1672 replies to this topic

[eyepeeler]

This should do the job of keeping the diff from rotating.



Weld that in and good to go.

[76lxhatch]

If its supposed to be a torque arm you will need to alter the front mount too

[eyepeeler]

Pipes clear no problem. Happy with that!!

If its supposed to be a torque arm you will need to alter the front mount too

Can you explain what needs to change? Not sure what you are looking at.

[ls2lxhatch]

Have a look at the setup on this page. 

http://www.rrs-onlin...-am-3-link.html

 

 

Edited by ls2lxhatch, 05 August 2015 - 08:27 PM.

[ls2lxhatch]

[eyepeeler]

Going to leave it the way it is albeit with another plate the other side of the arm.
Speaking with 2 Torana racers and I'm comfortable with where it's going.

Anyhow, don't want stuff round for lots of time on the arm and it's mounts, Hahaha.
I want to start the fuel lines.

[Bigfella237]

If its supposed to be a torque arm you will need to alter the front mount too

 

That's what I was talking about with the suspension binding, you have two sets of lower arms traveling in different arcs, at full squat the factory arms will be pulling forward while the longer 3rd arm will be pushing backward (relatively), either one set of trailing arms needs longitudinal movement built-in or the suspension will bind up trying to bend the diff housing like a banana.

 

My guess is that the weak point in this case will be the front mount (up near the gearbox), or more specifically the floor pan it's bolted to?

 

You could test this by removing the springs and shocks, then jacking the rear suspension through the full range of movement with a set of scales on the jack, if the weight of the diff changes then something is binding.

 

But I know you just want to get this done and move on Craig, so at the very least just keep a close eye on it for flexing / cracking?

 

What size fuel pump / supply / return lines are you using?

 

Without knowing the engine HP or what type of fuel you're using, I'd guess you'd want to go with something at least 50 GPH (25% more if you have to run ethanol fuels) with a 1/2" (-8AN) supply and 3/8" (-6AN) return?

[ls2lxhatch]

-6 will flow enough for a 700 hp naturally aspirated EFI engine.

http://aeromotiveinc.../power-planner/
 

[76lxhatch]

Can you explain what needs to change? Not sure what you are looking at.

If it operates as a 3 link (how you originally had it with pivot eyes at both ends) then you need sufficient vertical distance between the single arm and the original lowers to control diff roll.

If its to be a torque arm then its rigidly fixed at the diff end like a ladder bar, and the front operates more like slapper bars on leaf springs, its not supposed to be anchored in a manner that doesn't allow forward/aft movement. The reason for this is the binding mentioned, if all three arms had solid links you would find the diff wouldn't move up and down at all due to the different length arms - the bushings may take up some or all of this movement but its going to be hard on them and the suspension is still not travelling freely.

The shackle that lslxhatch posted is one option, a simpler and lower profile version uses a tube with an internal bushing that is free to slide back and forth as well as rotate but can't move sideways or up/down.

[Heath]

^ Yes, either of those would be a good solution.

The current system certainly has a minor flaw that I think needs to be addressed.

[ozyozyozy]

Most suspension design invovles some form of compromise somewere, even F1 struggles with this.

[eyepeeler]

That the plan, keep chugging along.
Fuel lines to run now.





I have 2 in tank Walbro fuel pumps out to filter, check valve, and "Y" branch and then onto the fuel rail.

[Dasman56]

Those pumps are awesome. They don't look that fancy but for the price really pack a punch

[ls2lxhatch]

Check that the hose you are using inside the tank is submersible fuel line hose with a SAE 30R10 rating. The outer cover on external fuel line hose will break down if immersed in fuel.

Edited by ls2lxhatch, 06 August 2015 - 09:20 PM.

[eyepeeler]

Check that the hose you are using inside the tank is submersible fuel line hose with a SAE 30R10 rating. The outer cover on external fuel line hose will break down if immersed in fuel.

Will do Andy,
That's the last thing I need happening.

[eyepeeler]

If it operates as a 3 link (how you originally had it with pivot eyes at both ends) then you need sufficient vertical distance between the single arm and the original lowers to control diff roll.If its to be a torque arm then its rigidly fixed at the diff end like a ladder bar, and the front operates more like slapper bars on leaf springs, its not supposed to be anchored in a manner that doesn't allow forward/aft movement. The reason for this is the binding mentioned, if all three arms had solid links you would find the diff wouldn't move up and down at all due to the different length arms - the bushings may take up some or all of this movement but its going to be hard on them and the suspension is still not travelling freely.The shackle that lslxhatch posted is one option, a simpler and lower profile version uses a tube with an internal bushing that is free to slide back and forth as well as rotate but can't move sideways or up/down.

Thanks for the info, I see what you are getting at. Makes sense.
I haven't welded the plate on yet. I am going to scribe a line on the arm along the plate, and when the car is back on the hoist I am going to see how much off the scribe line the plate moves with full travel of suspension. Curious to see how much it will move.

[eyepeeler]

Just keep building the car and getting it going.
 
Ive had a lengthy discussion with multiple people telling me to put a panhard bar in the back. then i was talking to a suspension bloke at the track and he was stating that " putting a panhard bar would bind up the back suspension arc" .
 whilst  the little torana's have a 4 link set up( well i call it this )  - the upper two arms are set so as to oppose each other and locate the diff in relation to the chassis rails. (body ) 
 I though that the LX /LH has the same system ? but i think not.now 
 three cents.
 if your not happy with the arm  then go " mr brock HDT style 05 "  - take it off   get the car sorted and then go an  fiddle. with the link. set up - you will probably be having too much fun to worry first up about the link - but time will sort this issue out.
 your smart talk to the other blokes they will tell you what to do.
 
 
G

That's the plan Grant. Get it done in the best way I know how and with the advise taken along the way and drive it. It's the only way I'll know if works or not.

[76lxhatch]

i was talking to a suspension bloke at the track and he was stating that " putting a panhard bar would bind up the back suspension arc" ..... the upper two arms are set so as to oppose each other and locate the diff in relation to the chassis rails. I though that the LX /LH has the same system ? but i think not.now

Yeah the later Toranas are the same, you're right the upper arm's roll centre location conflicts with the panhard bar roll centre and binds. That's why eyepeeler is putting loose/useless bushings in the top arms to make them redundant.

 

Curious to see how much it will move.

Yes will be very interesting. Assuming the bushings can take it up my main concern would be whether its fighting them enough to mess with your suspension spring rates or not, could make it hard to set up and a bit brutal on the mounts. But with extremely limited suspension travel maybe not, or maybe this could be tuned to be an asset?

[Bigfella237]

That is all true but the more immediate problem will be sway, at the moment there's a bolt through both ends of the 3rd arm, so when you go around a corner the body rolls but the diff stays flat on the road and the arm will twist along its axis like a swaybar.

 

I know you want to move on to the next job Craig but I think this really needs to be fixed, things that bind will only flex for so long then the weakest point fails.

[Peter UC]

That's what the rubber bushes are for, to allow for that rotation.

[Bigfella237]

The purpose of a rubber bush is to reduce NVH (Noise, Vibration & Harshness), you shouldn't be asking any more movement of one than you would of a solid pivot point.

[Racehatch]

I have been running this exact setup in my IP race car for a number of years without any issue, a rubber front bush is fine - bind in this system will only be an issue when the suspension is at the extremes of travel: ie completely compressed or at full droop - you will find that running on a racetrack they are (for the most part) pretty smooth so its less common for the suspension to go through its full range...Its important to control the working range esp on full compression say with adjustable bump stops.

Edited by Racehatch, 07 August 2015 - 01:46 PM.

[eyepeeler]

Fuel lines Well on the way