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Preparing a 1988 F150 for 600 ft-lbs of torque

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88F15088
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Posts: 182
Joined: Mon Sep 11, 2017 12:24 pm

Preparing a 1988 F150 for 600 ft-lbs of torque

Post #1 by 88F15088 » Sun Jun 16, 2019 7:25 pm

Me and Paul (pmuller9) have been discussing parts and potential power output for my turbo build and came to the conclusion that power output may be near the 600 ft-lb range. These trucks weren't made to handle that much power from the factory, so I am trying to figure out what I can do to beef it up. I have a Ford Performance limited slip carrier I will be installing in the 8.8" rear end, and plan to either upgrade or have a beefier driveshaft made at an offroad shop.

The current transmission is a ZF S5-42 that I am currently rebuilding, however, some research shows that it is only rated for 400ish ft-lbs of torque. My plan is to wait for it to fail, then swap a t-56 magnum rated at 700 ft-lbs.

Besides a stronger clutch, that's all I can think of right now. How will the rest of the suspension on this truck hold up to such frame-twisting power?

Phase3
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Posts: 84
Joined: Fri Aug 31, 2018 9:34 pm
Location: Pittsburgh pa

Re: Preparing a 1988 F150 for 600 ft-lbs of torque

Post #2 by Phase3 » Mon Jun 17, 2019 8:15 pm

Just noticed a few hours ago as i rolled around under my 96 half ton that it has broken another leaf spring. Second spring down on the passenger side now. The axle wrap is excessive due to the softer suspension. Any effort to control the axle wrap whether you try traction bars or a stouter stack of leafs would help id imagine.
Also ive sold slip yoke parts and transfer cases to 2 people so far that had the slip yoke bust its way out of the case. One 4.9 88 f250 and one 351w truck not sure if it was 150 or 250. The windor truck also broke the bell housing when the snout came out.
That being said, my truck still has the slip yoke. The one ton transfer case with bolt on flange is a nice piece, different rear shaft though.
1996 f150 turbo 4.9 OBD2 M5OD 4x4 12 lbs on 93
1997 f350 351w cclb

88F15088
Registered User
Posts: 182
Joined: Mon Sep 11, 2017 12:24 pm

Re: Preparing a 1988 F150 for 600 ft-lbs of torque

Post #3 by 88F15088 » Tue Jun 18, 2019 7:37 pm

Can you go into a little detail on your build (maybe I missed a build thread)? I see in your signature you are running 12lbs boost.

On the stock motor, I get absolutely violent wheel hop when I try to bark the tires.

My truck is 2 wheel drive, so no transfer case. I haven't found much info on guys blowing up the S5-42s. The last thing I want is a driveshaft to fail. I have seen the devastating damage caused by driveshaft failure as it flops around, destroying everything in its path.

Phase3
Registered User
Posts: 84
Joined: Fri Aug 31, 2018 9:34 pm
Location: Pittsburgh pa

Re: Preparing a 1988 F150 for 600 ft-lbs of torque

Post #4 by Phase3 » Tue Jun 18, 2019 8:37 pm

Yes the wheel hop is very noticeable. If the tires spin just from throttle all is fine but any clutch action and it starts carrying on in the back. Ill attach the post with dyno sheets that i put up awhile back. Im still daily driving the truck without any changes from then.

viewtopic.php?f=2&t=78999

Do you know what gear ratio your 1st is in the zf? The older diesel 1st of just over 4 to 1 looks to be a pretty useful ratio. I have a sf 47 from a 97 351w and 1st is 5.79 to 1 i believe and it is hard to use that in everyday driving.
1996 f150 turbo 4.9 OBD2 M5OD 4x4 12 lbs on 93
1997 f350 351w cclb

88F15088
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Posts: 182
Joined: Mon Sep 11, 2017 12:24 pm

Re: Preparing a 1988 F150 for 600 ft-lbs of torque

Post #5 by 88F15088 » Tue Jun 18, 2019 10:20 pm

Thanks, I will read through that thread.

First is 5.72:1 http://www.dieselhub.com/trans/zf-5-speed.html
Gas engines were only given the "wide ratio" version.

Very useful for towing, but I don't tow much so I start in 2nd.

Twinturbor
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Posts: 30
Joined: Sun Apr 24, 2016 3:20 pm

Re: Preparing a 1988 F150 for 600 ft-lbs of torque

Post #6 by Twinturbor » Fri Jun 21, 2019 11:37 pm

I'm running 18psi on my 4.9 with a ported head. I have the m5od in mine with a ceramic clutch. I'm over the 700 tq range and my tranny is holding up fine with the only mod being switching to 5-20 motor oil instead of atf

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