Third Member Question

[Silicon 70]

I wanted to know if 79' third members would fit on 70' FJ40's? Would it just bolt on or are there any mods to be done?

Searched a little bit and found other things, but not really specific to my question.

 

[Pin_Head]

They will fit, but the ratio for '79 is 3.7 (instead of 4.11) and the drive shaft flange is different. You can buy new flanges and drill the holes to match your driveshaft.

 

[Silicon 70]

Yep that's the answer I was looking for. I'm swapping them so my RPMs won't be so high.

These flanges can be bought from places like Marlin Crawler, yes?

 

[Poser]

Or Cruiseroutfitters

 

[PabloCruise]

You are going to replace both the front and rear - correct?

Otherwise, trying to spin one at 3.7 and one at 4.1 - t-case go BOOM!

 

[rgentry]

Has anyone taken 1/4" steel plate and drilled 8 holes (two sets of 4, 45 degrees out of phase) so that 4 of the bolts hold the plate to the later flanges and 4 of the bolts hold the plate to the earlier driveshaft. I know this may sound ridiculous ...

 

[Pin_Head]

I'm swapping them so my RPMs won't be so high.

?

Most people just get bigger tires. Going to 35s from 32s would accomplish the same thing and would be mo bedda off road too.

 

[Silicon 70]

Yep I'm replacing front and back. Once again thanks for the help.

 

[rgentry]

Flanges

Here is a schematic of what I was thinking using a steel plate drilled for the driveshaft and the flange. I have the older driveshafts with the 8 mm bolts and nobody that I know of makes a flange for those skinny old bolts.

 

[Poser]

Seems like a lot of variables with your system are already handled with a new companion flange.....

 

[cruiseroutfit]

Here is a schematic of what I was thinking using a steel plate drilled for the driveshaft and the flange. I have the older driveshafts with the 8 mm bolts and nobody that I know of makes a flange for those skinny old bolts.

So you need the 8mm small pattern on your diff? Are you running course or fine spline pinion? A used course spline is easy to find, or get a new fine spline one with the correct pattern...

 

[pygpen]

Here is a schematic of what I was thinking using a steel plate drilled for the driveshaft and the flange. I have the older driveshafts with the 8 mm bolts and nobody that I know of makes a flange for those skinny old bolts.

I would not recomend this because the DS flange has a ring that centers it in the pinion flange, indexing them together. The bolts are only used to clamp the two together. Either drill out the holes, use the smaller bolts, or get a round flange and drill your pattern into it.
I'm not sure if the marlin flange has the small hole pattern on it.....
PMK

 

[rgentry]

Hey Kurt. I am changing to 3.73 gears from a '79 FJ40 and want to keep my 1968 driveshafts with the small diameter bolts. I suppose that the diffs will almost certainly be fine spline. Do you have fine spline pinion flanges tha are un-drilled?

 

[cruiseroutfit]

Hey Kurt. I am changing to 3.73 gears from a '79 FJ40 and want to keep my 1968 driveshafts with the small diameter bolts. I suppose that the diffs will almost certainly be fine spline. Do you have fine spline pinion flanges tha are un-drilled?

Yes, I can get (out of stock right now) undrilled flanges...

However, if you are using the 68' pattern, my part number PN60040 should work

Or find a single pattern round flange, clock it and drill it...

Thanks!

-Kurt

 

[rgentry]

Not sure if your PN 60040 will work. The patten is the same but the early driveshafts had 8 mm driveshaft bolts and not 10 mm bolts. What is the hole size in your flange? If it's 8 mm then I need to pony up for a pair instead of making those crazy adapters.

 

[cruiseroutfit]

Not sure if your PN 60040 will work. The patten is the same but the early driveshafts had 8 mm driveshaft bolts and not 10 mm bolts. What is the hole size in your flange? If it's 8 mm then I need to pony up for a pair instead of making those crazy adapters.

8mm ID Bolt Hole - 64mm x 56mm pattern

LMK

 

[PabloCruise]

Lmk???

 

[cruiseroutfit]

Lmk???

Let Me Know...

 

[Silicon 70]

Kurt,

PM'ed you

 

[PabloCruise]

Let Me Know...

Oh good! I was afraid it was "lick my "!!!