98 Taco Front Diff Replacement?

Hello all.

Was hoping I can get some info from the experts.

I have a 98, SR5, 4x4, 6 cylinder, manual transmission, with manual hub locks, NOT TRD, 2.5 inch lift.

Here's what I think must have happened. Without my knowing, the needle bearings on the drivers side of the my front diff (the ones ECGS makes the replacement bushing for) exploded long ago which allowed the splined input hub of the CV axle to work its way loose from the front diff. By continuing to drive the truck like this for who knows how long, with the CV axle just rolling around in the drivers side diff opening, the CV axle wore that opening out so much it's no longer round and trying to install the ECGS Clamshell Bushing is impossible because the opening is so wallowed out the bushing has nothing to hold it in place. Not to mention the seals were disintegrated and sand and water got in there etc. It's a brown mess.

I'm assuming I need to replace the front diff.

The code on my door sticker says AT/M B06A/ R150F so from what I found, the gear ratio should be 3.91, please correct me if I'm wrong.

I have found 1 front diff for 98 Tacoma with 3.91 ratio but it has automatic disconnect. I've seen on YouTube that this is doable if I work a little magic on the automatic disconnect. Can I do that and will it work?

The other issue that was brought to my attention, I found in a 3rd Gen Clamshell page and it involves the actual size of the clamshell. According to that page, 3rd gens have different size clamshells depending on the gearing and engine size etc... Does anybody know if the same holds true for true for 1st Gens. It seems on 3rd gens manual transmissions all have the same size front diff but some automatics are smaller, basically 8.8 or 8.0.

I have asked the question from the seller if the diff is from an automatic or standard transmission, but have not heard back yet.

I know almost nothing about this stuff except what I already mentioned so I'm sure I'll have many more questions if anyone replies to my posting.

Thanks, and I hope someone can help.

Jim

 

You don't need to replace the entire front diff, you just need to replace the carrier. You can upgrade to a locker or even a Detroit Tru Trac. ID also suggest replacing that CV while you're at it as not to damage the new parts. If you got em, let's see some pics of the carnage.

 

CV absolutely in the works. I already have the replacement. I've actually already removed the old CV but cut the axle and left the end stuck in the wheel to hold it together. There is also some play in the backside of the diff where the front drive shaft connects. Maybe a 3/16 of play. I was told by my transmission guy there shouldn't be any back there, but I'm open to more info.

What is a Detroit Tru Trac and is moving to a locker an upgrade? I've seen lots of people convert from automatic to manual lock outs, if that's what you're talking about.

 

"Clamshell" locker Is different from manual locking hub

I'd seen door sticker wrong before. You might want to count the teeth to confirm what you have instead of going with the door sticker.

 

Should be zero play in the pinion. Sounds like you need new bearings. Google Detroit Tru Trac, it's a torsen style posi track. Locker is what the TRD off road trucks come with in the rear, but you'll have one up front. That's why I suggested Tru trac

 

I recommend going with a selectable in the front. The few guys I know break cv with trutrac style locker in the front

 

I see and appreciate your help. I'm looking up trutrac now.

 

What's a selectable?

 

There are not multiple diff sizes for the 1st gen front diffs. As far as I know, they all had a 7.5" diameter ring gear.

In fact, as far as I know, there is no difference in the diffs between an ADD setup and a manual hub setup. However, what could be different are the ratios and the axle tube type coming out of the passenger side of the diff.

I agree with what @02hilux said about not relying on the door sticker. If you already have the old diff off of the truck, open it up and verify the gear ratio. A 3.91 ratio is way less common than a 4.10.

 

I don't have the diff off of the truck yet, and believe me, I know 3.91 is less common than 4.0 but as is par for the course on this truck, if it's harder to do, or harder to find, that's what my truck has!

How would I figure the gear ratio with the diff open?

 

There is a slight difference in the diffs. The add diff has a slight modification to the area about where the breather tube is. It's an extension maybe 2" wide.

 

While looking up info on Truetrac for a 98 Tacoma, I was directed to another page her on TacomaWorld which provided a link to ECGS with what appears to be their answer to Truetrac (I think).

Would this work?

I'm going to call ECSG to find out, but if anyone has any experience or knowledge about this, please let me know.

https://eastcoastgearsupply.com/i-157180-tacoma-4runner-7-5-reverse-ifs-clamshell.html

 

I have seen the difference in the mod video I mentioned. Think the difference is great enough to hinder installation?

 

Spend some money, Call ECGS and have them build you a diff with your choice of gears. I just had them build me one with a Harrop e-locker with new 4:56 gears for under $2k.

 

That link is the same that I used to have mine built. ECGS is top notch. You are going to have to send your core to them for a core charge. You wont get your diff back, You will get one that they already have. They litterally have guys building diffs around the clock and the turnaround is pretty short.

 

SOLD!!!

Appreciate your input!!!

 

Selectable locker is one you can turn on/off via a switch in the cab. More desirable all around but also more expensive

Auto lockers or 'lunchbox' lockers are ones that engage when torque is applied, more commonly used in the stronger rear axle

 

I see and appreciate your help. I'm looking up trutrac now.

 

All you will have to install is both your seals. You can't install the seals all the way in, it's best to use a special seal driver. Be sure you order the handle as well or pick up a cheap seal driver kit and use the handle that comes with it.

If you go with a locker, I would reccomend the Harrop e-locker in the options. You obviously have to install your harness. I just did mine a couple weeks ago and it was pretty straight forward. Everything is labeled.
I would not reccomend a full time lunchbox style locker for the front.

https://absolute-wits-end.com/toyota-4wd-ifs-output-shaft-seal-driver/

 

I will do this!!!

What exactly is a locker, and what is a lunchbox locker? I noticed it mentioned on the ECGS page.