Clark 280VO

[Rodney]

I have a Herclules 3.7DT/Clark 280 VO in my M37. The transmission just developed a problem after 6,000 miles. I was wondering if anyone had insight into the particulars of this transmission (or general knowledge) that would help.
The transission will not go into 4th gear. All other gears work properly. I can get it to engauge the gear, but it will not lock in and immediately kicks out. I bought the transmission from Performance Gear and Axle in Miss (from the second owner). It seems they are out of business. Does anyone know who can help me troubleshoot the problem and/or can fix the problem if I pull the tranny out?
I noticed the hang tag on the rebuilt transmission called for 90Wt oil. I called Eaton to check which brand they liked, and the tech suggested I use 50wt full synthetic oil for better fuel economy. I did this.

Any thoughts would help.

Thanks in advance,

R

[Charles Talbert]

I have a Herclules 3.7DT/Clark 280 VO in my M37. The transmission just developed a problem after 6,000 miles. I was wondering if anyone had insight into the particulars of this transmission (or general knowledge) that would help.
The transission will not go into 4th gear. All other gears work properly. I can get it to engauge the gear, but it will not lock in and immediately kicks out. I bought the transmission from Performance Gear and Axle in Miss (from the second owner). It seems they are out of business. Does anyone know who can help me troubleshoot the problem and/or can fix the problem if I pull the tranny out?
I noticed the hang tag on the rebuilt transmission called for 90Wt oil. I called Eaton to check which brand they liked, and the tech suggested I use 50wt full synthetic oil for better fuel economy. I did this.

Any thoughts would help.

Thanks in advance,

R

I sympathize with you on your set up. We used to install Hercules DT3.7 engines years ago before the original Hercules Co was disbanned. Issues with Hercules supplied bell housing adapters, etc causing major clutch & transmission problems were COMMON. They offered no assistance in problem solving, really had basically a don't care attitude as if to say, "you bought it, deal with it".

You may have solely a transmission issue going on, but there is also a very high likelyhood that a component failure has occured due to improper alignment issues, etc. We had more than 1 input shaft broken as as direct result of poor design/workmanship issues with Hercules supplied adapter plates. This will directly affect 4th gear. This played a huge part in the decision with us changing over to Cummins diesels as our repower engine line, the smartest move we ever made for more than 1 reason.

Feel free to give me a call if I can help you, contact info on website below.

[Rodney]

Hercules Missalignment issues

Thanks Charles, what do you think the likelyhood that misalignment of the bellhousing adaptor is the problem here? I'm just interested because I hope to come up with a list of likely items to troubleshoot this problem. There are alot of custom mods here. I am using the m37 bellhousing adapted to the Clark transmission. Why is 4th the most likely gear to lose in the event of a missalignment issue?
Let's say I pull the engine/tranny, can any engine shop, or even a special shop fix/test misalignment issues before I reinstall?

Thanks

R

wc57@comcast.net

[Charles Talbert]

Thanks Charles, what do you think the likelyhood that misalignment of the bellhousing adaptor is the problem here? I'm just interested because I hope to come up with a list of likely items to troubleshoot this problem. There are alot of custom mods here. I am using the m37 bellhousing adapted to the Clark transmission. Why is 4th the most likely gear to lose in the event of a missalignment issue?
Let's say I pull the engine/tranny, can any engine shop, or even a special shop fix/test misalignment issues before I reinstall?

Thanks

R

wc57@comcast.net

Rodney, it's impossible for me to say exactly what you have going on unless I had your truck here to go into it. Like I said though, probability is extremely high that your issue has come from a Hercules supplied bellhousing adapter based on the experiences I had with them. We had one that would break centers out of clutch disc every 13,000 miles like clock work. Finally broke the input shaft. They offered 0 help as did the MARS middle man we were forced to deal with, we had to figure out each situation on our own as customers were of course not happy. Bad part was hardly any of the adapters were machined right, the issue was never the same. It was a challenge as each time an issue came up, you had to struggle to find where the problem was & use a different strategy to attempt a fix. 2 things you could count on was 0 help from Hercules & MARS, & the problem would always be in that adapter.

The reason I suspect an input shaft issue is because 4th gear is the problem. Misalignment can cause bearing failure, broken shafts, clutch disc failures, & other issues depending on the transmission design. In most 4 speeds, 4th gear is driven directly from the input shaft, thus would be the immediate problem area. 6,000 miles is definitely within the usual range that such issues came up.

You'll have to go into the trans for a look to see what is going on, then take it from there. If you find a bad front bearing or broken shaft, etc, there is a cause. That's the hard part that you will simply have to figure out & correct. That may not be easy. Good luck.

A source for service, well hopefully you know someone who would be willing to try & search out the issues for you. Don't just assume something happened without a real cause, it may show up again after another 6,000 miles. There is a possibility that your issue may be isolated to the trans only, but the info you have offered sounds very familiar to the Hercules set up. I'd almost bet something that will be sight unseen is at the bottom of your problem.

[Chris Olson]

Bellhousing alignment

Does the Clark transmission index off of a bore in the bellhousing?
If so you can check the alignment using a magnetic base dial indicator.
most times I have had to remove the pressure plate and disc then reinstall the bellhousing attach the mag base to the flywheel then put the dial into the bore and watch it as a helper bars the engine over. A small mirror helps when the dial is upside down too... Also dividing the bore into quadrants helps when trying to determine which way to move the bore to bring it into alignment with the crank.
It is too bad that the shop that made the adapters didn't do this before they sent out the parts.

[Rodney]

Clark/Herc alignment

The clark has a bearing retainer that indexes normally into the bore in the bellhousing. In this application, using the early dodge bellhousing, the bore needed to be machined larger to accommodate the Clark's larger bearing retainer. Unfortunately, this was done without the engine, so there is no telling if it is the adaptor, or (my fault) the machinist who adapted the bellhousing to the Clark. I see Novak has a piece on checking bellhousing alignment that follows your suggestion using the dial indicator. They add that missalignment is not uncommon in some GM and Ford engines. Link below.

http://www.novak-adapt.com/knowledge/clutches_etc.htm

So, thanks for your help and suggestions. I was a little concerned my Hercules was just a large boat anchor. It seems that there is a good possibility an alighment problem exists, I have no idea who caused it, but it appears fixable. I will get a (very good) professional engine builder to check/fix the alignment between the engine and tranmission before they go back in.

In a way, pulling the engine at this point is not too bad. I can now work on my wish and should-have lists and fine tune my conversion with the components out of way and easy to reach.

[Charles Talbert]

The clark has a bearing retainer that indexes normally into the bore in the bellhousing. In this application, using the early dodge bellhousing, the bore needed to be machined larger to accommodate the Clark's larger bearing retainer. Unfortunately, this was done without the engine, so there is no telling if it is the adaptor, or (my fault) the machinist who adapted the bellhousing to the Clark. I see Novak has a piece on checking bellhousing alignment that follows your suggestion using the dial indicator. They add that missalignment is not uncommon in some GM and Ford engines. Link below.

http://www.novak-adapt.com/knowledge/clutches_etc.htm

So, thanks for your help and suggestions. I was a little concerned my Hercules was just a large boat anchor. It seems that there is a good possibility an alighment problem exists, I have no idea who caused it, but it appears fixable. I will get a (very good) professional engine builder to check/fix the alignment between the engine and tranmission before they go back in.

In a way, pulling the engine at this point is not too bad. I can now work on my wish and should-have lists and fine tune my conversion with the components out of way and easy to reach.

You may have nailed your problem, very easy to get off center slightly when enlarging like you spoke about. If the machinist didn't take the time to go back & establish an exact center to begin with, he was literally asking for issues.

[Rodney]

Slipping out of direct

looking at the eaton service manual that covers the Clark 280 VO. In the troubleshooting section there is the following in the troubleshooting section:

SLIPPING OUT OF DIRECT

Misaligned transmission and engine
Worn pinion gear teeth
Worn clutching teeth on shift hub
Insuffient tension on detent balls
Improper linkage adjustment
Excessive shift lever whip action


So, at this point I'm going to guess it's the first item. I'll update when I get the engine/trany out.

[Rodney]

Checked BH alignment today

Took the engine with bellhousing attached down to the machine shop. My hole is ten thous off center. This is enough to tear up the input shaft bearings alone. We dial indicated the face of the bh which the transmission bolts to. That was out too. This tilts the transmission (up or down I can't remember) twenty two thou. Way out of wack.

The machinist said it was fixable, but wanted to sort out the best line of attack. I'll keep you up.

Don't think I'll ever bolt any engine to a manual transmission without first checking the alignment.

[Rodney]

Photos

Have a couple of photos, anyone know how to post photos? I am a subscriber, not sure if if i have premium status or not?????

[Desoto61]

Your still listed as just "registered". To get subscriber privileges you need to go into your User CP, select "Edit your details" and scroll down and put in your subscriber code. After it's confirmed you should be able to post photos directly to the site.

Otherwise you can always put them on an image hosting site like photobucket, flicker, or picasa and then link to them using the picture icon in the posting window.

[Rodney]

Sub Code

Entered, some of the letters changed at some time over the years. Still just "Registered" at this point. Will wait a day or two.

Thanks for the help

[Rodney]

Engine/adaptor/bh/transmission

Here is the setup on the messy shop floor, Not where it's suposed to be, but Fixed!

[Rodney]

The Fix

So the alignment problem is fixed. The Hercules/Old Dodge BH adaptor (as seen below) was somewhat wedge shaped. In otherwords, the engine side face and the bh side face were not parallel. I believe the amount out of parallel was about 0.022". So the first step was to measure everything off the crank shaft using a dial indicator with a magnetic base. The adaptor was removed, one side was made flat relative to the crank shaft. Then the otherside of the adaptor was milled flat. The result was a correctly machined adaptor assembly. It is unfortunate that the adaptor plate was not delivered from the factory Parallel and flat....
The NOS Bellhousing was checked as well and lightly machined on each end to ensure it too was parallel and flat. The BH was then bolted to the hercules adaptor plate on the milling machine and the hole for the bearing retainer was enlarged to 5.1250" to accept the Clark Transmission. By the way, the original bearing retainer hole was off center about 0.010" - too much. Everything was then bolted together and checked.

The transmission was disassembled and checked by a professional. There was no asymetrical wear which commonly results from missalignments. The shift lever needed to be replaced and a couple of shift fork pins needed replacement, but the unit was in good shape internally.

What happened here is that the missalignment created a situation where the throwout bearing needed to travel about 3/4" to disengage the clutch. This was a tall order. It was very difficult to adjust the travel correctly and it needed readjustment often. Since the clutch was only sort of disengaging, the shift lever bottom and shifting mechanism in the transmission wore out prematurely.

Currently the throwout bearing travels about 3/8" to fully disengage the clutch disk. Everything looks tight and good. Will let you know how it works.


BTW: Paul Caudell passed away this past April.

[Bill in MI]

Rodney,

Thanks for reporting and documenting the repair procedure on your power train.

A few years ago I had read a similar situation on a Cummins but the dowel locators on the bellhousing adaptor were off.

I am currently piecing together a 3.9L 4bt Cummins - just reminds me to check a few things before I put her together.