With everything stock in my SRX I was able to run 105 mph on speedometer in a 1/4 mile, and 118 mph on a long run. I was over revving on top end, pulling 8800 and holding there.
Then I tried this popular setup:
Stock 8dn-20 weights loaded with 4.5 gram rivets in the inner and tip
W-W-W primary spring
48/40 Advant Edge helix (a lot more aggressive than a 48/40, more like a 54/44)
Green spring at 6 and 1 for 70 wrap
Then I ran 108 mph on speedometer in a 1/4 mile, but was only able to pull 115 mph on a long run, despite my rpm being bang on at 8500 and staying there! So I wouldn't have thought my top speed would decrease given it was holding the ideal rpm for a stock motor.
So how can I get my top end back? I don't mind sacrificing back shift at this point. Maybe change the wrap of the green to 60, or try a red at 80? Any feedback would be great, thanks guys.
Then I tried this popular setup:
Stock 8dn-20 weights loaded with 4.5 gram rivets in the inner and tip
W-W-W primary spring
48/40 Advant Edge helix (a lot more aggressive than a 48/40, more like a 54/44)
Green spring at 6 and 1 for 70 wrap
Then I ran 108 mph on speedometer in a 1/4 mile, but was only able to pull 115 mph on a long run, despite my rpm being bang on at 8500 and staying there! So I wouldn't have thought my top speed would decrease given it was holding the ideal rpm for a stock motor.
So how can I get my top end back? I don't mind sacrificing back shift at this point. Maybe change the wrap of the green to 60, or try a red at 80? Any feedback would be great, thanks guys.
sounds like you gained... you hit a higher speed in your quarter mile. you may have lost that extra 3 mph from the motor no longer over reving to 8800 on the top end. you might be at the top of your gear ratio at 115 mph @ 8500 rpm if you know what im saying. not 100 percent sure how much mph a stock geared srx @ 8500rpm will pull tho. just an idea anyway.
YAMMIEGOD3:16
Active member
WHAT WEIGHTS YOU DO YOUR FIRST RESULTS WITH. 3:16 (yammie tony)
Hey andrew k I thought about that, but when an engine revs past it's shift rpm you lose efficiency, power and speed consequently. I believe my loss of speed can be attributed to the green secondary spring.
And Yammie I ran stock 8dn-20 weights with stock rivets. Everything in the sled was stock, I was surprised to pull 118 on speedometer considering I was over revving to 8800. Top end rpm was spot on after installing clutch parts as listed.
Would a wrap of 60 be better for lake / top end speed, or maybe just a stock red at stock setting of 80.
And Yammie I ran stock 8dn-20 weights with stock rivets. Everything in the sled was stock, I was surprised to pull 118 on speedometer considering I was over revving to 8800. Top end rpm was spot on after installing clutch parts as listed.
Would a wrap of 60 be better for lake / top end speed, or maybe just a stock red at stock setting of 80.
YAMMIEGOD3:16
Active member
118 ON A SRX SPEED-O IS 108 IN REAL LIFE. STILL VERY GOOD. HARD TO SAY WHATS BETTER. YOUR DOING IT RIGHT TESTING HERE. I LIKE THE RED SPRING WRAPED AT 80 , WORKED GREAT IN MY 8BU-10 SET-UP. 3:16 (yammie tony)
Yeah Yammi that's what I was thinking, red at 80. I just tried green at 60 and it under revved quite significantly. Would hold 8200 allowing me to get up to 114 mph or so, then backed off to 8000 even yielding 105 mph. Weird how a wrap change would skew my top end rpm that much. At 70 it was pretty well bang on, but the fact that I was using a green spring I believe was holding back top speed because it has more side pressure, gripping the belt for back shift, but results in more friction.
Although the temps were warmer. Could be a contributing factor, just tried red at 80 and still under revved to 8200, but held that rpm. Haven't tried green at 70 today, could just be poor conditions.
YAMMIEGOD3:16
Active member
THATS VERY IMPORTANT. TO MUCH, SPRING BIND, NOT ENOUGH, BELT SLIPS. have to find sweet spot. good job man. keep testing. 3:16 (YAMMIE TONY)
On hard acceleration with the red spring set to 80 I noticed my track (I believe) was ratcheting? And my rpm was holding 8200 steady. Obviously this calls for a track tightening, I'm just wondering why it wasn't like this with the green spring at 60 or even 70. Seems like the green at 70 is about the only thing that has worked so far, but from reading I discovered the red is better for top end wot riding, which is what I'm interested in. Not sure what wrap to go with next on the red spring.
mabey your getting more power to the track with the red sping. the primary and secondary will fight eachother resulting in a power loss if you have too much clamp load on the 2ndary clutch. 2ndary will try to keep the back shift while the primary is trying to up shift.
one more question? how did the heat in the clutches feel with the red at 80? mabey you may benefit overall now with a lttle less weight in your 8dn20's
Clutches were cool to touch with all combinations so far. Actually when the sled was stock it was quite hot to touch, I was over revving to 8800. I'd rather not have to mess with the primary, the w-w-w with weights loaded up works well, I was just trying to see if I could get the red spring to work in order to restore some top end loss. Not sure where to go from here, may try red spring again, 70 wrap?
youll never get that perfect combo. if you dont adjust all aspects of the clutch for fine tuning. my guess red at 70 would be a little worse for your top rpm being ideal. but as i learned its hard to go exactly by the book tho when i was doing some clutching. funky stuff does happen sometimes. could try it and see what happens tho.
davidgboy
New member
thats correct. u can only go so fast at 8500 r.p.m. for a given max. ratio that your clutches are able to achieve. thats why u had to hit 8800 to have more top end. i would shoot for the quickest time in the 1/4 and consider that peak performance.andrew k said:
bluemonster1
LIFE MEMBER ONLY ONCE!!!
all you can do is try..Go Red at 80,Red at 70 and even Red at 60 and see what happens.Don't take long to make the changes .Try Green at 60 also just for the hell of it.Write everything down with each test.One change at a time.Basically you start with stock..that is Red at 80..so now drop the wrap to 70 and then 60 with Red Spring..now take note of the outcomes.Do the same with the Green Spring.In a few hours you will know what works and what does not...test..test...test...never ends..
davidgboy said:
Right but a stock SRX motor makes the most hp at 8500, any above that and you lose clutch efficiency and therefore top speed. I believe I was able to hit that speed because of the red secondary spring. So if I can get that spring to work in my current setup and pull the proper rpm on top end... 8400-8500 I should get my top end back, if not increase it.
LaPorte429 said:
right you lose hp at 8800. at 8200 you lose as well but you were holding a straight shift curve with the red. thats the key. thats the only reason why i suggested grinding a little off the rivits. try grinding .2 g off the tip. will raise your rpm. and if your clutches are cool that typically means you have enough 2nndary clamping force. take good notes and change one thing at a time. edit: remember using excessive clamping force on the 2ndary is a bandaid and will cost you hp.
Last edited:
Macheater
New member
Couple other things to think about that haven't been mentioned yet. You say "long run" but not how long? Reason I bring this up is because with HOT pipes the peak horsepower rpm is rising. That combined with a few hundred rpm's of potential tach error could explain a higher top speed as well. It isn't always about clutching. Again, just something to think about.
YAMMIEGOD3:16
Active member
Macheater said:
great points. 3:16 (yammie tony)
I think you have too shallow finish angle..
IF your SRX will not bury speedometer, something it wrong
IF your SRX will not bury speedometer, something it wrong