Hi all. I recently had the primary primary chain front sprocket changed on my 1993 softail from a 24 tooth to a 21 tooth and the fun factor went up immediately. No more lugging and quicker through all the gears up to Hwy speeds than I'm used to with this old mule. I haven't rode with other bikes yet, but. .. Anyone else a front sprocket change?

 

What is your rear gearing? How many RPMs is it spinning at Hiway speeds?

I have a set sitting in a box to go on one day soon ...

 

Good to here , I am thinking of doing the same when new belt time is due , let us know how you like it on the hwy

 

Your '93 Softail came with 2.94 overall gearing ('93 only), thanks to a 61 tooth rear pulley. Up to '92, Evo big twins used a 70 tooth rear sprocket and had 3.38 overall gearing in top gear, so that '93 had pretty tall gearing from the factory.

My '94 Softail dropped a tooth or two on the front primary sprocket and went back to the 70 tooth pulley for that year only, giving a 3.18 top gear ratio. That's what I've run all these years and it seems to work well for me (I only weigh 150#).

'95 to '99 US Softails reverted to the "tall" gearing, thanks to a 65 tooth rear pulley, giving a top gear ration of 2.95.

Looking at the picture of your bike, you look to have a larger than stock rear pulley already for a '93, so I couldn't guess what you have for gearing now. How's she run at 75?

 

Yeah, let's work out the ratio now ...

21T compensator sprocket ... stock clutch basket?

Stock front pulley ... 70T rear pulley?

How many teeth on the rear equate to 3 teeth off the front?

 

At Hwy speeds it's running around 3500 rpm and before it was 3000rpm. This 21 tooth gets to Hwy speeds much quicker and the roll on in fourth to fifth gear is nice too. I think it better suits the power band on this year of bike.. Not sure my rear pully. Also haven't done 75 mph yet but so far I don't see any issues as all I see and is the benefits. :-)

 

Thanks for that info, Uncle G

 

Helpful and inspiring forum member Grbrown has mentioned the theory behind this a few times in the past.

The theory is, the factory had to overgear the bikes to get them through EPA noise test, i.e. give them far to high gearing with impossible theoretical speeds of around 140 mph, rather than realistic practical ones around the 120 mph mark.

Mind you, I would not want to do 120 mph on a 700lb, single disc front brake bike! Mine feels like a barge in high seas at high speeds.

Going to a 21T compensator sprocket quick and cheaply changes the gearing ratio offering 10% or so more torque and bringing the bike more "on cam" at normal riding speeds, by 3,000 - 3,500 rpm, you'll be close to maximum torque rather than lugging the bike below it.

Arguably spinning the engine is better for it than lugging it at low revs so many have habitually become used to.

However, the only slight blot to this practice might be the ratios of the gears which are not absolutely designed right to suit the new gearing, e.g. how is your first gear now?

Detractors from the practise claim that they don't like such gearing because they have to change gear before they get across a junction at traffic lights, but I don't know if this is true or just an exaggeration. I also know one who changed back from a 21T because he claimed he could not ride at 85 mph to keep up with his friends, the engine was spinning too fast. Again, I don't know if this is true or a gross exaggeration due to the habit of lugging at low RPM.

It might be that dropping some teeth on the front, and adding a 6 speed overdrive transmission might be the perfect solution? I cannot afford to try right now but, on paper, it seems logical Baker, for example, offers a selection of gearing allowing you to design your own gear box a little more.

Can I ask again what your complete gearing is, i.e. compensator, clutch, front pulley and rear?

I'm glad you've found more fun out of your old bus.

 

I suspect part of the tall gearing was for noise, the other part (at least for Evo Softails, which lack any counterbalancers or rubber mounts) was to move the point at which engine vibrations become unacceptable to a higher speed.

With my 3.18:1 top gear, my FLSTN has a sweet spot from about 55 to 75 where the engine runs very smooth. Push it faster, and the throbbing starts. You can feel it in the bars at 80 and by 85 the handgrips feel like they're 3 inches wide.

 

I did the same mod to my TC88. Made a remarkable difference! Gearing was about 20mph per 1,000rpm and the bike was a darned sight nicer to ride. Torque to the rear wheel was increased by 19%, which costs a lot more to get by any other way. Having owned Harleys since the '70s the TC at last rode like a 'proper' Harley, not one of those modern over-geared slugs!

I have also changed the gearing on my Glide, however that was International spec when new, with a 61T rear pulley. As well as my ickle S&S 107" engine I now have stock US gearing with a 70T pulley.