55 F-100 Wheelbase Mystery
 

Having a difficult time figuring this out.
55 F-100 Books all say 110" wheelbase. Near as I can figure mine measures 109". Working on the bare frame right now with the gear pulled off (yes.. should have marked it better!). Logic tells me the front axle lines up with the axle bumper + the TCI MII measurement also gets me to the same location. Rear, I used mid way between the two bolt axle bumper. I also bolted the original leaf springs back in place. Center of the leafs ends up in front of the 109" mark but moves to the rear as the spring compresses. Looks like it would end up at about the 109" point under load.
The truck is Canadian manufactured but it's difficult to believe that makes a difference.
Anyone brave enough to hazard a guess?

Don't know if this will help you or not. Sorry, after reading your question again this wont help you.


http://www.restoreyourford.com/image...3tdims0003.jpg

It might help but opens another question. It gives the dimension from the rear of the frame to the center line of the rear axle which should verify where my measurement is to BUT.... this dimension is for a bare cab model. Anyone know if I can assume the short box version is the same?

All F100's are short box those years. Yours is the same as posted.

Yes, I kind of know all this. If you go back to my original question, I'm wondering if I can get some reliable measurements from known frame locations. My truck measures 109" axle to axle which I know is wrong but I am trying to confirm locations before laying down a bunch of MIG weld bead. The chassis with cab gives a 35.80" that looks like it is from the end of the frame forward to the rear axle. Can I rely on that? Anybody with the same truck willing to take a measure?

Sask

I can't help with the details, but as I read the posts, it isn't clear to me what measurements are needed. Can you re-ask your question? It might help with the responses.

I read somewhere that you can't trust the bump stop holes as center of axle because they shifted them a little to compensate for the arc of the suspension under load.

This is your only question in your OP, not very descriptive of what you are looking for. I will cut you some slack as you are new here, welcome.:-X22

Your second post a little more descriptive as to what you may want so I measured my truck and the rear of frame to axle centerline is 36.25" at ride height.

Like Fortyniner said, be specific as to what you need or want and you will get a lot of help. Come off any other way and you will be on your own. There are people who know a next to nothing on here and there are guys that know everything. We never know who we are dealing with until you start to establish yourself, this helps us know how to help without assuming, which usually does not work out well for all.

If you need specific measurements from a truck one of us can help, I am sure.

Good luck.

Yes, I am new here. Yes, I am a first time builder. Thanks for the slack. I appreciate all the information and all the effort. As clear as I can state:
- I want to be sure of axle locations before I weld.
- Front seems good. I used the TCI MII measurement of 20.5" back from the original front spring mount and it lines exactly with the front bump stop hole. Good to go with the front.
- Rear doesn't work as well.
- Using the center point between the rear bump stop mount holes gives me a wheel base of 109". Not what Henry Ford designed!
- Today I measured from the rear of the frame forward to the same center point between the bump stop mount holes and get 36.125" (almost the same as diagram from avf100 (35.8") and verified by truckeemthfords (36.25" - thanks by the way for crawling under your truck)).
A possible issue with this is the truck had a 'highly modified' rear work bumper after I rescued it from the field after 30 years of work and 25 years of sitting. Maybe what I think is the end of the frame is not actually the original end. Anyone know the true length of an original frame rail?
- So the rear axle seems like it is actually is 109" from the front not 110" as it is supposed to be. See my dilemma?
I am wondering if I should just set the rear axle 110" behind the front and forget about the other measurements? Seems impossible the wheelbase is 109" but I'd rather be sure about where it goes - so I'm learning how to use this forum!

One thing to consider on the front axle is Henry had them to the rear of the front fender opening. Most,like me and others, move the front axle centerline forward to center it in the wheel opening. As far as the rear my suggestion would be to center the axle in the rear wheel opening, if you're using a bed. If you're using a flat bed go with what looks good. I know putting a bed on may be a pain but it will guarantee the tire is centered on the wheel opening. Wheelbase is not all that critical, mine stretched due to the front axle centerline being moved forward.

Yes you should move the frt axle center line 1 1/4" forward from the stock location, to center it in the wheel well.

Saskf100, it might help if you could post some pictures of what you have and especially the areas of your concern. I'm surely not the guy who will have the answers you need, but sometimes pictures can help our resident experts spot something that you may have overlooked.

Oh, and welcome to FTE it really is the best place for help and advice.

Sorry I'm no help but welcome to the club

First: The diagram shown above does not reflect chassis cab dimensions. It represents a completed fully loaded vehicle. This has always been the automotive standard for dimensions. The actual box picture is deleted for clarity of rear measurements.

Second: The rear axle does not move directly up and down because the shackles at the back of the rear springs modify the travel.

If you were to load your vehicle weight up to the Gross Vehicle Weight Rating shown in the figures below the diagram, you would probably find a number closer to the 110 target.

Also as stated earlier the bump stops are not always an exact reference for axle centerline. I know I have my rear axles offset 1" or so from the bump stops so that when the rear leafs compress, which makes them longer and changes the position of the axle, the axle will be centered with the stop under compression.
Your best bet is to mount the bed and get your center line if you have no reference.

https://cimg5.ibsrv.net/gimg/www.for...08b0f4a973.jpg

Thanks to everyone who has lent an opinion on this. At this point, I'm no closer to figuring out why the measurement seems off but I am closer to a game plan. I am certain of the front axle location. I had hoped not to have to reinstall the bed and rear fenders but if that's what it takes then...
I've attached a picture of my frame at the rear axle position. I've marked the center of the bump stop mounts and also the measurement back from rear of frame. The small bolt is at 110" back from the front axle (using these as frame squaring points). Seems reasonable that the axle will move rearward under load. Still not sure why the measure to the end of frame is off but..
I am interested in the opinions provided on moving the front axle position forward of Henry's original. I've heard of this but not sure if the 'better' location is built into the TCI installation dimension or if I need to do the math. I've sent the question off to the TCI Tech guys but no answer yet.
Does anyone have experience with a TCI MII install AND moving the axle forward? The TCI instructions give 20.5" back from the original front spring mount. So, does that put the axle in the 'right' place or would I use 20.5" - 1.25" = 19.25". No pressure for a response as I expect TCI will respond in the next few days.
Thanks!
Brian

Hate to say it but I trust no one when it comes to critical measurements like this, I always mock up the sheet metal to be sure. I would put the cab on and hang the fenders and bed, then you know what you are dealing with.

When I built my 47 cadillac I even mocked it up on the floor :)

http://i34.photobucket.com/albums/d1...%20rod/034.jpg

Just thought I would finish this off. Here's what I take away:
Front TCI MII - After a wait longer than I thought should be acceptable, TCI got back to me and verified their measurement would locate the front axle center line as on the original truck. They indicate it normal to move the axle 1.25" to 1.5" forward from this. Not sure why the instructions can not be clear on that but, problem solved (I chose 1.25" by the way).
Still can not decide where the rear center line was originally, but I got enough good advice that I will be patient and set the location after I get rear fenders bolted on temporarily.
As I mentioned in an earlier post, this is my first time on this (or any) forum. I got a lot of opinions and good advice. Appreciate everyone who waded in on the topic. I will definitely run things by the group next time I am baffled by something (probably sooner than I want to think).
Thank-you.
Brian

I feel your confusion. My TCI instructions said that the front center was 21'' and other TCI instructions I found online that said 20.5''. I called them for clarification but their answer didn't instil confidence as to which measurement was right. Good luck with everything, I'm sure you will figure it all out.