64 replies to this topic

[grizzler73]

The forces are in a completely different direction on helical gears, that's where the problem lies. So their solution is not really relevant to helical gears.

[Ethel]

The aim is still to transfer the torque from the primary to turn the input gear. Save for the gears being not in line, the forces the primary puts in to the idler are equal and opposite to the forces it puts in to the input gear. 

[mini13]

It's about time to post this...

http://mk1-performan...chain_drive.jpg

[nicklouse]

It's about time to post this...

http://mk1-performan...chain_drive.jpg

Ahh yes that. Heard about that in the late 80s early 90s and someone local was meant to have one. Never found them/it.

[Ethel]

Are they modified gears, look like they might be? You'd just have to persuade somebody to tool up to stamp out the chain links then.

But would we just move on to a topic on upgrading nose bearings?  

[nicklouse]

I think that the picture is just standard parts with a timing chain.

[mini13]

From here, I doubt mark would have put it up unless he know they were legit, would be interesting to know why they never went anywhere,

Also the early saabs (99s?) used a pair of chains if the more usual type to drive the engine to and underslung box



http://mk1-performan...k/exp_dept.html

[mini13]

Also the tooth profile dies look different to standard to me, and akin to somthing that would run with a silent chain.

https://ramseychain....ion-chains/rpv/

[Ethel]

Looks to me like they they've just been ground back on the shoulders to create some space & guide the sides of the chain. There'd be masses more contact than with a gear so I don't think it'd be an issue to compromise on the meshing faces a bit in order to use what ya already got.

 

Hard to think of a reason not to do it:

 

I can imagine the baulk ring eating inertia being less. Noise? Service life? Getting the input gear off to change a chain could be a bugger, could you have a split link?

[Steve220]

Guys, probably been discussed before, but what about machining to take a tapered bearing on the thrust side of the idler? So it's pushing against it?

[nicklouse]

From here, I doubt mark would have put it up unless he know they were legit, would be interesting to know why they never went anywhere,

Also the early saabs (99s?) used a pair of chains if the more usual type to drive the engine to and underslung box



http://mk1-performan...k/exp_dept.html

The SAAB had a triplex chain.

[Ethel]

Guys, probably been discussed before, but what about machining to take a tapered bearing on the thrust side of the idler? So it's pushing against it?

That's what Mokespider's done.

 

The helix attempts to twist the idler towards the clutch at the primary gear & towards the gearbox on the input gear, so you need summet to resist the thrust on both sides.

 

I guess it's the acute angle on the the leading edge of idler teeth on the bottom as opposed to the obtuse leading edge as they are driven by the primary gear that makes them eat in to inboard thrust more?

[Spider]

Don't MED make a roller bearing idler gear - seems I saw a vid where they were showing it. I don't remember if it was for a helical gear or a straight cut but they had a shaft that pressed intot he trans case, then the idler which ran on a roller bearing and attached to the shaft, then a spacer that fit into the cover. I'll try and find the video.....

 

Edit - straight cut gears, but it's a slick idea.

 

 

 

 

Back in the early 80's (and possibly prior to that too) Jack Knight had a Helical Gear kit that did have the bearings in the Gear. I've not seen one in a very long time. I'm not sure how they did theirs, it used Pre-A+ Gears and was, from what I've heard, quite successful. I'm suspecting they had custom bearings made for this as I can't find anything off the shelf that fits and has the right ratings.

 

The forces are in a completely different direction on helical gears, that's where the problem lies. So their solution is not really relevant to helical gears.

 

 

Yes and no. The Helical Gear (as far as the Bearings go) sees pretty much the same forces as a Straight Cut Gear and some added ones.

A 'straight' Roller Bearing can be used in a Straight Cut Gear as there's very little (or should be little) side thrust, so a Single Bearing of this type can be used here and since there's only the one bearing, more real estate is available for it, so a fairly high rated Bearing can be fitted. From the Bearing perspective, it's good and easy, just a pity about the racket from the gear !

 

There's similar forces on the Bearings with a Helical Gear, and also Side Thrust and Twisting too.

 

It's about time to post this...

http://mk1-performan...chain_drive.jpg

 

There was a racer in Australia, Warwick Augustin, who spent some time developing a chain drive on his Race Car. I haven't seen it, but I understand, while it took him some time to sort out (I'm not sure what issues he came up against) it was in the end very successful and he ran with this for many years.

 

I really like the idea of a Chain and have been toying with such a set up for a while, however, the loading on the Primary Gear Bushes is increased. I like it as it allows for a fairly easy means of have a Ratio Change and it can be a fairly wide departure.
 

[DeadSquare]

In the late 60s, the front wheel drive Toronado had a chain drive between the engine and the gearbox.

 

I was planning to do the same between a Rover V8 and an automatic 1800 box.

[r.tec]

Gearwheel drive cannot be that bad, when Mr. Costin and Duckworth conceived such a thing:

 

https://www.f1techni....php?f=4&t=3497

 

For myself I know, the next time I take the engine/gearbox out of my Cooper SPi I shall fit the straight cut drop gear set lying around here.