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5-Speed plus a 3.9 or stay with a 4.22

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Jim_Gruber

Jim_Gruber

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Team,

I've got the opportunity to pick up a 3.9 pumpkin to put into Bugsy II to go along with 5-Speed and Gerard's Kit. I thought about keeping the 4.22 in there for off the line grunt with my 1275 but also interested in ability to cruise more comfortably. Is the difference worth it in my BE or should I just stick with the 4.22 pumpkin? Thoughts gentlemen?

PS Engine and tranny that I sold with my parts car got picked up this morning. Steve Benson and his son Gordon in Cincinnati have a Father/Son Project going to restore my old parts car as a street BE. Steve with his wife as pit crew raced BE's for more than 30 years. Sold his race car more than 15 years ago and has wanted a BE ever since. He doesn't really need another engine and tranny, his wife told me there are more than 27 engine blocks down in their basement but the 948 and Smooth case that came with Bugsy III will get put to good use. Room under the workbench once more.
 
To me, having done it already, the 3.9 is the way to go. With the 1275, you'll never miss the "off the line grunt" but you will appreciate the higher speed you've attained before having to shift out of first. Also, cruising at 70 mph will now be 3500 rpms, just below maximum torque. The two changes together (5 speed/3.9) turn the car into a freeway cruiser, while taking NOTHING away from its back road capability.

my 2 cents.
 
1st on the datsun box is lower than the ribcase. IMO, 3.9 is the best match for the datsun gears.
 
I'll third the 3.9. Should be just right in a BE.

Kurt.
 
Thanks guys, for the advice. This pumpkin was promised cheap. We'll see if I can land it.
 
I did the 3.9 on 60Frog....and it was the right ratio.....good for the highway....and the Datsun is actually a lower ratio in the lower gears.
Q.E.D.
Cheers,
Scott in CA
 
Jim -

I checked with my friend; no decent diff available. But it sounds like you've found one.

Mickey
 
I think I've got a line on one. Thanks guys for your help.
 
I totally agree with Scott. I was on the freeway yesterday and I was at around 70 miles per hour at under 3500 RPMs and I was just cruising along.
I am glad I have the 5 speed and the 3.9. I am going to the English Motors at Fairbrook car show next Sunday which is about a 50 mile freeway drive one way.
I had a 4.22 with a 1275 in 59 Diamond and the combination of the 1275, 5speed and the 3.9 makes everything so much smother.
 
It looks like you have enough opinion for the 3.9, but I'll add another :smile: The car I got from John has the Datsun and 3.9 and for me its perfect. Low enough to lay a bit of rubber (accidentally of course!) and cruises the freeway with low revs and great mileage.
 
I've decided, 3.9 for me. Plus local friend just swapped a $.22 in a BE to a 3.9. Even have a source of local expertise if needed. I'll let folks know if I land a 3.9 . Odds I was told are good.
 
As usual, when you change the diff, carefully check the ends of the axles for twisted splines. Very common on our little cars.
Scott in CA
 
Will do have 3 spare EN17 axles so pretty good to go there. Thanks.
 
Are you going to use a GPS speedo or have an adapter for your original speedo? If you are going with an adapter, wait until you decide on a tire size before ordering.
 
Speed hut GPS Speedo and Tach. 14" VTO Classic 8's along with some185x60 is the plan.
 
Trevor, where and how are "adapters" ordered for speedos?

I put a 3.9 in my BE, currently partnered with a ribcase, and 155-80r13's.
I also have a dogleg Datsun 5 speed on the shelf, which I may put in one day. For now I'm happy with the ribcase.

Fred
 
Fred
Gerard can provide I do believe.
 
Jim_Gruber said:
Speed hut GPS Speedo and Tach. 14" VTO Classic 8's along with some185x60 is the plan.
Click to expand...

Do they have the templates for Smith's gauges, or are you doing something "custom"? .. also, will their tachs work on +ground?
 
I just mentally add 10% to my BE. GPS shows that is close to what I need. [Ribcase and 3.9]

Kurt.
 
In the past I've ordered my adapters from Rivergate for the 5-speed. For other adapters you can try some transmission shops?
 
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