Transmission basics (for racing)...

[Press1]

I have a 510 race car with a L20 and a "period correct Nissan 5-speed" (no other details yet).  I was racing at Palmer MA last weekend and had intermittent difficulty shifting from 5 to 4 at the end of the straight.  Just went from 5 to 3 which was quicker anyway.  Otherwise transmission shifts fine.  

 

I've been hearing a lot about Datsun/Nissan transmissions.  One of the local guys who very successfully runs a 510 never uses 5th because he says it's a weak gear.  He uses a higher-ratio rear end and only uses 1-4.  Other things I've heard are "Option 2 (or 3)", "dogleg" and "T-5" when it comes to transmissions.

 

Other facts about the car:  Jeff Winter L20B engine with 2 Weber DCOE45s. Quartermaster dual 5.5" disk clutch (basically an on/off switch).  Welded 3.9 or 4.4 rear ends. 

 

Is there a good source of information on transmissions in one place?

Thanks!

[datzenmike]

There were no period correct 5 speeds for the '68-'73 510. The earliest L series 5 speed was the FS5W63A in the '77 200zx and the optional FS5W71B in the '77 280z and 620 trucks. The earliest production 5 speed I know of was used in the SR311 Fairlady Roadster through '69.

 

Competition 5 speeds were rare, expensive, hard to get.

 

In '70 when the 240Z car came out these Roadster 5 speeds were fitted with an L series bell housing and steel Porsche synchros in Europe to go racing the Z with. You could get them here through Nismo Racing Parts, the racing arm of Nissan... well you could if you had racing connections. Not sure if it was that easy for the public to do this and besides importing this 5 speed would be vastly and prohibitively expensive. Affordable only to racing teams or more likely factory sponsored race teams. There are a few of these transmissions around but hard to tell if they are the true racing FS5C71A  the C is for competition use with steel synchros, or the FS5W71A, the W is for the brass Warner synchros because the L series bell would fit either one. A true FS5C71A came in Option One, Two and Three gear ratios for racing and are pretty much made of unobtanium. Racing attrition has used them and all rebuild parts up. Very rare and priceless, highly sought after by Roadster owners.

 

Around this time or late '71??? a newer FS5C71B  (the S is for Special Overdrive) 5 speeds and F5C71B direct drive 5 speed with a 1:1 5th gear to eliminate the severe counter bearing load from racing in over drive. You said something about 5th being a 'weak gear'... it isn't, but all gears exert a side load on the countershaft bearings. Fifth is even worse for this so a 1;1 5th is just a straight through connection from clutch to driveshaft. I'm not sure but some of these may have been a dogleg shift pattern. The dogleg pattern has reverse above first...

R..2..4

1..3..5 The reasoning is that first is used the lease in racing and the 4th to 5th is a faster straightforward shift.

 

The T-5 is a Borg Warner transmission used only for the last year and a half in the 280zx turbo. It's large, heavy, not particularly strong but easy/cheap to rebuild. First is very low geared (3.50) to get the turbo spooling faster. If using you would want a high geared differential so that you might actually get to use first once in a while racing.

 

A welded differential does not sound very professional no 'racing' and I can't imagine any race track allowing one on the course. You should be using a clutch LSD not a weld.

 

If looking to identify what transmission you have in your 510 look up the back issue of the Dime Quarterly Volume 11 Issue 4 on Google Docs. If you can't identify what it is you can at least identify what it isn't. There are about 9 pages in all with lots of pictures. This guy really knows his transmissions.

 

[flatcat19]

 

If looking to identify what transmission you have in your 510 look up the back issue of the Dime Quarterly Volume 11 Issue 4 on Google Docs. If you can't identify what it is you can at least identify what it isn't. There are about 9 pages in all with lots of pictures. This guy really knows his transmissions.

 

 

 

 

Are you fucking kidding?  He's a hack. And Canadian. 

[datzenmike]

We're all related up here. Wait! that didn't sound right. Affirmative nepotism. And anyone named Mike can't be half bad. 

[flatcat19]

That guy loves Asian trannies. What more to say?

[Press1]

I actually have stopped using the word "tranny" because of the whole Bruce Jenner thing...:). Thanks for all of the info - very helpful!!

 

As far as the welded spiders go, lots of people run them - especially with the small ring gears. LSDs in the R-160s can have issues with overheating. I only have 1 LSD 180, but it's a 5.13 and of little use. Winter project.

 

I crewed for a trans am team (first a camaro and then a Penske Javelin) both had welded rear ends (and 1 degree neg camber in the back - done by bending the solid rear axles...pretty crude)

[datzenmike]

Transmissions have owned the term 'tranny' long before it became mainstream for another use. You can't have it Caitlyn but you can use it. Imitation is the sincerest form of flattery.

[flatcat19]

I thought Katlyn had the full monty. No junk to qualify being a tranny. i

[datzenmike]

I gave up trying long ago. Even Wikipedia can't keep up with it.

[Dime Dave]

The Subi STi R180 w/CLSD can be sourced fairly easily and there are ratios suitable for vintage racing. Stub axles have been available to mate the Subi R180 to the Datsun half shafts as well.

 

The direct drive comp boxes are all dog leg pattern (they came in 4 different sets of ratios, Opt 1, 2 & 3 and a Rally). And Mike, you are correct, they are very hard to find parts for and expensive when you do.

 

The OD street gearbox and the direct drive comp box used the same basic cases (the early comp boxes were based on the Roadster case). The physical gear positions internally within the case differ only by having 1st where 5th is on a street OD gear box (physically behind the center plate). The shift rods are configured so that the striker engages 1st - Rev on the left side of the "H" pattern rather than the right when 5th is paired with reverse in the OD trans.

[Press1]

Hey Dave - thanks.  I'm the one who bought your half-shafts. (They have been trouble free - as opposed the the Wolf Creek ones).  The R180 (5.13:1) that I have is LSD - thought I would try to find 3.9 gears for that one as a winter project.  Not sure I want to bite the bullet for the comp gear box.  People are telling me the 280zx version is pretty good and relatively easy to find.

 

Joe Teplitz

Laughlintown PA

[datzenmike]

The zx box has an all but useless 5th gear. It's an insane 25.5% overdrive. You would be better off with the 280z or first year only zx which was the same. These come with a 14% overdrive. 

[Press1]

Thanks - I have to say...this group REALLY knows Datsuns!

[Dime Dave]

Joe,

For a rebuilt Z transmission for racing contact Sam Neave. LNA Enterprises in Franklin, NC 336-824-1605 or sam@lnaenterprises.com

 

Sam has built engines and gearboxes for 2013 SCCA EP Champion Greg Ira's 240Z. I met Sam at the Runoffs in 2013. He has worked out different combinations of stock gear ratios to come up with a combination that works for racing. It is all based on brass synchro 5 speed parts

[Dime Dave]

Joe,

I was at Whiskey Hill for the SCCA Regional last weekend running my '82 RX7 in the IT7 group (I know I should at least be racing a Datsun). The car was running excellent until the pinion gear came right out thru the side of the diff. I managed to pull out a 1:59.2 before it blew.

 

Whiskey Hill Raceway is a brand new track carved out of the side of a mountain in Palmer, MA. 2.3 miles long, 14 turns and 160+ feet of elevation change. IMO its an awesome place to race.

[Press1]

Dave - I did Palmer the previous weekend in the VRG event. What a hoot and what a workout! My thought after the first practice was "demonic serpent". But by the end of my 8th session on the track I was in love with the place! (lots of track time in VRG - could have done 1 more).

 

I was running 4.4 gears and that felt like a good setup. I was having trouble with the 5 to 4 shift at the end of the straight ((thus the tranny discussion) but went from 5 to 3 for turn 1 anyway. Hope they're successful - it's a great track!

[Press1]

BTW - my best laps were in the 2:06s but I'm still learning the car. It'll do a lot more than I'm asking from it. John Morton was the last guy to drive it in a race before I bought it and finished third nursing a bad clutch in a vintage TA at Elkhart Lake.

 

Sorry to hear about the rear end. I've never seen a pinion gear leave like that.

[DISLEXICDIME]

Could he get a way with using a ka or Sr transmission bolted to a l series bell housing or would he be braking rules Dave ? Seems like a stronger more cost efficient way to have a 5 speed

[Press1]

Thanks.  The VRG rules (where I race) are pretty open.  They say "...has to have the same number of fwd speeds" (basically the same number of speeds as the old B-Sedan days).  Always seemed odd to me that the Trans Am and B-Sedan 510s were homologated with 5 speeds when they were only available with 4 speeds in the US.

[datzenmike]

There was a 71C 4 speed used on the D21 trucks.

[Stoffregen Motorsports]

Are you bound by any rules to continue using the Datsun trans? There are ways to get a more durable trans in there. At the top of the food chain is the Saenz "lift-and-shift" box. It's a direct drive, dog ring trans that is purpose built for racing. Winters also makes some very good transmissions. A modified bellhoisng will be needed for either one.

 

The Datsun Comp transmissions are very hard to source and parts for them are haaard to find. I went as far as having custom billet shift forks made for the trans I was using because the forks wear out and eventually need to be welded up and machined flat again. Doing this over and over again gets tiresome. Steel synchros are brittle and wear quickly too.

 

I agree with the earlier statement that 5th gear is weak.

 

If you want to continue to use a Datsun trans, give Troy Ermish a call. He will likely have one he can sell you.

 

Mike - the welded diffs are ery common in racing. They are a lot cheaper than LSD's and they make the car very predictable. It's easy to tune the suspension around a welded rear while tuning a suspension for a LSD can be more involved. As far as tearing up the track, it's not an issue. The tires get hot and the rubber squirms creating a slip angle that helps the car slide around turns. All four tires will be slipping at some point and the track surfaces hold up fine.

[Press1]

Thanks! Very helpful!