Suspension Travel Question

PDenbigh · 10-08-2007, 11:10 AM

Those of you that track/race or read a lot...

I'm working on the suspension setup of the XR. (Yeah, finally working on it again...)

I'm going to be riding with the frame rails roughly 6" off the ground. How much suspension travel is considered appropriate for a pretty stiffly sprung/even stiffer swaybar'd track only car? 2" each direction enough ya think? 3"?

Anyone care to share what some of the "Tune to win" type books say? Or personal experience?

Thanks,
Peter

**Mike** · 10-08-2007, 11:11 AM

I have "How to make your car handle." If you'd like to pay shipping ($3 for media mail), you're welcome to borrow it.

It's a pretty advanced book... I haven't gotten to it yet.

.RJ · 10-08-2007, 11:18 AM

I had ~2.5" of suspension travel in bump on the front of my racecar (850# springs, ~425# at the wheel) - any more and the shocks would hit the bumpstops, upper a-arms hit the frame rail and the springs would coil bind - it was a fine line between ride height and spring length. You may need less travel with struts.

white_2kgt · 10-09-2007, 09:19 AM

Depends on the track, you want more travel at Summit and less at VIR. I had 2 sets of springs, I'd run stiffer springs at VIR and therefore had less travel. I was just at 2" bump and ~3" droop with the stiffer springs (needed internal limiters on the shocks but never got around to it).

PDenbigh · 10-09-2007, 09:51 AM

The shock I am looking at is a ProShock double adjustable. It technically has 8" of travel. With the car at the desired ride height I'm looking at 2-3" of compression travel limited by what I can physically clear. I guess I could put droop limiters on if there's an advantage to that.

As far as changing the travel - I can see the advantages to this. VIR and WGI I could keep the car pretty tight. Summit Main is pretty bumpy (or was, pending outcome of pavement rumors) so is that why you had more travel? And then there's Shenandoah where I feel like I'd need my truck going into the bowl to prevent bottoming out dangerously hard. Interestingly, I've never driven Shenandoah though.

In the end, I'd really like to just fine one setting that worked well and not have to bother switching stuff around. Is that a pipe dream?

.RJ · 10-09-2007, 09:52 AM

Pete, you can also have your konis revalved and the bodies shortened if you are looking for 'more' shock. [Image: kool.gif]

PDenbigh · 10-09-2007, 09:56 AM

Really? They're pretty generic Koni's. The fronts started life as struts, were then ground down and converted to coilovers. The rears won't work because they are smooth and I want coilovers in the rear.

Thoughts?

.RJ · 10-09-2007, 10:02 AM

PDenbigh Wrote:Thoughts?

Koni can rework 'em - sending you an email now.

white_2kgt · 10-09-2007, 01:05 PM

PDenbigh Wrote:Really? They're pretty generic Koni's. The fronts started life as struts, were then ground down and converted to coilovers. The rears won't work because they are smooth and I want coilovers in the rear.

Thoughts?

My rears were originally smooth, few hrs in a machine shop and you can convert just about anything into something else. I know nothing about 'ProShock' but if I were you I'd stick to a company that knows a thing or two about racing shocks. Koni fits the bill for this although they will need regular maintenance and probably cost more, but if you are going to do it, do it right.

.RJ · 10-09-2007, 01:08 PM

white_2kgt Wrote:Koni fits the bill for this although they will need regular maintenance and probably cost more

What regular maintenance? Never heard of that...

**Mike** · 10-09-2007, 01:10 PM

.RJ Wrote:
white_2kgt Wrote:Koni fits the bill for this although they will need regular maintenance and probably cost more

What regular maintenance? Never heard of that...

even i've heard of the lack of koni longevity stories.

Evan · 10-09-2007, 01:13 PM

white_2kgt Wrote:if I were you I'd stick to a company that knows a thing or two about racing shocks. Koni fits the bill for this although they will need regular maintenance and probably cost more, but if you are going to do it, do it right.

..except Koni Sports are street shocks. You can dump a ton of money into them to change the valving and shock length to make them kinda sorta race shocks, but you are still left with a overpriced small piston street shock and its limitations. If that fits your goals and your budget, then it could be a good choice. Personally, I think its wiser to spend a bit more and get real race shocks if that is your goal.

.RJ · 10-09-2007, 01:14 PM

Mike Wrote:even i've heard of the lack of koni longevity stories.

Please enlighten me... I've never heard of an issue where konis have had 'reliability' issues. I tried to kill mine (not intentionally) and couldnt, even at 90+ mph through grass and gravel traps, with 4 wheels off the ground.

Evan Wrote:Personally, I think its wiser to spend a bit more and get real race shocks if that is your goal.

No doubt a Koni 28xx (or its equivalent strut insert) is going to be better, but they're going to be over $2000 for a set of dampers. The 'real' dampers usually also have a compression adjustment too, and this may or may not be a good thing depending on what your goals are.

I think a set of revalved/reworked yellows, while not the 'best', is a pretty good value in terms of whats out there and they certainly get the job done - I know i'm all up in the kool aid on this one, but plenty of lap records have been set with these "street shocks".

**Mike** · 10-09-2007, 01:26 PM

.RJ Wrote:
Mike Wrote:even i've heard of the lack of koni longevity stories.

Please enlighten me... I've never heard of an issue where konis have had 'reliability' issues. I tried to kill mine (not intentionally) and couldnt, even at 90+ mph through grass and gravel traps, with 4 wheels off the ground.

search honda-tech.

.RJ Wrote:I think a set of revalved/reworked yellows, while not the 'best', is a pretty good value in terms of whats out there and they certainly get the job done - I know i'm all up in the kool aid on this one, but plenty of lap records have been set with these "street shocks".

agreed.

.RJ · 10-09-2007, 01:29 PM

Mike Wrote:search honda-tech.

The BS factor is too high there to take much seriously. If you have some links with reputable info, I'd like to read them and see what you're getting at but I'm not going to go digging through there looking for it.

**Mike** · 10-09-2007, 01:30 PM

.RJ Wrote:
Mike Wrote:search honda-tech.

The BS factor is too high there to take much seriously. If you have some links with reputable info, I'd like to read them and see what you're getting at but I'm not going to go digging through there looking for it.

I am also not going digging.

.RJ · 10-09-2007, 01:31 PM

Mike Wrote:I am also not going digging.

Ok then...

white_2kgt · 10-09-2007, 02:17 PM

.RJ Wrote:
Mike Wrote:search honda-tech.

The BS factor is too high there to take much seriously. If you have some links with reputable info, I'd like to read them and see what you're getting at but I'm not going to go digging through there looking for it.

Search corner-carvers then.

Evan · 10-09-2007, 02:32 PM

.RJ Wrote:I think a set of revalved/reworked yellows, while not the 'best', is a pretty good value in terms of whats out there and they certainly get the job done - I know i'm all up in the kool aid on this one, but plenty of lap records have been set with these "street shocks".

I figured you have been on the receiving end of Scott Giles LogicÔäó way too many times to try to use it yourself Wink

Because of course you know it doesnt mean much.

Id agree with you on a dual purpose street/track car, but as soon as you get into a purpose race car, and dumping money into revalving and shortening the shocks, they arent too cheap anymore, at least in comparison to their performance.
I still stand behind the back to back comparison at Beaverun between your car on konis and my showkar jdm shocks. You felt it, I felt it, the konis sucked bad in comparison.

I guess this really brings up the question, what affordable real race shocks are there? Is advance design still around? Any other brands for $1k-$1.5k ?
I dont think the race konis at around $2k for the car is crazy expensive and probably worth it over the yellows imo.

.RJ · 10-09-2007, 02:39 PM

Evan Wrote:Id agree with you on a dual purpose street/track car, but as soon as you get into a purpose race car, and dumping money into revalving and shortening the shocks, they arent too cheap anymore, at least in comparison to their performance.

If you can pick up a used set of yellows it will run you at most a total investment of $1000-$1100 for a shortened/revalved set. I was pretty happy with their performance, and I've driven other cars with them as well.

The 'off the shelf' yellows are definitely a street shock and they're soft to maintain ride quality - its a pretty significant difference once they're revalved and worth the $$ IMO.

Quote:I dont think the race konis at around $2k for the car is crazy expensive and probably worth it over the yellows imo.

Just depends on what your budget and goals are. If you've got the $$ and can do some fabrication to get things to work on an uncommon application like an XR, then its certainly money well spent - you wont be dissapointed. If you're not into the Koni thing you can get custom applications from Penske, dynamic suspension, moton and a few others. Everything I've read about the advanced designs is they're fragile and the customer service is horrible.

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