Technical Suspension travel and shock range

I put a dropped axle in my 37 Coupe and noticed that the 48 Ford style mounting shocks had only about 1 3/4" travel from at rest installed height to bottomed out with engine and trans installed - but no exhaust manifolds, power steering pump, radiator or front sheet metal. But I had just under 3 1/4" from that same at rest position before the shocks would top out. The shocks that came off had nearly 5 inches total travel from compressed to extended. 9 1/2" compressed to 14 7/16" extended. They have a 1/2" hole in a metal sleeve surrounded by rubber bushing at the top and a 5/8 hole in a rubber bushing at the bottom. NAPA found me some shocks that are the 5/8 hole at both ends - and I could easily drill out the hole in my upper shock mount to take the 5/8 bolts -- BUT the extended length of the new shocks is only 7/8" from topping out in the car's current at rest position and 3" from bottoming out the shock from that same at rest position. The new shocks have under 4" total travel. (8 5/8 collapsed 12 1/2 extended) Does anyone know a part number for some shocks that have the 5/8 hole in the bushing at the bottom and either the 1/2 hole in the metal bushing surrounded by rubber or 5/8 hole in the rubber bushing at the top with a collapsed length of around 8 1/2 to 8 3/4 and an extended length of more than 13" I'm thinking that less than an inch before the shock tops out is not enough -- unless when the rest of the "stuff" is added to the front of the car it would lower enough that there is no way the suspension would rebound enough to top out the shock.

 

It also depends on the angle that you mount the shocks at. The more angle the less travel.

 

not a lot of angle in the shock mounts - they lean in at the top a few degrees

 

Pictures please.

 

Pictures

OK on the left side of the car is a new black shock that has limited travel before it tops out but pretty good travel before it bottoms out. I might not have had it totally compressed since its a gas shock and I only had one hand to compress it and had to be back far enough to take the picture with the other hand.

on the right side of the car is an old white shock which has plenty of travel before topping out but probably not enough before bottoming out when you consider that I still have exhaust, ps pump, a/c, radiator and sheetmetal to add to the front of the car - not to mention interior in the middle.

Trying to avoid the bad stuff that happens when you top out or bottom out a shock -- broke many a shock on my Camaro because they topped out. and those were those stud ends -- the eye ends on these would be tougher and might rip lower shock mount out of the axle.

 

I'm not sure which is which with topping and bottoming out. I suspect bottoming out is running out of travel under compression. I'm reasonably sure that damage occurs with insufficient travel under compression with the dynamic weight of the car bearing on the shock and mount. Under extension there's only the wheel, tyre, hub etc which comparatively isn't much.

Black shocks look fine to me. Added weight shouldn't reduce the static height too much and should leave sufficient travel under compression. Couple of chunky buddies would help you check.

Chris

 

With full vehicle weight, measure suspension travel available. Whatever shocks you use, their travel available should be a little more, to avoid bottoming out.

rear mounting of the shocks is unusual to me.

 

first, make no mistake that from where you think you are starting until you have put some miles upon it, the spring will settle upto an inch more than you think IF its a new 2040 reversed eye.
.
also you initially think that you require 2 inch up and two inch down from you given starting position - this is not the case, or it is impossible to know where to start really as the spring has as of yet not settled. - you dont need the 2 down, one down three up!!
your numbers are the common or garden 9.5 closed and 14.5 open LONG aftermarket shock lengths
the smaller size is a 'shorty' shock.
NEITHER of those in real terms are of any use on a 35-40 with half a ton of motor, okj in an a or b..

it is most aggrevating that you cannot run a spring shackle with shock boss on those 48'' wide 36.5'' perch axles , as the wheel hits the shock pin, with an f1 hub and a 16 inch wheel...................

--------

oh, if you are struggling for a pitmann arm the one you WANT FOR SURE is
IF you fit a saginaw 800 into a 35-40 ford.....
use the pitman arm from a
1971 TO 1974 PONTIAC PITMAN ARM # 7809957 GMTI7A
the part number is actually 7809956
but they are forged with the 7 on the end.
erm, they are 6 and a smidge long
BUT they share the early ford tie rod taper perfectly 1.5'' per foot 7.? degrees

IF you happen to have a 48 inch wide aftermarket axle - the same width as a stock 40 axle at 48''
you can use the stock solid 37-40 drag link, you nibble 5mm from the end of the tie rod 'long side' and 5mm from the short one, you leave a HALF turn for adjustment in the turn buckle, and its bob on.............

yes, so BEFORE you go and spend the 200 bucks on the double borgeson steering uj in stainless steel.
FIT A 14 to 1 dual reciprocating ball input worm at 30 splines from a mk1 jeep cherokee.
also note, the short port on them is metric at m16, the large is th return at m18,
the input shaft spline is 30 splines at 3/4''
the mounting bolts still imperial at 7/16 UNC
you need some sort of cooling in the low pressure return line.


OE 1971 Oldsmobile Steering Pitman Arm ~ GM # 7809956 | eBay

damn the prices have gone up, they were 30 bucks -

 

To fit a shock that has the travel you need, you may have to lengthen the upper shock mount.

 

am i imagining it, or is there an offset lower leaf spring shackle with an offset shock pin
like a shackle but the plate has three points on it - one for a shock pin

 

Plain Shock Shackle Plate W/ Shock Mount Hole (speedwaymotors.com)
will they work with a 2'' wide spring is the questions.
is the bush 19mm or even 3/4'' OD

 

Yes, this is what I forgot to add to my earlier post. Thanks BJR.

 

the lower mount is a bolt thru the axle like a 48 Ford

 

Trying my best to leave as much of Dad's original work intact as I can, so I'm going to try to leave those shock mounts as is.

 

The dropped axle you fitted has moved the bottom (axle) shock mount upwards. You should move the top mount up by the same amount to keep the same dimension for the installed shock.

If you want to keep the top mount brackets, you will have to find a way to move the bottom point down on the new axle.

 

The bottom mount is as down as its gonna get. There has to be a shock that is between those two - Something that when collapsed is 8 1/2 - 8 3/4 and when extended is 13+ If the black shock had the same travel amount as the white one it would be perfect -- but for some reason it has an inch less. I'm going to call Gabriel shock tech support on Monday.

 

Good luck. Let us know what you find out.

 

I allow an inch restriction on suspension between the shock bottoming out and the suspension travel. So that gives me the inch leeway where it can't ever bottom out. If I need to I install urethane bump stops on the frame where any part of the axle might contact to stop the metal to metal contact, and avoid bottoming out the shock.
For rebound or topping out I like 2" above the static ride height, which keeps the shocks from being damaged.
I just had to build new lower shock mounts on my '39 Chev coupe when I installed new front leaf springs and the shocks weren't long enough. I could have ordered new shocks that were longer, but these are only 2 years old, so making a lower axle mounting bracket gave the extra clearance to keep from topping out.

For your shock search you need to go to Monroe's shock specification chart online. They list shocks by min/max length of travel, type of ends, and size of the end attachment points. Once you get all the correct measurements you can take their shock number and do a search online to see what vehicle they were for, and then buy whatever brand you want.

 

You need to be more concerned with bottoming out a shock than you need to be about topping out.

If you are topping out a shock absorber while driving, as opposed to just having the frame on jack stands, then your driving style needs some serious reflection.

Modern shock absorbers are designed with the weight of modern cars in mind. As with all shock absorbers, the intent is to convert excess suspension movement, in a controlled fashion, into heat, before it disturbs comfort and control of the vehicle. On a heavier modern vehicle, more spring, more travel, and more dampening is needed to do this.

Lighter cars, such as Model A's and T's have a whole lot less functional travel than a modern car.

The last two T's through my shop each have a real-world measured vertical front suspension travel between 2-1/2" and 3-1/8", all-in. A Model A may have a little more.

A shock absorber, in your application, that has 4-inches of travel, mounted at a 20º angle, at mid-travel at static ride height (fully constructed, with ALL of the weight on the chassis, including occupants) will be fine.

This may require that you re-make your upper mounts. I understand that this is a potential issue of contention, but forcing a fit that is not appropriate is not something that you want to do on a suspension component.

 

My posts in this thread might help you:
https://www.jalopyjournal.com/forum...length-and-compression.1290250/#post-14835307

@studebakerhawk Also scroll up in that link to my other post for info on the end type on shocks.

 

My A speedster has very little travel in the front and I think none in the rear - rides like a go-cart - it still has lever action shocks. The shocks that came with the 37 had precious little travel room on the compression side but the ones I got the other day have about 3 inches in that direction with only about one for rebound before topping out. Maybe they will be center of travel by the time the car is fully constructed and all will be good. In a perfect world I'd like to have 3 inches for compression and 2 for rebound.

 

I used to find shocks like that when I worked in a parts store in the 80's but I think I remember the guide being arranged by length instead of by part number. Wish I had a hardcopy of that guide I used to use !

 

I believe that to be incorrect, shock travel remains the same, but suspension travel increases the more the shock is mounted off vertical....

 

Are you serious? Draw it out on a piece of paper and report back.

 

Older shock guide. Mount info at end of shock list

 

One picture is worth so many words....

 

some shocks that I have used
-monroe 5850-9.5 to 14
monroe 5752 8.5 to 12.75

 

So you are saying that if you angle a shock from vertical, it moves less than a shock mounted straight up and down if the axle moves the same vertical distance. Correct?
This is what I said in post #2.

I believe we are saying the same thing, just differently.

 

Not only do they move less, they are less efficient. You fine tune a shock just by leaning them over or standing them up.