47-55.1 Ground Clearance

[Root2812]

I need some advice and opinions about my 1950 with a stock frame but custom everything else. I know some of you guys have pretty low static ride heights or you set your ride heights on your air ride system. I am still working on my project so its not drivable, in fact it still just a chassis with a cab on the floor next to it. I have my LS engine, 4l60e, and full suspension installed. I bolted some 26 inch diameter wheels on for rollers and found the truck is really low. I could go with a bigger wheel and tire combo to gain some height but I am hoping to not have to rely on that.

For reference, I have a Fat Man fabrications mustang II with standard spindles and a TCI rear leaf spring kit.

I have found that my ground clearance is less than I would have expected. I have 6.5 inches of clearance at the transmission pan and 7 inches at the running board. I hate that my tranny is the lowest point. I am looking to swap to the shallow trans pan instead of the deep one I have. That will gain me 3/4inch more transmission clearance.

I also did come googleing and found that I still have more clearance than a modern Camaro or Mustang but the trans makes me nervous. What ground clearances are you guys running and how often do you bottom out? Does anyone know of a shallow trans pan that's either stronger steel or armored? I could make a skid plate but then I would lose even more clearance to the ground.

Thanks

[mongocanfly]

lots of these trucks run 5.5-6in at front of the running boards...might try some 28in tires and see what it looks like....can you raise the engine/trans up a inch or so?

[dsraven]

quick questions:
what type of springs are under the front, coils or air?
how do the lower control arms look on the front end?
if all is new with coil springs and no weight on the frame then the control arms are likely angled down towards the wheels. with weight on the frame like a finished truck the control arms should be parallel to the ground for proper geometry. what I have done in the past during mock up is remove the springs and shocks, then use some threaded rod where the shocks go to adjust the ride height to what it should be for proper suspension geometry. they should be parallel to the ground at ride height. figure in your rake angle, front to rear, and the control arms should be level fore to aft at this point. that's in a perfect world but if your control arms are angled down to the wheels right now then the truck will be even lower with the weight on it. if you have room to jack the engine and trans up a bit you may save some headaches later. the rear springs are possibly going to be the hard part to get right in the end. the front springs, if coils, will also need some time to find their "set" height after some driving time. trying to get the suspension to ride height without knowing how the weight will distribute over the wheels will drive you bonkers trying to figure it out. best is to get the body parts back on there and see what it looks like. even better would be to find somebody with a set up like you have and have them weight the truck at a commercial scale. total weight, then weight on each axle with no driver inside. then you could simulate that with sandbags or whatever if you really want to get the weight like it will be, well, close anyway.
don't drive yourself crazy till you get the truck assembled for body mock up, then you get an idea of how it will sit. after that you can mess with different spindles, coil springs, leaf spring packs, lowering blocks if the axle is above the springs or flip the axle to be under the springs, different leaf spring shackles etc if it isn't like you want. you are not the first guy to have the issue but we can't tell you exactly how to fix it for a specific ride height until the truck has the weight on it. otherwise it will be a guess just like you would do. that is unless somebody on here has the exact set up as you, with the engine placed like yours etc etc.

here is a gearing calculator, there is also one on the tire size calculator link if you poke around on the tabs at the top of the page

https://spicerparts.com/calculators/...rpm-calculator

here is a tire size comparison chart with some extra stuff in different tabs

https://tiresize.com/comparison/

both are pretty handy. another source to understand how the MII should be set up is Heidts. they have a quick read called "understanding independent front suspension" and they will usually send you a link to download it if you call them. it is very informative and explains some do's and don'ts when you are setting things up.


another informative quick read

https://www.hotrod.com/articles/inde...nt-suspension/


good luck, post some pics of what you're working with.

[mr48chev]

Ideally I'd like the pans to be higher than the crossmember. 99.9 % of the time a bit of careful driving will keep the pan from hitting anything but then that speed bump you didn't expect on a side street or that man hole that they raised because they are getting ready to repave the street and while the F350 4x4 in front of you cleared it you didn't have time to react. I took the drain plug of my 48 on one of those in Texas.

Just let the lowered Honda that roared past you fart pipe blasting away run in front of you and take the hit for you. He will think it's cool that you didn't pass him even though he heard the LS when he went by and the honda can be the designated bad spot finder.

This was static road height with the front of my 48. The front tires weren't in a hole.


My uncle was taking a photo of my aunt beside the truck when we held a family reunion at our house. I could lay a coke can on it's side under the bumper and jump on the bumper and put a dent in the can.

[dsraven]

Good idea on the pans. Same for headers. Sometimes just not do-able though.
If you haven't got stuff written in stone yet it would be good to raise the engine and trans now before you start cab work.

[oldman3]

Root, my 50 pickup has been on the road for 16 yrs and has almost 28,000 miles.
It is a static drop, MII with 2 inch drop spindles, and QA1 coil overs. The lowest point on my truck is the MII crossmember, it's 4-1/2". The front of my running boards are 5-3/4". I haven't hit anything with this ground clearance, but my driving and roads could be alot different than yours.

I don't think you should have any trouble, but if the trans pan is lowest point, and you are worried about it hitting, then now is the time to change.

Here's a couple pics for reference...Jim

Forget to say I'm also running a 26"tall tire.

[MiraclePieCo]

At 6-1/2" transmission and 7" running boards, you don't have to worry. That's plenty safe for normal driving. If you're worried about your trans pan, you can install an aluminum pan; they are heavier gauge and more dent-resistant than sheet metal pans. BTW, I'd much rather have my trans pan hit the pavement than my front fenders (behind the tires). Trans pans are easy to change, front fenders not so much.

Here's my pickup with 5" clearance at the front of the running boards, 6" at the rear. I drove it for two years and it never touched the ground ever.

[mr48chev]

Where you live and the roads you drive on all the time do have a lot to do with exactly how you can be and not have issues. If you lived in Bountiful Utah you would want the truck to sit a couple of inches higher than if you lived most anywhere in Texas. I got hung up on a grocery store parking lot entrance ramp even when hitting it at an angle in Bountiful and the wife and kids had to get out so the truck would lift up enough to get off the hump. That didn't sit too well with the wife.

[jwhotrod]

just a quick note to let you know, a stock out of the box Nova, camaro or Chevelle during the 70s came standard with 5,5 inches of clearance under the crossmember. you are not too low.

[mr48chev]

The Novas were 6=1/2 at least the two that I measured when I subframed my 51 Merc and had one of my students take his Nova in the shop so we could measure it. We found a piece of cross tie that was 6-1/2 inches and set My Nova crossmember on it and blocked the Merc up at intended final ride height to get things lined up.

[Root2812]

Thank you all for the replys. It sounds like my height won't be an issue which makes me happy. I will still look into a pan swap because doing to the shallow pan will save me 3/4 inch at the trans pan. I am also looking at spacing the motor and transmission up another half inch. I used these engine mounts from Dirty dingo and I think that I can add a washer made of 1/2 inch plate below the rubber isolator to space the engine up.
https://www.dirtydingo.com/shop/inde...63d7ac1b13b58e

Then I can just as easily space my transmission crossmember up the same. That should be all I think I need to do to have piece of mind.

DSRaven, I wanted to comment on your post specifically because you asked what springs I had in the front. The FatMan kit comes with spacers to put in place of the springs to keep the truck at ride height while you're building it. So right now the lower A-arms are parallel to the ground. When the truck is completely done is when the instructions told me to put the springs in because they may need shortened.

[e015475]

My 49's running boards are a beer can's height at normal ride height. I've not had any ground clearance problems (I did scrape a speed bump I didn't see, but if I'm paying attention it isn't a problem)

But the real answer to your question isn't ride height - it's 'scrub line'.

Here's an explanation on the HAMB that might throw some light on the subject.......

https://www.jalopyjournal.com/forum/...ub-line.77804/

[Chris(NJ)]

Originally Posted by e015475

My 49's running boards are a beer can's height at normal ride height. I've not had any ground clearance problems (I did scrape a speed bump I didn't see, but if I'm paying attention it isn't a problem)

But the real answer to your question isn't ride height - it's 'scrub line'.

Here's an explanation on the HAMB that might throw some light on the subject.......

https://www.jalopyjournal.com/forum/...ub-line.77804/

Learn something new every day.

[Chris(NJ)]

Here ya go.....Static, Just under 4" clearance at bumper and running boards. I kinda wanna bring it up to just over 4. But thats gonna require coilovers so I can dial everything in.

[joedoh]

here is my 47 GMC, it was stupid low but looked great. it would find the crown of the road with the bumper haha

Originally Posted by e015475

My 49's running boards are a beer can's height at normal ride height. I've not had any ground clearance problems (I did scrape a speed bump I didn't see, but if I'm paying attention it isn't a problem)

But the real answer to your question isn't ride height - it's 'scrub line'.

Here's an explanation on the HAMB that might throw some light on the subject.......

https://www.jalopyjournal.com/forum/...ub-line.77804/

hows this for scrub? I went and looked at this camaro for my brother yesterday.

[nikwho]

Man,
Hearing the clearances being discussed in this thread makes realize how painfully low my truck is. It has a Camaro sub-frame, Eibach coil springs and drop spindles, and my cross member sits a mere 2" from the ground! My transmission pan has about 5" of clearance, and sits about level with the bottom of my frame rails, and higher than my rockers. I can say that it scared the crud out of me when driving my truck through a gas station and my cross member struck one of the steel fuel tank caps in the gas station parking lot! It's low enough to cause problems, but I sure love the way that it looks! LOL.

[mr48chev]

In this state a chassis part hanging down below the scrub line will get you pulled over by the state patrol so fast that it will make your head swim.

As it was explained to me by the patrolman who pulled me over when my truck was red as in the earlier photo, no chassis parts below the scrub line that can hang up on the pavement and hinder him pushing it out of the traffic lane if all four tires happen to be flat.

[MiraclePieCo]

Originally Posted by nikwho

Man,
Hearing the clearances being discussed in this thread makes realize how painfully low my truck is. It has a Camaro sub-frame, Eibach coil springs and drop spindles, and my cross member sits a mere 2" from the ground! My transmission pan has about 5" of clearance, and sits about level with the bottom of my frame rails, and higher than my rockers. I can say that it scared the crud out of me when driving my truck through a gas station and my cross member struck one of the steel fuel tank caps in the gas station parking lot! It's low enough to cause problems, but I sure love the way that it looks! LOL.

Haha, if we wanted practical vehicles, we'd all be driving a Ford Focus!

I once built a '34 Ford rat rod with about 2-1/2" clearance. I fabricated some steel rollers under the frame. When I went in driveways it would ride on the rollers with a horrible metallic scraping sound. Everyone assumed I was scraping bottom. All part of the outlaw image!

[nikwho]

Haha. I love it! I've always said that I lower my vehicles until they're undrivable, then raise them back up one inch!

[Root2812]

All of your posts put my mind at ease. Thank you. I decided to swap transmission pans to save an extra 3/4 inch just to be a bit higher. Now my trans pan is atleast higher than the running boards. I started to work on my exhaust and found the only way it will work is to go under the cross member so I'll end up with about 5-5.5 inches of ground clearance at the exhaust pipe. I should be good to go.