Hyperblade's KP61 Racecar "KP61R" Discussion

[Truenotch]

Ouch!

Reckon the crack was caused by the vibration? How solid are your engine and gearbox mounts? 

[Hyperblade]

30 minutes ago, Rhyscar said:

Great news that the vibration is solved - not so great about gearbox housing. Weld up and re-use or replace?

 

I've always found the sniff test for identifying which oriface is leaking a fun game  

 

17's on a starlet look like hard work! Unsure if it would be worthwhile. 

I'm sure welding is doable, but a fairly big job, my guess you would have to cut out all the strengthening ribs, then also get it from the inside (and not sure what it may be impacting internally).

Preference is to find a new housing.

17" would also add 80kg of weight, so going to rule them out, 15" on the other hand might be worth going too to get a stronger wheel.

28 minutes ago, Truenotch said:

Ouch!

Reckon the crack was caused by the vibration? How solid are your engine and gearbox mounts? 

It's really hard to say, it's had a hard life.

• Potentially was originally from a car which went off the port hills road.
• Original driveshaft with 2 UJ's had terrible vibration at 100km/hr which made it undriveable, right at the gearbox end until i replaced with CV.
• 4-5 mis shifts going from 5 to 4th, at well over 100km/hr where the rear did not lock up so instantly tried to immediately spin up gearbox and engine (that must be a massive amount of torque)
• misifiring coil causing large vibrations
• Wheels unbalanced/bent (and me doing a race event like that)
• Moving and welding the shifter.

Engine/gearbox are fairly solid, but not crazy.

So hard to pin point exact cause, and probably a combination.

[tortron]

because racecar, just grind it all flat and weld a patch over the top

[Truenotch]

1 hour ago, Hyperblade said:

Original driveshaft with 2 UJ's had terrible vibration at 100km/hr which made it undriveable, right at the gearbox end until i replaced with CV.

I'm going to stick to my original stance here and say I think your driveshaft may be the issue. From a distance, the combination of problems is screaming tail shaft. 

The CV might be lessening the amplitude of the harmonic, but not removing it completely. 

[Hyperblade]

2 hours ago, tortron said:

because racecar, just grind it all flat and weld a patch over the top

Ideally would like to move to a bolt on shifter relocation rather then welding, which would make replacing it in the future easier. But always plan b.

33 minutes ago, Truenotch said:

I'm going to stick to my original stance here and say I think your driveshaft may be the issue. From a distance, the combination of problems is screaming tail shaft. 

The CV might be lessening the amplitude of the harmonic, but not removing it completely. 

Could well be, but not sure what I can do further? Only thing I can think of is going to CV on the rear as well?

[Rhyscar]

Single or two piece driveshaft?

If your angles are too little/too much, a CV will still suck. We went down this road on a hayabusa powered starlet rally car, and spent a few seasons replacing CV's instead of UJ's... 

Driveshafts and powertransmission is a true mechanical engineers game to get right - I don't even pretend to know the basics, but know it can bite you in the ass for anything non-standard (unless it's a BA falcon of course). 

[Hyperblade]

49 minutes ago, Rhyscar said:

Single or two piece driveshaft?

If your angles are too little/too much, a CV will still suck. We went down this road on a hayabusa powered starlet rally car, and spent a few seasons replacing CV's instead of UJ's... 

Driveshafts and powertransmission is a true mechanical engineers game to get right - I don't even pretend to know the basics, but know it can bite you in the ass for anything non-standard (unless it's a BA falcon of course). 

one piece which is only like 840mm long.

2 Piece doesn't solve the problem as you still end up with joints out of sync, engine/gearbox are in at an angle (left to right).

I can understand a CV might be impacted by to much/to little angle, but on the other side a standard Honda S2000 is an IRS rear end so has basically no movement in the stock CV joint (2 piece shaft)?

I've seen that orange beast, he drives it really well!

[Rhyscar]

48 minutes ago, Hyperblade said:

I've seen that orange beast, he drives it really well!

 

Different starlet... but it's been seen in the wild a couple times recently. 

 

This one is now sporting a supercharger and 450hp at the wheels. He's moved away from the CV after spending 5yrs designing a bespoke output shaft relocator to get better driveshaft angles. It's a work of art. 

[Hyperblade]

15 minutes ago, Rhyscar said:

 

Different starlet... but it's been seen in the wild a couple times recently. 

 

This one is now sporting a supercharger and 450hp at the wheels. He's moved away from the CV after spending 5yrs designing a bespoke output shaft relocator to get better driveshaft angles. It's a work of art. 

Ohh nice, hadn't seen that one, looks really tidy in the engine bay!

450hp seems a bit overkill...

[mjrstar]

Off topic bit did this get some body modifications at taupo 2wd rally?

 

The orange one is going 1440cc stroker.

[kpr]

mixing  a uni and cv in the same shaft doesn't seem right.   but assuming the uni is on the diff end;  you'd want the the diff pinion to point directly at the pivot point of the cv, or a touch down to compensate for the diff rotating under acceleration.   This would make the cv deal with the angle  and  let the uni run straight.     Of course will only work  if your drive line is straight side to side with the diff.   

this is what i meant in previous post 

 

[Truenotch]

 After watching this, it looks like the driveline vibration is still there. The gear knob still flails around on the straights and it shouldn't. 

I know @kpr spent a while trying to get his starlet driveshaft working as a single piece, but ended up going 2 piece to solve the issue, even though it's only about 1m long. Yours is even shorter, but maybe it's worth looking into so you can have two sets of UJs running and closer to ideal angles?

[Hyperblade]

1 hour ago, kpr said:

mixing  a uni and cv in the same shaft doesn't seem right.   but assuming the uni is on the diff end;  you'd want the the diff pinion to point directly at the pivot point of the cv, or a touch down to compensate for the diff rotating under acceleration.   This would make the cv deal with the angle  and  let the uni run straight.     Of course will only work  if your drive line is straight side to side with the diff.   

this is what i meant in previous post 
 

Yes I agree, doesn't seem right, but as you point out ideally the diff angle would be 0 degrees in relation to driveshaft (although people don't recommend them running at 0 degrees due to wear), but it's within spec of what DDS recommended. I can say it's been smoother with the new driveshaft then it currently is now.

29 minutes ago, Truenotch said:

After watching this, it looks like the driveline vibration is still there. The gear knob still flails around on the straights and it shouldn't. 

I know @kpr spent a while trying to get his starlet driveshaft working as a single piece, but ended up going 2 piece to solve the issue, even though it's only about 1m long. Yours is even shorter, but maybe it's worth looking into so you can have two sets of UJs running and closer to ideal angles?

I think we need to be careful here, the gear stick has been extended and is making any vibrations appear significantly worse. Not saying there is no driveline vibration there is, but not as bad as it potentially looks (none would obviously be ideal).

That's also under significant load while I have massive crack in the gearbox so that is certainly not helping with keeping things stable...

I don't see how I can run 2 UJ's with 2 piece drive shaft to make it better? The gearbox is in at an angle so at some point either the diff UJ's or carrier bearing UJ's will be at an angle to each other and out of phase?

 

One thing you are all missing is vibrations from the engine...

We have run it up without the gearbox and clutch and there is still quite a lot just from the engine.

The engine comes as standard with 5kg of balance shafts, which I've removed and replaced with a standard oil pump.

Now the argument is "well the Integra didn't have them and it's fine".

But I'm pretty sure the harmonic balancer will have been tuned to the stock engine, and the balancer differs between Euro R and Integra Type R.

To that end I have a fluid damper on it's way to remove that from the equation so will be interesting to see how big a difference that makes.

 

[kpr]

2 piece shaft is more  to get away from critical driveshaft speed.     shorter you make it faster  can spin it before it nukes itself.    There is plenty of calculators online to work out how the critical speed.  material, diameter and length.   On mine the math worked out i was going past max shaft speed at pukekohe, when i actually drove my car.     from memory it was around 8000rpm shaft speed.   the 2 piece is good for a lot more.

the first half of the 2 piece should pretty much carry on straight from output shaft.  2nd half does the work of what a single would do.   so yes  if you  engine/ box arent aligned well.   will make that problem worse. as you are increasing the angle since said 2nd shaft is shorter.  

how much angle is you engine actually on?  assuming is a major to straight it ?  

Re running the uni at zero degrees.   You are probably fine in race car situation since doesn't have to last forever.  it just stops the needle rollers  from spinning. so your loading the same points all the time.  so the needles dig into the cross over time.     on a 2 piece shaft the first uni often gets a tight spot for same reason. 

[Hyperblade]

45 minutes ago, kpr said:

2 piece shaft is more  to get away from critical driveshaft speed.     shorter you make it faster  can spin it before it nukes itself.    There is plenty of calculators online to work out how the critical speed.  material, diameter and length.   On mine the math worked out i was going past max shaft speed at pukekohe, when i actually drove my car.     from memory it was around 8000rpm shaft speed.   the 2 piece is good for a lot more.

the first half of the 2 piece should pretty much carry on straight from output shaft.  2nd half does the work of what a single would do.   so yes  if you  engine/ box arent aligned well.   will make that problem worse. as you are increasing the angle since said 2nd shaft is shorter.  

how much angle is you engine actually on?  assuming is a major to straight it ?  

Re running the uni at zero degrees.   You are probably fine in race car situation since doesn't have to last forever.  it just stops the needle rollers  from spinning. so your loading the same points all the time.  so the needles dig into the cross over time.     on a 2 piece shaft the first uni often gets a tight spot for same reason. 

Yep that was my understanding on 2 piece as well. Current one is 3" carbon fibre at only 840mm odd long so easily covers the shaft speed of 9000 rpm.

Enough to matter unfortunately, was done for weight balance and fitment around clutch area, in hindsight I wish we had worked out a different solution, but it is was it is. significant fab to change, starts impacting on pedal box.

Changing diff angle would mean all new diff mounts, and then potential clearance issues to tunnel, so not easy either.

[NickJ]

Finding a flat surface on castings is always a pain! Would it be possible to extend your new mounts up to the top cover of the shifter housings?

Then you would be able to work to a nice flat datum to get everything lined up, may need a new/modified top cover to joint the two if thats even possible?

What scanner are you using?

[Hyperblade]

4 hours ago, NickJ said:

Finding a flat surface on castings is always a pain! Would it be possible to extend your new mounts up to the top cover of the shifter housings?

Then you would be able to work to a nice flat datum to get everything lined up, may need a new/modified top cover to joint the two if thats even possible?

What scanner are you using?

Yeah I've looked at it every which way, and trying to mount from the bottom seems to be a world of hurt, hence why no further progress!

I had discounted from the top, thinking clearance issues.

But actually, I think I'm fine I have 30mm to play with from top of existing bolts

And seems to be enough room up front of it for the bracket.

Then I just have to deal with shifter location inside the housing which I think easier to deal with.

It's an interesting effect, but whenever I see something in CAD it feels way bigger then real life, the rear housing in reality is not actually that big so I have more space around it then I thought.

 

 

I'm using an Shining 3D Einstar (they are terrible at naming and have changed there naming schemes over the years), picked it up for a really good price second hand a few years back.

This one: https://www.einstar.com/products/einstar

[NickJ]

Looking at the layout again, my head is now thinking sheetmetal, would just need to machine the mating face on the rear housing down 1.2mm then sandwich it all together? Not much more than an afternoon to put it all together

[Hyperblade]

6 minutes ago, NickJ said:

Looking at the layout again, my head is now thinking sheetmetal, would just need to machine the mating face on the rear housing down 1.2mm then sandwich it all together? Not much more than an afternoon to put it all together

Na will need to be much stronger then that, lot of load/leverage when gear lever is being moved.

I'm thinking 10mm plate across top and will work out the internals to suit.

[mjrstar]

How about small box section.

This is the homemade cd009 shifter for the mx5.