Which Flywheel do I have?
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4wd Low
Joined: Mar 2024
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Which Flywheel do I have?
Hi everyone, I have a 1987 F250 "Custom" 4x4 (Light duty, no full float rear < 8500 GVWR). I have a NP435 4 speed transmission and a 4.9L cylinder.
I bought a ZF5 small block bell housing 4x4 transmission and the all the stuff that came with it.
I spent a couple hours on various parts sites cross referencing the parts between a 1987 F250 with the 4speed and the parts for the F250 with ZF5 from 1993.
From cross referencing part numbers it looks like if I have the 164 tooth flywheel the swap is straight forward. Starter is different and (of course) the slave cylinder and master kit is different.
I have read on other posts about drive shafts, etc. I have no questions about that stuff.
My question: is there some way to know if my flywheel is 157 tooth vs 164, besides a paint pen and a ratchet? If I have the light duty 4.9L F250, do I have the 157 tooth?
Thanks, in advance.
I bought a ZF5 small block bell housing 4x4 transmission and the all the stuff that came with it.
I spent a couple hours on various parts sites cross referencing the parts between a 1987 F250 with the 4speed and the parts for the F250 with ZF5 from 1993.
From cross referencing part numbers it looks like if I have the 164 tooth flywheel the swap is straight forward. Starter is different and (of course) the slave cylinder and master kit is different.
I have read on other posts about drive shafts, etc. I have no questions about that stuff.
My question: is there some way to know if my flywheel is 157 tooth vs 164, besides a paint pen and a ratchet? If I have the light duty 4.9L F250, do I have the 157 tooth?
Thanks, in advance.
Last edited by Joosh; Mar 30, 2024 at 04:59 PM.
Hotshot
Joined: Jul 2020
Posts: 10,551
Likes: 2,669
From: Near Salt Lake City
Call Ford parts and check the OEM tooth count
Small block VS big block bellhousing pattern is the difference between the flywheels
You should need the 164 tooth flywheel ring gear for your truck iMO
Simply get the flywheel from the donor truck?
They put those ZFs behind 6 cylinders, maybe find one and take everything?
Small block VS big block bellhousing pattern is the difference between the flywheels
You should need the 164 tooth flywheel ring gear for your truck iMO
Simply get the flywheel from the donor truck?
They put those ZFs behind 6 cylinders, maybe find one and take everything?
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4wd Low
Joined: Mar 2024
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When I check auto part sites I see 2 fly wheels with what I assume are different diameters. I had trouble confirming the diameters of the 2 different fly wheels. My understanding is that the 10 spline input shaft on the ZF5 will work fine with either flywheel’s respective clutch and pilot bearing. My concern is the zf5 starter location not engaging the 157 tooth flywheel. I read that the ZF came with the 164 tooth.
I also found matching part numbers for flywheels between 1987 and 1993, but I found another flywheel was available for that engine in 1987, according to various parts sites.
Thanks for the help.
I also found matching part numbers for flywheels between 1987 and 1993, but I found another flywheel was available for that engine in 1987, according to various parts sites.
Thanks for the help.
Thread Starter
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4wd Low
Joined: Mar 2024
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I bought one from rock and everything else, yesterday.
I will probably do the rear main while I’m in there, but I originally posted hoping I could stab the other transmission in with no other work.
It will probably take me a couple of months to get around to install it, but I’ll make a note of which flywheel I have once I know.
i have the bone stock version of the 6 cylinder with 4x4 why I figured it would be a smaller fly wheel if one was offered.
While I’m here. I bought the drive shafts out of the donor truck and the transmission cross member. (They were delivered).
The rear drive shaft I received is a 2 part shaft. Was that on all zf5 trucks? Or, was that only for long bed extended or crew cab trucks? Mine is a 7.x FT bed with a single cab. I think the front shaft should be ok, but I’m wondering if there is some chart or something that shows which shafts go to that body lengths?
I will probably do the rear main while I’m in there, but I originally posted hoping I could stab the other transmission in with no other work.
It will probably take me a couple of months to get around to install it, but I’ll make a note of which flywheel I have once I know.
i have the bone stock version of the 6 cylinder with 4x4 why I figured it would be a smaller fly wheel if one was offered.
While I’m here. I bought the drive shafts out of the donor truck and the transmission cross member. (They were delivered).
The rear drive shaft I received is a 2 part shaft. Was that on all zf5 trucks? Or, was that only for long bed extended or crew cab trucks? Mine is a 7.x FT bed with a single cab. I think the front shaft should be ok, but I’m wondering if there is some chart or something that shows which shafts go to that body lengths?
Hotshot
Joined: Jun 2015
Posts: 12,879
Likes: 2,446
You could have swapped out the transmissions without changing the clutch and flywheel but why wouldn’t you replace the clutch unless you had replaced it recently?
No. A two piece rear driveshaft was not on all ZF trucks.
No. A two piece rear driveshaft was not on all ZF trucks.
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4wd Low
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I figured. So what truck gets the 157 tooth flywheel? They list it as a possibility for the 4.9L on the parts sites, what gives?
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4wd Low
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Update
All. I have installed the ZF and BW t-case in the truck. Even with the cross member from the donor truck, had to move the cross member back to a hole that was already in the frame rails that is about an inch toward the rear. Drive shaft is about 3.5”-4” shorter. All this is coming together but the master cylinder from 1993 doesn’t have the same length of push rod as the 1987 master. My question: can I simply use a 1987 master cylinder with the internal slave of the 1993 ZF-5? Or will I blow out the slave due to different displacement of fluid? I don’t want to have to drop the trans for a replacement if I get this wrong. I checked the forums and haven’t seen an answer to this and no one mentioned an issue with this. Thoughts?
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4wd Low
Joined: Mar 2024
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Answering my own questions…. Went to parts store and looked at the master cylinder for the 87 F250 with 4speed. The push rod is longer and adjustable. The hard line exits out the rear instead of the bottom, like the 93 version which matches the zf-5. Looks like I could pop that push rod into the master that matches the ZF-5. Too bad I already inserted the push rod into the newer master cylinder and I can’t get it out. The bore of the two master cylinders looks to be the same. Trying to avoid a custom clutch line. Will report back.
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4wd Low
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I took the push rod from the 1987 clutch master clone and used it in the clutch master for a zf-5. It worked well. Been driving it for months now. Had original rear drive shaft shortened and used the front shaft from the donor truck. So glad I swapped from 4 speed to 5.
Laughing Gas
Joined: Feb 2016
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Basically zero chance OP has one. It would probably take some ghetto-*** modification to even make a 157 engage the starter properly.
Edit: should have read the whole ****ing thread first.
Cargo Master
Joined: Mar 2003
Posts: 2,333
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it comes down to an 11" clutch or a 10" clutch.
Ford cars were the only ones to get the 10" clutch (157 tooth) EXCEPT some 1966 V8 Broncos came with a 10" clutch and Ford discontinued that in 1967 (probably not suitable for a heavier vehicle).
Ford cars were the only ones to get the 10" clutch (157 tooth) EXCEPT some 1966 V8 Broncos came with a 10" clutch and Ford discontinued that in 1967 (probably not suitable for a heavier vehicle).
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