35 inch and trans zf8

[Dan1419]

Hi, I have a jlu sahara and I installed 35 inches and the 8 doesn't fit I know I'll have to change my ratio. My question is what will it wear out my transmission? The question is for those who drive like that right now. Thanks

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[jludave]

Hi, I have a jlu sahara and I installed 35 inches and the 8 doesn't fit I know I'll have to change my ratio. My question is what will it wear out my transmission?

I assume you mean you aren't seeing 8th gear?

Have you done anything (Tazer, JSCAN, etc.) to update the vehicle's tire size? That's the first thing you should do after putting on larger tires.

 

[TheRaven]

Yeah you need to update the computer so it knows the correct tire size, or your shifting will be all out of whack. Also, what tires did you put on?

I'm running 35's on my 80th (essentially a Sahara) and I still see 8th gear regularly...but I did update the tire size in the computer and I also made sure I didn't buy really heavy tires. That makes a big difference.

 

[tomk62]

I'm running 35's on my 80th (essentially a Sahara) and I still see 8th gear regularly...but I did update the tire size in the computer and I also made sure I didn't buy really heavy tires. That makes a big difference.

Same here.

 

[Dan1419]

I assume you mean you aren't seeing 8th gear?

Have you done anything (Tazer, JSCAN, etc.) to update the vehicle's tire size? That's the first thing you should do after putting on larger tires.

Yes, I adjusted the tire size with jscan

 

[Dan1419]

Yeah you need to update the computer so it knows the correct tire size, or your shifting will be all out of whack. Also, what tires did you put on?

I'm running 35's on my 80th (essentially a Sahara) and I still see 8th gear regularly...but I did update the tire size in the computer and I also made sure I didn't buy really heavy tires. That makes a big difference.

Yes i update the cumputer with jscan and my tire is nokian rockproof

 

[jludave]

Yes, I adjusted the tire size with jscan

So then please explain what the issue is. Are you asking if you need to re-gear?

 

[Dan1419]

So then please explain what the issue is. Are you asking if you need to re-gear?

I wonder if it will break my transmission if I only drive with 7 speeds?

 

[jludave]

I wonder if it will break my transmission if I only drive with 7 speeds?

Short answer, no.

But, if you set the tire size correctly you should be able to get 8th gear.

If the tire size is correct and you struggle to see 8th, then you should consider a re-gear.

 

[Dan1419]

Short answer, no.

But, if you set the tire size correctly you should be able to get 8th gear.

I will change the ratio of my differential more during next winter but I was wondering if I can drive my jeep without breaking my transmission this summer even if the 8-speed does not embark? Is it clearer?

 

[jludave]

I was wondering if I can drive my jeep without breaking my transmission this summer even if the 8-speed does not embark?

I just answered no in my post above.

 

[TheRaven]

Yes i update the cumputer with jscan and my tire is nokian rockproof

Yeah those are heavy...you may very well see 8th gear a lot less, especially if you drive aggressively. You don't need 8th gear for anything but fuel mileage, so it's only really a problem if you decide it's a problem.

 

[Stuckinthesand]

In essence 7th and 8th gears are overdrive gears. Do you need to regear? No. I have heavy 35's and wheels on my 19 sport s and I wheel regularly as well as it being my daily driver. I still see 8th if I stay below 72 mph. Anything above that it will stay in 7th. You aren't going to gain anything significant back in terms of gas mileage. I just did a trans fluid change on mine about 12k miles ago and the fluid looked good and nothing out of the ordinary was on the magnets. Keep up on the regular maintenance and you'll be fine.

 

[Oncorhynchus]

My Sahara with the factory 3.45 gear ratio and 35x12.5R17 (110 lbs wheel +tire) and Jscan, only reaches 8th gear on flat highways. Have driven 34k miles like that and have seen no issues yet. Admittedly you may be worrying about even longer term wear issues than my 34k miles of history so take this one data point for what it’s worth.

 

[Dan1419]

I just answered no in my post above.

Oups thank you

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