Towing with 4 speed versus 5 speed? (1 Viewer)

[Root Moose]

After spending too much time and money turning my XJ into an über overlanding rig I'm seriously thinking about finally getting into a UZJ100.

Want to avoid the touch screen NAV/MFD but am interested in the 5 speed transmission for the +1 mpg and potential easier towing.

Towing will be a ~5000 lb race car trailer, boat etc. Not right to the wall on the tow rating but potential is there.

Currently towing a Starcraft 11RT with the XJ and it is not enough truck even with full engine bolt ons - it hates the coastal mountains we've been encountering the last three weeks.

Any UZJ100 I bought would end up on 33-35" tires, headers and exhaust out to the tail pipe.

Is the 5 speed worth fixating on in this scenario?

I'm not terribly afraid of the factory NAV since there are places that can fix it if things break but I abhor factory NAV systems as a general rule (they all suck). I'd rather put in a two DIN android head unit and tune to my tastes.

Was there ever a LHD HZJ-105? That would be my dream to import...

I'd consider a 200 series but am not a fan of modern vehicles. I have a 2013 Audi A4 and while it a nice car the electronics and nannies drive me nuts.

Any input appreciated.

 

[hkeller]

I've had the 4 speed and the 5. I'd say the 5 speed is definitely worth it. The lower first gear helps greatly in initial acceleration. There is less RMP jump between gears. Really, it was a much more enjoyable vehicle to drive with the 5 speed.

 

[re_guderian]

I've got both and towed with both. 5 speed all the way. Don't worry about the nav screen until (if) it ever happens.

 

[APKhaos]

I'm 100% sure the 5 speed is better, but I've towed my close to 6000# race rig thousands of miles from Watkins Glen north to Daytona south with my '99 and its humble 4 speed. Its been fine.

 

[Root Moose]

Was the 2003 the only year where 5 speed and manual HVAC controls were possible? Just how rare is this combination?

I'm not 'afraid' of the MFD, just would prefer to have an integrated solution in the centre stack with modern/useful turn-by-turn and topographic navigation instead of having a tablet hanging off a RAM mount making the interior look hill-billy.

Adding exhaust doesn't more or less equalize the inequities due to more torks? Anyone here done that with acceptable/reasonable results?

 

[codertimt]

Since I completely understand not wanting to mess with the integrated '03+ Nav stuff, I will give you a theoretical argument for the 4 speed... Ratio info stolen form https://forum.ih8mud.com/threads/a343f-vs-a750f-transmission-gears.60863/

A343F "4-sp Auto" (Effective Ratio=Gear X Diff gear)
- 1st Gear 2.804 (12.06)
- 2nd Gear 1.531 (6.58)
- 3rd Gear 1.000 (4.3)
- 4th Gear 0.753 (3.24)
- Reverse 2.393 (10.29)
Diff Ratio 4.3

A750F "5-sp Auto" (Effective Ratio)
- 1st Gear 3.520 (14.43)
- 2nd Gear 2.042 (8.372)
- 3rd Gear 1.40 (5.74)
- 4th Gear 1.00 (4.1)
- 5th Gear 0.716 (2.936)
- Reverse Gear 3.244 (13.3)
Diff Ratio 4.1

In my very humble opinion, the 5 speed advantage is getting up to speed, with it's super low first and second gears. So obvious low range first gear crawl advantage and obvious getting up to speed advantage for towing. But once you've spent the extra few seconds to get up to speed, most of your time towing is going to be spent in 2/3 on the 4 speed and 3/4 on the 5 speed. In those gears, with the lower diff ratio, the 4 speed actually has the mechanical advantage. I'm sure there would be times when it would be nice to have that 2nd gear on the 5 speed to kick down to if you need to pass some slow traffic...and if you're pulling any real grades at altitude, I'm sure every little bit helps...I know my '01 felt like a fat pig at 10000'+ in CO...

But I say if you want control of your Nav/stereo, just go for it. If it's too much of a pig, throw in 4.88s...mileage be damned...but that's just MHO...

 

[Root Moose]

Good points on the ratios.

I compared the boxes using the grimmjeeper calculator (4-speed/4.3:1/315-70-17 vs 5-speed/4.56:1/315-70-17) and it is a wash at highway speeds in top gear. With a Mark's reduced transfer case gear set in the 4-speed truck that makes up for the crawl ratio difference almost tit-for-tat. Regearing the axles in the 5-speed truck vs t-case in the 4-speed truck is probably a wash for total costs to modify.

I see the extra gears in the five speed working for better acceleration but with more power added to the engine that'll probably be a wash if the 5-speed truck isn't warmed up.

I didn't realize the early UZJ100 and the Jeep XJ essentially use the same automatic transmission. I can deal with the acceleration I currently have, more would be nice but it's livable.

I dunno. I guess it depends on what machine I find to buy. I'm hoping either will be a lot better than what I have now.

 

[Root Moose]

Btw, what gear does the owners manual state to use for towing?

 

[hoser]

I compared the boxes using the grimmjeeper calculator (4-speed/4.3:1/315-70-17 vs 5-speed/4.56:1/315-70-17) and it is a wash at highway speeds in top gear.

I'm not aware of a 4.56 gearset available for the 100 (off the shelf). There might be a work-around though.

As far as to which transmission gear to tow in.... I've always been under the impression 1:1 is where you want to be for heavy loads. So that is 4th gear on the A750F.

 

[TeCKis300]

If it were just upsized tires or just towing, I'd say you could get away with the 4 speed. But considering that you'll be adding 33's or 35's AND towing, the 5 speed makes more sense to be an enjoyable vehicle under those conditions. Money spent modding the 4 speed for more power etc, could be applied up front for the newer 5 speed model.

And then you can always mod further after that. A cheap way for the 5 speed models to get additional gearing is to source the abundant 4.3 diff gear sets from the earlier model.

 

[Root Moose]

I thought I saw 4.56 gears at the Slee site but maybe I was reading in interlaced mode again.

There's so many ways to cook a truck build... If I keep the truck for the long term (owned the XJ for 12 years) it will likely get all the mods over five years or so regardless of which I start with.

So, we'll see. Just browsing the pictures of dashes at auto trader makes me angry though... So many beautiful trucks relegated to navigation obsolescence by the MFD (IMO).

I'm in Canada so I have the added wrinkle of finding the right LX or importing a TLC from the south. Not a big deal, may get something from the far south and keep the XJ for winter workhorse duties to save rust damage on the UZJ.