Help mating zf and dart block!!

[Pedro]

On page 25 of the ERA manual (attached) they mention the fact that there are some rare transaxles with a much longer input shaft.

This manual may not apply directly to your installation as their bellhousing may be different to that of the Safir but I find it to be very good reading with lots of good information.

I think Rod is correct; you may want the check for the input shaft bottoming out on the crankshaft without any bellhousing or clutch installed but using you choice of bronze bush or bearing when checking the distance.

I am not an expert so these are just suggestions; you don’t want to damage that transaxle.



Pedro

 

[Pat]

Pat,
I had a similar, but not so extreme, experience mating a ZF to a Dart block via Safir's SBF Clutch pkg. Everything assembled and appeared OK, until I torqued the Bellhousing to the block and ZF to the Bellhousing. Everything then 'locked up' and the crankshaft wouldn't move. I checked & re-checked everything a number of times, just as you have, to no avail. I finally discovered the flywheel WAS slightly in contact with the bottom of the bellhousing and ground enough off to negate that situation. I also discovered that the ZF's input shaft seemed to be bottoming out on the end of the crankshaft, so took apptox. 3/32" of the end. Not sure if those 'fixes' were a bodge masking some other problem, but everything mated & torqued up nicely after that. I now have about 1000 miles on the car and it all seems to be working as it should.
Also, note that Bob Wood at Safir was a great help to me with any questions I had on the proper assembly order of the clutch components.
HTH, Rod

Well at least I know I’m not going crazy then that it happened to someone else!!!

 

[Pat]

Well i measure the length of the input shaft stick out to the depth of the crank center and got a .0975” difference with it being too long although there is a ‘hump’ inside the center of the hole in crank and there is a hole in the center of the input shaft so that should easily make up the clearance difference giving me a perfect fit and how accurate my caliper is. Next I need to assemble the clutch again and try to measure the distance for the outer most clutch disc and input shaft spline to make sure there is enough clearance there.

I sent an email to Safir but it doesnt send me a confirmation so I dont know if it went through. Also I couldn’t find a phone number to call them directly. I wanted to talk to them before shaving off the bottom of the bell housing for clearance with the flywheel. The flywheel is definitely sitting solid on the crank although I do want to mount the starter with just the block to make sure it reaches the flywheel as it does seem a ways out.

 

[David Garton]

Pat, I had the issue but noticed it while installing the bellhousing. I made mine where I can pull Trans without bellhousing. See pictures where teeth touched and where a had to massage the bellhousing. I'm sure Bob from Safir will confirm. Keep at it.

 

[Pat]

I’ve made mine future proof to be able to pull just the trans by replacing the top two bolts with just ‘bolt studs’.

 

[Lee Patterson]

I just measured the input shaft on my -2. From the ZF mating surface (the little raised ring that runs around the inner surface of the flange) to the tip of the input shaft snout is exactly 4 and 7/8". Bob Wood knows his setup inside out. I would call him. He has already confirmed for me that the snout "just" enters the pilot bearing and does not run up on the input shaft any distance. Here is my bearing sitting on the end of the ZF input. Bob has stated that is further than it will run when installed. I hope this helps you.

 

[Pat]

I assume I’m measuring from the same spot you are and I got 4 3/16”?

 

[Pat]

Also when I tried installing just the trans and bellhousing with the bushing in the block I could see when the input shaft started into the bushing and I went in at least what you show in your picture (guessing roughly) by how far the bellhousing was from the block still. It’s almost like the bellhousing housing was cut too thin or need to add a spacer. I hope Bob reached out to me so I can verify the dimensions on these pieces so I can figure out what’s wrong.

 

[Lee Patterson]

No - I put a straight edge across the face of the ZF and measure from there out. No bellhousing on it.

 

[Pat]

Ok, thanks. I’ll take it off tomorrow and measure it to check.

 

[Lee Patterson]

My bellhousing measures 3 and 15/16" thick from mounting face to face.

 

[Pat]

That’s what mine is also. The plot thickens!!! Can you measure from where I did on the input shaft to see if you get 4 3/8”?

 

[Lee Patterson]

4 and 3/16”

 

[Pat]

Ok, well I started 2025 with the same problems as I left 2024 but what else is new. I’ve been digging around the forum and other sites trying to find answers to my problems. Also I’ve been unable to get in contact with Bob Wood, I’m not sure if my messages have been going through or if his server has been down. I was hoping he would jump in. One this site.

As to Lee stating the Bob told him the input shaft should just barely enter the pilot bushing, I can assure that is wrong. At least on mine and we seem to have the exact same measurements on shaft and bellhousing. Unless my crank sticks out of the back of the block further than stock???

Here’s my current situation. Bell housing was binding on the flywheel on the lower side (bottom side of the flywheel). I grinded that out with the high end being close to 1/4” to finally get good clearance. Assembled to whole thing again and still no good. Sad, so sad. Called it a night

Today I stripped it all down again. I left the pilot bushing in, put the bell housing on and put the ZF on. Doesn’t fit. Put the Borescope in there and still have a little room before the input shaft bottoms out on the splines, a little more than the gap I need to close so thats not it but saying the input shaft barely goes into the pilot bushing is way off. That thing goes all the way in!

So now I now I’m bottoming out on my crank. The widest part of the gap I can tell between the ZF and bellhousing is 0.1945. I’ll call it 0.20 for clearance sakes. From what I see I have two options
A: make a 0.20 spacer plate between either the ZF and bell housing or the bell housing and block (block side might interfere with guide pins though)
B: shave off 0.20 off the ZF input shaft. I assume it’s hardened steel and not sure how exactly I could safely do that.

So I’m looking for opinions!! I’ve measured the distance from the clutch fingers and the throw out bearing and they seem to be good although with the 0.20 spacer I may need to shim but I can worry about that when I get to it I guess. Hopefully I kept the shims!!!!

Does anyone know of anyone that makes a spacer plate for a ZF???

 

[Pat]

Also just thought it could be an imperfection or taper in the input shaft restricting the bushing at the bottom of the shaft. I’ll have to take it apart again and pull the bushing, check the bushing on the input shaft all the way for clearance, remove pilot bushing and reinstall just to rule out the bushing. Process of elimination and I’ll eventually get it.

 

[Mike Pass]

Make up some steel washers of the correct thickness or slightly larger and refit before you go to all the trouble of making a spacer. Glue them temporarily in place with epoxy for ease of assembly. If this sorts the issue you can them make a spacer plate or get it laser/waterjet cut.. Or shorten the shaft with an angle grinder with 1mm metal cutting disc covering everything carefully first and marking out carefully . Make the end of the shaft as neat and square as possible and chamfer the end of the shaft to ease entry into the crank bush.
Cheers
Mike

 

[Lee Patterson]

To clarify what Bob told me regarding the position of my pilot bearing on my ZF input shaft in the picture I posted herein, he said the bearing was sitting further on the shaft that it will be in the final installation. I probably had poorly stated what he said earlier. I have yet to do this so I can't offer anymore knowledge at this time.

Take the pilot bearing out and try it without it? and the ZF shaft is hitting the crank? Something else is wrong. I measured the distance you asked and it is 4 and 3/16". You wrote that yours measures 4 and 3/8". Is that correct? There should be no difference if your ZF is a -2.

 

[David Garton]

Pat, I have Bob's cell number. I am surprised that he has not replied. DM your contact and I will call you with his contact. David

 

[Julian]

The crank end position had crossed my mind previously, I had an engine builder screw up on thrust washers once, that was a very short lived engine.... You definitely don't want the ZF input shaft inducing any thrust on the crank.

Perhaps you could mate the bellhousing to the engine and mount the starter to see where it engages on the flywheel as a further data point? On that note a spacer between engine and bellhousing would alter the starter to flywheel engagement, but honestly this should be solvable without the need for spacers.

 

[Pat]

To clarify what Bob told me regarding the position of my pilot bearing on my ZF input shaft in the picture I posted herein, he said the bearing was sitting further on the shaft that it will be in the final installation. I probably had poorly stated what he said earlier. I have yet to do this so I can't offer anymore knowledge at this time.

Take the pilot bearing out and try it without it? and the ZF shaft is hitting the crank? Something else is wrong. I measured the distance you asked and it is 4 and 3/16". You wrote that yours measures 4 and 3/8". Is that correct? There should be no difference if your ZF is a -2.

Sorry typo on post 52. I got 4 3/16 as seen in post 47.