Need the flange to flange (front) and the e. brake drum to flange measurements for a '71 (or similar setup) with F, 3 speed/T-case. Trying to figure out how much adjustment was factored in for a fully collapsed driveshaft to an in-place driveshaft. I am in the process of upgrading to a 3B/5 speed and need to get my new driveshafts cut down. I wish I had measured for this when I still had my F/3speed installed but it is long gone...
Need 1971 Driveshaft Measurements
- Thread starter Recon1504
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Living in the Past
SILVER Star
Did you place the engine exactly the same location as in a BJ42? Otherwise referencing the old three speed won't help. The flat surface to mount the transmission on the bellhousing is in the same location on the HJ, FJ and BJ. If you have a lift that will change things. I have driveshafts from BJ42 that had a five speed coming but still in Australia. Up until a few days ago could have gotten you measurements. Now probably in a container waiting to ship. Not sure when I will actually have possession of them to measure. Not changing engines but figure going original driveshafts was the easiest way to add a five speed. Takes all the guess work out.
- Thread starter
- #3
I used the .pdf for the BJ frame that has factory measurements for the engine mount locations. They were located as close to the factory specs as possible.
I did find in another thread today where it was stated that the fully collapsed length of the driveshaft should be approx. 1" shorter than the flange to flange measurement. Can anyone confirm this?
I did find in another thread today where it was stated that the fully collapsed length of the driveshaft should be approx. 1" shorter than the flange to flange measurement. Can anyone confirm this?
I have a 71 with 3 speed and f155. I can measure for you. I would prefer you make a diagram or take a photo indicating exactly where you want me to measure. That way we are sure I am getting it right. Maybe a diagram from the FSM? Oh, I do have about a 2 inch spring/shackle lift on it, if that makes any diff.
thebigredrocker
SILVER Star
Hopefully someone will double check my measurements. These are off my 71. Pretty sure it's all original.
thebigredrocker
SILVER Star
I think this is the collapsed measurement you were asking about
It seems you're going about this the hard way.
Assuming you've got stock suspension and driveshafts, as apposed to shackle reversed, 1" compression will be the magic number. The old timer hot rod guy who built my shafts in 1996 recommend this amount and 21 years later, it's still going strong. I've had no vibration, binding, or other problems... regardless of how much I've punished them with a healthy SBC.
I'm not abusive to my rig, but it has been used both on and off road. You're safe with 1" of compression at a rest position... that should give you about 3/4 of your splines engaged.
Assuming you've got stock suspension and driveshafts, as apposed to shackle reversed, 1" compression will be the magic number. The old timer hot rod guy who built my shafts in 1996 recommend this amount and 21 years later, it's still going strong. I've had no vibration, binding, or other problems... regardless of how much I've punished them with a healthy SBC.
I'm not abusive to my rig, but it has been used both on and off road. You're safe with 1" of compression at a rest position... that should give you about 3/4 of your splines engaged.
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- #12
Those measurements are great. They, along with bikersmurf's post confirmed the 1" +/- difference between collapsed length and installed length. Driveshafts heading to the transmission shop this afternoon to get cut down and balanced...
Living in the Past
SILVER Star
I have a 70 with the stock setup. But pretty springs are still original. Just like a lift effects the measurements, flat springs do too. Going by my pictures of the BJ42/H55F driveshafts I would not put much lift. Front could probably add 10" and be fine. My original plan was use 82 FJ40 with a four speed driveshafts add and deduct the about of the section the overdrive gear is in. Curious how your doing off three speed measurements? If I did use a three speed as a base it would be off the driveshafts main tube. The measurements from flange to flange with change from vehicle depending on arch in the springs.
I didn't see the exact plan in your post, but what shafts are you having modified? Did you already pick up some used 60 series takeoffs, or are you doing some splitcase flange voodoo and using the 3-speed stuff? I'd go 60/62 series if you have the opportunity. Means you'll need to get some used 62 differentials but all in, a stronger setup.
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- #16
The reason I was asking for stock 3 speed measurements, I was trying to establish a correlation between installed length versus fully collapsed length. Based on a couple of responses and a thread that I found while searching, I am using a 1" deduct from installed length to fully collapsed length. Since I know what my installed length is from actual measurements, I can give the shop an actual measurement for the fully collapsed length. Before I dropped them off, I made sure both shafts were fully collapsed.
Living in the Past
SILVER Star
Personally don't like how your rear driveline only has 15/16" until it bottoms out. When I inspect my drivelines there is always at least a inch left past the wear pattern. I would be sure your bump stop pads are there and probably re-arch the springs.
As for size of the drivelines I wouldn't reinvent the wheel. Since Toyota produced a short wheel base cruiser with a 3B and H55F five speed I would have drivelines made to match the ones they used. Curious to check mine once I get them if the difference between the 8/80 and later FJ40 drivelines with a four speed is the length of the extra length of five speed transmission.
thebigredrocker
SILVER Star
I scraped old grease off my rear for the picture of the 15/16" measurement. It had years of old grease buildup. I think that's what you are concerned about. I do still have old grease on the backside I can use to determine collapse. Once I get my seats installed perhaps I'll hammer some big bumps a report back. It does have factory bump stops.
Living in the Past
SILVER Star
Okay that makes sense. In the picture by clean area it looked like when you bottomed out you right up against end. I should crawl under my 70 and check the distance to the end if the shaft.
