4 Speed info

[dave76]

After doing tons of research on the Evo 4 speed, I figured I'd put together a thread to help people with 4 speeds. Not an expert on the Ironhead but I'll give it a shot.

The Ironhead basically falls into two catagories: 1957- Early 1984 these motors had the generator mounted up front. The Late 1984 and 1985 Ironheads had the generator removed and now used an Alternator which was mounted behind the clutch shell and used a completely different clutch gear. There are lots of other changes made to the Ironhead tranny between 1957 and 1985. Most notably the shift pawl change in 1972 to the more modern one. In 1971 the ball & ramp clutch release replaced the right side worm release type. 1975-76 used a linkage system to convert shifting from right side to left. 1977 trans shift lever redesigned for proper left side shifting. 1979 was the last year you can outfit a sportster with a kickstarter

1 st 2.52

2 nd 1.83

3 rd 1.38

4 th 1.00

The Evolution Sportster 4 speed is the same as the late 1984 and 1985 Ironhead, however in late 1986 Harley decided to change the clutch gear from 17 tooth to 18 tooth and the countershaft gear from 27 to 26 tooth, which tightend the ratios closer. The new gear ratios are:
Late 1986-1990
1 st 2.29

2 nd 1.66

3 rd 1.25

4 th 1.00

My problem with the close ratio gears is I think it kinda takes a bit from off the line to keep the engine in it's peak at the higher speeds. This is great if your drag racing, but for highway crusing it sucks. Stock secondary gearing is 21 tooth trans sprocket and 48 tooth rear wheel sprocket. This gives a 3.98final drive ratio, combined with stock tire size your turning about 4000RPM at 70 MPH, she's basically screaming at that speed. Gearing it down to a 22 tooth sprocket helps but again your pulling more from down low, going with a 23 tooth helps even more, but now 1st gear is sluggish and you end up riding the clutch a bit.

I figured to get the best of both worlds, you can still get the Late 84 to early 86 17 tooth clutch gear and 27 tooth countershaft gear. This raises first gear to 2.52 from 2.29. Now you can gear your secondary down to a 47 tooth rear and a 23 tooth front this gives a 3.54 final drive, pretty close to what a 5 speed sportster runs. This will lower revs at 70 MPH to around 3200 to 3300 RPM. This is much better then a buzzing 4000. Going with the 47 tooth rear will take a little bit from first, but it won't be too noticeable. Going with a 48 tooth rear actually gives a better first gear then stock (9.12 ratio to 9.08) and with rev about 3400 at 70, I might actually take this route.

Here is a comparison of all the ratios I came up with
Stock L1986-1990
Engine Sprocket: 34
Clutch Sprocket: 59
Trans Sprocket: 21
Rear Wheel Sprocket: 48
Primary final drive 1.735
Final drive: 2.285
Overall drive: 3.966

1st gear: 2.29 Overall ratio 9.08
2nd gear: 1.66 Overall ratio 6.58
3rd gear: 1.25 Overall ratio 4.95
4th gear: 1.00 Overall ratio 3.96

Using the L84-E86 clutch gear and geared down secondary
Engine Sprocket: 34
Clutch Sprocket: 59
Trans Sprocket: 23
Rear Wheel Sprocket: 48
Primary final drive 1.735
Final drive: 2.08
Overall drive: 3.62

1st gear: 2.52 Overall ratio 9.12
2nd gear: 1.83 Overall ratio 6.62
3rd gear: 1.38 Overall ratio 4.99
4th gear: 1.00 Overall ratio 3.62

There is also another route you can take, Andrews sells a wide ratio 1st gear set for the Ironhead which will fit the Evo. The Ironhead 1st ratio becomes 2.68 and the Evo will get you to 2.44. To use the Andrews Ironhead wide ratio gears in an Evo you'll need to replace the Evo countershaft with an Ironhead unit then the gears will work. The main difference being the Ironhead uses a brass sleeve bearing on countershaft 1st gear were the Evo uses a Torrington needle bearing. I'm going the clutch gear route as I'd rather have the needle bearings instead.
Andrews gears are way better then Harley's gears but like I said earlier I'm not racing it so the H-D gears will be fine.

Some pics of an Evo 4 Speed:













Here is the trans with the Zippers Billet trap door installed and the gear space checker tool installed

[dave76]

Also for anyone rebuilding their Evo 4 speeds I got some part numbers, for replacment parts. There are only a few but these are the usual ones that'll need replacing. Also the shift cam on these things tends to be a bit rough on the edges, a lot of books I've read recommend polishing the shift points and cam follower area for smoother shifting. It definitly works as i did it to my fathers bike. A lot of people recommend and myself included the Zippers billet trap door with double row bearing, this thing takes all side to side play out of the clutch reducing the chances of the magnets scraping the stator and causing a costly replacment. It's an expensive piece but well worth the cost IMO.

Measurments:

Mainshaft Endplay: 0.006-0.020

Countershaft Endplay: 0.004-0.015

Gear Spacing between the shift dogs: 0.040-0.080
__________________________________________________

Shiftshaft: 34628-86

Shift Cam Follower: 34063-84B

Shift Cam Follower Springs: 29980-84

Finger Rollers: 34168-52

Shifter Pawls: 34476-72

Clutch Friction Plate H-D: 36788-84 (7)

Clutch Steel Plate H-D: 36787-84 (5)

T27 Stator Screws: 2712 (4)

Shifter Fork Standard: 34291-52C (Surdyke H-D still has all the shift forks available)

Shifter Fork .020 Shorter: 34293-72A

Shifter Fork .020 longer: 34292-72A

If anyone is interested in changing back to the wide ratio gear set to get the taller 2.52 first gear, these are the part numbers. Surdyke H-D still has them.

Clutch Gear: 37448-84A

Countershaft Drive Gear:35695-58

Unfortionatly H-D dosn't carry the Main and Countershaft spacers anymore. NOS parts will have those. I'd rather use H-D then cheap Tiawan made garbage.

Mainshaft Thrust Washer - 0.0965: 35380-84

Mainshaft Thrust Washer - 0.0905: 35381-84

Mainshaft Thrust Washer - 0.0845: 35382-84

Mainshaft Thrust Washer - 0.0795: 35383-84

Mainshaft Thrust Washer - 0.0725: 35384-84

Mainshaft Thrust Washer - 0.0675: 35385-84

Countershaft Spacer - 0.055: 35860-86

Countershaft Spacer - 0.050: 35861-86

Countershaft Spacer - 0.045: 35862-86

Countershaft Spacer - 0.040: 35863-86

Countershaft Spacer - 0.035: 35864-86

Countershaft Spacer - 0.030: 35865-86

Mainshaft H-D: 35036-84A

Countershaft H-D: 35613-84
__________________________________________________

Here are some Andrews Part numbers for gears and shafts:

STOCK 2ND GEARS.
Part #252020 2nd main (23T) (replaces 35296-56 & 56A)
Part #252040 2nd counter (20T) (replaces 35750-58 & 58A)

STOCK 3RD GEARS.
Part #253050 3rd main (20T) (replaces 35305-56 & 56A)
Part #253030 3rd counter (23T) (replaces 35709-54A & 54B)

Part #258190 mainshaft (alternator) (mid-84-’90)
(replaces 35036-84A) (Solid shaft; no through hole)

STOCK 1ST GEARS.
Part #251050 main 1st (27T) (replaces 35277-52A)
Part #251060 counter 1st (17T) (replaces 35760-73 late only, 1973-1985). To fit 1986 and later requires early countershaft #259010

WIDE RATIO 1ST GEAR SETS
Changes 1st from 2.52 ratio to 2.68 for more low end torque with 21T or 22T trans sprockets.
Part #251010 (late only, 1973-1985). To fit 1986 and later requires early countershaft #259010

Part #259010 countershaft (1956-mid-84)
(replaces H/D# 35613-58)

I scanned some pages from the manuel to help people without one. However you should have one by your side when doing the work. This is for reference:

[enginetorque]

I'm just about to rebuild my 89 evo 4 speed - it's just spat the dummy and eaten the output needle bearing (again) - is this common ?

[jay1100]

Also the shift cam on these things tends to be a bit rough on the edges, a lot of books I've read recommend polishing the shift points and cam follower area for smoother shifting. It definitly works as i did it to my fathers bike.


Do you have any more info on polishing the cam follower and the shift points?
i am rebuilding my 86 4 speed and its a to shift.
details and a maybe pictures would be great

[dave76]

Well after all the reasearch rebuilding the trans and actually enjoying the highway cruising, I am going back the close ratio gears and stock 21/48,,, read more here.

http://xlforum.net/forums/s....php?t=1539783

[Jason's Sporty]

it's just spat the dummy and eaten the output needle bearing (again) - is this common ?

What? Spat the dummy?
Also your talking about the bearing on the output shaft right? did you replace that pressed on race too? It is not common, I think your tranny has other issues going on too.

[enginetorque]

Hi - thanks for the response - yep I actually replaced the mainshaft - the large gear and the sleeve along with the output needle race - just got it apart (it gets so much easier with practice...) and the needles have gone blue and flat - obvious lack of lube, yet she was filled to the mark with light gear oil - should have been fine but............

I can't think of an outright reason why this failure has occurred twice in five or so thousand miles (only) - open to suggestions but been inside engines all my life and nothing obvious leaps out - wonder if this is a known Sportster malady but given the half century that the beast has been around, I would think not???

[dave76]

Originally Posted by enginetorque

Hi - thanks for the response - yep I actually replaced the mainshaft - the large gear and the sleeve along with the output needle race - just got it apart (it gets so much easier with practice...) and the needles have gone blue and flat - obvious lack of lube, yet she was filled to the mark with light gear oil - should have been fine but............

I can't think of an outright reason why this failure has occurred twice in five or so thousand miles (only) - open to suggestions but been inside engines all my life and nothing obvious leaps out - wonder if this is a known Sportster malady but given the half century that the beast has been around, I would think not???

Are you checking your mainshaft and countershaft endplay's???

Just a thought but my neighbour had the same problem with breaking the output bearing, and it turned out to be a bent countershaft. Even though you replaced the mainshaft, you should
or should of check the countershaft for trueness and straightness. A bent countershaft puts stress on the mainshaft causing it's bearing to give out. Make sure your not too tight on the endplays, try to keep it within factory recommendations. Mainshaft endplay ahould be .006-.020 and Countershaft endplay should be .004-.015 Use the correct shims to correct any clearence issues.

[enginetorque]

Thanks for the feedback - I will indeed check same - I did only replace the mainshaft last time round - endfloat was checked with a dial pointer (a fiddle as you have to put the box back and then remove again etc) and shimmed as per the specifications - all worth checking though.

The main output bearing sits very high compared with the rest of the box - mine certainly seems not to have been getting sufficient lubrication - I have seen posts where folks put a whole litre of oil in the box - any thoughts?

[dave76]

Originally Posted by enginetorque

Thanks for the feedback - I will indeed check same - I did only replace the mainshaft last time round - endfloat was checked with a dial pointer (a fiddle as you have to put the box back and then remove again etc) and shimmed as per the specifications - all worth checking though.

The main output bearing sits very high compared with the rest of the box - mine certainly seems not to have been getting sufficient lubrication - I have seen posts where folks put a whole litre of oil in the box - any thoughts?

The box is splash lubed so I wouldn't think it'd be a problem. I've never ran accross any problems due to poor oiling.