Front suspension too soft - Baja Rey

[elRayRay]

I've got a Baja Rey with SSD front bulkhead, Hot Racing steering setup, and RPM front arms. I understand that I added a bit of weight to the front end, but the shocks simply won't properly support the front end. After setting the truck down, there is very little sag. When I press down on the front, it bottoms out and barely springs back up, almost zero rebound.

I've got my stiffest springs (Gmade XD "HARD") of nearly identical length to the stock springs on them. I've taken emery cloth to all of the hinge pins, scrubbed the contacting surfaces on the arms, put the anti-roll bar back in, and wound the preload all the way down. There doesn't seem to be any binding in the suspension with the shocks removed and I'm fairly certain that I have enough spring to support the front end. I'm left looking for any other possibilities. Anyone have any ideas?

 

[mass-hole]

To heavy of shock oil for winter? I put some decently heavy oil in mine, it seemed to work well in my living room, then i took it outside into 20 something degree weather and the shocks got super stiff and wouldnt rebound pike you were saying. The truck would get stuck at lower ride height than i had set them and drop tested them inside too.

 

[elRayRay]

To heavy of shock oil for winter? I put some decently heavy oil in mine, it seemed to work well in my living room, then i took it outside into 20 something degree weather and the shocks got super stiff and wouldnt rebound pike you were saying. The truck would get stuck at lower ride height than i had set them and drop tested them inside too.

Thanks for your suggestion, but I'm not comparing inside to outside. Does your rig return to a decent ride height after compressing the suspension? Mine doesn't.

The other discussion

 

[JDM74]

Take the shock off and cycle the suspension.

Does it move freely? It flop around under its own weight and offer very little resistance. If it does not, you have binding somewhere in the suspension linkage.

Compress the shock by and and make sure it extends as far as it can when you release. If it doesn't something is wrong with the shock.

That should help you narrow it down to where the binding is.

 

[TheLetterJ]

You're over thinking it. The reason that it won't return to "static" height is... tire scrub. Remember, as the front suspension cycles from full droop to full compression, your track width goes narrow-wide-narrow. Unless you're doing your experimenting on a polished surface that is greased with pig snot, the tires are going to have lateral resistance which will prevent the front suspension from moving as easily as it would if the tires were rolling. I'll still suggest: go drive it and report back!

 

[elRayRay]

Take the shock off and cycle the suspension.

Does it move freely? It flop around under its own weight and offer very little resistance. If it does not, you have binding somewhere in the suspension linkage.

Compress the shock by and and make sure it extends as far as it can when you release. If it doesn't something is wrong with the shock.

That should help you narrow it down to where the binding is.

I just disassembled and reassembled the front suspension again. I did find a tiny bind in the ball at the knuckle end of the right hand tie rod at the very bottom of the cycle. Reassembled and no binding detected.

Shocks work fine. I put new 30w and significantly uprated springs on it yesterday. Still won't prevent skid slaps from more than 6" off the floor.

You're over thinking it. The reason that it won't return to "static" height is... tire scrub. Remember, as the front suspension cycles from full droop to full compression, your track width goes wide-narrow-wide. Unless you're doing your experimenting on a polished surface that is greased with pig snot, the tires are going to have lateral resistance which will prevent the front suspension from moving as easily as it would if the tires were rolling. I'll still suggest: go drive it and report back!

I'm possibly overthinking it. Tire scrub is the first suggestion I've heard that I hadn't considered already. I might have to go give it a bit of a shakedown in the rain.

 

[mass-hole]

I just disassembled and reassembled the front suspension again. I did find a tiny bind in the ball at the knuckle end of the right hand tie rod at the very bottom of the cycle. Reassembled and no binding detected.

Shocks work fine. I put new 30w and significantly uprated springs on it yesterday. Still won't prevent skid slaps from more than 6" off the floor.



I'm possibly overthinking it. Tire scrub is the first suggestion I've heard that I hadn't considered already. I might have to go give it a bit of a shakedown in the rain.

Best thing to do would be to take it off a jump and then let it roll to a stop to see where the suspension ends up. That way the tire scrub won't be as much of a factor.

The other thing I have done is put a napkin or dryer sheet under the front tires when I do a squish test on my dining room table, and that lets the tires slide in and out. It's not perfect, but its better than the rubber tires gripping the table.

 

[elRayRay]

Best thing to do would be to take it off a jump and then let it roll to a stop to see where the suspension ends up. That way the tire scrub won't be as much of a factor.

The other thing I have done is put a napkin or dryer sheet under the front tires when I do a squish test on my dining room table, and that lets the tires slide in and out. It's not perfect, but its better than the rubber tires gripping the table.

I took it for a quick thrash in the park yesterday. I haven't hit any jumps, but it's definitely way too low for my liking. The left and right edges of the pan are in the dirt on fast turns that keep all 4 wheels on the ground. The front plastic bumper skid is the first thing to contact uneven sidewalk joints. It is definitely fast enough and handles well, it just drags the front of the skid through the dirt.

Answer me a simple question, please: If you set your Baja Rey on a smooth, hard surface and compress its suspension to the floor, how much clearance do you have under the front of the skid after rebound? If I press down on my front suspension, there is almost no detectable spring resistance and the front skid rebounds to less than 10-12 mm above the floor.

*edit - I actually just knocked most of yesterday's mud splatterings off and checked again. The shocks give no detectable rebound and all regained ground clearance is from the tire foams expanding. I'm probably going to take the suspension arms off and hit them with a Dremel in a few key areas and try it again. Either they are creating more friction than I can feel or I'm on the hunt for the stiffest front springs I can find.

 

[TheLetterJ]

24mm on mine, 7mm at full compression, 68mm at full droop, so it's sitting VERY deep in its travel. I'll go ahead and say there's a good bit of error in there for my tires squishing and my "squint one eye real hard and bite my tongue while it sticks out of my mouth" measuring technique, but I hope that's enough for the reference you're looking for.

 

[elRayRay]

24mm on mine, 7mm at full compression, 68mm at full droop, so it's sitting VERY deep in its travel. I'll go ahead and say there's a good bit of error in there for my tires squishing and my "squint one eye real hard and bite my tongue while it sticks out of my mouth" measuring technique, but I hope that's enough for the reference you're looking for.

I'm assuming that you're running the stock shocks and bumpstops, correct?

 

[TheLetterJ]

Correct. 10mm of thread showing on the front shock bodies, 42wt oil. Rear has 8mm of thread showing and 60wt oil. My tires (rc4wd baja claw sct) are a smidge taller than stock too. It could still benefit from firmer springs with less preload, but it handles fairly balanced front/rear right now

 

[elRayRay]

Thanks for your responses and to all for your help and suggestions. I think I'm on my own here.

I took off the lower arms again and sanded them enough to get them to flop around on their own weight. Reassembled and still have the same issue. This is incredibly frustrating as I really think I'm going to love this thing when I finally get it dialed in. I'm just very confused as to why I need such stiff springs up front when nobody else seems to.

 

[mass-hole]

I was running Powerstroke XT's in the rear. I just got my Powerstroke front shocks(after the first pair got ground to a pulp by a USPS sorting machine) and I agree that this thing seems to be tough to get dialed in. I did also get the Powerstroke spring assortment to let me perfect it. Just to give you an idea of what I am finding works in the front:

Primary(little) Spring: 9.5 in/lb - Red
Secondary(big) spring: 3.6 in/lb - Green

This gives it a 2.6 in/lb rate while both springs are engaged. It then switches to 3.6 in/lb once the primary collapses. I had to run the heaviest primary because the lighter ones were basically fully collapsed just sitting at ride height. So I still get some light bump compliance but it stiffens a little ways into the travel. It seems to be enough where I don't have to run an insane amount of pre-load and it still comes back to 30% droop after a squish test.

Now I am having an issue getting the rear to work well with the front. I had a lighter spring on it that seemed to hold the truck up well, but now that I have the new springs out front, the rears are relatively weak. If I put the truck into full articulation the rear will compress while the opposite front shock stays somewhat extended. I am imagining that a stiffer rear spring will result in the two tires having enough strength to lift the truck without fully compressing.

I put together this spring calculator if you wanna play with it:

https://docs.google.com/spreadsheets/d/1q1a64YEeYJUrd48o_KJYfrF52XRyJApzmDxMqC03x-w/edit?usp=sharing

 

[elRayRay]

I was running Powerstroke XT's in the rear. I just got my Powerstroke front shocks(after the first pair got ground to a pulp by a USPS sorting machine) and I agree that this thing seems to be tough to get dialed in. I did also get the Powerstroke spring assortment to let me perfect it. Just to give you an idea of what I am finding works in the front:

Primary(little) Spring: 9.5 in/lb - Red
Secondary(big) spring: 3.6 in/lb - Green

This gives it a 2.6 in/lb rate while both springs are engaged. It then switches to 3.6 in/lb once the primary collapses. I had to run the heaviest primary because the lighter ones were basically fully collapsed just sitting at ride height. So I still get some light bump compliance but it stiffens a little ways into the travel. It seems to be enough where I don't have to run an insane amount of pre-load and it still comes back to 30% droop after a squish test.

Now I am having an issue getting the rear to work well with the front. I had a lighter spring on it that seemed to hold the truck up well, but now that I have the new springs out front, the rears are relatively weak. If I put the truck into full articulation the rear will compress while the opposite front shock stays somewhat extended. I am imagining that a stiffer rear spring will result in the two tires having enough strength to lift the truck without fully compressing.

I put together this spring calculator if you wanna play with it:

https://docs.google.com/spreadsheets/d/1q1a64YEeYJUrd48o_KJYfrF52XRyJApzmDxMqC03x-w/edit?usp=sharing

Thank you so much for this response!

I'm curious about your units, though. I thought that spring rates are lb/in, not in/lb. One would be understood as "the amount of force needed to compress the spring one inch," the other is "the number of inches the spring compresses under one lb of force." Based on your reference of "the heaviest primaries," I think you have it backwards. Just looking for clarification here.

At present, I have borrowed a pair of 110mm Desert Lizard shocks that have a soft, short upper spring to limit the length to 100mm and a very stiff longer spring for suspension travel. It seems to finally have the targeted ride height, but I haven't been able o drive it to check it out, yet. Maybe this afternoon.

I'm afraid that I'm going to have to bite the bullet and spend $120 on a set of shocks for this thing...and I still need to finish my crawler. :roll:

 

[mass-hole]

Thank you so much for this response!

I'm curious about your units, though. I thought that spring rates are lb/in, not in/lb. One would be understood as "the amount of force needed to compress the spring one inch," the other is "the number of inches the spring compresses under one lb of force." Based on your reference of "the heaviest primaries," I think you have it backwards. Just looking for clarification here.

At present, I have borrowed a pair of 110mm Desert Lizard shocks that have a soft, short upper spring to limit the length to 100mm and a very stiff longer spring for suspension travel. It seems to finally have the targeted ride height, but I haven't been able o drive it to check it out, yet. Maybe this afternoon.

I'm afraid that I'm going to have to bite the bullet and spend $120 on a set of shocks for this thing...and I still need to finish my crawler. :roll:

Your right on the units. Just typed it in wrong.