Bypass theory

Hey @ADSRACINGSHOCKS thanks for all the awesome info.

I'm running a chaos lt with bypasses up front, and a sua with cantilever in the rear, with 2.5x10in triples on an extended cab Tacoma.
I know I really need to run heavier compression and rebound. All tubes are a half turn from closed, and the truck still bucks like crazy when getting any kind of speed.

I'm thinking of bumping up to 3.0's (or 3.5's if they fit) because I'm seeing a big heat difference front compared to rear.

At what point does it become too much bypass, and I'd start seeing dramatic diminishing return?
 
Hey @ADSRACINGSHOCKS thanks for all the awesome info.

I'm running a chaos lt with bypasses up front, and a sua with cantilever in the rear, with 2.5x10in triples on an extended cab Tacoma.
I know I really need to run heavier compression and rebound. All tubes are a half turn from closed, and the truck still bucks like crazy when getting any kind of speed.

I'm thinking of bumping up to 3.0's (or 3.5's if they fit) because I'm seeing a big heat difference front compared to rear.

At what point does it become too much bypass, and I'd start seeing dramatic diminishing return?
A lot of your heat is coming from the tubes being closed, nearly all of the fluid flow is trying to go thru the piston which creates heat, allowing the fluid to bypass in the right zone and the right amount is obviously the goal here, revalving what you have would yield you big gains, and most likely help you run cooler temps for a longer range. To answer your question about when does a shock become too big you have to look at flow, just by going up a size does not guarantee performance its all about tube size and placement, if you have a 2.5" with .75" tubes on it now and you jump to a 3.0 or 3.5 with the same .75" tubes your going to be flowing quite a bit more fluid thru those tubes or at least attempting too. You may not be able to put the valving in that you are expecting. You will see alot of older style shocks with staggered tubes and small tubes from back in the day they were learning back then what worked and what they could get away with in manufacturing costs. On our cantilever 3.0" x10" we run 4 tubes 2 compression and 2 rebound they are overlapping and set up to function in the motion ratios of the cantilever.
 
What's your thoughts about free bleed tubes without a spring just a plunger to slow the oil down under faster speeds? I believe fox does them with a Gold housing instead of the blue/red for comp and rebound?
 
What's your thoughts about free bleed tubes without a spring just a plunger to slow the oil down under faster speeds? I believe fox does them with a Gold housing instead of the blue/red for comp and rebound?
They are very effective if used correctly, generally they need to be in the 1st (lower) compression zone, they will eliminate all low speed valving in that zone so its not for every application, consider it a tool in the tool box that works on some things but not everything.
 
Ok that's what I noticed when I had them on my Fox 3.0 bypasses. They made smaller chatter feel smooth but they had too much free bleed for slower shaft speeds. I changed them out to normal compression adjusters and plugged 2 free bleed in piston to control the slow speed flow. I also had overlapping tubes so even with them open a little bit it was too little valving for slow speed. Changed from the middle tube to bottom tube and it helped but not enough so I eliminated them.
 
This is all great information. I have a somewhat related question. In ur opinion what is the ideal motion ratio and why? I like to hear what different manufacturers and tunners theories are. Most I have talked to like to shoot for a 1(shock) to 1.75 (suspension) motion ratio. Also would like to know what ur stance on digressive shock geometry? I have heard that if you are within 10 degrees (10* being extraleam) of 90 the effect on the shocks is not noticeable. That being said I fell like that would mainly apply to big shocks and not smaller diameter stuff.
 
Yeah I've heard the same things as Ryan has said. Always like to hear different or the same opinion on these from different manufacturers
 
This is all great information. I have a somewhat related question. In ur opinion what is the ideal motion ratio and why? I like to hear what different manufacturers and tunners theories are. Most I have talked to like to shoot for a 1(shock) to 1.75 (suspension) motion ratio. Also would like to know what ur stance on digressive shock geometry? I have heard that if you are within 10 degrees (10* being extraleam) of 90 the effect on the shocks is not noticeable. That being said I fell like that would mainly apply to big shocks and not smaller diameter stuff.
There is no ideal motion ratio because all vehicles are different, generally from our experience more than 2:1 and your really working the limits of component strength, and asking the damper to do a-lot of work creating more heat and wear. We did work on a product for a industrial SxS that had a little over a 2:1 ratio on it it turned out working great but took quite a bit of tuning to make perform to their needs, and it was really pushing the limits of the arm design. to summarize, if your shocks are of old design and you are struggling with flow issues and cant get the shaft speed out of them it is the shocks fault not the ratio, more ratio could help the issue by slowing down the shaft but its not the fix. ALL of our bypasses have high flow reservoir ports to prevent the shaft displacement from being a fluid restriction. and we match tube flow to shock size for each application.

Ratio is help full for packaging realistic lengths into trucks, it would be really hard to get a 16" coil over under the hood of a Tacoma, and a 30" travel axle mounted bypass sticking out the back end of a truck would be silly. If your specific shock can flow enough fluid to keep up with the shaft speeds you are developing, then you would be in the operating window of your hardware. the closer you are to 1:1 or even less ratio the shocks would run a little cooler in theory since it wouldn't be working as hard to control the forces, think less valving to do the same work. (see the back of Kyle Leduc's pro 4 truck.)
We compensate for these scenarios by going to larger shocks with greater fluid capacity and flow that can generate greater damping forces.
choosing the right tool for the job is a better way to look at it, if your running a 1500lb dune buggy im not going to recommend a 4.0 shock its would be the wrong tool for the job would i recommend a 2.5 shock for the back of your trailing arm race truck also no its not the right tool.



I don't want to start the argument on "my buddy has digressive shock geometry and it works fine", "fine or good" is all relative, if your asking what we design and work with, you always want your suspension to be progressive or linear in design. don't go past 90 degrees the forces are nearly impossible to control, you start fighting flow issues because you have to nearly go solid with valving which feels like trash, most of these guys that say it works are HEAVILY relying on the hydro bump to catch all the slack.

We have recommended to many, that they make changes from digressive to progressive and they have been extremely thankful after making the changes, you might loose a little travel depending on your design but you will be able to effectively control your suspension which is the whole point of what an high end shock is for.

You guys can debate all you want but that's all we will contribute to it hahaha
 
There is no ideal motion ratio because all vehicles are different, generally from our experience more than 2:1 and your really working the limits of component strength, and asking the damper to do a-lot of work creating more heat and wear. We did work on a product for a industrial SxS that had a little over a 2:1 ratio on it it turned out working great but took quite a bit of tuning to make perform to their needs, and it was really pushing the limits of the arm design. to summarize, if your shocks are of old design and you are struggling with flow issues and cant get the shaft speed out of them it is the shocks fault not the ratio, more ratio could help the issue by slowing down the shaft but its not the fix. ALL of our bypasses have high flow reservoir ports to prevent the shaft displacement from being a fluid restriction. and we match tube flow to shock size for each application.

Ratio is help full for packaging realistic lengths into trucks, it would be really hard to get a 16" coil over under the hood of a Tacoma, and a 30" travel axle mounted bypass sticking out the back end of a truck would be silly. If your specific shock can flow enough fluid to keep up with the shaft speeds you are developing, then you would be in the operating window of your hardware. the closer you are to 1:1 or even less ratio the shocks would run a little cooler in theory since it wouldn't be working as hard to control the forces, think less valving to do the same work. (see the back of Kyle Leduc's pro 4 truck.)
We compensate for these scenarios by going to larger shocks with greater fluid capacity and flow that can generate greater damping forces.
choosing the right tool for the job is a better way to look at it, if your running a 1500lb dune buggy im not going to recommend a 4.0 shock its would be the wrong tool for the job would i recommend a 2.5 shock for the back of your trailing arm race truck also no its not the right tool.



I don't want to start the argument on "my buddy has digressive shock geometry and it works fine", "fine or good" is all relative, if your asking what we design and work with, you always want your suspension to be progressive or linear in design. don't go past 90 degrees the forces are nearly impossible to control, you start fighting flow issues because you have to nearly go solid with valving which feels like trash, most of these guys that say it works are HEAVILY relying on the hydro bump to catch all the slack.

We have recommended to many, that they make changes from digressive to progressive and they have been extremely thankful after making the changes, you might loose a little travel depending on your design but you will be able to effectively control your suspension which is the whole point of what an high end shock is for.

You guys can debate all you want but that's all we will contribute to it hahaha
Good information. I am no shock goerue but I do believe that you have to start with good shock geometry and suspension geometry. You can band-aid alot with tuning but how much are you leaving on the table. In the end a truck that is comfortable to someone may be horrible to another based on their driving style. I listened to one of the JEHC pod cast and he talked about digressive geometry and it not being a big deal so I like to get perspective from the guys that have to work with it hands on.

Thanks for the reply!
 
Good information. I am no shock goerue but I do believe that you have to start with good shock geometry and suspension geometry. You can band-aid alot with tuning but how much are you leaving on the table. In the end a truck that is comfortable to someone may be horrible to another based on their driving style. I listened to one of the JEHC pod cast and he talked about digressive geometry and it not being a big deal so I like to get perspective from the guys that have to work with it hands on.

Thanks for the reply!
You nailed it on the head, just like building a wall its only as strong as the first brick you lay, if you start with good geometry the rest of the system will function correctly and falls into place. Its always a joy of mine when i get to tune on a car that is set up correctly from a geometry stand point the shock tune always comes out so much nicer and easier.
 
A lot of your heat is coming from the tubes being closed, nearly all of the fluid flow is trying to go thru the piston which creates heat, allowing the fluid to bypass in the right zone and the right amount is obviously the goal here, revalving what you have would yield you big gains, and most likely help you run cooler temps for a longer range. To answer your question about when does a shock become too big you have to look at flow, just by going up a size does not guarantee performance its all about tube size and placement, if you have a 2.5" with .75" tubes on it now and you jump to a 3.0 or 3.5 with the same .75" tubes your going to be flowing quite a bit more fluid thru those tubes or at least attempting too. You may not be able to put the valving in that you are expecting. You will see alot of older style shocks with staggered tubes and small tubes from back in the day they were learning back then what worked and what they could get away with in manufacturing costs. On our cantilever 3.0" x10" we run 4 tubes 2 compression and 2 rebound they are overlapping and set up to function in the motion ratios of the cantilever.
Would it be worth trying to tune and see if the 2.5 can handle it? Or should I start planning on getting a 3.0 with bigger tubes?
When I first started being able to stretch the rear end, I hit up the shop that did the work, and was told the valving is stock Fox valving, with overlapping compression tubes.

I see you talking about motion ratios. I think I'm about 17in of travel on the 10in shock.
 
17 - 10" shock is normal for front end that's 1.7:1 ratio. Some shock tuners feel the need for larger diameter bypass tubes, like the link killer bypasses for the spring under leafs. Do you guys ever have people order a 2.5/3.0 bypass with larger 1-1/4" bypass tubes from the larger 4.0+ shocks?
 
Would it be worth trying to tune and see if the 2.5 can handle it? Or should I start planning on getting a 3.0 with bigger tubes?
When I first started being able to stretch the rear end, I hit up the shop that did the work, and was told the valving is stock Fox valving, with overlapping compression tubes.

I see you talking about motion ratios. I think I'm about 17in of travel on the 10in shock.
I would definitely revalve them first, they have the wrong name on them, so I'm happy to sell you something if you dont want to go that route :)
 
17 - 10" shock is normal for front end that's 1.7:1 ratio. Some shock tuners feel the need for larger diameter bypass tubes, like the link killer bypasses for the spring under leafs. Do you guys ever have people order a 2.5/3.0 bypass with larger 1-1/4" bypass tubes from the larger 4.0+ shocks?
There are brands that have flow issues and the bigger tubes help, we size all of our tubes to each shock design, we have made large staggered tube layouts on smaller bodies but it was only due to space constraints, if you over tube a shock the adjustment resolution can get funny. Without naming brands you will see them add what they consider large tubes to things bit in reality the flow rates of the tubes were just too low to begin with it's not just the size of the tube valve design and ports are also part of the equation
 
I'm running a chaos lt with bypasses up front, and a sua with cantilever in the rear, with 2.5x10in triples on an extended cab Tacoma.
I know I really need to run heavier compression and rebound. All tubes are a half turn from closed, and the truck still bucks like crazy when getting any kind of speed.

rebound damping doesnt stop bucking, typically makes it worse.

as mentioned figure out the valving in the shock before anything, since they are foxes they should have a part number stamped on the dust cap 980-02-xxx if its an off the shelf shock or 980-02-xxx-1 if its custom. depending on the canti kit they do some goofy stuff as they approach the bump zone. it is possible its a geometry issue.
 
rebound damping doesnt stop bucking, typically makes it worse.

as mentioned figure out the valving in the shock before anything, since they are foxes they should have a part number stamped on the dust cap 980-02-xxx if its an off the shelf shock or 980-02-xxx-1 if its custom. depending on the canti kit they do some goofy stuff as they approach the bump zone. it is possible its a geometry issue.
Everything above is correct, as he stated make sure that thing cycles cleanly a big travel number that swings dirty is not as effective in real world usage make sure it doesnt become digressive at bump
 
Question for you. When running both a bypass and coilover on the front end, do you normally remove the valving from the coilover all together and let the bypass handle all of the work or do you still leave some valving in there to help?
 
Back
Top