1672 replies to this topic

[eyepeeler]

Its been a long time between posts. Life gets in the way.

 

I have started on the 3rd link. Not finished yet. The tail shaft hoop will be integrated into the bracket.

I used the seat plates in the floor as the mount point. Sandwiched them with 3mm plate.

There will be a bend set into the trailing arm to set it up to the bracket.

 Fully weld it all up, when all parts fitted up.

 

 

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[Ice]

Jesus Christ thats a loop nice work Craig first run on the track seems to be getting closer

[eyepeeler]

Hahaha Gene, the masking tape hoop, LOL

[Bigfella237]

3rd link? Or 5th link? Or 7th link?

 

I haven't read the IPRA regs but I assume you're allowed to add trailing arms so long as the original mounts are still used?

[eyepeeler]

Yeah that's right Andrew. I can add longitudinal arms as long as I don't weld in brackets.

The original top arms will still be there albeit with non existent bushes. I cant fully delete them or their brackets.

Lateral location being done by the watts link

It has 5 arms but only 3 that will do anything.

[eyepeeler]

It takes  a lot to build a race car up and it all counts the effort and time it takes to get stuff right.
 
 
jesus that's gota stop the diff rotation under load ! 
 
good work on this keep going .
 
g

Cheers Grant, appreciate it mate.

[eyepeeler]

Got a bit of tube welded to the end of the 3rd link to house the bush. Fitted beautifully.

 

Also the bloke doing the brakes has all but done, 1 tube left to run on the passenger front.

All I have to do it clip it back. Sorry Datto, will catch up with you later? Drop in sometime.

 

Will work on finishing the 3rd link tomorrow night.

 

 

 

 

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[ozyozyozy]

Im getting excited seeing this move forward😊.

[eyepeeler]

[eyepeeler]

[eyepeeler]

Now for the hoop.

[eyepeeler]

Brakes hooked up. Bracket the pipes back and nip up the nuts and test.

Rear brake tee



Used the spring mount to bulkhead fitting between hard and flex pipe.

[Bigfella237]

Looking good Craig but a few more questions, which you've no doubt looked at already, but...

 

How does your exhaust fit back on with that torque arm bracket?

 

And are you adding a top hoop to that bracket to make a 360° tailshaft loop, or is that not required under IPRA?

 

Is there more to go on the diff end of the torque arm? Don't they usually bolt to the pinion support as well to stop the diff rotating (or torquing)?

 

Lastly, does that flexible brake line have enough slack to remove the caliper without disconnecting the hydraulics (I realise it's a radial-mount but it still needs to slip off the disc)?

[eyepeeler]

Cheers Andrew,

The exhaust merge is before the bracket. If you hear a faint "FARK!!!!!" on the south coast of NSW, it may have come from Perth, LOL.

Yep the hoop which I haven't made yet will be welded into the bracket. And yes it will be a full 360 degree hoop.

I've seen others do that, it may be something I have to do, I will check it out. Good pick up.

Yes there is enough slack to remove caliper from its mount. Its tight but not that tight I cant remove the caliper.

[eyepeeler]

This photo is for BIG KEV.

 

 

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[Bigfella237]

Thanks Craig, definitely not criticizing, I can't wait to watch the YT videos of this beast on the track!

 

I did go back a few pages and have a look at your exhaust and it looks like the pipe pretty much runs under that seat support plate, which is why I asked...

 

Bit more done.

 

The reason I asked about the torque arm is that I recall you mentioned your plan to remove the bushes from the upper trailing arms, so if the diff is then only located by the two lower trailing arms and the single bolt through the torque arm, there'd be nothing to stop it rolling around under acceleration/braking?

 

EDIT:

 

BTW, if the above is true, would there be some way to build-in some pinion angle adjustment to the torque arm?

Edited by Bigfella237, 05 August 2015 - 12:29 AM.

[eyepeeler]

Yeah I can see what your looking at in the photos.

 

See the square nut for the seat rail bolt, that is right next to where the single bolt in the SHS is in the bracket. The pipes entering the muffler are in front (engine side) of that bolt.

I did want the SHS to span the whole plate but that why it doesn't, the SHS with the hoop cut out would clash with the muffler.

The muffler was the main clash in that area.

 

I have emailed a friend of mine who has done a 3 link in his Torana race car. He has a plate welded to the arm and bolted to the carrier.

[eyepeeler]

More work to do, you are right Andrew. I need to make a plate from the carrier to the arm.

[Bigfella237]

Just looking around on Google and most custom made torque arms have some kind of pinion angle adjustment but I didn't really see one that could be adapted to your existing setup, so I started tinkering around with CAD.

 

First, the easiest option has no adjustment at all, where ever it gets welded is where the pinion angle stays...

 

 Torque Arm - Fixed Pinion Angle_sml.jpg   45.34K   6 downloads

 

Option two has the front plate on a pivot & the rear hole slotted...

 

 Torque Arm - Rear Adjustable Pinion Angle_sml.jpg   30.34K   6 downloads

 

Finally, if you have some spare heim joints laying around (the rear pivot remains fixed)...

 

 Torque Arm - Front Adjustable Pinion Angle_sml.jpg   46.16K   6 downloads

 

The other thing I noticed is most setups have the front pivot point (up near the gearbox) also adjustable to change the Instance Centre but your Roll Centre will be with the adjustable Watts Link so I guess this would only be useful in tuning anti-squat in your case?

 

Although I'm not exactly sure how anti-squat is tuned with only three lower links?

 

EDIT: I just remembered that you have a (somewhat) flexible bushing in the rear pivot, that would cause problems if the pinion flange is solid mounted?

 

EDIT 2: Ah disregard, after looking again it's the front that has the bush and the back is solid so she's all good after all.

Edited by Bigfella237, 05 August 2015 - 03:43 AM.

[76lxhatch]

A torque arm is rigidly mounted to the diff, and does not have an eye at the front (it needs to be captive left/right and up/down but have freedom to slide back and forth a little). The setup here is not a torque arm at all, its a 3 link with the third arm below instead of above and very long. It does seem like a concern that there is very little height difference between the two outer arms and the centre one but perhaps the original upper arms are still doing something?

[Racehatch]

A torque arm is rigidly mounted to the diff, and does not have an eye at the front (it needs to be captive left/right and up/down but have freedom to slide back and forth a little). The setup here is not a torque arm at all, its a 3 link with the third arm below instead of above and very long. It does seem like a concern that there is very little height difference between the two outer arms and the centre one but perhaps the original upper arms are still doing something?

 

A torque arm is what he is aiming for, but as you say, without the tube being fixed to the diff with a plate to the pinion support as above it will not control for/aft diff pinion angle/movement, I would say a non adjustable plate that fixes the diff pinion angle is all that is needed. The main reason for making this change is to remove the roll centre defined by the converging top arms, by removing the bushes from the top arms they are basically doing nothing. Left right location and roll centre is controlled by the watts link, for/aft is controlled by the torque arm/3rd link, The arm is as long as possible to reduce the geometry change as the suspension moves through its range of travel

[Bigfella237]

~ however i'd want a stronger adjustable arms with a big HP engine ~

 

Thanks Grant, yeah I thought about that afterward, nothing unusual, none of my designs ever stay at version 1, maybe this looks better...

 

 Torque Arm - Front Pinion Angle 02.JPG   40.06K   6 downloads

 

...I'm not really doing this to scale anyway, just illustrating some ideas, I suppose you'd want to use the biggest heim joints you could get, which would mean making the mounts thicker too.

 

You could probably get away with not having any pinion angle adjustment at all but you'd want to make sure it's set to how you want before you reach for the welder?

 

This suspension setup will certainly act differently to a 'normal' upper and lower trailing arm design, the pinion angle should travel in an arch with the 3rd arm instead of moving down on squat (usually counteracted by torque moving it up at the same time).

 

EDIT: One last point, with such a huge length difference between the factory lower trailing arms and this 3rd arm, and with the factory arms not parallel, would you see some bind happen between the two?

Edited by Bigfella237, 05 August 2015 - 01:17 PM.