View Full Version : SYE Comparison: JB Conversions & Advance Adapters

November 7th, 2017, 21:30
Since I wound up with two, different, SYE kits on hand I thought I should take some pictures and share some observations.

Several years ago I did my homework and decided that I would go with a JB Conversions SYE. The time finally came around, I found my bookmarks and placed my order. I got most of the way through the job and discovered that the snap rings which I thought were for the speedometer gear were actually for the mode hub retaining ring and the front input shaft (I had ordered a rebuild kit too, I didn't realize these were for that part of the job). Oops. At this point I had the case almost entirely buttoned back together. And this was a Saturday afternoon. I could not reach JB Conversions until Monday. Once I did the missing parts were on their way, but they still had to come from Louisiana to San Diego. From the initial order I knew that was probably going to take a full week.

I have a second NP231 project. It is a basket case of parts, from two different transfer cases, but it should all add up to one complete case. Of course it will need an SYE too. And if I order something from Summit Racing I will usually receive it the next day. And Summit carries the Advance Adapters SYE kits. So I ordered one of those in order to get my needed snap rings in hand ASAP. That is how I came to have both of these kits in hand at one time.

I have seen some comments about SYE kits all being the same, just order one and move on. I have not laid eyes, let alone hands, on any great variety of these products, but I can tell you that the JB Conversions SYE is not the same as the Advance Adapters SYE. These are definitely different products.

Following are some pictures so that folks can see a bit of a comparison.

First up is a comparison of three output housings, the factory late model housing, the JB Conversions housing and the Advance Adapters housing:






Here are the different oil return channels, factory late model:


JB Conversions:


Advance Adapters:


Here are how the oil pump tabs register, factory late model:


JB Conversions:


Advance Adapters:


Here are how the rear output bearings are supported, JB Conversions:


Advance Adapters:


Here are a couple of side views, JB Conversions:


Advance Adapters (note the rough machining around the speedometer mount and the threading):


November 7th, 2017, 21:33
Here is the output seal on the JB Conversions, note the spring:

And here is the Advance Adapters, without the spring:


Note the difference in the quality of the threading. Here is the JB Conversions:


And here is the Advance Adapters:


The following three pictures are of some of the less refined elements of the Advance Adapters housing. This first one shows the distance to which the machining extends in order to get the clearance for one bolt hole:


This next one highlights a few areas where the machining was left with prominent burrs. I realize that blood sacrifices are often part of working on cars, but I donít see the need to promote them.


This next picture shows the extent of random pitting in the casting:


But it is at least made in the USA:

I would think American quality should be better than thisÖ

Lastly, I have some comparison pictures of the yokes. In all of these the JB Conversions piece is on the left and the Advance Adapters piece is on the right.





This last one really shows the difference in the quality of the casting:


I expect both products to work fine, but I think the JB Conversions parts show a more refined product and greater attention to detail. The double lipped seals (with springs on both sides) are also used throughout the JB Conversions overhaul kit. Having to get missing parts shipped to me afforded me the opportunity to inquire about these seals and where to get replacements. JB Conversions actually has the seals specially made for them. The rear output seal can be replaced with a National 472572 seal, but those wonít come with the double lip.

My impression of the Advance Adapters seal housing is that they decided to save money on the casting and make up for the rough casting by machining every single important dimension. Unfortunately, the machining isnít particularly refined either. It makes for a remarkably heavy seal housing, coming in a 4 lbs, 2 oz. The JB Conversions seal housing weighs 3 lbs, 8 oz and the OEM late model (missing the seal) weighs 2 lbs, 8 oz.

At any rate, there are some differences between these two products. Hopefully this helps folks who are trying to decide what to buy.

Johnnie Walker
November 8th, 2017, 01:24
Good work.

You can send me your OE extension housing.. haha.

November 8th, 2017, 04:17
JB has always been top of line for the parts they sell, you get what you pay for.

November 8th, 2017, 06:37
Good work.

You can send me your OE extension housing.. haha.

PM sent.

November 8th, 2017, 15:59
Cool pics, thanks. I know I was disappointed in the AA housing for their 242 SYE.

November 9th, 2017, 14:20
intersting, I don't recall my AA having sharp edges like that. the jb does look a bit better

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