I had a mcleod rxt street twin installed awhile back maybe a year and a half ago? I've only put about 1-2k miles on it since. (Sorry I have a terrible memory) Anyway, I've had electric cutouts the whole time and have had them open the whole time. I drove the car today, haven't in awhile, and decided to keep the cutouts closed for once and noticed a few things.

1. when I go from idle and start to step on the gas at about 1500 rps there is a metallic click sound, does it every time, but only from idle. Maybe its because the TT bushings need to be replaced?

2. If I have the car in neutral in the parking lot and rev it up to 3k rps there is no vibration or anything. With the car still in neutral if I push in the clutch it starts to vibrate and continues after I release the clutch and repress it. The only way to stop the vibrations after that is to put it in first let the clutch grab and then let off and put it back in neutral and the extra vibrations go away.

3. It seems like its quite a bit harder to shift then it used to be. Both downshifting and upshifting seem like I need to put a little muscle into it. I can't shift quickly at all, instead it takes about a second to shift into each gear, but there is no noise when I do it.

If you guys have any ideas I'd definitely appreciate it.

Thanks,
Brett

 

I would be giving your driveshaft couplers a serious look. Until you can confirm things, I would advise against any sort of "frisky" driving and try to keep the rpms as low as necessary to minimize the chances of any sort of co-lateral damage in case they really are coming apart.

You don't say, so I'm assuming you have the OE rubber couplers?

 

I do and I made a thread asking if I should go aftermarket when I replace them and just about everyone said to stay with the stockers, but they aren't made for 600+ hp are they?

 

bump

 

Well, yes and no,......kinda. I mean A4s tend to be less destructive on OE couplers then MM6s, by virtue of how the power is applied mainly. Some people swear by them and others swear at them. I've seen quite a few pix of OE units that have met their maker and also seen what happened to the inside of the torque tube as well. Not pretty.

In the end it's really more about their age, power application, i.e. A4 vs MM6, tires (sticky vs not so sticky) and driving style. Six-speed cars in the hands of more aggressive drivers with significant power increases can make the OEs go away quicker than autos generally as autos tend "roll into" the power due to the torque converter. The sudden shock loads are minimized with A4s.

Even though I don't typically thrash on mine very much, I really didn't want to have to be dealing/worrying with the OEs so I chose Prothane polys. If I hadn't used the Prothanes, I definitely would have gone with the DSS pieces. I picked Prothane due mainly to the design wherein the poly inserts are surrounded by the metal "cage" of the design so-to-speak, and if a bolt were to break or a bushing got spit out, at least the remaining bolts would keep things from coming apart completely resulting in the kind of collateral damage than can happen when a totally unrestrained driveshaft starts whipping around inside the torque tube. Plus, they are almost like a solid, but have just enough poly (in each individual bolt cavity) to help with NVH. When I first tried them I was unsure as to NVH issues, but have been satisfied with them now for about a year and a half.
Being poly, I also take measures to protect them from the heat of the exhaust directly under the torque tube, since high heat and polyurethane are not friends. Using an aftermarket 1/4" tunnel plate along with EE's Tunnel ABS heat insulator on the underside.

Get those checked asap, as well as anything else a good inspection up underneath may reveal.

HTH

 

Any idea why its hard to shift? TT wouldn't have anything to do with that would it?

 

Not the TT but the driveshaft. Given enough slop in the drivetrain, maybe. Not for certain though.

I would definitely find out what's going on in any event. Don't want to wind up stranded in traffic or on the side of the road, waiting for a roll-back wrecker.

 

Could you provide a link or tell me the best place online to buy the couplers? Should I get 2? How much hp are you pushing? I definitely don't want to have to replace these again anytime soon.

 

 

Google/Bing Prothane Six-Shooters and shop til your hearts content. There's LOTS of places selling them and prices vary all over the place as well. Take your time and shop around. I think you can expect to pay in the low (very low) $100s each, but some sources try to scalp you too so keep shopping. Thirty minutes taken to shop around can save you considerably, just watch out for "shipping" costs though.

You don't say what year model you have so be aware that there are 2 different couplers to chose from (regardless of who makes them). There's a 10mm version and a 12mm version and that strictly refers to the diameter of the fasteners they use, and of course the size of the bolt holes in each. Generally the earlier C5s use 10 and the later use 12.

The car has two couplers so I would get two. I'm "pushing" 520 rwhp.

The DSS pieces also have a good reputation as well, although they tend to run a bit more on pricing. They use a different design philosophy, but they are also polyurethane as well.

As I may have mentioned earlier, I would recommend installing some sort of heat protection/barrier under, or to, the tunnel plate. I have an aftermarket 1/4" thick aluminum plate and I used a Elite Engineering "Thermal Abs" heat shield as well. It keeps the heat off the couplers and provides an additional heat barrier for heat getting into the cabin. Killing 2 birds here. Even if you don't get the thicker plate, I still recommend something for heat suppression, so......

HTH

 

Sounds good. I made a (can't remember if it was .125 or .250) 7075 t6 tunnel plate and installed it a year ago or so instead of buying one haha. It's an 03 z06 so I believe it is the 12mm bolts. I put 600 to the wheels a year ago, was just wanting to make sure the couplers wouldn't have to be replaced again anytime soon. Well I appreciate your time. Thanks for helping me out, I'll order some tomorrow.

 

Nice going on the DIY tunnel plate.

Like I say, I think Elite Engineering's Thermal Abs stick-on heat shield is a pretty good value since it's also held in place by the tunnel bolts as well. It doesn't just rely on adhesive to stay in place.

There are other heat shield products out there for C5s, like the one made by Thermo-Tec. It looks like excellent quality (as are most of their products) but as it's thicker and covers a great deal more of the tunnel area, it's also more than twice the price of EE's product too.

Which ever product/vendor you go with, I really think it's worthwhile using something that does a decent job with the heat aspect. I have only seen one picture of a poly coupler that was badly deformed from exhaust heat, and that was enough.

rpmspeed.com is listing the couplers for $119.99. Don't know what their shipping charges are or if they are an "in-stock" item. I would prolly call them first. You would need the 7-1651s (12mm)

 

Update. the shop said the couplers look fine, but the slave cylinder is cracked as well as a bad pilot bearing. Would these cause the issues i described? Also what slave cylinder should i go with? Should i have then install the couplers or take then back to offset costs? If i could get the answers pretty quickly I'd be really grateful, shop is waiting in my reply and i don't hasn't time to research it right now.

 

A trashed pilot bearing can definitely cause vibration. It should always be replaced when doing a clutch job or slave cylinder replacement. Cheap insurance. If your input shaft wasn't damaged in the process, that's fortunate for you.

Since the couplers on hand, I would go ahead and install them. I'm not sure how old the OE rubber couplers are, but you are putting down significantly more power than stock. So, unless it's going to break the bank......... Also, address that exhaust heat matter at your first opportunity. Regardless of the particular company or vendor, I highly recommend using something.

I would use the GM slave assembly 89059282. It is the current version and works well.

HTH

Keep us posted on your progress.