TCase Howell TBI upgrade, speedo sensor question

[Scottyp1134]

I am in the process of installing the Howell TBI system on my 86 CJ7 .

Jeep has NV3550 Transmission , Dana 300 Transfer Case , and Terra Flex HD Output shaft.

The problem I think I am having is due to the Transfer Case being turned to fit the NV3550 it puts the speedo cable pretty high. When I put the inline speedo sensor for the Howell kit I am running out of room and I'm the cable is going to be too tight of a bend radius. See pictures below.

I am wondering if one of the 90-degree speedo adapters would be worth it for me. What do you all think?




AUTO METER #990414 Speedo Cable 90 Adapter

 

[CJ]

Yea, that's a pretty tight bend. That ninety adaptor would semi work but it has draw backs. Needs greasing and causes some drag.
Why not just get a longer cable or put the sensor on the back of the speedometer?
I have a friend with a Howell setup. I'll text him and ask for pics on his placement.

 

[CJ]

Heard back from my friend with a Howell setup. No trouble with the sensor at the Dana 300 but you have a different Transmission . Your stock speedo cable was already stretched.
I would look into a longer one or try rerouteing your current one.

 

[Jeep-CJ Google Gemini AI Bot]

I am in the process of installing the Howell TBI system on my 86 CJ7.

Jeep has NV3550 transmission, Dana 300 Transfer case, and Terra Flex HD Output shaft.

The problem I think I am having is due to the transfer case being turned to fit the NV3550 it puts the speedo cable pretty high. When I put the inline speedo sensor for the Howell kit I am running out of room and I'm the cable is going to be too tight of a bend radius. See pictures below.

I am wondering if one of the 90-degree speedo adapters would be worth it for me. What do you all think?

View attachment 104317View attachment 104318View attachment 104319


AUTO METER #990414 Speedo Cable 90 Adapter
View attachment 104320

Okay, I understand the problem. The Dana 300 rotation for the NV3550 is causing clearance issues with the Howell TBI speed sensor due to the tight bend radius on the speedo cable. A 90-degree adapter seems like a viable solution, but let's break down the pros and cons and consider alternatives:

**Pros of using a 90-degree adapter (like the Auto Meter #990414):**

* **Solves the Immediate Clearance Problem:** It directly addresses the issue of the cable bend being too sharp, preventing binding and potential cable damage.
* **Relatively Simple Installation:** Typically, 90-degree adapters are a straightforward bolt-on solution.
* **Protects the Howell Sensor:** By reducing stress on the cable connection, it minimizes the risk of damage to the Howell sensor itself.

**Cons of using a 90-degree adapter:**

* **Potential for Inaccuracy:** While most adapters are well-made, they introduce another mechanical point that *could* potentially impact speedo accuracy. Cheap, poorly made adapters can definitely degrade accuracy. Reputable brands like Auto Meter are usually okay.
* **Another Point of Failure:** More connections mean more potential points for cable binding or failure down the road. It also needs to be properly lubricated.
* **Could Introduce New Clearance Issues:** While it solves one clearance problem, it's essential to ensure the adapter itself doesn't interfere with anything else under the Jeep. Measure carefully!
* **Cost:** It is an extra expense on top of the Howell Kit

**Alternatives to a 90-degree Adapter:**

* **Longer Speedo Cable:** A slightly longer cable *might* provide enough slack to create a gentler curve without the adapter. Measure the existing cable length and see if a longer one could work. This is often the best and most accurate solution.
* **Custom Speedo Cable:** A custom speedo cable, tailored to the exact length and routing requirements, would be the best option for a clean and optimal solution. It can be expensive, but will be the most reliable.
* **Different Routing:** Consider if you can carefully reroute the existing speedo cable. This may be difficult, but look for opportunities to reduce binding.
* **Electronic Speedometer with GPS Input:** If the mechanical cable is a constant problem, consider upgrading to a GPS-based speedometer. This eliminates the need for a mechanical connection to the Transfer Case entirely.

**Recommendations:**

1. **Measure, Measure, Measure:** Before buying anything, carefully measure the available space and the clearances needed with the 90-degree adapter. Make sure the adapter itself won't hit anything. Pay close attention to the amount of free space you have for the sensor and cable, especially at full suspension compression.

2. **Try a Longer Cable First:** Before going the adapter route, check if a slightly longer speedo cable (a few inches) would give you the necessary slack for a gentler bend radius. This would be the cleanest, simplest, and most reliable option.

3. **If the Longer Cable Doesn't Work, Go for the Adapter:** If you are unable to find a longer cable, a quality 90-degree adapter from Auto Meter (or a similar reputable brand) is a good solution.

4. **Lubricate Properly:** Use a good quality speedo cable lubricant (graphite or silicone-based) when installing the adapter. This will help ensure smooth operation and prolong the life of the cable and adapter.

5. **Check for Accuracy:** After installation, verify the accuracy of your speedometer, especially at highway speeds. You can use a GPS app on your phone or a standalone GPS unit for comparison. If there's a noticeable discrepancy, you might need to recalibrate your speedometer (somehow, I doubt you can with this system).

**In summary:**

The 90-degree adapter is likely the best solution if a longer cable is not enough. Measure carefully, use a good quality adapter, lubricate well, and check for accuracy. Make sure to check for adequate clearance on and off road. If you are already running the Howell kit, it seems like the adapter would be a good and easy solution.

 

[Scottyp1134]

Heard back from my friend with a Howell setup. No trouble with the sensor at the D300 but you have a different trans. Your stock speedo cable was already stretched.
I would look into a longer one or try rerouteing your current one.

Thank you for the help looking into this. The length of the cable isn’t the problem. The problem is with the Speedo sensor added in there now the cable is tight against the bottom of the body/floor pan. This is creating a tight bend radius that I am worried about

 

[KRUPP]

I have the Howell speedo sensor too, but fortunately I have no clearance issues.

Other than the 90 elbow, I would look into putting that sensor in-line by having another short speedometer cable made up. There are shops that can make it for you, like this one... (Link)-> Speedometer Cables - Speedometer Repair & Calibrations -<

 

[boney]

I hadn't thought of the "at the speedometer" solution. That's thinking out of the box!

The howell system (GM TBI) measures speed, but I don't know how accurately or to what detail. I've been playing with an ADX file and ALDLDroid to get live dash data from the system. There is a calculation for speed to get accurate numbers from the computer (and I just use the GPS function anyway.)

In short, I think it just needs to spin relative to your movement and not be amazingly accurate. We all know the jeep speedo isn't the definition of precise already. So do what you need to do to make it work and it will likely be just fine.

 

[Scottyp1134]

I have the Howell speedo sensor too, but fortunately I have no clearance issues.

Other than the 90 elbow, I would look into putting that sensor in-line by having another short speedometer cable made up. There are shops that can make it for you, like this one... (Link)-> Speedometer Cables - Speedometer Repair & Calibrations -<

I like this idea. A short piece to make the bend would be a great solution.

 

[Scottyp1134]

I hadn't thought of the "at the speedometer" solution. That's thinking out of the box!

The howell system (GM TBI) measures speed, but I don't know how accurately or to what detail. I've been playing with an ADX file and ALDLDroid to get live dash data from the system. There is a calculation for speed to get accurate numbers from the computer (and I just use the GPS function anyway.)

In short, I think it just needs to spin relative to your movement and not be amazingly accurate. We all know the jeep speedo isn't the definition of precise already. So do what you need to do to make it work and it will likely be just fine.

You bring up some good points. I may try the behind the speedometer first before I try the short piece previously mentioned. I’m interested in looking at the live data view you are talking about