ESE's works engine tuner

**wobbly** · 26th March 2022, 10:37

VRO , your press fit guess was close but the final number depends upon two main factors.
Solid pin or hollow pin , and crank material/heat treat.
For a hollow pin and or a case hardened only material ( 4140 ) the number is 0.08 to 0.1mm.
For a solid pin and or thru hardened tool steel ( EN36B ) the number is 0.05 to 0.06mm.
Pin diameter has a smaller effect , wherein a big ( 25mm ) pin needs less press fit than a smaller ( 20mm ) due to the circumferential interference area.

**Muhr** · 26th March 2022, 10:44

Hi someone who has some good suggestions on rubber quality for the shock absorption to the clutch basket.

**husaberg** · 26th March 2022, 16:06

Originally Posted by Muhr

Hi someone who has some good suggestions on rubber quality for the shock absorption to the clutch basket.

don't use rubber
use urethane instead
ask Grumph what or what Shore range.

**Muhr** · 26th March 2022, 21:03

Originally Posted by husaberg

don't use rubber
use urethane instead
ask Grumph what or what Shore range.

Thank you Husa, I will do a little research into what I can get my hands on. Yes, then it is these shore values, for which there are several different measurement methods. I know very little, but may try to do a simulation and see if I can understand something

**husaberg** · 26th March 2022, 21:55

paging Greg

Originally Posted by Grumph

Steve Ward told me the other day he uses genuine on his fleet - at $15 each...Pretty sure we'll be nowhere near that expensive.

The materal supplier cocked up the order and it's arriving today - approx a week late - so the test set will be off to Dave Monday - PM me a postal adress Dave please.

**peewee** · 27th March 2022, 04:31

**Flettner** · 27th March 2022, 07:43

Urethane? I think thats what its called. I made a wee die and get these molded for me, special.

**wobbly** · 27th March 2022, 08:25

I had a Hinson clutch cush drive destroy itself , due to having 100RWHp put thru it I suppose.
I had 70 shore urethane bar made up , has worked perfectly since.

**vro46i** · 27th March 2022, 19:09

Originally Posted by wobbly

VRO , your press fit guess was close but the final number depends upon two main factors.
Solid pin or hollow pin , and crank material/heat treat.
For a hollow pin and or a case hardened only material ( 4140 ) the number is 0.08 to 0.1mm.
For a solid pin and or thru hardened tool steel ( EN36B ) the number is 0.05 to 0.06mm.
Pin diameter has a smaller effect , wherein a big ( 25mm ) pin needs less press fit than a smaller ( 20mm ) due to the circumferential interference area.

Thanks Wob, much appreciated,

It is a solid 24mm pin replacement, going into the original suzuki crank web. I can assume anything about the material without a proof test with a vickers hardness tester or equivalent.

**Muhr** · 27th March 2022, 20:08

I hope I can find some options in the 8mm sheet that I can water cut.
wobbly, hope to be able to approach your loads in my 50cc. 75nm and about 300nm on the clutch and shock loads on significantly more

Vro

If it is not as hard on the side you are cutting more on, there is a risk that it will start rolling off material when you start pressing on the pin. Evidence of experience

**Muhr** · 28th March 2022, 07:55

Found this, may be useful sometime

Before I show you the calculation, you should be aware that there is not a direct relationship between a Shore scale and Young’s Modulus! The calculation allows you to approximate ‘E’ based on a range of Shore-A (20 to 80) or Shore-D (30 to 85) durometers for simple static analysis.** If you routinely work with plastic and rubber materials, you should be using SOLIDWORKS Simulation Premium with the actual stress-strain curve for the material(s) you design with!

For a durometer given in Shore-A, multiply this value by 0.0235. Then subtract 0.6403 from this result. The next step is to find the inverse base-e logarithm of this new result. The answer is an approximation for Young’s Modulus in megapascals (MPa). To convert this to pounds per square inch (psi), simply multiply this number by 145.0377.

Shore-A to Young’s Modulus (in MPa):
=EXP((Shore-A Durometer)*0.0235-0.6403)

Shore-D to Young’s Modulus (in MPa):
=EXP((Shore-D Durometer + 50)*0.0235-0.6403)

**wobbly** · 28th March 2022, 11:10

Most all Jap factory cranks are induction hardened around the pin bore and the bearing surfaces.
You are going bigger in diameter , but may well have bored thru all the hardened material when moving the hole.
My guess would be to replicate the original interference in this case - and use Loctite Bearing Fit as a sort of lube and to help with retention.

**vro46i** · 28th March 2022, 15:36

Originally Posted by wobbly

Most all Jap factory cranks are induction hardened around the pin bore and the bearing surfaces.
You are going bigger in diameter , but may well have bored thru all the hardened material when moving the hole.
My guess would be to replicate the original interference in this case - and use Loctite Bearing Fit as a sort of lube and to help with retention.

Hi Wob, I was pondering that question, but thank you for confirming it for me.
I'll have another meeting with the machinist to ensure that we are replicating the factory interference fit.

**vro46i** · 28th March 2022, 15:44

Originally Posted by Muhr

I hope I can find some options in the 8mm sheet that I can water cut.
wobbly, hope to be able to approach your loads in my 50cc. 75nm and about 300nm on the clutch and shock loads on significantly more

Vro

If it is not as hard on the side you are cutting more on, there is a risk that it will start rolling off material when you start pressing on the pin. Evidence of experience

Hi Muhr, I appreciate your advice.
Based on your comment, I will have to design a localised support press plate to minimise the anticipated deformation on the 'soft side' of the new pin hole.
I'll measure up the crank web dimensions and see what I can come with that is effective.

Cheers

**husaberg** · 28th March 2022, 19:05

Originally Posted by vro46i

Hi Wobbly, I have arrived at the stage of destroking the engine from 125cc to 110. Using an oversized big end pin (24mm dia) where previously a 22mm dia. The machinist is going to offset bore it to fit the new big end pin to achieve the required stroke. Can you please tell me, how much of an interference fit does the big end pin to the new crank web hole is acceptable? 2 -3 thou? Thanks in advance.

Have you considered inserting sleeves into the 22mm bore and doing an offset bore to destroke using a 18mm or 20mm pin.

24mm pin is pretty big for 110cc
You can key the sleeve but i doubt it's required.

the opposite of this powroll

The other other option just use a shorter stroke crank.
or get the crowd that built the pin for Speedpro to do you an offset pin.

Originally Posted by speedpro

My crankpin was made by heat treatments. machined, heat treated, and ground. Hasn't let go yet but still early days. 20mm ends with a 22mm centre, offset .75mm. Very helpful guys.

https://www.kiwibiker.co.nz/forums/s...post1130471126