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Old 10-07-2014, 01:36 PM   #706
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The HPI Sprint2 is not all that bad for entry level sedan car. We sell lots at the LHS for VTA and an oval class that is run locally. We recommend replacing most of the rod ends with Lunsford or RPM 4-40 type cups. There is a nut on the servo saver that comes loose 99% of the time and that contributes to lotsa steering slop.

A drive shaft type car is always best for a stony/debris environment. Belts usually don't last long. There are several of these type cars at reasonable prices available.
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Last edited by rcwck; 10-08-2014 at 06:08 PM. Reason: MoInfo
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Old 10-08-2014, 01:44 PM   #707
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Thanks for the replies guys. I was just looking at upgrades for the Sprint 2 (like aluminum parts and carbon chassis) to make it really handle well but it's tough to justify the upgrades when a kit like this one comes in at the same price as a fully upgraded S2 and this one looks to be higher quality. Just want to make sure it doesn't make more sense to start with another platform, or just say screw it and upgrade the S2 and enjoy it. All the guys here at work are already buying nicer cars and I don't know that I can keep up with their spending habits, so upgrading the S2 incrementally might work better for my needs. I just don't want to be the one running a crappy car while they all run laps around me with their higher end kits (one of the guys here is waiting for his H4 to be delivered). Luckily I think I'm a better driver than most of them.

I'm actually waiting for my RPM cups to arrive this week.
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Old 10-08-2014, 06:40 PM   #708
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Quote:
Originally Posted by Ludachris View Post
Thanks for the replies guys. I was just looking at upgrades for the Sprint 2 (like aluminum parts and carbon chassis) to make it really handle well but it's tough to justify the upgrades when a kit like this one comes in at the same price as a fully upgraded S2 and this one looks to be higher quality. Just want to make sure it doesn't make more sense to start with another platform, or just say screw it and upgrade the S2 and enjoy it. All the guys here at work are already buying nicer cars and I don't know that I can keep up with their spending habits, so upgrading the S2 incrementally might work better for my needs. I just don't want to be the one running a crappy car while they all run laps around me with their higher end kits (one of the guys here is waiting for his H4 to be delivered). Luckily I think I'm a better driver than most of them.

I'm actually waiting for my RPM cups to arrive this week.
You might want to contact these guys:
HPI Sprint 2 Mods - Making a silk purse from a sow's ear.
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Old 10-09-2014, 04:21 PM   #709
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All the guys here at work are already buying nicer cars and I don't know that I can keep up with their spending habits, so upgrading the S2 incrementally might work better for my needs.
At club racing events I've seen the most expensive setups driven by the worst drivers. If you want to outperform your co-workers I personally would tune your car for performance not bling. The cars I race have parts that are meant to increase performance and/or shave weight (thus increasing performance). My shelf queens are blinged out. Also not all aluminum parts are better than their plastic counterparts. You have to think, will that part bend even slightly if it takes a hit? It is hard to tell if an aluminum part is bent and it can really mess up performance.

I think it would be more fun to whip your co-workers with a more stock looking car than one that is blinged out. Create a sleeper! Show them you know how to tune a car ...not just throw $$ at it (it really won't make you or your car perform better w/o knowledge of how each part is actually effecting the car).
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Old 10-09-2014, 04:29 PM   #710
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by the way,
my season is officially done.

my H4 performed really well. I only broke that CVA joint in the first race it ran at the beginning of the season. I replaced it w/ the upgraded version from Ofna, no issue for the remaining 6 months worth of races. The car ran strong, consistent and was a contender in every race I ran. At this point I am mostly improving my own skills, staying on line and working on getting the best grip I can. The car is really doing everything I ask. Couldn't be more pleased w/ this car and how it performed all season.

Going to be tearing it down over the winter, checking every part and getting ready for next spring 2015 season! Oh, also plan on painting a new body for the 2015 season. My 2014 body held up well, but has some cracking around the front and front wheel arches.
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Old 10-14-2014, 07:51 AM   #711
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Default First carpet race of the season

We had our first Carpet race of the new season last weekend. The H4(dark blue car) started second and finished 2nd. This was the 8 minute VTA Main. Good job Mike and it's very difficult to keep up with Erik.

https://www.youtube.com/watch?v=MHp2wajaDr4

This is the sedan 17.5 stock class. Turnout was a bit small because the weather is still nice here and there are still outdoor activities. H4(black monster car) on the pole and the win.

https://www.youtube.com/watch?v=f1xpYWRqI_o

Filmed with a GoPro extreme wide angle config.
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Old 10-14-2014, 09:56 AM   #712
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Way to go RCWCK, and way to go H4

-my diff is leaking like crazy again. I've had this problem in the past and usually cleaning everything, drying, and putting back together solves the issue. -until I have to open it up again.

It is a really finicky process, I've now done the process 2x and it still leaks. I've checked the o ring, it is in great shape. I even tried putting some green slime on it this time. Still leaked.

I am kind of sick of the rear diff leaking and how finicky the thing is ...I'd like to be able to open it dump the oil, wipe clean, replenish and go. I don't have time to go through this crazy process at the track!

Question, is there a recommended replacement rear diff that will work? One that obviously does not leak? Something from another company like XRay? Kind of done playing around w/ this diff'.

edit: I looked through the posts on this thread, I did not see an alternative diff that is recommended. Only the wipe clean and green slime fix.
thanks,
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Old 10-14-2014, 11:53 AM   #713
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Originally Posted by eR1c View Post
Way to go RCWCK, and way to go H4

-my diff is leaking like crazy again. I've had this problem in the past and usually cleaning everything, drying, and putting back together solves the issue. -until I have to open it up again.

It is a really finicky process, I've now done the process 2x and it still leaks. I've checked the o ring, it is in great shape. I even tried putting some green slime on it this time. Still leaked.

I am kind of sick of the rear diff leaking and how finicky the thing is ...I'd like to be able to open it dump the oil, wipe clean, replenish and go. I don't have time to go through this crazy process at the track!

Question, is there a recommended replacement rear diff that will work? One that obviously does not leak? Something from another company like XRay? Kind of done playing around w/ this diff'.

edit: I looked through the posts on this thread, I did not see an alternative diff that is recommended. Only the wipe clean and green slime fix.
thanks,
You are correct about that being annoying. Both my rear diffs leaked until I found some larger O.D. o-rings for the output shafts. I assume you are talking about this area for leakage. Unfortunately I don't have a part # because I found the correct size in my misc o-ring box. I would take a stock one to the local hobby shop and look around for one with a bit larger outside diameter but keeping the same id.

You could also install another shim on top of the stock ring. That would help it to seal but would also create more drag/wear.

Might even try a thin coat of atv/silicone glue around the ring pocket before installing it making sure all is very clean beforehand. I would also let that glue cure with the ring installed before continuing.

Hope you figure it out without creating a Frankensedan.
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Old 10-14-2014, 12:55 PM   #714
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uh, i think it is leading from the large o-ring that is inside the rear diff'. There is a main o ring that is supposed to create a seal between the two halves of the rear diff assembly. It seems oil is leaking from this spot as I can see it leaking onto the outside of the gear teeth. It makes a huge mess as it gets all over the belts and such.

thanks, I may go to the hardware store, ..they have a ton of o rings. Will just look for one that is a tad thicker w/ the same OD. I think that is the issue, the supplied o ring is just a tad too small ...or if they made that channel that the o ring sits in not so deep then I could get a better seal.
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Old 10-14-2014, 01:22 PM   #715
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Quote:
We had our first Carpet race of the new season last weekend. The H4(dark blue car) started second and finished 2nd. This was the 8 minute VTA Main. Good job Mike and it's very difficult to keep up with Erik.

https://www.youtube.com/watch?v=MHp2wajaDr4
was a fun day. I was doing pretty good until I got hit and the upper front bumper support popped out from under the aluminum bulkhead. when that happens, the body posts lean forward and my body drags. I couldn't turn left very sharp for about 3 laps. I kept banging it against the boards trying to pop it back. finally got it right, but lost a lot of time. I don't think I could have kept up w/ Erik anyway, he is very hard to keep up with. planning on coming back next week too. gonna try the 17.5 sedan class. i'll try to stay out of your way.
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Old 10-14-2014, 05:31 PM   #716
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planning on coming back next week too. gonna try the 17.5 sedan class.
Cool, we need more.
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Old 10-14-2014, 06:28 PM   #717
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Quote:
Originally Posted by rcwck View Post
We had our first Carpet race of the new season last weekend. The H4(dark blue car) started second and finished 2nd. This was the 8 minute VTA Main. Good job Mike and it's very difficult to keep up with Erik.

https://www.youtube.com/watch?v=MHp2wajaDr4

This is the sedan 17.5 stock class. Turnout was a bit small because the weather is still nice here and there are still outdoor activities. H4(black monster car) on the pole and the win.

https://www.youtube.com/watch?v=f1xpYWRqI_o

Filmed with a GoPro extreme wide angle config.
Congrats RCWCK!! H4 FTW!!! I managed to get second in the B main at an IIC warm up trophy race last weekend in 17.5.

Quote:
Originally Posted by eR1c View Post
Way to go RCWCK, and way to go H4

-my diff is leaking like crazy again. I've had this problem in the past and usually cleaning everything, drying, and putting back together solves the issue. -until I have to open it up again.

It is a really finicky process, I've now done the process 2x and it still leaks. I've checked the o ring, it is in great shape. I even tried putting some green slime on it this time. Still leaked.

I am kind of sick of the rear diff leaking and how finicky the thing is ...I'd like to be able to open it dump the oil, wipe clean, replenish and go. I don't have time to go through this crazy process at the track!

Question, is there a recommended replacement rear diff that will work? One that obviously does not leak? Something from another company like XRay? Kind of done playing around w/ this diff'.

edit: I looked through the posts on this thread, I did not see an alternative diff that is recommended. Only the wipe clean and green slime fix.
thanks,
I use 500k diff lube to seal the o rings and my diff doesn't leak any more . Beware 500k its more like a grease and if you put to much on the drive o rings it will need time to "break in" sort to speak. It will cause your drive rotation to be stiff like your locking the rear diff but after a while it will loosen up. It will leak for a little bit but once the 500k sets say good bye to leakage. Next build I will try 100k I think 500k is overkill .
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Old 10-15-2014, 11:14 AM   #718
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Quote:
I use 500k diff lube to seal the o rings and my diff doesn't leak any more . Beware 500k its more like a grease and if you put to much on the drive o rings it will need time to "break in" sort to speak. It will cause your drive rotation to be stiff like your locking the rear diff but after a while it will loosen up. It will leak for a little bit but once the 500k sets say good bye to leakage. Next build I will try 100k I think 500k is overkill
Thanks, I thought about increasing the weight of the diff oil to stop the leaking, but the 1,000 seems to be working for me performance wise. I have some 10k maybe i'll try that since it shouldn't make much of a performance difference but is slightly thicker and may help w/ the leaky diff.

I notice that after taking apart (again) and re-cleaning everything that it wasn't leaking this morning. -So i may be okay for now.
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Old 10-15-2014, 03:55 PM   #719
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Quote:
Originally Posted by eR1c View Post
Thanks, I thought about increasing the weight of the diff oil to stop the leaking, but the 1,000 seems to be working for me performance wise. I have some 10k maybe i'll try that since it shouldn't make much of a performance difference but is slightly thicker and may help w/ the leaky diff.

I notice that after taking apart (again) and re-cleaning everything that it wasn't leaking this morning. -So i may be okay for now.
Note: I use 1000 to fill the diff and 500k is just for the O-rings seal.
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Old 10-17-2014, 12:26 PM   #720
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ah, yeah, 500k seemed really heavy/thick.

I took my diff apart, cleaned, blasted with air gun to be sure I got every drop of moisture and grease out. Filled w/ 7000k oil and put back together.

It's been 3 days and no leaking. I have rotated the diff every morning before work and still it is staying dry.

So far I am good, wondering if i just wasnt drying it enough before or if the heavier weight oil is helping. Regardless I am happy that I have no leaks.
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