The Stovebolt Site Forums The Parking Lot Big Bolts NEED HELP - The truck is mine........

Okay, I purchased the truck today:) It took me 3 hours to drive it home because of the top speed of 45. It ran well and the suspension is stiff as heck. I plan to start work on it soon. I will repaint the truck the same color, white. I will remove the hideous piece of wood for a front bumper and replace it with, well I'm not sure. I plan to repaint the flatbed then replace the wood. So again, I need to solve the MPH problem and I'm thinking a 5 speed transmission with OD. 3B, I will get you those tranny numbers and rear axle numbers tomorrow..... Here are a couple of pictures of the truck "Brutus"....

http://ironclad.shutterfly.com/72
http://ironclad.shutterfly.com/71
http://ironclad.shutterfly.com/70

Looks like a nice truck. I love the bigger trucks with dual wheels with the "shorty" bed look.

Hy Iron Clad, I'm glad you got her home, she's a short little thing isn't she. Could you get us some pictures from the front side of the rear axle?

Sure thing 3B. It will have to be tomorrow, it's pitch black outside. I cannot get the truck in my shop yet because I have an 1800's farm wagon in there I'm restoring. Good grief I have too many hobbies, LOL.......I will get you the numbers off the tranny as well.

Thanks Achipmunk. I have never owned a "Big Bolt" before, but I had the same feeling you do about the shorter bed, I think it looks cool.

Iron Clad, ditto on Alvin's note. Those short beds are really neat. The paint in the pics looks great! I'm wondering why bother with a paint job ... at least for a while? Again, awesome truck, have fun, and keep us updated.

Thank's Husker. The paint has some surface rust in spots, nothing serious, no bubbles in the paint and no serious cancer anywhere. The entire underside of the cab has been Rino Lined, not the GM factory stuff but Rino Line by a previous owner. Also the interior of the cab floor and behind the seat has been Rino Lines as well. The bed length measures 8.75 feet and it's width is 7.5 feet.

Looks good.

You should be able to find an original type Front Bumper at your local junk yard.

Bill

3B, here is the transmission numbers that I can find so far. I will write them here exactly like they are on the tranny:

0116
8
GM
3837334

Also, here are a couple of pictures of the rear axle:

http://ironclad.shutterfly.com/75

http://ironclad.shutterfly.com/74

http://ironclad.shutterfly.com/73

I couldn't find any numbers on the axle yet, I will have to clean things up and look closer...

Iron Clad,

Check out the "0116" again. If that is the Date Code, I believe the "0" will actually be a "D". If that is the case, it looks like it would be the original trans Dated April 11, 1966.

You also have a single speed rear. Did you check on the back side of the Glove Box Door for a factory label?

Bill

Hy Iron Clad, thanks for the pic's, that is a corporation (GM) single speed rear axle. I think those axles were 15,000 lb. max., most of the ratios I have found in my parts book for that axle are in the low to mid 6s which should give a decent speed. What size tires are currently on the rear of the truck? That transmission casting number is very close to a case p/n for a Muncie four speed.

3B the tire size is 9 R 22.5.

Bill, the only I.D. plate I could find says the following:

Axle C15
Ratio 72
Trans C4

Thanks.

Hy Iron Clad, I think your rear axle ratio is 7.2 to 1, with those tires and the engine turning 3000 r.p.m. your speed would be 45 m.p.h.. Taller tires, an overdrive transmission, and a lower (numerically) rear axle ratio will give you a higher top speed. What do you intend to use the truck for?

For one, I plan to restore the truck. Besides that I need the truck to haul lumber and supplies to my property in Eastern Oregon, also to haul coal up to 2 tons. It's 84 miles of highway. I only need 10 to 15 MPH more. If I can get up to 55 MPH I would be happy. Would a transmission swap do the trick? If I could get away with JUST a transmission and not break open the rear differential I think it would be easer on me anyway......

As far as transmission, how about a Spicer 3153 5 speed with OD. Will this bolt right up??

Hy Iron Clad, if I did my figuring correctly an overdrive transmission with a 0.73 overdrive ratio will give you a top speed of 61 M.P.H @ 3000 R.P.M. with a 7.2 rear axle ratio and 9 X 22.5 tires. Your available power in overdrive goes way down, just be aware of that. A Spicer 3153 is a pretty old transmission, and while I'm not positive, I think you might have to change bellhousings to mount it to that engine. The Dodge version of the NV4500 will bolt to the same pattern bellhousing you have now, but I think it requires a 1" spacer between the trans. and bellhousing. Google NV4500 for more info, there are Chevrolet specific NV4500s but it seems to me the Dodge designed transmission is a better swap for a reason I can't recall at the moment, hope that helps.

Iron Clad;

Congratulations on your Big Bolt. You have a very clean truck.

The Clark 264VO and the Spicer 3153 may bolt up because the Chevy 292 and V8s share the same block bolt patterns. But those two transmissions are pretty hard to find. I've been searching for months. No luck yet.

You might have better luck with a two speed rear end. They were in a lot of the Chevy medium duty trucks. The beauty of the two speed rear end is that you can have eight speeds which may be more flexible with heavy loads. I think the high range ratios came in the high fives or the middle sixes which is about what you're looking for versus your current 7.20. Keep us posted on your progress with Brutus.

SimS

What happened to brutus' wrecker bed? Is it for sale?

Thanks guys for the info. What would be the easer swap, the tranny or the rear differential? If I go with an NV4500 tranny would I have to shorten the drive line? Oh, don't forget about the E-brake set up, it's one of those drum set-ups connected to the back of the current tranny and drive line, will this bolt up to an NV4500? Thanks again....

Hy Iron Clad, I don't think the NV4500 ever had a driveshaft parking brake, so that could be a problem to fabricate. there are older Clark, Spicer, or New Process with overdrive which would be more of a drop in, but they will be more difficult to locate, and probably more expensive. You could change the whole rear axle to a two speed Eaton, or find a lower ratio for that housing. Getting taller tires will help as well. There really are a lot of choices when you want to increase speed, you need to decide what your level of expertise is and what you can do or afford to pay someone else to do for you.

In my opinion, I would be looking for a 2-Speed Rear. Just be real sure it interchanges and has the correct Higher High Range Ratio (Lower in Number). This way not only will you have a higher MPH, but you will also have 8-Speeds as mentioned above.

Bill

They are around. Mostly on one-ton 2WD trucks. I recently saw a '93 Chevy trans for sale with a parking drum on the back. You still have to make the linkage work.

Well, it looks like I have a dicision to make. Thank you guys for all of the advice. I have changed a transmission before but never tried to retrofit one in a case like this. I have never changed a rear differential, not that I couldn't. I'm just looking for the best route to get the truck on the road by early summer. It almost sounds like a differential change to a 2 speed might be the best option. I will look around and research both options and I will keep you all posted.....

Hy Iron Clad, in my experience corporation two speeds are rare, an Eaton two speed is the most common. If you could find a whole rear axle that uses the same hubs as yours, you could swap the whole thing over. You could rebuild the rear brakes, or transfer yours over while your doing the project. It really isn't that difficult a job, jacking the truck up and blocking it up securely is probably the most difficult part. Just ask us questions we'll help wherever we can.

Thanks 3B, I really appreciate it. Now, when you say to match up hubs, are you talking about measuring the size by diameter, or identification by specific features, or are there number codes for indentification? In other words, what differentiates one hub from another?

Hy Iron Clad, the hub is the part that the wheels bolt to, if you can find a whole rear axle assembly that will allow you to use the same wheels as the ones on your truck now, then you wouldn't have to carry two different spares (one for the front, and one for the rear). I know such rear axles are out there.

Thanks again 3B, I guess that was kind of a dumb question on my part, LOL..... I have rebuilt engines, changed trannys, done my own brakes and oil changes but I have never work on a Big Bolt or have never changed a rear axle. So I'm sure I will ask more dumb questions in the future!!!

Oh, I may already have a line on a new axle, I'm not sure yet but I will be talking to the guy this Friday, I will keep you posted........

I found a place here in Oregon that may actually have the rear differential in stock...I just need to find the numbers off the rear axle and measure the brake diameter and brake pad width. They also said I may need to alter my drive line, something about the old style U-joints. Can anybody explain this???

Hy Iron Clad, if you change from a corporation diff. to an Eaton, the driveshaft might have to be lengthened or shortened, and the "U" joint may be heavier than the one your driveshaft currently, so a different end yoke would have to be installed on the driveshaft to match the new diff., all minor stuff actually. Are you talking about changing the entire rear axle or just the differential? What ratio(s) is the new diff/axle going to have?

I was thinking about changing the entire rear axle. I'm not sure of the ratio yet, they need the information from me first to see what I have in order to check their stock. I'm planning to climb under the truck this weekend to start cleaning and searching for numbers. I guess the rear tires will have to come off as well so I can check the brake dimensions. He did mention that the U-joint on the new axle would be heavier.