387 replies to this topic

[toryman76]

Yes!! I did notice my previous post was 999. Quite an acheivement 😂

[Heath]

Measure up the Dragway wheels you want to run and post the measurements. Should not be hard to find most Dragway wheels with roughly a 0 offset (with 7" or 8" width) for the front, and that will work fine.

 

I wouldn't change the 3.36 diff, or at least I would go for 3.08 rather than 2.78. I had 225/65R13's on my first Torana (with 8" wide wheels) and that was good with the 3.36 ratio.

5spd swap is obviously recommended, but you may have your reasons against that.

[toryman76]

Heath I actually have one dragway fitted to the front now but I was really struggling to work out correct offset because I haven't had a professional wheel alignment done. Just my string line for toe and large wooden sqaure to measure camber angle. I have no idea what castor is set to. 225/65r13 has a dia of 623mm and my current tyre 205/60r13 is 576mm. That's a pretty big difference so I can see your point about diff ratio in your car being ok with a 3.36. What sort of revs was it pulling at 100km/h? Perhaps I was too quick to jump the gun but I am committed now. Will see when it's bolted up.

[Bigfella237]

With a 205/60R13 and a 3.36:1 diff ratio, my calculator says you should be doing 3091rpm in 4th gear (1:1 ratio) at 100km/h...

Tyre Size = 205/60R13
Tyre Revolutions = 552 per km
Gear Ratio = 1.00 : 1
Diff Ratio = 3.36 : 1
40 km/h = 1236 RPM
60 km/h = 1855 RPM
80 km/h = 2473 RPM
100 km/h = 3091 RPM
120 km/h = 3709 RPM
140 km/h = 4328 RPM
160 km/h = 4946 RPM
200 km/h = 6182 RPM

 

The same parameters with a 3.08:1 diff ratio equals 2834rpm at 100km/h...

Tyre Size = 205/60R13
Tyre Revolutions = 552 per km
Gear Ratio = 1.00 : 1
Diff Ratio = 3.08 : 1
40 km/h = 1133 RPM
60 km/h = 1700 RPM
80 km/h = 2267 RPM
100 km/h = 2834 RPM
120 km/h = 3400 RPM
140 km/h = 3967 RPM
160 km/h = 4534 RPM
200 km/h = 5667 RPM

And just for comparison, with a 2.78:1 diff ratio...

Tyre Size = 205/60R13
Tyre Revolutions = 552 per km
Gear Ratio = 1.00 : 1
Diff Ratio = 2.78 : 1
40 km/h = 1023 RPM
60 km/h = 1535 RPM
80 km/h = 2046 RPM
100 km/h = 2558 RPM
120 km/h = 3069 RPM
140 km/h = 3581 RPM
160 km/h = 4092 RPM
200 km/h = 5115 RPM

 

Edited by Bigfella237, 27 May 2020 - 06:10 PM.

[Bigfella237]

More useless information while I've got your figures plugged in...

 

 

 

[toryman76]

That's awesome data! Love it bigfella. That looks like a pretty neat program you be got. Im guessing it's running off excel?

[Bigfella237]

Nah, it's a standalone program I wrote in Java when I got tired of doing the various calculations manually all the time...

 

 

 

 

 

That's just one of many different programs, here's another one I wrote back when I was designing a fuel delivery system...

 

 

 

 

 

 

And to answer the next question that everybody asks, no, I'm not handing out any of these programs but I'm happy to run anyone's numbers for them.

Edited by Bigfella237, 28 May 2020 - 09:26 AM.

[Cook]

Wow Andrew.  Not sure what your field of expertise is but that's some impressive stuff.  You know you are going to get a heap of requests.  Cheers Ron

[toryman76]

Super impressive mate!! Thanks heaps for sharing. I wouldn't ask for your program but some numbers in the future would be cool.

[toryman76]

Cleaning up a few parts this weekend ready for the new diff. The brake tee fitting looks quite scored in one end possibly from over tightening over the years. Is this going to cause me issues? Can you buy new ones?

Attached Files

•  Screenshot_20200531-155631_compress91.jpg   112.43K   6 downloads

[toryman76]

Like most things the new diff build took much longer than expected. The current pandemic has not help things, making it very slow in getting parts and materials etc, but finally got there. Whilst the car was up on stands I noticed a few issues with leaking front hub seals, so off came the front hubs for new bearings seals and re-packed grease and gave everything a lick of paint while I was at it. Finally kicked it in the guts over the weekend for the first time in several months. I was stoked with how quick it fired up. It sure did put a smile on my face! First minor test drive this morning and I was extremely happy with the diff ratio choice. I had no issues getting off the line, and I felt each gear had more legs than the previous ratio. Yet to get it up to speed, and won't do so for some time until everything beds in, but initially I am happy. I am still yet to sort out rims, so this will affect things again, and will need to revisit the speedo drive gear to get the ratio right once I decide on wheel & tyre size.

 

Heres my little helper in the making 

 

 

Attached Files

•  Annotation 2020-09-03 151750_3.png   587.25K   6 downloads

[rodomo]

I noticed a few issues with leaking front hub seals

If you used Commodore type seals that will happen.

[toryman76]

I stuck with the hub seals that are meant for the LX Torana. I did quite a bit of research on the different type of seals. Although I read the earlier types were meant to be better I decided it was best to stick with what the car was designed and manufactured with. Time will tell if I made the right call but I always have the metal backed seals to fit if I ever have issues.

Several drives now with the 2.78 diff ratio. So far I love it. The car is much happier at cruising speeds. Bit harder to get off the line but I have plenty of torque up front to help with that and I am in no great rush!