Topic: Detroit Speed Front Sub Frame / Soild Body Mounts / Weld in Sub Frame Connectors

[OD_Simple]

Hi guys,

I own a 1976 Trans Am.  32,000 original miles.  400 4-Speed Car.  I am the second owner.

In 2008 I had a ladder bar set-up installed, mini tubs, and an 8 point weld in cage installed.

I've recently ordered Detroit Speed's Powder Coated Single Adjustable Shock Front Subframe (SBC/LS).  I've also ordered their Weld in sub frame connectors.

Unfortunately, Detroit Speed does not sell solid body mounts for 2nd Gen Firebirds...only for Camaros...

So, with that I'm put between a rock and a hard place.  Weld in sub frame connectors require solid body mounts and now my builder and I have to figure out what solid body mounts to purchase.  Detroit Speed said that the core support body mounts are the solid body mounts that cause the difference between the two cars.  Has anyone experienced this by any chance?

Knowing this...I'd like to hear the opinions of others that have made the switch.  Just how drastic of a change was it?  How much louder etc.


Thank you,
Andrew

[NOT A TA]

I would use a set of PTFB solid mounts. They're not as "pretty" as the DSE's and some other brands but I like them because the steel sleeve makes them stronger in the event of a bad accident. They're unfinished aluminum but you can paint to suit. http://www.pro-touringf-body.com/chassis_components.html

[OD_Simple]

Thank you!

$99 is a great deal.  Ordered them a moment ago.

Pro-Touring's website stated that they can be 'adjusted'/reverse the sleeve in order to lower the car approx. one inch.  Have you adjusted them to lower your car?  I don't believe I'm going to go that route due to the geometry and engineering D.S.E. put in to develop their unit.  I wouldn't want to over complicate final adjustments/ride height/wheel clearance etc.

I did stumble upon another thread on this website from 2012-2013 where many members went in to a lengthy discussion about solid/poly/rubber body mounts and suspension in general. 

It was a very informative and articulate thread indeed.

I'm curious if this thread will pick up steam.  I'm curious if those same members went through with their plans to install 'said' material of body mount and if their respective opinion(s) have changed???

One thing I didn't see pointed out in the previous thread was that poly body mounts typically have a very short lifetime, even when properly greased.  From my personal experience from talking to heavy tracked cars in general...the lifetime is typically less than 20,000 miles.

I'm going solid regardless but that thread being from 2012...I wonder if any birds with poly mounts could chime in.




Thank you again,
Andrew

[NOT A TA]

I ran poly body mounts back in the day on my own car (I build cars for others also). I believe they were Energy suspension and they didn't hold up and sheared/deformed. About 20 road track days but less than 20,000 miles. Yes, they were properly lubed, torqued to spec, checked regularly for torque, etc. and were used in conjunction with bolt in frame connectors. I believe the problem is that the durometer of the poly is too stiff and not elastic enough to rebound like rubber but not hard enough to prevent movement of the sub frame in relation to the body. My car was tracked on road courses as well as 1 mile Land Speed races and drag strips while also being street driven. 

The PTFB mounts can be run full height or used to wedge the body however when you do that it can cause other issues that may need to be addressed. I say MAY because every car is different and not all issues affect all cars. I've installed them several ways on various cars.
As examples:
The engine to hood clearance is reduced which can become an issue with aftermarket intake systems on the older engines with shaker scoops and induction systems on the LS swap cars.
When stock radiator & fan shroud is used on stock engines the fan may hit the shroud.
Trans clearance in tunnel is reduced on the top of the trans so if a larger OD trans is used tunnel modifications may be necessary.
Inner fender clearance to sub frame changes and inner fenders may need to be modified. (see pic below)
Drive line angle changes and may require adjustments to get drive shaft angle correct so U joints operate smoothly.
Depending on suspension, tire sizes, wheel dimensions, and use of the car, tire clearance might be an issue.


I'm sticking with coil/leaf spring set up on my car which is my choice for a bunch of reasons not related to money. I'm using PTFB solid mounts at full height and then tuning the ride height for performance, not looks.

This thread may not "pick up steam" because this forum isn't as active as it was previously. So it won't get as many views (or responses) as it would have back when the other thread you read was active.

Deformed Poly bushings in top pic. Bottom pic shows where inner fender was rubbing on sub frame of customer car with 1/2 height bushings. The rubbing/vibration noise was transferred through the sub frame which effectively becomes a sounding board making the noise louder. In this case the mounts were switched to full height rather than modify the mostly original 70 TA parts because the owner isn't making changes that can't easily be reversed. So although I replaced everything from the floor pans down (suspension etc.) on the car he didn't want me to start modifying original inner fenders etc..

[NOT A TA]

This is my car at Sebring.

[OD_Simple]

Beautiful car.  I adore the 1970-1973...but who doesn't.  I'm very jealous.  I was even considering hunting down OEM '70 - '73 'bird front end parts but opted not to.

Thank you for the informative response!

Random question(s) for you since I have your attention:

I want to replace the front bumper of my car.  The enduro material is cracking.  I've located an OEM '76 front bumper in Arizona for $450 I believe (plus shipping to my state of NY).  My question is:  Have you any experience with Year One and Classic Industry's bumper replicas for our cars?  How good of a fit are they?  They would cost a bit less than the OEM stuff but I'm concerned the fit wont be as 'good'.

Also, have you any experience with replica core supports (radiator housing) from Year One or Classic Industry?  Same situation as before.  I've located an OEM one that is rather perfect but more expensive than the re-manufactured core supports and I'm worried it may not be as good a fit as I'd like.




Thank you again!

[Wallington]

Unfortunately, Detroit Speed does not sell solid body mounts for 2nd Gen Firebirds...only for Camaros...

I'll ask the dumb question.....what's the difference with Camaro body mounts? Or is it strictly due to the radiator support area?

[OD_Simple]

From what I remember from my conversation with a tech rep from Detroit Speed (just the other day actually); the only difference in the body mounts they sell for 2nd Gen F-Bodies is that the two front body mounts (the core support body mounts) are slightly taller for the Firebird vs. the 'Maro.

He mentioned that it's due to height clearance of required of the Core support.

Just to clarify...this is specific to the Detroit Speed body mounts that they make; not every body mount reproduction (in other words I believe the mounts from Pro-Touring F-Body fit both 'Maro and T/A although I could be wrong).  I also want to point out to anyone reading this opting for a D.S.E. front sub frame...that every measurement is completely identical of their product vs. the stock sub frame.  The difference / discrepancy strictly results from those front two body mounts that D.S.E. is producing.  There is a disclaimer of this on their website too when you look at the body mounts.

Tech rep said they are in the process of developing a set of solid body mounts for 2nd Gen Firebirds as we speak because people have called with the same question.  D.S.E. pointed me in the direction of pro-touring's mounts as well.  Should be good to go.

[Wallington]

Yes, that's the only area I could think of that may have been different, or specific. Wouldn't have thought it too hard to have an extra 2 bushes and cater for a whole extra car type. Seems to be marketing with one eye closed.

[NOT A TA]

Yes the 2nd gen Camaro top mount core supports used a thinner bushing similar to the Nova bushing.

The bumper on your car is Urethane, not Endura. The 70-73 birds used the Endura but then the Urethane covers took over and are better overall because they're lighter, hold up better, are easier to repair, paint didn't crack as easily, etc.

I don't have any experience with the repro covers for your car. An original bumper will probably be kinda dry since it's 40 years old and probably deformed a bit over the years but they can be "worked" with a heat gun and reformed before bodywork/paint.

I searched for years to get a good core support for my own car before they started reproducing them for early 2nd gen birds. I would get the OEM one if the price difference isn't too much. I haven't installed a repro later style one but haven't heard any complaints either. I do believe there were minor changes for certain years so if originality is a concern I'd go with the original.

Aus78, I thought the same thing about the DSE mounts and why not just throw the other bushings in but because of the way the DSE mounts are machined compared to the PTFB ones it's a more expensive process and probably requires a different set up on a CNC just to make those bushings. I've installed the DSE bushings and they've got a really nice finish on the aluminum and very nice washers. It's almost a shame no one ever really sees them once the car is finished.

[OD_Simple]

Thank you for the follow up on those questions:

Now another.  You mentioned you've installed the D.S.E. solid body mounts before (I'm assuming you mean on 2nd Gen Birds).  Did you have to do any alteration to where they mount on the sub frame?

I'm just curious because the D.S.E. tech rep said he used them on his Trans Am but installed them several years ago and had forgotten what modifications he had to do (if it was the sub frame itself or the core support).  You'd think with how established D.S.E. is that they would have these answers readily available.  I've talked to them at SEMA, the Detroit Speed show and over the phone 3 or 4 times already this past week.  Great bunch of guys, super nice and knowledgeable.  I'm just surprised I guess they don't have the solution for this issue.

And I completely agree D.S.E.'s body mount looks amazing.  You can tell from the photos alone that they are second to none.

[NOT A TA]

I've only installed DSE's in 1st gen Camaros.

Many early 2nd gen birds with bottom mount core supports require some modification to the core support to open up the mounting holes the bushing passes through because most of the bushing kits (like the PTFB's) were designed to fit the later cars that were produced in much greater numbers. Even though a lot of companies list their solid mounts for 70-81 the originals were not all the same. So if the person you spoke with had an early 2nd gen bird they may be recalling the mods needed to fit the bushing through the core support rather than something related to the height of the bushing. I've seen many cases where the wrong stacking of bushings and/or wrong heights of bushings were used and then the body panels, core support, etc. were adjusted so that looking at the car you'd never know.

It's been a year or two since I last installed bushings (rubber) in a later 2nd gen Camaro (a 76) but IIRC the core support bushings were smaller in diameter where they pass through the core support. If that was the case and all the later Camaros had a smaller diameter hole in the core support then the DSE bushings might also be smaller and not fit snug in a bird core support on top of also being a different height.

You should not have to modify the sub frame for any of the replacement bushing kits, whether rubber, poly, or solid. The differences  in the 2nd gen bird and Camaro applications that require various stacking and possible core support modification are only due to the hole diameter in the core support, height of bushing between frame and core support, and whether the core support is top or bottom mount. Although there were changes in sub frame design over the 2nd gen run the sub frames used for birds and Camaros were the same during various years other than the engine mounting holes (as far as I know) even though the bird might have used a bottom mount and the Camaro may have used a top mount during the same year.

Part of the difficulty for companies making 2nd gen products is that they're trying to fit both birds and Camaros over an 11 year period so there's at least 22 possible vehicles and they don't have access to every year of both to measure, test fit, etc. So in some cases a part designed based on one or a few cars may not work well on other years or models. I believe this may have been what happened with the DSE mounts. I try to be very careful about this with the parts I design for Lab-14 and have early and late frames I use for mock up etc.

[OD_Simple]

Damn,

About 2 months ago I bought OEM 1977-1978 Inner Fender Extension Panels...they call them "splash guards".

I just clicked on your website and looked around.  I see you're selling them as well!  Only, not for a 1976.

The ones I bought are OEM 1977 style and are in near mint condition.  What modifications will I need to have done in order to have them fit my 1976?  Please tell me its possible.  They car will never see any rain at all ever again so they don't have to be a perfect fit.

I just want/hope the holes match up.

[OD_Simple]

Also,

Would your "70-81 2nd gen F body Sub Frame Body Mount Reinforcements for Cowl Mounts" work with my Detroit Speed Front Sub frame?

It may be overkill with it being powdercoated along with the solid body mounts but since I'm "under" there I wanted to ask.


Thank you,
Andrew

[NOT A TA]

I hesitate to call the inner fender extensions "splash guards" because there's rubber inner fender "splash guards" used on some of the 2nd gen Firebirds that are stapled to the inner fender where the upper A arm opening is.

 I started making the 77-78 and 79-81 versions when I got requests for them because they weren't being reproduced and 77-81 owners were told to use the 70-76 reproductions and modify as necessary to try and make them fit. They do look different so those doing correct "restoration" type builds wanted a better fitting correct looking piece. The  bead rolling in the center of the 77-78 conforms to a bead rolled in the other parts like the inner fender. I think Aus78Formula has some good pics of how they fit together. The stamping for the U nuts is angled differently and centered differently on the mounting holes. A lot of people think the stamps were just poorly done because the stamps are offset different ways on the bolt holes but they are like that for a reason. The area that bolts to the core support is different also as you can see in the pic below.

Dunno how much you paid for the 77-78 style ones you have but you can probably flip them and have enough money to buy a set of more original looking 70-76 repros.

While they're often referred to and thought of as splash guards they're also important to aerodynamics and help maintain a pressure difference between the front and back sides of the radiator. Not having the inner fender extensions can increase the air pressure in the engine compartment making it more difficult for the radiator and fan to cool the engine coolant and noticeably reduce AC performance.

I can (and have) made 70-76 inner fender extensions but I can't make them as cheap as suppliers can have them stamped out over in China. I'm a small batch operation using higher quality steel in the original 18 gauge and making them by hand where they can use a punch press and cheaper possibly thinner steel. I make the 77-81 versions more as a favor to the Firebird community, I loose money on every one I sell because of the time involved in making them even though I sell them for more than the 70-76 repros sell for. So I don't promote them and if one of the "big guys" starts having them reproduced overseas it won't hurt my feelings a bit.

Pic below is of 70-76 style and a 77-78 style. I also made the 70-76 in the pic.

I'm not sure what gauge steel DSE uses in the cowl mounts but I'd suspect they may have beefed them up over stock specs. So my reinforcements might be overkill, I'd be interested to know what gauge they're using.  You should however consider a set of PTFB Pro G braces and a set of my upper cowl supports to go with them based on the Pro Touring style build I've seen you talk about on other forums.

I saw your builder question on another forum also. I work on upgrade projects and build cars for people. Mostly for locals and occasionally someone ships a car down. I'm cheap comparatively so the shipping cost is often covered by the price difference plus those who dealt with me when I lived up North have peace of mind I'm not going to screw them over. Like some of the others I only do jobs by the hour, it's just too hard to "guess" an estimate because every car is different and usually some things get changed along the way by the owner anyway. I work mostly alone and for some types of jobs have other experienced old guys like me help to make the job go quicker. I have an old body guy help with large body/paint jobs and an old ASE master tech help on some of the more extensive mechanical stuff. I like to get cars in, get them done, and get them out. I don't understand why soo many shops keep cars like they're hostages (although I worked in shops that did that). Below is a pic of a 70 TA that got shipped down from GA recently by someone I dealt with before when we both lived in CT. It was here for sub frame repair, complete replacement of all steering and suspension components, solid body mounts, and bolt in sub frame connectors. Was here about two weeks.

I'm not trying to sell you on shipping your car down, can't take it now anyway. Just figured I'd babble during my break and maybe someone local will read this and perhaps inquire about work in the future. I'm doing trunk pan, drop offs, frame rails, torque boxes and fabricating some floor pan sections on a 67 Camaro RS SS conv. this week soo as soon as I post pics, back to the shop I go!>>>