Tips of installing an S4D in place of an S4

[John@Outfront]

A friend of mine has a wicked sandcar and he needs a stronger tranny. he currently has an S4 and looking at doing an S4D

questions:

i assume it has the same mounting for the nose cone area. i Know the bellhousing has a different mounting pattern but is the length from nosecone to the bellhousing mounting the same as the S4?

i also assume the shaft spacing is the same too so the motor in relation to the drive flanges--is it the same or would the motor be higher? i ask because the room is really tight where the motor resides. is the measurement of drive flange to drive flange the same so axle length doesn't change?

his current setup uses the old adapter plate set up, does the chevy bellhousing push the motor further back

asking for a friend

 

[Pennywise]

It’s up 1” and back 3/4

 

[Sutton]

Following for knowledge. Also, let me know if he is selling his s4, bellhousing, clutch, shifter set up or any associated parts.

 

[John@Outfront]

From those dimensions it doesn’t show there is any upward movement of “ drive flange center to input shaft center. They look the same. Only the belly of the bellhousing appears to go down a bit more. Can we see the whole dimensions I do see where the motor would be set back an inch.

 

[J Alper]

Drop the trans down low or have Midboards

 

[Pennywise]

From those dimensions it doesn’t show there is any upward movement of “ drive flange center to input shaft center. They look the same. Only the belly of the bellhousing appears to go down a bit more. Can we see the whole dimensions I do see where the motor would be set back an inch.

The full pdf is on Weddle's site https://weddleindustries.com/products/S4D-TRANS/S4D-TRANS I know on the two I have done we had to raise motor mounts. If the frame allows I supposes you can drop the rear mount down as long as you can maintain correct angle.

 

[lincster]

Weddle’s site has all the dimensions you need in PDF documents.

 

[John@Outfront]

If the guy has an s4 with a cracked case and bad ring and pinion I am assuming you could buy the s4D case and ring and pinion and add side plates, drive flanges, diff and bellhousing and use all the gears and intermediate case from old trans? Is there something I’m missing

 

[lincster]

Why not call @SeanRitchie ?

 

[GBR]

Why not call @SeanRitchie ?

This for sure

 

[SeanRitchie]

I can explain in detail over the phone.

Same distance from center of drive flange to input shaft. But...

1. Bottom of "D" trans case sits lower (larger diameter ring gear), trans and engine have to move up in chassis, unless S4 is already positioned high enough, which is unlikely.

2. You will increase the CV angle at full droop and loose some travel on trailing arms and need to hike up or install limit straps due to trans sitting higher in chassis. Will probably also need new axles.

3. Longer distance between forward trans mount, and bell housing mount. Will need to cut all mounts out of chassis and make new.

4. Engine will need to move back, I forget the approximate distance, but it's at least 1". Unless there is room and CV angle allows for trans CV flanges to move that far forward. Again, unlikely.


Not an easy swap, the D trans is quite a bit larger. Cars are built around the transaxle. Sometimes its best to just cut off the entire cage and rebuild around the larger trans.

 

[John@Outfront]

I can explain in detail over the phone.

Same distance from center of drive flange to input shaft. But...

1. Bottom of "D" trans case sits lower (larger diameter ring gear), trans and engine have to move up in chassis, unless S4 is already positioned high enough, which is unlikely.

2. You will increase the CV angle at full droop and loose some travel on trailing arms and need to hike up or install limit straps due to trans sitting higher in chassis. Will probably also need new axles.

3. Longer distance between forward trans mount, and bell housing mount. Will need to cut all mounts out of chassis and make new.

4. Engine will need to move back, I forget the approximate distance, but it's at least 1". Unless there is room and CV angle allows for trans CV flanges to move that far forward. Again, unlikely.


Not an easy swap, the D trans is quite a bit larger. Cars are built around the transaxle. Sometimes its best to just cut off the entire cage and rebuild around the larger trans.

SEAN
thanks for the reply, i gathered most of that above, but to confirm let me ask it a different way:

if I was to be able to mount the drive flanges in the exact position they are with the S4, then............

axle length would not need to change? (drive flange from flange to flange is still the same?)
the nose cone mount would need to be cut off and moved forward in the car approx .75" (but same bolt pattern for this mount?)
the mount on bellhousing near the engine is larger and wider but if that wasn't an issue, tthis mount would need to also move .75" further back in car with a new bolt pattern? (6 bolts, 3 per side instead of 2 per side on the S4)
noted: that the belly of the tranny is larger and would hang down approx .75" to 1" lower
and finally with all this work, the motor would effectively be pushed back 1.75"? that would be approx .75" for the differential growth and 1" for the chevy
bellhousing (as it has a VW bellhousing and adapter plate now)

the is a larger "wicked sand car" and i think it might work with maybe relocating one lower tube under the tranny
pics coming

 

[SeanRitchie]

SEAN
thanks for the reply, i gathered most of that above, but to confirm let me ask it a different way:

if I was to be able to mount the drive flanges in the exact position they are with the S4, then............

axle length would not need to change? (drive flange from flange to flange is still the same?)
the nose cone mount would need to be cut off and moved forward in the car approx .75" (but same bolt pattern for this mount?)
the mount on bellhousing near the engine is larger and wider but if that wasn't an issue, tthis mount would need to also move .75" further back in car with a new bolt pattern? (6 bolts, 3 per side instead of 2 per side on the S4)
noted: that the belly of the tranny is larger and would hang down approx .75" to 1" lower
and finally with all this work, the motor would effectively be pushed back 1.75"? that would be approx .75" for the differential growth and 1" for the chevy
bellhousing (as it has a VW bellhousing and adapter plate now)

the is a larger "wicked sand car" and i think it might work with maybe relocating one lower tube under the tranny
pics coming

Yes to most all of that.

The engine will move back 1.385" (S4 with VW BH/.500" thick adapter plate), but stay in the same vertical position.

I actually don't know the difference in spread between the S4 mounting tabs and S4D mounting tabs. Weddle does not show that dimension on the diagrams. I never thought about that before.

 

[John@Outfront]

The S4 main case is 15.5” long. The S4D main case is 17.25”. So 1.75 longer overall and I am assuming that 50% on both sides of the center of the drive flanges. That = 7/8” both directions of the diff

 

[John@Outfront]

Here’s the car The nose cone mount looks easy. Make a plate that welds to the front of the cross tube rather than the top of tube. Then the motor mounts could go on the back side of the back tab and simply add one more tab per side. That just happens to be 1.75”. Almost the exact added length if I also move the front tab .75” forward