The 5.29 Mega Thread!!

What thing?

 

I read through the first 15ish pages of this thread and didn't see anything about it. I installed the 5.29s and when I drive down to St. George UT on I-15 where the speed limit is 80 is the only time I have had a problem with it. The truck governs out at about 82 mph, and you have to let your speed dip below 80 for the truck to give you any power back. I have contacted OV tune and they said they plan on making a specific tune for the 5.29s sometime in the near-ish future that would fix this issue. Is there a cheaper way to deactivate or re-calibrate the governor that anyone knows of?

 

That's odd, I've gone over 80 before without issue. I think the truck governed out at 95 if I recall.

Are you on stock tires?

 

If you’re accelerating pretty fast you can get to 90. If you accelerate slowly the power cuts back at about 82.

I’m running 33s so my actual speed is 4-5 mph faster than what my speedo reads.

Just sucks when you need to go just a couple mph faster to pass someone in the shit show that is southbound I-15.

 

Hypertec speedo calibrator will allow you to recalibrate for change in tire size
http://www.hypertech-inc.com/vehicle-results.aspx?AAIAID=469405

 

Sounds like I need 35s or 37s!!

 

I read earlier in this thread that the speedo runs off of your ABS sensor or something like that.

Which makes sense because I double checked my speed with a GPS and the difference didn’t change before and after my gears. It’s still a few mph fast because of the 7.18% difference in tire size from factory.

I also got a speeding ticket doing 86mph a couple weeks ago... which confirms this.

 

Well if it reads at the wheel, then yeah, the gear change shouldn't affect it

 

I retract my earlier statements, I called Nitro gear, they confirmed the speedo is reading at the ABS on the wheel, and you only need to account for tire size changes. I will delete my earlier comments to keep from confusing anyone.

 

I think the ECU may make some speed assumptions via gear and RPM as well. Mat was talking about it in the Ovtune thread. I think he stated that the ecu governs speed at 105mph. Which should be about 2600 RPM stock gear and tire size (auto 6th gear). 2600RPM should be 82.5 Mph on “33” and 5.29’s (auto 6th gear). Seems to match @three zero seven observations above.

It would be interesting to know if the hyper tech actually changes the ecu behavior. Mat is creating gear calibrated tunes but it’s currently not clear (doubtful) this will change what’s displayed on the speedo.

This leads me to believe the ecu is running off of internal tables not the speedo signal. If that’s the case hypertech will not be a solution for the governor.

@OVTune prob the only one that knows unless someone with a hypertech, 4.88’s and “33’s” can do >90. For science... on a closed course.

 

This is an interesting discussion. I don't really have a stake in it since my new tires have a max speed of 65 but I am curious to what is going on in the ECU

 

I can do some radar testing when I am off shift regarding speeds at different gear sizes.

1, speedo is read off the ABS and is independent of the gears, so don't recalibrate your hypertech if you get different gears, only different tire sizes.

2, stock gears + 33s can do 89 confirmed via radar.

 

3.9’s plus 33’s @2600rpm (6th auto) is ~111mph. Please don’t!

 

I don't know what to tell you other than I know it goes 89 with that setup. Not sure what the RPMs were but your math seems incorrect.

 

245’s 16 inch rim bounced off speed limited at 114 mph auto trans 3.91 gears...

 

I have 4.88’s, 35’s, OVTune, and hyper tech and I do 90-95 all the time without a problem.

 

Interesting! 2600 rpm with 4.88 and 35’s 6th AT would be 94MPH.

If MT share the same 105MPH limiter it would happen at ~3500rpm on stock tires and gearing. Does the ECU know what gear you’re in on a MT?

So @Trident904 theoretically you should hit the limiter at 103.4. But don’t please!

 

At 95 I’m at 3300 RPM in 6th. At 70 I’m at 2500.

I’ve hit 105 but being on 35s and heavy, the truck didn’t like it too much.

 

Kind of curious too,I have 3 weeks until my appointment and I'm still just trying to decide if I'm making the right choice. I drive a short highway drive most days of the week, but here in the deep mountains of Tn you'd be lucky to move a mile without multiple up and downs. I have no doubt the gears are needed as its almost unenjoyable to drive anymore, its just the ratio choice I am stuck on.

 

I got mine I just haven't put them in yet. Probably going to wait till I find someone who wants these 4.30s that are in my axles to eat up the cost. They fixed a lot of problems for me but just not enough uhmp to get up the mountains and the grapevine in Cali.