Nitro savage center diff and general race upgrades

[Samrsnow]

I have gotten the green light with local race club groups in my area to run nitro MT in the truggy class and I’m going all in this race season.

I have a few questions here:

I am out of the loop on compatibility of transmission parts. I see @rc4me.US offers the drop in center diff modded flux trans but I have scoured the internet and this forum for anyone with any info worth anything on the matter. I understand some have done it and just lose front brakes which is fine but there is NO build info anywhere. My truck started as a Savage 25 for reference.

Suspension wise I know the RSC is discontinued and is non existent on eBay or anywhere else I’ve seen. I see many companies offer rear aluminum hubs that are adjustable so that’s a plus. On the front end I could do adjustable upper arms, sway bar kit, and the rubber bump stops for the big bore shocks along with the small top springs.

I just got NOS HPI MIP CVDs off eBay and I already have shaved steering knuckles so I don’t think I’ll necessarily need aluminum upgraded ones unless the ones I’ve seen offer better steering angle.

 

[Richards1008]

I just finished mine and took second to Jared Wiggins in an MT410.

AFAIK I am the only one to do this.

It's a flux center diff, RC8 bulkhead and brakes bolted to my Fastlane machine servo plate. Hardest part was maintaining the alignment of the lower shaft bearings since the RC8 Bulkhead holds the front one.

Custom brake linkage obviously. Gave me zero issues all weekend aside from trying to keep 2nd gear in it.

This did everything I wanted, truck steers so much better and was honestly hooked up all weekend.

 

[Samrsnow]

WOW! That is impressive. I know Wiggins is a good driver too, seen him racing the TNR Challenge last week. Are those FLM tvps? Did the flux diff not fit the case originally? I see you cut it out and sealed it back.

This is what I’m working with. I will have to go to X/XL arms and bulkheads in order to get the sway bars to work. I’m guessing the transmission cases are essentially the same minus the quick access that the flux models have? Then theoretically I could use rc4me’s center diff trans he sells? https://rc4me.us/product/hpig89017/
My mid tank plate is CF so I’d have to go back to the FLM one and do that you did there to have good brakes I suppose.

 

[Richards1008]

I don't see why you couldn't use the CF plate as long as it's decently thick. Not much area there before the first cross brace so I would imagine the top being bolted to the plate and the bottom being bolted to the brace I put in below the bulkhead would hold just fine.

Yes, FLM TVPs in the Extended X Length. So it's shorter than an XL, but longer than an X.

Yes, flux diff doesn't fit inside the lower part of the case, I wonder if that guy sells just the case and if the 2speed fits in it? It would save a bit of hassle as the bulkhead would just hold the brakes and not have to be aligned to the trans.

 

[Ben_ger84]

Hi guys, thanks for sharing the pics.
I'm also interested, to prepare one of my Savages for the (carpet) track.
Which things are important to change?
Which suspension do you use for the racetrack. I'm sure, the CG must become much lower...
Minipin-tires like you use, would also work on a outdoor carpet track, I'm sure.

Would you share some "how to prepare for racetrack"- tipps with me (us) please? Perhaps in an seperate thread.

Would be glad.

Ben

 

[Richards1008]

Hi Ben,

Some things I found racing my savage over the years...


Modify the front hubs for longer steering throw, the steering angle is limited by the steering C hubs and knuckles, and you can gain a significant amount of steering by modifying them so they travel further.

A center diff is almost a necessity. Even on Carpet I think a center diff would be good to keep the diff's alive and to allow you to tune the bias front/rear when driving into and out of the corner. I ended up on 60F/100C/40R oils on low traction, so you'd probably want to nearly double that to start on carpet.

Sway bars are a necessity, even on low grip the truck was nearly getting out of it's working range of the suspension geometry when in corners (see my pics above). I ran soft rear, hard front from the HPI kit, but wish I had much bigger bars, especially when the grip is higher.

Ride heights and droop should be tuned a bit, this will help immensely on carpet. I might start with 5mm downtravel limiters in the shocks and see how the truck works. Again, for the reasons above, roll centers not being adjustable makes things difficult, so you';ll need to rely on droop, ride height (to an extent, don't want to get the suspension out of the working range), and sway bars to control chassis roll.

Lower CG is good, but not everything, pretty soon they'll just turn into a truggy. Embrace the big dumb rolly polly.

I would recommend the solid rear hubs, stock config is dumb and you can save some unsprung weight and get more strength out of the alluminum standard hubs. Space them forward for more rear traction and better cornering.

Good quality shocks are hard to come by, but the HPI alluminum big bores are the best I've tried. Most of the cheap big bores have 5mm shafts and don't have the bladder volume or proper bladders at all to compensate for the volume that the shaft takes up when compressed. Don't waste your time.

I've settled on something between the XL and X length and X width. I would like to go slightly shorter so I can have more rear wheelbase adjustment but FLM is currently out of stock on the X TVPS. My current ones are FLM, longer than X but shorter than XL and the rear driveshaft is a problem. Ended up finding out the Kyosho rear center shaft from the old truck KYOISW052 is a good fit. (I wanted center unis/CV's as I hate dogbones).

Speaking of dogbones. Get rid of them and get a CV setup. They provide more support to the suspension when on power, and I think it was the only thing keeping the truck in the working range of the suspension when in corners on power.

I think that's about it ;-)

Also, if nitro, 2 speed gears will be a problem with decent power (I ran the standard version [black head] Alpha .28) and had to take 3 of them to the dentist in one weekend. I found the stock gears or alluminum gears to be the most durable.

 

[Ben_ger84]

Hello Richard,
thank you very much for your detailed reply!
The grip on the carpet is high till very high and we have a fullspeed corner and also tight corners in the infield. So the shockoils will have to be thicker I think and the sway bars also. Actually everything is stock, only withouth the engine. Its an LRPZR.32 installed.
Some others at the track with nitro buggys also cut the front inner pins on their tires! Otherwise the car is turning over in the fast corner. I've tried it ( just for fun), with my stock LRP S8 nitro truggy
I got great pictures by the photographer, but precise and fast is something different.

Ben

 

[Samrsnow]

Rich, how is that Alpha? I saw it online recently but not much info on them. I know the buggy engines are supposed to be good and that’s what Lutz and several other pros use.

I’m trying to get my STS D28M back running but the company has been out of business for so long now you can’t find any parts especially a one way bearing which seems to be a proprietary design. Only thing I’ve seen close if the Ofna Hyper 21 turbo fan one way bearing.

I truly appreciate your insight on this topic. I am curious what rear hubs you are running?

 

[Richards1008]

I bought the .28 roto start variant since starting solutions that aren't pullstart are a PITA on this truck. (In fairness, so is a pullstart)

It's okay, makes plenty of good useable power running 28% JTP fuel here in the states. I was surprised to see that it didn't hold a ton of pinch through break in and one race weekend though. I did have it apart to set squish clearance for the 28% and the quality is ok. Not bad or budget per se, but a far cry from a race motor. Quality is decent and I would say it's good value if it holds up. Never gave me issues and I didn't touch needles all weekend after getting it tuned in to the conditions on friday night. I installed an 8.5mm reducer in the carb which probably helped the tuneability.

I'm interested in trying the "hot" Alpha... the one with the orange head, But unfortunately I think the crankshaft has different port timing and a narrower duration. My thought was to buy the race motor and the parts to make it a rotostart, but that crankpin is an issue. I may buy it anyway, do a timing chart and see if I can port the budget .28 to match the pro version. I'd expect quality to be the same.

This one hated the rear exit exhaust I put on it, basically no back pressure. I assume that may be part of why the pinch went away. Once I put the polished HPI tuned pipe on it the top end came in and it was making better power. I raced with that pipe for the rest of the weekend.

 

[Ben_ger84]

Rich, how is that Alpha? I saw it online recently but not much info on them. I know the buggy engines are supposed to be good and that’s what Lutz and several other pros use.

I’m trying to get my STS D28M back running but the company has been out of business for so long now you can’t find any parts especially a one way bearing which seems to be a proprietary design. Only thing I’ve seen close if the Ofna Hyper 21 turbo fan one way bearing.

I truly appreciate your insight on this topic. I am curious what rear hubs you are running?

Thanks for your warm welcome here ; )

What you mean with "Alpha"? The engine brand?
Its just an standard LRP S8 TX and installed is also an LRP ZR32. Like in my Savages.
It was with the preinstalled pullstart, but changed the backplate and mounted the rotostart- plate on the engine. Its a little bit "shame" to use an pullstart at the track . And the rotostart is still more practial in my opinion. The rearhubs of the LRP TX are also original. Nothing changed.

It was the first try with the TX on the track and the suspension have been much to soft and the engine was not runned in completely. Stabilizers in front and the end wasnt also installed.
I did it after first track test last year.

Of cause, its not a car/ engine, to set the next track record! But its fun and rare to see the S8 on a racetrack.

 

[Ben_ger84]

I bought the .28 roto start variant since starting solutions that aren't pullstart are a PITA on this truck. (In fairness, so is a pullstart)

It's okay, makes plenty of good useable power running 28% JTP fuel here in the states. I was surprised to see that it didn't hold a ton of pinch through break in and one race weekend though. I did have it apart to set squish clearance for the 28% and the quality is ok. Not bad or budget per se, but a far cry from a race motor. Quality is decent and I would say it's good value if it holds up. Never gave me issues and I didn't touch needles all weekend after getting it tuned in to the conditions on friday night. I installed an 8.5mm reducer in the carb which probably helped the tuneability.

I'm interested in trying the "hot" Alpha... the one with the orange head, But unfortunately I think the crankshaft has different port timing and a narrower duration. My thought was to buy the race motor and the parts to make it a rotostart, but that crankpin is an issue. I may buy it anyway, do a timing chart and see if I can port the budget .28 to match the pro version. I'd expect quality to be the same.

This one hated the rear exit exhaust I put on it, basically no back pressure. I assume that may be part of why the pinch went away. Once I put the polished HPI tuned pipe on it the top end came in and it was making better power. I raced with that pipe for the rest of the weekend.

Hi,
yes of cause, you are right. We are not talking about an offroad high-end motor for sure.
But as I answered before, the hole LRP S8 truggy is for me only a "just for fun" car.
28% nitro is very much to me in germany, and I think not possible to get it legal in the EU.
The standard for onroad competitions (where I come from) was 20%, since some years only 15%nitro are allowed to sell / buy and use in competitions in the EU.

I cant tell you experiences in Alpha engines, in my Asso RB8 I installed an "OS Speed tessmann 110%", some weeks ago. Used by a friend but not tested until now.

Ben

 

[Ben_ger84]

General question to you Richard and Sam,
you are booth from the US right?

Whats your availability of spare - and tuning parts in the US?
Because here in the EU/ germany, you really get problems to find an online shop, who can deliver searched parts. Small things, break disc's, springs, muffler ... for example.

Are in the US more parts still available in usual stores and online shops?


Thanks.

 

[Samrsnow]

General question to you Richard and Sam,
you are booth from the US right?

Whats your availability of spare - and tuning parts in the US?
Because here in the EU/ germany, you really get problems to find an online shop, who can deliver searched parts. Small things, break disc's, springs, muffler ... for example.

Are in the US more parts still available in usual stores and online shops?


Thanks.

In my experience HPI is not supported by hobby shops as much as the likes of Traxxas and Arrma. There’s places like Amain hobbies and maybe a few other online retailers that have some kits and parts.

Honestly after they were sued by Traxxas over some bs as you may know they had to change hands and lots of kits and upgrades were discontinued. The best place I’ve seen for parts is Amain for new or eBay with new chop shopped kits from Jennysrc.

 

[Samrsnow]

Resealed the engine, new air filter, installed servo (PITA), and installed a Dynamite 053 with custom hanger. Much help from the cats lol.

 

[guinnessdublin]

General question to you Richard and Sam,
you are booth from the US right?

Whats your availability of spare - and tuning parts in the US?
Because here in the EU/ germany, you really get problems to find an online shop, who can deliver searched parts. Small things, break disc's, springs, muffler ... for example.

Are in the US more parts still available in usual stores and online shops?


Thanks.

https://wheelspinmodels.co.uk/s/?q=hpi+savage+

 

[Samrsnow]

@Richards1008 the rotostart on the STS ate itself this weekend and I have till Saturday to have a viable engine for my race. I ordered the pullstart Alpha like you have, how long did take to break in if I may ask? Gonna be burning some midnight oil in my shed come Wednesday looks like LOL.

 

[Samrsnow]

Got my order from rc4me and wasted no time. Flux transmission with center diff ready to go. Diff oils are what Rich was running, 60F,100c,40r. 1972 C10 body on deck, already put liquid mask, need to stencil out the design. Engine should be here Wednesday if not Thursday now. Waiting on FullForce for a HD brake hub, the original was shot. Racing the clock now!!!

 

[guinnessdublin]

Fingers crossed my savage friend, looking good so far!

 

[Samrsnow]

Progress:

Sway bars
front CVDs
Engine

Waiting on:
Brake hub
Shock sleeves
The will to paint
The rain to hold out for this race…not looking good apparently.

 

[Samrsnow]

Well as I thought, race rained out and rescheduled for 4/5 - 4/6. Give me time to work out the kinks.

Got my order from FullForce RC, these shock sleeves look awesome. Aluminum brake hub fits like a glove

Heat cycled through 2 tanks idling of 4 so far for the Adam Drake break in, might get a good portion finished tomorrow.

 

[Samrsnow]

@Richards1008 do you have any more info on the brake setup? I see what you’re doing there for the most part, not sure what’s totally custom and what’s not there. Especially curious about the linkage.

 

[Samrsnow]

Paint done

 

[guinnessdublin]

Love the rear mud guards, are they made/modded by you?

 

[Samrsnow]

Love the rear mud guards, are they made/modded by you?

Yeah I took clippings from the body and painted them.

 

[Samrsnow]

I was doing some yard ripping yesterday afternoon and heard some loud crunching when letting off the throttle. This flux transmission has almost all metal shielded bearings in it which have only had about 3 quarts of run time on them now. Only did one practice tank at my local track not even tuned up yet. All but maybe two of the larger bearings and the input shaft ones were blown up or had excessive play in them. Luckily I bought a bearing kit from Full Force RC that had the right bearings and swapped everything out yesterday night, buttery smooth now.

First race of the season is this weekend at Saratoga RC in Magee Mississippi.

 

[guinnessdublin]

Yikes that’s not great I would ping HPI an email saying what has happened they come with 2 year warranty!