SV to SIV prop shaft

[SIVAllan]

I pulled a syncro gearbox off a SV 25 spline parts car to use with the SIV, along with the parts car clutch assembly and prop shaft.

I thought it would bolt right up, but noticed that the parts car prop shaft looks very roughly ~ ½ inch shorter than the SIV prop shaft. The rear plate that bolts to the differential has the same bolt hole pattern, but is slightly thicker, but I can’t tell if that accounts for all the difference in lengths.

Has anyone done this? Will such an assembly bolt up without changing the rear axle carrier?

Or must the SIV prop shaft be used, with the parts car prop shaft's 25 spline section moved to it?

Thank you.

Allan

 

[jumpinjan]

Allen,
Please show a picture
Jan

 

[SIVAllan]

Allen,
Please show a picture
Jan

Jan, I based the observation that the rear plate is thicker on the drawing in a parts manual (attached) but now think that does not account for the difference.

Allan

 

[jumpinjan]

Something looks screwed up with your shorter shaft on the right. The yoke's wear marks look the same height on both. Which is the later splined one? R or L?

 

[SIVAllan]

The rusty one on the right came off the SV parts car and is the later splined one. It looks different (shorter) where the u joint fits.

 

[SIVAllan]

Did some more looking -this axle part appears to account for the difference in prop shaft length.

Perhaps the prop shaft's splined end will fit the SIV prop shaft, or else the axle part might transfer to the SIV differential housing...

Allan

 

[mxp01]

Allan:

Earlier this year I swapped out the differential on my SIV to address a growling noise. Afterwards the prop shaft would not fit into place, it appeared too long. After some consternation we found that there was a difference in the length of the differential by about 1/2 inch.

I posted this conundrum on the site and was told that I likely had a differential from a 1969 Alpine GT. We did the necessary modifications between differentials and everything fit.

The moral of my story was that there were some differences in differentials. I think it is possible you are dealing with something similar.

MXP

 

[SIVAllan]

I believe you are correct.

A parts manual shows 2 S IV differentials (non O/D). The 2nd was also for S V.

S V had that differential, plus 2 more, the last one occurring with chassis B395017309. (Parts car S V is ...18059.) Looks like the Driver Coupling (companion flange) changed too. I'm assuming the flange I measured is the companion flange...

So it looks like the wheelbase remained constant, but the drive shaft and coupling to the differential did not through S IV - S V.

What other changes took place, guess I'll find them via trial and error

Perhaps your parts came from a late SV, not a 69 Gt...?

Thanks!

Allan

 

[Wombat]

Allan

I think you will find the oil seal in the front of the diff is different too. I know that a seal for the Arrow range does not fit the Series IV.

Best fix might be to swap the 25 spline yoke onto the longer shaft.

 

[SIVAllan]

Thanks Robert.

Have ordered new U joints from SS.

Am weighing options on the 25 spline gearbox vs another one. Either way will use the other prop shaft with new U joints.

Allan

 

[65beam]

series 4

i have a complete differential out of a 69 GT with the 3:70 gears in my series 4. it is mounted in the original series 4 rear end housing . my series 4 is a full syncro trans ( coarse spline) and i am using the original drive shaft.