I recently re-geared my 85 automatic 4Runner to Nitro 5.29s (from the stock 4.30) and at the same time installed new RCV axles up front. The re-gearing was professionally done but I put the third members back together and did everything else. The 4Runner runs well and overall I am pleased but there is a lot of heat build-up around my feet when I drive it. It feels like it is coming from the transmission area. It's so hot that I am thinking of getting a fire extinguisher in case the thing starts flaming. I am going to check the tranny fluid level just to make sure it isn't too full which might cause the overheating but I am thinking the increase in revolutions as a result of the re-gearing is the culprit. I am only running 33 inch tires as well. I don't drive over 70 mph and maybe I should tone it down to under 65mph on the highways but has anyone else experienced the same thing after a re-gear? Is this normal?

Thanks,
JARED

 

Get one of those digital thermometer guns, shoot it cold and then shoot it hot.

 

thanks for the suggestion. What temp should I be concerned with? Also, i assume you mean I should shoot the gun at the transmission directly and not the floor board?

 

is the heat shield above the exhaust still in place?
when you say gears professionally set up but you put the 3rds back together you mean you installed the thirds correct?
5.29's and 33's will make your RPM's higher therefore generating more heat from the transmission. I am running 5.29's w/35's and an A340h
definitely check your fluid levels.

 

Thanks dropzone. Yes, both the manifold and exhaust heat shields are still in place. I removed the third members and took them in to a shop to have the gears installed and once completed, I reinstalled the third members. I did a ton more work like replaced rear/front axle seals while they were out but the gears themselves seem to be installed fine. I just checked my ATF fluid and the level is correct and the color light pink - still has the sweet smell. I checked my records and the ATF was replaced around 3 years ago which equates to around 7,000 miles. This is no longer my daily driver. For good measure, over the weekend I also drained/refilled the transfer case which also takes ATF. For both tranny and transfer I am using dextron II Toyota ATF.

 

It should not be getting that hot but 5:29s are for bigger tires. You plan on upgrading to 35s later or? Have you looked at installing an aftermarket transmission cooler. Those little tru-cool units help a ton in the diesel world. I know I installed a larger transmission cooler from a 6.0l diesel in my 7.3l a solid 25+ degree drop in temp empty and towing but I read it was a super common upgrade for the 7.3l and wow! the oem trans cooler was the same size as some gasser trucks I have. Its only a bandaid but cooler atf last longer so give it a shot and consider slowing down as I go around 55-65 max in my 84 with 33s but im not running the proper gearing and running a 5spd.

 

Thanks Jloffermann. I considered 4.88s when I re-geared but most sources (including the installer) recommended 5.29s with 33 inch tires since my 4Runner is an automatic. I could go with slightly larger tires but then I would have to think about cross-over steering and I'm not ready to make that leap yet. I'll look into a larger cooler...that probably would help. Thanks

 

5.29s with 35s and an auto for sure.

4.88s and 35s for a manual. 5.29s for 37+

 

Well I guess I will live with it as I have no plans to upgrade to 35s anytime soon. Change the ATF more frequently in order to avoid damage and drive slower.

 

Look into the small aftermarket transmission coolers. Usually cheap and very effective. Had them installed on some of my wifes previous vehicles to haul a little 4x8 trailer for her hobby and well worth the $150 for parts and couple hours of my time. Have you checked your speedo with a simple phone/map GPS?
larger tires mean you are traveling faster and farther than the speedo.odometer tracks unless you find a way to re-program or change it. I just did the math to get a rough calculation for my speed and dont use it all too often unless im going into an area I know liked to ticket etc.

 

I'll look into a larger transmission cooler. Does anyone have a recommendation for a direct bolt up to an 85 4runner? I did check my speed against my wife following me in another car and the speed showing on my speedometer is actually about 10% over actual (gets higher off as I go faster). When my speedo says 25, I am actually going around 22....when my speedo says 75 I am going around 65 or so.

I also need to get a laser thermometer to check the temp of my atf. Would pointing the laser beam at the pan be an accurate reading or would it be better pulling the dipstick?

 

I had an 85 5 speed and I ran 5:29's and 33's. I was 5 over at 30 and 10 over at 60. So sounds about right in that regard.

 

They don't make a direct bolt one kit for the older vehicles anymore but etrailer.com will at least sell you a kit with the right size cooler and hoses needed. Many come with some brackets and straps to mount it on the front end. Tons of people buy them for the cars and works great. I personally would aim at the pan as most trans temp guage sensors are very close to the pan from the factory anyways.

 

So I bought an IR thermometer and shot it at the transmission pan right after driving it for about 20 miles. the lower part of the pan is 155 degrees while the middle section is around 183. I assume these numbers are reasonable?

Thanks,
JARED