shelbymustangdan

Hi guys! Looking for some suggestions.... (67 Mustang)

I have a Toploader 4 speed with a Hurst competition plus shifter. When I shift into reverse, the car "shutters" as I try to back up, but it only surfaces that are inclined. There are no problems when reversing on a level surface. (ie...no load)

The car shifts solid in all forward gears. No slipping, shutttering, etc. The transmission was inspected, cleaned, and reassembled some time ago. The rear end gears were replaced almost a year ago, to a 3:50 posi unit. The clutch is also relatively new. Everything has less than 500 miles on them so far.

The clutch seems to be adjusted properly. The Hurst shifter linkage was aligned with the 90 degree alignment tool, etc. Again, I don't appear to have any problems with 1st-4th gears.

Any ideas? What is causing the "shuttering" in reverse? Could it be something with the new posi unit in the rear??

Thanks!!
Dan

Stepman

How about bad shocks in the rear? When I got my car running and moved it around before I had the shocks in it, I had a bad wheel hop in reverse. It worked fine going forward.

2+2GT

Check your RH motor mount.

shelbymustangdan

Thanks 2+2

The RH mount was missing a bolt up into the engine. I replaced it and tightened up the others, but still had the same problem. The RH mount rubber does look a little odd, so I am going to purchase a couple of new mounts (RH & LH) ASAP, install them, and see if that solves the problem. Maybe the RH rubber is breaking loose under reverse torque. Hopefully that is the solution......

Starfury

Which motor do you have in that? If it's a 289, you're in for an interesting ride as you literally can't get replacement motor mounts. I'm sure 2+2GT will explain why in more detail shortly, but the ones the parts store lists as working for 66-70 won't work. There's a slight variation that puts them in the frame brackets at the wrong angle.

There are several solutions:
1) Redrill your frame brackets for the new mounts. 2+2GT has a template for this. I'm not a fan as it puts the new hole really, really close to the old hole. In theory it's not a problem, but I didn't want to take the chance.
2) Buy '68 frame brackets and then use the commonly available mounts. This i what I ended up doing.
3) Buy a set of the Ron Morris adjustable mounts. Pricey, but they're nice and will allow some adjustment in the motor's position, helping with header and T5 shifter clearance.

shelbymustangdan

Thanks for all the info!

I've got a 67 Mustang fastback with a 351W stroked out to 408. Edelbrock Performer RPM top end package (heads, intake, cam, carb).

I wasn't aware of the issue with replacement engine brackets. Thanks for bringing that to my attention! Yeah, I really like those Ron Morris mounts, but I'll have to consider the price difference. I just hope that whatever route I go, that it solves the problem. The last thing I want to do is spend the money on those Ron Morris mounts, and have the same problem.
As I'm writing this, and the first of "many" cups of coffee hit the brain cells, it just dawned on me to pull the RH motor mount from a 67 coupe I have with a 5.0l engine. (fuel injection conversion project) That would at least allow me to confirm that the RH mount is the problem, before going shoping.

Starfury

With a 408W, I'd really recommend the Ron Morris mounts. I run a 331 (which I drive pretty hard) and I'm running through stock motor mounts about every 10-15k miles. The stock mounts just don't hold up to high torque applications.

2+2GT

Yeah, the 67 289 (all) mount is the same as the 68-72 convertible mount, and every vendor extant either has it wrong, or thinks the 66/68- mount is interchangeable. They actually sit at about a 20° different angle, so they can't even be forced in.

With luck, there may be some news on this soon.

shelbymustangdan

Yes....it is probably time to go with the Ron Morris or TCP motor mounts. I'd hate to spend that kinda of money, but to prevent a motor mount failure in the future, it's probably money well spent. (insurance!) Also, I noticed that RM offers a kit that provides two sets of brackets, one for stock height and one for a 1/2 inch drop. I like the idea of the drop, since it has been a BEAR trying to find an air filter to fit under the stock hood with the Edelbrock RPM intake. It wasn't a problem with the old Torker II intake, but the RPM intake is just a bit taller. ( I know...running off topic!)

Back to the mounts: I plan to order them on Tuesday and hope to receive them within a week. (unless CJs has them in stock) I'll update the post to let everyone know what the resulst were, and if it solved the "shuttering" problem.

valley firearms