it to a Porsche shop since this sounds like your first rebuild.

 

The $1500 sounds like Comp trans $$$ to me, so you may very well have a comp tranny. You may want to try some SWEPCO in there. Makes the steel synchros MUCH easier to work with.

 

Jon

[heavy85]

Thanks for the info - would that SWEPCO stuff improve being able to shift into second? Any alternative fluid like synthetics that would be locally available maybe do the same thing? I looked on the GPR site and they dont list it and the SWEPCO company site lists several grades and types - any idea which one I would need?

 

I've got the flanged output shaft so it's the earlier one. I also talked with the PO who didn't mention this problem originally and he said the PPO (pre,pre owner) told him to double clutch it? I cant see where it would have been built like this on purpose but I'm not a tranny guy so could there be any truth to this?

 

Finally, I will be autox'ing this car on ocassion (sp?) and some day would like to turbo it so what tranny should I be looking at that could take some abuse if I need to replace mine?

 

Thanks

Cameron

[JMortensen]

J260 is right, could be a worn synchro, but are you heel/toeing? Double clutch usually isn't necessary with synchros.

 

If you want to turbo it, you'll want wider ratios, and probably want to sell me that trans and driveshaft. The 240SX tranny is supposedly bulletproof and has apropriate ratios.

 

I know that link to swepco is wrong, but the name stands for South West Petroleum Company, or South Western Petroleum Company.

 

If you call GPR they will sell some SWEPCO to you. I used to pick it up there every couple weeks when I worked for the Porsche shop. Works great in the clutch LSD diffs too. This stuff won't fix a bad synchro, but if there is ANY life left in it you'll see a big difference vs regular gear oil and probably Redline and all those types too. Nobody who raced a Porsche and brought their car into the shop I worked at used anything other than SWEPCO. To be honest I never realized they had so many. The stuff we used was the 201. They'd probably all work fine.

 

Can't believe I actually had a hard time remembering which it was, but I guess it has been 6 years or so since I worked for that shop, and at least 2 years since I've had a bottle in the garage.

 

http://www.drivewerks.com/catalog/shopcart/CARE/POR_CARE_swepco_pg3.htm#12

 

Jon

[johnc]

Don't use Swepco 201 with the normal Datsun tranny and the brass synchros. Before a race at PIR I changed the trans fluid to Swepco 201 in my Type B 4 speed and by the end of the day the synchros were gone. Prior to that I had been running a 50/50 mix of regular 75-90 gear lube and Dextron transmission fluid without any problems.

 

I do run Swepco 201 in my Quaife trans and diff.

[JMortensen]

I deg to biffer. We put 201 in every 924, 944 and 993, 996, and 928 that came in the shop and I've been cutting it 50/50 with ATF with my brass synchro tranny for the last 7 or 8 years. No problems in any of those cars with the synchros. In fact all my friends run it in their Datsun trannies (steel and brass) and a couple of Toyota 4x4 guys too with no problems.

 

There was a discussion some months ago about how GL5 used to automatically mean that it would eat yellow metal, but not necessarily anymore, but a lot of people still associate GL5 with that. Not true in the case of Swepco 201!!!

 

EDIT--My old boss even told me that the ATF Swepco mix is essentially what comes stock in 3 series Bimmers from the factory. Don't know how much truth there was to that one. He said, "You ever change the trans fluid on an M3? It's purple, because they are using the same stuff I am telling you to use in your car. Swepco and ATF." He seemed to know his stuff.

 

Jon

[johnc]

Well... is just goes to show you that a person can't reply on anecdotal information. I had heard the same good news about 201 from a lot of Porsche racers and had to try the stuff.

 

Literally in one day of racing (3 hours of track time) I lost the second and third gear synchros. The morning session began fine and then a little graunch started during the shifts at the end of the session. By the end of the day I had to double clutch the downshifts into third and second.

 

Air temps were 105F and track temps were about 140F which may have had something to do with it, but the coolant and oil temps stayed resonable the whole time. I checked the tranny fluid levels twice and they were fine.

 

I've still got the tranny and haven't torn it apart to check it. When I drained the 201 out it was still that nice blue/green color and there wasn't much stuff on the plug magnet.

 

The only change before the PIR event was the change to straight 201.

[heavy85]

I drained the trans oil the other night and it was full of very fine brass and steel - even had a gold tinge to it. The magnetic drain plug was full of what looked like gritty anti-seeze. I'll refill it and try it again but looks like this one's shot. and for PO not tell me before shipping it across the country!

 

Oh and yeah I do heel-toe but never had to double clutch a car before. I assume that's where you clutch - shift to neutral - release clutch - rev - clutch again - put it in gear? By some off chance it wouldn't require double clutch just because is a comp box would it? I cant imagine someone would make a box like this on purpose - would be a real PITA to double clutch.

 

Last question - what's up with the 50/50 oil/atf mix? Why not straight gear oil?

 

Thanks for the info.

Cameron

[JMortensen]

When the Porsche synchros break they BREAK! The worst I've ever seen happen to a brass synchro is one cracked, but I've seen the Porsches rip a third of the synchro off and little bits of the synchro float around in the oil and stick to the magnet. I've never seen the Porsche style unfixable. Despite the huge amount of apparent damage, every one I've seen was fine after just replacing the synchro ring, and NOTHING else. So don't think the tranny is dead, because I bet you can fix it.

 

Double clutching is what you have to do when you have a tranny that doesn't have synchros. Your description is exactly right. Lots of open wheel cars require double clutch downshifts.

 

The gear oil by itself is really thick, and makes for a slower shift. 50/50 is much thinner, but still has good wear characteristics, and it shifts much easier. Before I found that trick out I had been using 50 weight motor oil and had not been liking the way my car shifted. ATF and gear oil works MUCH better. ATF and Swepco is the ultimate IMO.

 

For a comp box you may not be able to get away with too much ATF, but if you put it back together and didn't like the way it felt with straight 201 you could maybe go 75/25 with a little ATF and see how that works.

 

Jon

[j260z]

that totally sounds like a broken synchro. i'll bet if you dropped the tranny yourself and took it in, it would probably cost you around $200. i'd definately get a couple of quotes. it's not hard to drop the tranny and either way you'll need to do that. if it is a comp tranny, i would think you would be farther ahead to get it repaired than to replace it with your buddies tranny. you really don't know what the condition of that one is anyway.

[heavy85]

Double clutching does allow me to downshift into second without grinding but the 1-2 shift still grinds pretty good so I'll pull it. How can I tell if it's a comp tranny so I know if it's worth rebuilding or just swapping and who supplies parts for them? I assume they have different internals than the standard tranny?

 

Thanks

Cameron

[JMortensen]

Since you said it has a flanged output shaft it must also have a 2 piece driveshaft with a slip yoke in the middle. If that is the case then it has Porsche steel synchros and the same 5 speed bearings as the regular transmissions IIRC.

 

Take it to a Porsche shop. They can rebuild it and get the synchros. They can either order bearings by number, or get a bearing kit from somewhere.

 

Jon

[heavy85]

Thanks for all the advice, but I've got one (ok maybe two) last questions. I got the tranny out and looking into it through the fill/drain ports and can see some wear on the two synchros I can see and both have a couple teeth broken off them. Now, I went against advice and decided to try another tranny and keep the old one as a winter project. The replacement tranny synchros look perfect (at least the two I can see through the drain/fill holes) but I dont really know the condition other than it's been sitting for 12 + years and before that was behind a turbo'ed 240 motor. Not much in the oil - it was sludgy but very little metal. It looks nearly identical to mine but slightly different so I wanted to ask if anyone knows what's the difference. The old one has a 6 bolt output flange that mates to a cv type joint and the fill port is on the right side. The replacement box had a 4 bolt output flange that mated to a u joint (I have since swapped them) and the fill port is on the left side. So, what's the difference?

 

Second question, what is the torque for the big nut that hold on the output flange - the Haynes manual doesn't say.

 

OK so I lied, third question is what's this replacement box worth? We didn't work out a price it was just a if it works then we'll figure out payment kind of deal. So if it does works what's a fair price?

 

Thanks again

Cameron