• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

5 speed vs. 3.9 diff - either or both?

Share this page

Yes, Gerard, it certainly makes sense. Most of the bits are just plain different (what with the machining of your adaptor, construction of the mounting bracket, adding the U-joint, assorted bolts, machining of the clutch slave cradle and on and on). Then, of course, there is your time to put all this together.

Besides, anyone that has done any proto-typing for production knows that there is a huge amount of time spent in experimentation (R&D).
 
Mark - you called it right. Hats off to Gerard, and all the others! Doug
 
Follow-up report:
As previously reported, my shifter boot wasn't staying in position (even with a little adhesive). So, I recently changed the boot from an "outie" to an "innie" and that made all the difference! This changed the pivot point of the rubber (and that ridge in the right-hand photo is now enough above the pivot point). 1st is a tiny big scrunched but not excessively so. 3rd and 4th seem perfect (and 5th and Reverse are fine). Here are two photos of the stick in NEUTRAL (boot off and boot on). I could have probably fussed with tweaking it (endlessly) but I think I'm close enough.
Neutral with boot off - side.jpg
Neutral.jpg
 
Follow-up #2:
Using a GPS app on my phone (app is "DigiHUD" for Android - excellent), I checked the speedometer. I also checked the revs on the tach at various speeds and found the following. First, a repeat of the components: Datsun 210 trans, 3.9 diff, tire size is 175/70R13 and an excellent Paul Asgiersson speedo adapter.

At GPS-measured 50mph (stock speedo read 51-52 mph) = 3100 rpm in 4th and 2400 in 5th.
Haven't had a chance to take it to 60 or 70, but it won't be difficult with this set-up! :eek:
 
Last edited:
It's not neutral that is the issue. Centering it in the opening in neutral is easily accomplished, it's when it's in gear that is the problem. If you worked it out, you got lucky... 1 in 100. In addition, the rubber is giving you extra resistance as you are really pushing it beyond the limits for which it was intended. In the end this will also shorten the life. Not a big deal, but a nuisance if the have to replace it frequently. But that's is not the main feature of the redesign. The travel of the shifter is reduced by 50%, and makes for a more positive feel. That was the option of my test subject who tried the 1st finished prototype in his car.

Boink said:
Follow-up report:
As previously reported, my shifter boot wasn't staying in position (even with a little adhesive). So, I recently changed the boot from an "outie" to an "innie" and that made all the difference! This changed the pivot point of the rubber (and that ridge in the right-hand photo is now enough above the pivot point). 1st is a tiny big scrunched but not excessively so. 3rd and 4th seem perfect (and 5th and Reverse are fine). Here are two photos of the stick in NEUTRAL (boot off and boot on). I could have probably fussed with tweaking it (endlessly) but I think I'm close enough.
View attachment 48803 View attachment 48804
Click to expand...
 
Yes, I think I got lucky. Only 1st seems a little bit scrunched, but, again, not excessively. Seems like the throw to 1st with the Datsun tranny is fairly short. All others seem pretty good.
One thing is certain, changing the boot to the proper orientation made a big difference.

Here's 2nd gear:
Second.jpg
 
I'd like to see 3rd and 5th.

Boink said:
Yes, I think I got lucky. Only 1st seems a little bit scrunched, but, again, not excessively. Seems like the throw to 1st with the Datsun tranny is fairly short. All others seem pretty good.
One thing is certain, changing the boot to the proper orientation made a big difference.

Here's 2nd gear:
View attachment 48808
Click to expand...
 
Gerard, here are a few more. As you know, when one goes into 5th and lets go, the stick sort-of springs back to where it would sit in 3rd.
So, here are 3 pics: 3rd & 5th, 5th and 4th. If I were to do it over, I'd have the stick off-set about another 1/8" to the passenger side, and MAYBE another degree toward the rear.
Third and Fifth - same.jpg
Fifth.jpg
Fourth.jpg
 
You have pretty good results there. I've never seen them that good in other cases. I think between using my mount and the guidance on the angle on the shifter, you came out as good as possible. I'm not sure if the results are with the Rivergate kit. Between the thicker plate and their mount, this may or may not be attainable.

Boink said:
Gerard, here are a few more. As you know, when one goes into 5th and lets go, the stick sort-of springs back to where it would sit in 3rd.
So, here are 3 pics: 3rd & 5th, 5th and 4th. If I were to do it over, I'd have the stick off-set about another 1/8" to the passenger side, and MAYBE another degree toward the rear.
View attachment 48829 View attachment 48830 View attachment 48831
Click to expand...
 
Well, I owe it to you! :eek: I had a photo of your shifter (prior to the current short-shifter version)... and I tried to copy the angle as well as the point at which that happens. I also had a chance to physically play with the one that Gary (on this board) used, and to try measure his set-up (though he opened the hole a bit more and used a Big-Healey boot - which I was prepared to do).
As previously posted, I think I could have fussed with it a bit more (and my TIG-welding friend was willing to just tack it while I experimented), but I just decided to go for it... and got lucky. There certainly isn't a lot of wiggle-waggle room.
 
Last edited:
I don't mean to belabor this lengthy thread, but I originally stated I'd report back on performance with the overdrive at higher speeds. LOVE IT!!!!

3000rpm (maybe more like 2900) at 60mph
3500rpm (maybe closer to 3400) at 70mph
Could easily drive at 80 (and would estimate that I'd be at 4000rpm).
I'm thinking 90 would be possible at 4500rpm (if the extrapolation holds up).

Amazing. We were cruising yesterday (back from wine-country SW of Portland) and high speed driving was a dream!

[Again: 1275cc (+.20 over), 3.9 diff and Datsun 5 speed - with the kit that Gerard now sells. Wonderful clutch performance with the Datsun clutch.]
 
Last edited:
I had similar results driving Bill Mayer's BE last year. Formerly 60FROG aka FROGI 1,275 +.20, 5 Speed, 3.9 and Paul A's Kit which Gerard has now improved. Coming back on the I-15 into San Diego. Cruised effortlessly at 80 very stable just keeping up with the traffic, 85 still no issues, and I even touched 90 for a brief moment and the car tracked perfectly and felt very stable. The key is a rebuilt front end properly set up, a good set of Peter C's Shocks all around, new bushings all around, Sway Bar, and no worn out parts in the front or rear suspension. At 90 engine still would be able to go some more. Now I'm pretty sure doing that same thing on Ohio Frost heaved roads would cause some major puckering of certain parts of my anatomy.

Bugsy just got Rear End Reinstalled. need Clutch and Brakes Bled, Gas Tank Reinstalled, and Fluids added and Vroom, Vroom noises very soon. 948 for now but 1,326 and 5 speed will come late Summer..
 
I don't have a sway-bar, and have often wondered if it's worth adding.
 
I would add the sway bar. I think it helps the handling quite a bit. I have had a BE with a 948, 4 speed and 4.2 rear end and there is just no comparison with what I have now.
Minor correction to Jims statement above. The BE is BUG I, Not FROG I.
 
Sorry Bill. Ii that not enough room up there to retain Factoids any more.
 
Thanks. On the sway-bar, is there a particular size (thickness)?
 
Moss Motors has a 3/4" sway bar which is what I have. You will need the following part numbers . 264-555,263-435,280-915,683-062,263-430.
 
Its been several years since I have visited this site regularly. Finishing a degree took all my time.
I did my own 5 speed conversion and only bought the adapter plate. In fact I ended up with 2 plates, one from rivergate and one from Paul.
I decided that the rivergate did not put the starter in the right place, so I used the other one.
I wanted to gear the car up as far as possible, so I put in 3.55 diff gears and the 5 speed. The original car had the 3.90 gears and I changed them out.
In the end, 3rd gear in the car felt about like what 4th used to be and 4th is a good normal driving gear for here in the mountains. 5th is a true overdrive and it really lowers the RPMs for just puttering around and is right for highway driving. From everything I could read at the time, the max torque of the 1275 was at 3000 RPMs and I wanted that to be 65-70 and that is where it is at. I don't have a speedo converter. I just used my GPS and saw what the speedo read at 60 and then pulled the needle off and moved it so that 60 was 60 and I figure that is close enough. The odometer is off by 21%. I am running 175/70/13s on it. First gear in the Datsun gearbox is lower than 1st in the original, so it seemed fine on takeoff. The only thing that I don't like is that the original clutch master does not move enough fluid to move the Datsun slave very far. I only have about and inch or so clutch travel. I am used to it by now but wish it were better.

Kim
 
Since this thread has been all over the board and Kim has added first hand experience on the 5-speed AND 3.55, I'll add a bit of personal info just for novelty sake.

On my car (1275/3.9/5-speed) there is a speed (not mentioning exact speed) at which the car ends up in no mans land. Once you climb to the peak hp rpm in the power band in 4th, shifting to 5th the car can not over come air resistance. So, you can climb a little faster in 4th by going well over the peak of the power band, but a shift to 5th can only hold the speed (now near the peak of the power band), but it can not go beyond it. Based on gearing alone, my car should run 120+ mph. But there is a big aerodynamic wall around 100-105 mph.
 
Back
Top