Rembrant Posted March 22, 2021 Share Posted March 22, 2021 Hello again gents, Not really a Bullnose question, but the same information should apply regardless. The 1995 F150 chassis/driveline under my 1980 has a BW1356 transfer case? I need to swap in (I assume) a 1988-1991 BW1356 transfer case with the speedo drive in the tail shaft. They're relatively easy to find here...I know a couple guys that have at least a couple each. So the question is...by the time the late 80's rolled around...and the F150's all had 8.8 rear diffs, they were almost always 3.08 or 3.55 geared. Would the transfer case use the same speedometer drive gear for each diff option (and just change the cable's driven gear for the different ratios)? Or would there be a different drive gear in each situation? The reason I ask is that I was reading about the M5OD trannies, and they part number or engineering number on the side of the trans refers to a specific rear diff gearing. The one in my 1984 indicates that it was designed for use with 2.73-3.08 differentials. I assumed that only meant that this is what the speedo drive gear was set-up for. Any comments from the experts? If I'm going to pick up a used transfer case, I'm just curious if I should look for one from a 3.55 geared truck, or does it even matter? Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 22, 2021 Share Posted March 22, 2021 Cory - The answer is yes, there was a difference, as shown below. But the break is in question as this says a 3.55 ratio could have either a 8 or 7-toothed gear. Also, note that it is for a 1345, not a 1356. Oddly enough, the MPC doesn't list a 1356. Nor does it have a similar table for 1989. But, you can still use the same driven gears. You just may run out of available gears. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 23, 2021 Share Posted March 23, 2021 Cory, With the 1356 you can change driving gears just removing the output shaft housing. There's a spacer clip behind the gear. Remove that, push the gear forward and remove the retainer ball from its hole in the shaft. (a magnet can help) Slip the gear off the shaft. Edit: they do not use the same metal sleeved gear as the 1345. My truck uses a slip yoke and a yellow gear for 4.10:1. If your truck has a fixed yoke then you're going to have to remove the nut from the output shaft, but it doesn't require splitting the case in either case.... I might suggest that if you do go back with a 1356, instead of a 1345, that you split the case and do the oil pump finger mod so it cannot wear through the magnesium webbing and spin with the shaft. There's no gasket or anything to buy, just a bead of RTV on the case flange. You will need a stout pair of snap ring pliers! I ran into that carnage last summer, and I couldn't find a replacement. Link to comment Share on other sites More sharing options...
Rembrant Posted March 23, 2021 Author Share Posted March 23, 2021 Cory, With the 1356 you can change driving gears just removing the output shaft housing. There's a spacer clip behind the gear. Remove that, push the gear forward and remove the retainer ball from its hole in the shaft. (a magnet can help) Slip the gear off the shaft. Edit: they do not use the same metal sleeved gear as the 1345. My truck uses a slip yoke and a yellow gear for 4.10:1. If your truck has a fixed yoke then you're going to have to remove the nut from the output shaft, but it doesn't require splitting the case in either case.... I might suggest that if you do go back with a 1356, instead of a 1345, that you split the case and do the oil pump finger mod so it cannot wear through the magnesium webbing and spin with the shaft. There's no gasket or anything to buy, just a bead of RTV on the case flange. You will need a stout pair of snap ring pliers! I ran into that carnage last summer, and I couldn't find a replacement. Awesome, thanks Jim. I didn't know the drive gear was that easy to change out...I'm not as concerned now. The t-case in the truck has a slip-yoke. The front mounting flange of the t-case is corroded badly (there's actually a hole in it...lol) so I need to swap it out for that reason anyway, but my main concern is to get the speedo drive. The t-case works fine...I tried it out on the weekend. It surprised me a bit at just how short the throw of the shifter was...I was having trouble finding the t-case gears until I realized that all 4 positions were in about an inch of lever movement. It's all good, I just want one that fits right back in the same place and utilizes the same shifter, etc. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 23, 2021 Share Posted March 23, 2021 Awesome, thanks Jim. I didn't know the drive gear was that easy to change out...I'm not as concerned now. The t-case in the truck has a slip-yoke. The front mounting flange of the t-case is corroded badly (there's actually a hole in it...lol) so I need to swap it out for that reason anyway, but my main concern is to get the speedo drive. The t-case works fine...I tried it out on the weekend. It surprised me a bit at just how short the throw of the shifter was...I was having trouble finding the t-case gears until I realized that all 4 positions were in about an inch of lever movement. It's all good, I just want one that fits right back in the same place and utilizes the same shifter, etc. It's too bad the magnesium has a hole in it. You could have just changed the tailshaft housing for one with a speedo cable hole(4 bolts!) If the '95 you have now has the ball recess in the output shaft. I would have to look at the part breakouts to know if BW did away with the ball divot on later production. Link to comment Share on other sites More sharing options...
Rembrant Posted March 23, 2021 Author Share Posted March 23, 2021 It's too bad the magnesium has a hole in it. It was my fault...I hit it with the needle scaler and poked a hole in it...not realizing it was corroded as badly as it was. I can live without a speedo, but I do want it to work properly. I'll be getting antique plates for this thing, so that will require a test drive by the mechanic...so I'll need it working regardless. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 23, 2021 Share Posted March 23, 2021 It's too bad the magnesium has a hole in it. It was my fault...I hit it with the needle scaler and poked a hole in it...not realizing it was corroded as badly as it was. I can live without a speedo, but I do want it to work properly. I'll be getting antique plates for this thing, so that will require a test drive by the mechanic...so I'll need it working regardless. If it was that corroded its probably for the best you found out when you did. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 23, 2021 Share Posted March 23, 2021 If it was that corroded its probably for the best you found out when you did. Yes, good you found it. And changing the speedo drive gear on a 1345 is easy as well. Just remember to tighten the output shaft nut. Link to comment Share on other sites More sharing options...
Rembrant Posted March 24, 2021 Author Share Posted March 24, 2021 Yes, good you found it. And changing the speedo drive gear on a 1345 is easy as well. Just remember to tighten the output shaft nut. Do Broncos usually have the same transfer cases as the pickups? Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 24, 2021 Share Posted March 24, 2021 Do Broncos usually have the same transfer cases as the pickups? It varies. From our page at Documentation/Driveline/Transfer Cases and the Applications tab: Link to comment Share on other sites More sharing options...
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