BJ 74 re-gearing

[herco]

I fellows

I would apprecciate your advice regarding "re-gearing" my TLC BJ74, 13 BT turbo diesel, AT, year1989, floating axles.

I ve just instaled 35" tires and the performance with the current 4.11 gear became rather slow/tortoise, so:

What would an enough gear in your experience?: 4.56, 4.88 or even 5.13??

what d be a reliable gear brand?...I guess american ones would be great..?

thanks and enjoy

alvaro

 

[crushers]

factory 4:56
i have yet to find a slow 13BT, maybe do a compression test... boost test...

 

[Hulsty]

How do you find low range? If low range is good for your IMO I would up the hp of the 13BT to make use of the gearing better.

I have 2.29 low range through a H55F and 4.11 diffs with 35'' tyres and find it great in low range and high range.

Mine is tweaked abit though, 19-20psi boost, 3'' exhaust and dump pipe, intercooler and adjusted fuel pump, even with the 35'' tyres on the highway it goes better than when I got it on 31'' tyres. Still gets around 600km to 75L too.


I prefer this to the shorter more factory gearing which has you forever changing gears.

 

[herco]

Thank buddys

I have "improved" the performance of my 13BT....clearly not as much as you Hulsty:I reach 0.6-0.8 bars (whahts normal range ?) that barely permits 100 km/hr in highway.....and for speeding in a sand/mud hill...it became an issue.....thats why instead of tweaking the engine I would try goin to 4.56 or 4.88.....I have to think about...

 

[crushers]

i have owned a few 13BT engines and even with 35" boots they would do 100 easily in stock condition. have you done a compression test?
there are a few guys running these with 38" meats on them and cruising down the highway with no issues.

you have more to concern yourself with than gearing.

 

[herco]

thanks crushers.....actually I have pending a compression/fuel pump test.....I'll check them

 

[Radd Cruisers]

The automatics are really high geared and with 35s it will be a slug.

My auto with 255s is fairly sluggish once it hits 4th gear and lock up.

I would suggest some 8% under-drive Marks Gears as a great first step, then re-gear if that's not enough. 1.08 high range & 3.05 low range will make a pretty big difference to things.

If you need lower gears after that, then get some 4.56s.


~John

 

[Malahki]

I am running 4.56's with a manual transmision and 35's. Puts it back very close to stock gearing with the speedometer registering only about 2-3% off. Top speed at 3000RPM is somewhere just under 125km/h. Power feels much better on the hills then when I was running the stock 4.11's

 

[herco]

Sorry fellows if I insist but in order to get the closest factory gear relation with my 35" tires, in my BJ 74, 1989, please I need the following information:


gearbox relation? (I assume my TLC has a A440)
1st gear:
2nd gear:
3rd gear:
4th:
No Over drive

Transfer relation?: (I assume my TLC has a H55)

Hi :
Lo :

Original tire size?:

Thak you again...any information will be highly apprecciated!!!!!

Regards

Herco

 

[Radd Cruisers]

TLC FAQ - 8.1 Transmission & transfer Case Ratios (All :1)

4th gear in the A440 is a tall over drive.

I would really suggest an Extreme Valve body, synthetic ATF and a big trans cooler with a temp gauge. The valve body is very worthwhile for pulling third gear on long hills while locked up.

And that's pretty much all you need to know...

except that the torque converter has a ~2:1 stall.



~John

 

[Radd Cruisers]

Sorry fellows if I insist but in order to get the closest factory gear relation with my 35" tires, in my BJ 74, 1989, please I need the following information:

Transfer relation?: (I assume my TLC has a H55)

Hi : 1:1
Lo : 2.296

Original tire size?: small-ish about 30" diameter depending on the market and trim level.

and now I need to add 5 characters.


~John

 

[JuanJ]

Hello,

You may want to check the manufacturer's plate on your truck. It details your engine, transmission and axles.

The H55 is a transmission, not a transfer.

I attached is some information I have at hand on the A440 and the transfer. I do not have ratios at hand right now.

Hope this helps.







Juan

 

[herco]

Thanks so much John/Juan!!!!.....once I get a decission about "the issue" I will back to you to tell what I have installed.....

Herco