Jump to content

Tech Spam thread - because 1/4" BSP gets 5 hand spans to the jiggawatt


Roman

Recommended Posts

  • Replies 6.1k
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Is it normal for a 4 link kit to taper in 20mm each side?

each arm is angled off at one end of the arm where it connects to the bushing.

 

would’ve thought that they would be all straight.

 

IMG_8647.jpeg

  • Like 1
Link to comment
Share on other sites

I suppose they are building in a bit of triangulation to control side to side movement?

They don't have to be straight as there needs to be compliance in the bushings to allow wheel articulation.

  • Like 1
Link to comment
Share on other sites

Any of you good folk know of an app or whatever that can calculate the correct driveline angles for a 2 piece driveshaft?

I need to sort out if the hanger bearing needs relocating and pinion angle.

engine sits around 6.5 degrees to sit the carb level.

i can’t find any info on standard rx7 driveline angles to start with.

from there the first driveshaft is on a 3 degree down slope, then the second hauls arse upwards to ride height.

my thinking is the hanger needs lifting up. But lack of good online info has me baffled. Most only go into a single piece set up which is piss easy

Link to comment
Share on other sites

 

Most of the online diagrams go out the window with bagged stuff because they are geared toward the pinion being far lower than the output shaft on trans.

 

Spicer has a good angle calc.

Link to comment
Share on other sites

4 minutes ago, RXFORD said:

What angle is the 2nd shaft on?

I took a pic though.

 

ill be making a new shaft for this one cos it doesn’t go into the box far enough now that I’ve changed a couple of things

IMG_8738.jpeg

Link to comment
Share on other sites

Looks like raising the hanger bearing would be pretty easy.

How much more penetration do you need into the box? Can you make a 30-50mm spacer with a male and female spigot to go into the front of the diff flange to space the shaft forward? If you do it at the same time as the hanger move it will look 'stock' too

Link to comment
Share on other sites

Just now, fletch said:

Looks like raising the hanger bearing would be pretty easy.

How much more penetration do you need into the box? Can you make a 30-50mm spacer with a male and female spigot to go into the front of the diff flange to space the shaft forward? If you do it at the same time as the hanger move it will look 'stock' too

Yup I could do a spacer for the rear.

it will be about 40mm at most by the time I raise the hanger, this will push the shaft in a little more at the same time.

that entire hanger crossbeam can disappear in favour of a new one.

 

luckily this sits in behind the cab too

Link to comment
Share on other sites

Because you have a greater angle on the gearbox than the first shaft, raising the hanger will make the operating angle of the front UJ worse and its already at 3.5° based on the angles you mentioned on box and first shaft, so wouldn't really want to go any more than that. 

The lower the first shaft angle, the less rotational pulsation the second shaft will have to try cancel out. The higher the rpm, the lower the operating angle should be. 

 

If it was the other way around like most vehicles, for example the gearbox was 3° down and the first shaft was 6.5° down, then raising the hanger would help get the front UJ to a lesser angle.

 

Are you sure the box is 6.5° with carb where it needs to be? Are you measuring that off the crank pulley/sump? Seems like alot. I can't remember what the last rotary I mounted ended up being with the carb level tbh.

Post up a rough/close enough angle of the rear shaft when you get a chance. I'l calc it how it currently sits and see what the pinion ends up at.

Link to comment
Share on other sites

@RXFORD

I tried relocating the engine and box a bit.

this crossmember is from the other ute that the previous owner mounted.

 

so I dropped the front crossmember 25mm, and raised the box 25mm.

now the out put shaft/engine is at 5.2 down, first shaft is 5.4 down, second shaft is 11.2 up if the rear pinion is at 5.2 to match the hanger uj. 
is that ballpark correct now?

 

this pulls the carb 2 degrees forward

Link to comment
Share on other sites

Please pardon my ignorance of all things rotary but why are they configured like that? Is there any reason for the inlets not being at right angles to the rotational axis of the rotors?

Link to comment
Share on other sites

2 minutes ago, igor said:

Please pardon my ignorance of all things rotary but why are they configured like that? Is there any reason for the inlets not being at right angles to the rotational axis of the rotors?

Maybe to accommodate from the massive Gs on mega torque clutch dumps and wheel stands? Haha :badgrin: 

yeah right. 
 

not sure, but by my retarded thinking, if the engine is flattened off and the carbs leans forward 5-6 degrees then the rear rotor may be more likely to lean out and heat up. Which is what kills most 12a’s - dead rear rotors.

going to injection would fix that, until it dies eventually anyway (I am yet to have one die).

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...